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MSc thesis by Jacob Meijer SDPO.15.002.m
Faculty of Mechanical Engineering and Marine Technology Ship Design, Production & Operation
Production of composite ship hulls
Developing cost price estimations for composite ship hulls
Thesis for the degree of MSc in Marine Technology in the specialization of production
Production of composite ship hulls Developing cost price estimations for composite ship hulls
By
Jacob Meijer
Performed at
Defensie Materiaal Organisatie
This thesis SDPO.15.002.m is classified as confidential in accordance with the general conditions for projects performed by
the TUDelft.
29-01-20115
Company supervisor
Responsible supervisor: P. Everts
E-mail: [email protected]
Thesis exam committee
Chair/Responsible Professor: Prof. Ir. J.J. Hopman
Staff Member: Dr. Ir. J.M.G. Coenen
Staff Member: X. Jiang
Company Member: Ir. P. Everts
Author Details
Studynumber: 1508288
Author contact e-mail: [email protected]
Preface This report is the result of a study where I developed a model for cost prices estimations of composite
ship hulls. This report is my MSc thesis and is the final part of my study Marine Technology with
specialization in production.
The study is performed at the Defensie Materieel Organisatie (DMO). The DMO takes care of all the
material for the Royal Netherlands Army. I would really thank DMO for the oppurtunity to graduate
there. The topic is very interesting and I learned a lot about how the Royal Netherlands Army works.
I would like to thank P. Everts, head of the life cycle management deparment for his daily supervision
during the research. I would also like to thank H. post of DMO for answering my question about cost
price estimation for minecounter measure vessels. I also want to thank J.M.G. Coenen of the TU Delft for
the supervision. I would like to thank W. Leenders of Airborne and L. Morel of Damen Navel Shipbuilding
for their help during the development of the model. I also want to thank my fiance, Rinske, for her
support during my graduation
Jacob Meijer
Den Haag, January 2015
Production of composite ship hulls 1 Summary
Summary This report describes the study of the production of composite ship hulls. The graduation project is about
the structural composite work for the hulls. It does not include the whole building process including all
the work for the installation of the equipment which is partially composite building. The first part of the
study is the investigation of possible production methods for composite ship hulls and the description of
the production of the Alkmaar class vessels of the Royal Netherlands Navy. This production method is
used to develop a model to estimate the cost price for composite ship hulls in the second part of this
report.
Different production methods can be used for the production of maritime structures. Hand lay-up is used
for the production of the Alkmaar class vessels. However, this technique is quite old. Due to emissions of
styrene, this method is prohibited today. Examples of production techniques are vacuum injection, resin
transfer method. Different structures types can be used for the production of composite hulls. These
structure types are: monocoque structure, sandwich structure and single skin stiffened structure. Several
materials can be used for the construction of the vessels. Most used materials are glass fibres, carbon
fibres, polyester resin, and vinyl ester resin. Materials for the core of sandwich panels are balsawood and
foams.
The aim of the model is to be able to make estimates for the production for monohull vessels. These
estimates can be made in early design stages but also in later stages in more detail. The size and the
form of the hull should not matter for the estimates. The calculations necessary to come from a hull to
production parameters for that hull are independent of the calculations for the production process itself.
As a result the hull form can be changed easily in the model
The production process is used to determine the necessary steps in the production of these vessels. The
process order is determined and every step in the production of the vessels is described. Lots of different
processes has to be done. Production rates for each type of work were established to be able to estimate
the time necessary for each step in the process. However, the most time consuming are the lay-up of the
fibre, the lamination of the fibres, the placing and positioning of the decks, bulkheads and the scouring
of the materials. The developed model uses three parts to calculate the cost price for the production of
composite vessels. The three parts are the man-hour cost, the material cost and the investments or the
non man-hour related cost. Only the cost directly related to the production of the vessel are used for the
calculation. The cost for the production of the Alkmaar class vessels produced nowadays with the
production technique used in the 1980s depends on the number of ship. For one ship is the price
€123/kg and the cost price for fifteen ships is €81,80.
The model can be used to determine improvements in the production of composite ship hulls. The model
gives insight in the process necessary for the production but is made in such a way that change in the
production can be evaluated easily. Future use of the model could be the evaluation of the whole
process and calculation the effect of applying for different techniques to lower the cost price for
composite ship hulls.
Production of composite ship hulls 2 Content
Content
Preface ........................................................................................................................................................... 3
Summary ....................................................................................................................................................... 1
Content .......................................................................................................................................................... 2
List of figures ................................................................................................................................................. 6
List of tables .................................................................................................................................................. 7
Abbreviations ................................................................................................................................................ 9
1. Introduction .........................................................................................................................................10
1.1 Background .................................................................................................................................. 10
1.2 Problem ....................................................................................................................................... 11
1.3 Research question and sub questions ......................................................................................... 12
1.4 Structure thesis ........................................................................................................................... 12
2. Production of composite ship hulls .....................................................................................................14
2.1 Materials ...................................................................................................................................... 14
2.1.1 Resin .................................................................................................................................... 14
2.1.2 Reinforcement ..................................................................................................................... 16
2.1.3 Core materials for sandwich ................................................................................................ 17
2.2 Joints ............................................................................................................................................ 18
2.2.1 Adhesive bonding ................................................................................................................ 18
2.2.2 Secondary bonding .............................................................................................................. 18
2.2.3 Butt joints ............................................................................................................................ 19
2.3 Production methods .................................................................................................................... 19
2.3.1 Contact moulding ................................................................................................................ 21
2.3.2 Closed moulding .................................................................................................................. 23
2.4 Structure design ‘philosophy’ ...................................................................................................... 24
2.4.1 Framed single skin structure ‘philosophy’ ........................................................................... 24
2.4.2 Monocoque ......................................................................................................................... 25
2.4.3 Sandwich structure .............................................................................................................. 25
2.4.4 Corrugated hull .................................................................................................................... 25
2.4.5 Possible construction methods ........................................................................................... 26
3. Why a production model? ...................................................................................................................27
Production of composite ship hulls 3 Content
3.1 Cost aspects ................................................................................................................................. 27
3.2 Model aspects ............................................................................................................................. 27
3.3 Production aspects ...................................................................................................................... 27
4. Requirements model ...........................................................................................................................28
4.1 Model type .................................................................................................................................. 28
4.1.1 Production cost estimation ................................................................................................. 28
4.1.2 Cost price estimation ........................................................................................................... 28
4.1.3 Production process oriented ............................................................................................... 28
4.1.4 Accuracy .............................................................................................................................. 29
4.2 Requirements regarding hull to be estimated ............................................................................ 29
4.2.1 Hull type and dimensions .................................................................................................... 29
4.2.2 ‘Structure philosophies’....................................................................................................... 29
4.3 Use during a project .................................................................................................................... 29
4.3.1 Applicability ......................................................................................................................... 30
4.3.2 Multiple production of the same hull ................................................................................. 30
4.3.3 Compare different concepts ................................................................................................ 30
4.3.4 Evaluation improvements production ................................................................................. 30
5. Production process AMBV ...................................................................................................................31
5.1 Lay out production yard .............................................................................................................. 31
5.1.1 Station 1............................................................................................................................... 33
5.1.2 Station 2............................................................................................................................... 34
5.1.3 Station 3............................................................................................................................... 34
5.1.4 Station 4............................................................................................................................... 34
5.2 Production steps .......................................................................................................................... 34
5.2.1 Make mould ready .............................................................................................................. 34
5.2.2 Apply release-/separation agent ......................................................................................... 34
5.2.3 Lay-up fibres ........................................................................................................................ 35
5.2.4 Lamination ........................................................................................................................... 35
5.2.5 Scour surface ....................................................................................................................... 35
5.2.6 Make water courses holes ................................................................................................... 35
5.2.7 Make foam core .................................................................................................................. 36
5.2.8 Glue foam cores................................................................................................................... 36
Production of composite ship hulls 4 Content
5.2.9 Apply rubber emulsion ........................................................................................................ 36
5.2.10 Drilling holes ........................................................................................................................ 36
5.2.11 Glue glas pens ...................................................................................................................... 36
5.2.12 Positioning of the components of the ship ......................................................................... 36
5.2.13 Making angle connection deck/bulkheads/skin .................................................................. 37
5.2.14 Production sandwich panel ................................................................................................. 37
5.2.15 Placing sandwich panel........................................................................................................ 37
5.2.16 Remove release-/separation agent ..................................................................................... 37
5.2.17 Break off mould ................................................................................................................... 37
5.3 Production order AMBV .............................................................................................................. 37
5.3.1 Station 1 production order .................................................................................................. 41
5.3.2 Station 2 production order .................................................................................................. 41
5.3.3 Station 3 production order .................................................................................................. 42
6. Conceptual model ...............................................................................................................................43
6.1 Structure model ........................................................................................................................... 43
6.1.1 Global bending moment ...................................................................................................... 43
6.1.2 Local water pressure ........................................................................................................... 43
6.2 Cost price estimation model ....................................................................................................... 46
6.2.1 Dimensions .......................................................................................................................... 46
6.2.2 Production parameters ....................................................................................................... 46
6.2.3 Production process en man-hours ...................................................................................... 46
6.2.4 Material cost ........................................................................................................................ 47
6.2.5 Non man-hour related costs................................................................................................ 47
6.2.6 Learning curve ..................................................................................................................... 47
7. Parameters production model ............................................................................................................50
7.1 Process parameters ..................................................................................................................... 50
7.1.1 Preparatory work................................................................................................................. 50
7.1.2 Producing laminate.............................................................................................................. 50
7.1.3 Scouring ............................................................................................................................... 51
7.1.4 Making stiffeners ................................................................................................................. 52
7.1.5 Placing decks and bulkheads ............................................................................................... 52
7.1.6 Super structure .................................................................................................................... 52
Production of composite ship hulls 5 Content
7.1.7 Overview process parameter .............................................................................................. 52
7.2 Structure and material parameters ............................................................................................. 53
7.2.1 Number of layers ................................................................................................................. 53
7.2.2 Buffer layer and strength layer............................................................................................ 54
7.2.3 Glass pins ............................................................................................................................. 55
7.3 Cost parameters .......................................................................................................................... 55
7.3.1 Inflation rate ........................................................................................................................ 55
7.3.2 Material prices ..................................................................................................................... 55
7.3.3 Investment ........................................................................................................................... 56
8. Experimental model ............................................................................................................................57
8.1 Dimensions ship .......................................................................................................................... 57
8.1.1 Hull form .............................................................................................................................. 57
8.1.2 Macro’s dimensions ship ..................................................................................................... 58
8.2 Characteristics ship ...................................................................................................................... 59
8.2.1 Main dimensions ................................................................................................................. 59
8.2.2 Stiffeners ............................................................................................................................. 59
8.2.3 Bulkheads ............................................................................................................................ 60
8.2.4 Decks ................................................................................................................................... 62
8.3 Production parameters ............................................................................................................... 62
8.4 Production process ...................................................................................................................... 63
8.5 Determination material cost ....................................................................................................... 63
8.6 Total cost calculation series ........................................................................................................ 64
8.7 Optional steps conceptual model................................................................................................ 64
9. Results and sensitivity analysis ............................................................................................................65
9.1 Results ......................................................................................................................................... 65
9.2 Sensitivity analysis ....................................................................................................................... 68
9.2.1 Sensitivity other ship ........................................................................................................... 70
9.2.2 Sensitivity other materials ................................................................................................... 70
9.3 Building other structure .............................................................................................................. 71
9.4 Using other process ..................................................................................................................... 71
10. Verification and validation model ...................................................................................................73
10.1 Verification weight structure ...................................................................................................... 73
Production of composite ship hulls 6 List of figures
10.2 Verification production skin ........................................................................................................ 74
10.3 Verification production stiffeners ............................................................................................... 74
10.4 Verification investment ............................................................................................................... 75
10.5 Verification other processes ........................................................................................................ 75
10.6 Comparison decks and bulkheads ............................................................................................... 75
11. Implementation in DMO estimation model ....................................................................................76
12. Conclusion and recommendations ..................................................................................................77
12.1 Conclusion ................................................................................................................................... 77
12.2 Recommendations....................................................................................................................... 78
Bibliography .................................................................................................................................................79
Appendix 1. Midship section AMBV ........................................................................................................83
Appendix 2. Description hull form ...........................................................................................................84
Appendix 3. Production parameters .......................................................................................................85
Appendix 4. Weight parts of the ship ......................................................................................................87
List of figures Figure 1. Alkmaar class mine hunter. .......................................................................................................... 10
Figure 2. Most used weave patterns (Xu, sd). ............................................................................................. 17
Figure 3. Different sandwich structures (Vinson, 1999). ............................................................................. 18
Figure 4. Examples of butt joints (Smith, 1990). ......................................................................................... 19
Figure 5. Male en female mould (Empire West Inc., sd). ........................................................................... 20
Figure 6. Impregnation (MagnumVenusPlastech, sd). ................................................................................ 23
Figure 7. Gantry crane for the construction of a GRP minehunter for the Royal Navy (Smith, 1990). ....... 23
Figure 8. Connection types hat stiffeners. .................................................................................................. 24
Figure 9. Layout GNM yard (GNM Naval construction, 1985). ................................................................... 31
Figure 10. Layout van der Giessen-de Noord marinebouw (GNM Naval construction, 1985) ................... 32
Figure 11. Flowchart production process AMBV. ........................................................................................ 38
Figure 12. Flowchart station 1. ................................................................................................................... 39
Figure 13. Flowchart station 2. .................................................................................................................... 40
Figure 14. Butt wise built laminate. ............................................................................................................ 41
Figure 15. First two stations. ....................................................................................................................... 42
Figure 16. Last two stations ......................................................................................................................... 42
Figure 17. Schematic overview cost price estimation model. ..................................................................... 44
Figure 18. Static water pressure (Van der Giessen - de Noord marinebouw BV, 1988) ............................. 45
Figure 19. Dynamic pressure caused by the relative motion. ..................................................................... 45
Figure 20. Difference between NATA formula and the DMO formula for the learning curve. ................... 49
Figure 21. Graph thickness vs. layers. ......................................................................................................... 54
Production of composite ship hulls 7 List of tables
Figure 22. Division ship ................................................................................................................................ 57
Figure 23. Width decks ................................................................................................................................ 57
Figure 24. Cross sections ............................................................................................................................. 57
Figure 25. Division ship ................................................................................................................................ 59
Figure 26. Bulkheads in the ship.................................................................................................................. 61
Figure 27. Decks in ship ............................................................................................................................... 62
Figure 28. Cost per ship for series of different sizes ................................................................................... 65
Figure 29. Effect learning curve ................................................................................................................... 65
Figure 30. Decomposition of the material cost. .......................................................................................... 66
Figure 31. Decomposition different processes. .......................................................................................... 67
Figure 32. Production parts of the construction. ........................................................................................ 68
Figure 33. Cost of a project. ........................................................................................................................ 68
Figure 34. Influence manhour cost. ............................................................................................................ 69
Figure 35. Influence of the price of the fibres. ............................................................................................ 69
Figure 36. Influence production stiffeners ratio ......................................................................................... 70
Figure 37. Midship section AMBV ............................................................................................................... 83
List of tables Table 1. Main dimensions AMBV ................................................................................................................ 10
Table 2. GRP MCMV's in service at 1999-12-03 .......................................................................................... 24
Table 3. Production speed several part of the ship. .................................................................................... 50
Table 4. Characteristics buffer layer and strength layer. ............................................................................ 51
Table 5. Overview process parameters. ...................................................................................................... 53
Table 6. Thickness vs. layers ........................................................................................................................ 53
Table 7. Mass percentage fibre and thickness buffer layer ........................................................................ 54
Table 8. Weight composite material ........................................................................................................... 55
Table 9. Mixing ratio matrix ........................................................................................................................ 55
Table 10. Cost price different material to be used. ..................................................................................... 55
Table 11. Height waterlines ......................................................................................................................... 58
Table 12. Main dimensions ......................................................................................................................... 59
Table 13. Changes stiffener spacing ............................................................................................................ 60
Table 14. Stiffener spacings ......................................................................................................................... 60
Table 15. Dimensions deck girder ............................................................................................................... 60
Table 16. Longtidunal stiffener end location. ............................................................................................. 60
Table 17. Bulkheads ..................................................................................................................................... 61
Table 18. Decks ............................................................................................................................................ 63
Table 19. 'Normal' Alkmaar class vessels and Alkmaar class vessel with thicker skin. ............................... 71
Table 20. Weight different parts according to the model and to the GNM calculation ............................. 74
Table 21. Production skin. ........................................................................................................................... 74
Table 22. Production times girder and stiffeners ........................................................................................ 74
Table 23. Percentage of the time used for the lay-up and lamination of the stiffeners. ............................ 75
Table 24. Overview production times processes not directly related to the GRP work. ............................ 75
Production of composite ship hulls 8 List of tables
Table 25. Production cost decks and bulkheads. ........................................................................................ 75
Table 26. Description hull form ................................................................................................................... 84
Table 27. Production parameters skin. ....................................................................................................... 85
Table 28. Production parameters bulkheads. ............................................................................................ 85
Table 29. Production parameters deck. ...................................................................................................... 86
Table 30. Material buffer layer skin ............................................................................................................ 87
Table 31. Material strength layer skin ......................................................................................................... 87
Table 32. Material decks and bulkheads ..................................................................................................... 87
Table 33. Material buffer layer skin ............................................................................................................ 87
Table 34. Material strength layer skin ......................................................................................................... 88
Table 35. Material decks and bulkheads ..................................................................................................... 88
Table 36. Material matrix buffer layer skin ................................................................................................. 88
Table 37. Material matrix buffer layer skin ................................................................................................. 89
Table 38. Foam core. ................................................................................................................................... 89
Table 39. Material matrix buffer layer skin ................................................................................................. 89
Production of composite ship hulls 9 Abbreviations
Abbreviations AMBV Alkmaarklasse Mijnenbestrijdingsvaartuig CSM Chopped Strand Mats DG Dutch Guilder DMO Defensie Materiaal Organisatie/ Defence Material organisation DMP Defensie Materieel Proces ELFE Extreme Low Frequency Electric GNM Giessen-de Noord Marinebouw GRP Glass-Reinforced Plastic ICC Initial Construction Costs LCC Life Cycle Costing LCM Life Cycle Management LCU Landing Craft Utility MCMV Mine Counter Measure Vessel NATO North Atlantic Treaty Organisation RNLN Royal Netherlands Navy RTM Resin Transfer Moulding SCRIMP Seemann Composites Resin Infusion Moulding process (SCRIMP) SPRINT SP resin infusion technology SWBS Ship Work Breakdown Structure TSSE Total Ship System Engineering UEP Underwater Electric Potential VARTM Vacuum-assisted Resin transfer Moulding
Production of composite ship hulls 10 1. Introduction
1. Introduction The first part of this chapter describes the background of this graduation project. The second part of this
chapter is the problem to be solved, the third part gives the research question for this graduation project
and the associated sub question and subsequent questions. The fourth part describes also the structure
of this thesis.
1.1 Background The Alkmaar class mine hunters (AMBV), see
figure 1 of the Royal Netherlands Navy reach the
end of their expected lifetime around 2020. The
main dimensions of the AMBV can be found in
table 1. The mine hunters are planned to be
replaced by other vessels. The Defence Material
Organisation (DMO) is performing feasibility
studies for a new Mine Counter Measure Vessel
(MCMV). DMO uses the Total Ship System
Engineering (TSSE) process as a framework for
managing the developed concept studies
(Defence Material Organisation, 2012). This
process has several standard steps to come to a
design. A key step in this process is the verification
of the proposed concept(s). The costs are
estimated during this step. Furthermore, the
compliance with the performance requirements
and available budget is checked.
The development of the concepts has reached the stage that it is necessary to make a cost estimation.
However that does not imply that the development is almost ready. The TSSE process is an iterative
process.
The cost estimates are important for the Defensie Materiaal Proces (DMP). This process is used to inform
the government and the politics about investment programs of the army for their decision-making
(Ministerie van defensie, 2007).
Main dimensions AMBV
Breadth 8,9 m
Depth 6, 75 m
Draft 3,8 m
Length overall 51,5 m
Displacement 543 ton
Table 1. Main dimensions AMBV
Figure 1. Alkmaar class mine hunter.
Production of composite ship hulls 11 1. Introduction
Being almost undetectable for mines is an important feature for a MCMV. Sea mines can use one of the
six signatures or combinations of those signatures to detect a ship in their circumference, these
signatures are: acoustic, seismic, magnetic, pressure, extreme low frequency electric (ELFE) and
underwater electric potential (UEP). A magnetic steel MCMV is thus not possible due to the signature
produced by the ship. Therefore, nonmagnetic materials are necessary for a MCMV.
Three concept designs are proposed for a MCMV by the designers of DMO.
Two materials are used for these concept designs. The first concept is a proposal to use glass-reinforced
plastic (GRP) (Takken, 17 December 2013). The second one is also a proposal in GRP, although this design
is smaller compared with the first one (Takken, 17 December 2013). The current AMBV's at the Royal
Netherlands Navy (RNLN) have also been built in GRP.
The third concept design is to use stainless steel with nonmagnetic properties (Bruijn, 17 December
2013). The RNLN does not have experience with the design, cost estimation and production of
nonmagnetic steel vessels.
1.2 Problem Normally, warships are built in normal shipbuilding steel. Changing material requires other production
methods, depending on which material will be used. Other production methods and other materials lead
to a change in the acquisition price of the MCMV's.
The Life Cycle Management (LCM) department of DMO makes cost estimates for the total life of the
ships developed by DMO as part of the TSSE process. Due to the proposed different materials, difficulties
arise for the LCM department. Estimates based on the use of magnetic shipbuilding steel cannot be used
and proper estimates for nonmagnetic material are not yet known. The estimates based on the use of
magnetic shipbuilding cannot be used because the different nature of the production processes in
nonmagnetic steel.
The man-hours related to the Alkmaar class have been registered during the building of the first Alkmaar
class AMBV in 1982. The current estimates used for the concept studies where the structure is made of
GRP material are based on that data. However, it became clear during the analysis of the estimation that
an update of the method is required due to development of production techniques. DMO has got a price
indication for an Alkmaar class build with newer techniques. The results of this price indication will be
used in this graduation project.
The LCM department of DMO uses the NATO Ship LCC hierarchy as a structure to estimate the costs of a
project. Part of the NATO ship LCC hierarchy is the Initial Construction Costs (ICC), all the costs related to
the actual building of the vessel (Anon., 2005). The NATO Ship Work Breakdown Structure (SWBS) is used
to make an estimated for the ICC (Anon., 2005).The NATO SWBS uses a division of the ship to come to an
estimate for the LCC. At the first level of the breakdown structure, four main groups can be
distinguished: design and support, hardware, software and programmatic. Design and support are all the
costs related to the development of a vessel. Hardware are the cost of all the physical parts of the vessel,
software are all the costs related to computer programs to be used on the vessel and programmatic are
all the costs the other costs. These four groups can be broken down into several subgroups related to
several functions of the vessel.
Production of composite ship hulls 12 1. Introduction
1.3 Research question and sub questions The problem described above results in the following research question with associated sub questions.
The research question will be:
How can construction costs for ships with composite hulls be estimated by means of a model and can
such a cost model be employed to evaluate possible improvements in the ship production process?
The sub questions are:
1. What are alternative production methods for composite hulls and can a costs model be used to
determine which method is preferable?
2. Would such a model be suitable to estimate the production costs for the specific ship type
AMBV?
3. Could such a model be helpful in identifying process or product improvements that can lower
the production costs significantly and what are these improvements?
A subsequent question is:
How can the developed hull construction costs method be implemented and integrated in the current
existing costs estimation methods used by the Defence Material Organisation?
One of the groups within the hardware group is selected for investigation in more detail during the
graduation project. From a ship production point of view, the hardware costs are of interest most.
Within the hardware group are the biggest changes due to the use of another material, the others ones
do not have that big change. The hardware group is divided in seven sub groups. This graduation
research focuses on group 100, which is the hull structure group. The newer production techniques have
the most consequences for the production of the hull. Most of the work related to the composite work is
within this group.
The developed concept designs for the replacement of the AMBV class vessels are in a preliminary
phase. As a result, no detailed construction plans are available; the concepts are in the stage that only 3d
hull shapes are available. The model will be developed to predict the price already in this stage. The first
step is to come from the general arrangements to information about the production and to relate that to
production parameters. A section plan is necessary and also a building strategy.
This graduation focuses on the effect of the use of composite materials on parameters used to estimate
the initial construction costs (ICC). The ICC has two parts, the material costs and the man-hour cost. The
ICC for the stainless steel concept will not be reviewed in this graduation project.
1.4 Structure thesis The second chapter of the thesis is the part that gives an overview of the materials used for maritime
composite applications, the structure types used in composite shipbuilding, a overview of methods used
nowadays for the production of composite applications for the maritime industry. It describes also some
important aspects about the production in composite materials.
Production of composite ship hulls 13 1. Introduction
The third chapter gives reason for the development of a cost price estimation model during this
graduation project. The fourth chapter describes the requirements used for the cost price estimation
model. The fifth chapter describes the production process of the AMBV class vessel, this production
process is used as benchmark for the model. The sixth chapter describes the conceptual model, thus how
the model should be build theoritically. The seventh chapter gives the parameters for the production of a
composite ship hull, this is the input of the model. The next chapter is the experimental model, the
actual building of the cost price estimation model. Chapter nine describes the results of the model. The
tenth chapter is about the verificaiton and validation of the model. The implementation in the DMO
estimation model is described in chapter eleven and chapter twelve contains the conclusions and
recommendation regarding this graduation project.
Production of composite ship hulls 14 2. Production of composite ship hulls
2. Production of composite ship hulls This first chapter will describe the characteristics of composite materials. It will cover four subjects
related to producing ships in composite materials: the materials, joints to produce the materials,
production methods and construction philosophies. The literature describing these concepts sometimes
uses different wording for concepts. In this chapter, most of the different names of the concepts will all
be addressed.
A composite is a material which consists of two or, in some cases, three elements. The first part is called
the fibre or reinforcement. Its function is to carry the loads. The second part is called the matrix or resin
and this gives the material ductility and toughness. Another important feature of the resin is to protect
the fibres for damage (Ashby, 2013). The optional third part is called the core. Constructions made from
materials with a core are called sandwich constructions. Cores are normally added to create additional
stiffness and strength for a low weight penalty (Stewart, 2010). The advantages of a lighter construction
are lower fuel consumption, a higher payload or a higher speed. For the construction of composite
products it is not necessary to use a core.
Composites have been used for building naval ships since the 1940s. The first boat built was a 28-foot
fiberglass personnel boat in 1947 (Spaudling jr., April 1966). The first successfully composite mine
counter measure vessel was built in 1973 (Mouritz, et al., 2001). Globally, the use of composites
increased at a high speed during the last decades. This increased use of composites has led to the
development and improval of production techniques for composite products.
This chapter describes the possible production techniques of marine structures. Its purpose is to present
an overview of the techniques suitable for the production of ship hulls; not to present an overview of all
production techniques for composite materials.
Not only the production methods are important to investigate, the construction methods are important
as well. This is because the choice for a structure method influences the production method and its
different steps.
2.1 Materials Many different materials may be used to produce ship hulls made from composite materials. The choice
of the materials for ship hulls influences their design. It is therefore important to have some knowledge
about the key features of the materials used. The following paragraphs describe they key features of the
most commonly used materials for the production of marine structures.
2.1.1 Resin
A resin or matrix is used to hold the fibre together. Resins can be divided in two categories: thermoset
resins and thermoplastic resins (Biron, 2013). The difference between these two groups is the behaviour
at higher temperatures and the curing of the materials. Curing of a thermoset materials is a catalytic
chemical reaction. During the curing, the molecules are cross-linked. The result is a strong binding and
solidification. The chemical reaction is irreversible, therefore thermoset materials are hard to recycle.
Curing of a thermoplastic is not a chemical reaction. A thermoplastic resin is liquid if it is heated and/or
pressure is applied. Thermoplastic resin is solid at room temperature, during the cooling the material
undergoes a physical change, from liquid to solid (Johnson, sd).
Production of composite ship hulls 15 2. Production of composite ship hulls
Thermoplastics are hardly used for maritime structures, some small boats and recreational boats have
been build using this material (Eric Green Associates, 1999). Thermoplastic boats up to 7.2m have been
build (Antosiewicz, 2007). Therefore, thermoplastics are not yet applicable for the construction of a
vessel larger as the MCMV and will not be described in more detail.
2.1.1.1 Polyester resin
Polyester is a thermoset material. Polyester is the most applied material for the construction of maritime
structures (Otheguy, 2010). Polyester is the most used material for composite shipbuilding because of
relatively low cost, curing at room temperature and water immersion properties (Chalmers, 1988).
Polyester resin does not cure when exposed to air. Paraffin is added in order to make curing possible.
The paraffin creates a seal on the surface of the material. The material is no longer exposed to air and
the cure process can take place. The paraffin film creates problems if other parts have to be bonded to it.
The paraffin film has to be removed before another part can be bonded to the structure. An accelerator
is used if the construction should cure at room temperature.
Polyester resin can be divided in orthophtalic and isophtalic resins. The former is the most widely applied
polyester resin. The second one has water immersion properties and is mostly used for constructions
which are in contact with the water (Eric Green Associates, 1999, p. 70).
2.1.1.2 Vinylester
Vinylester is another thermoset material. The performance of vinylester resin is similar to the
performance of polyester resins. Polyester resins are cheaper but vinylester resins are better resistant
against corrosion, have better hydrolytic stability and have good properties against impact loads and
fatigue (Eric Green Associates, 1999, p. 71).
2.1.1.3 Epoxy resin
Epoxy is also a thermoset material. Epoxy resins have the best properties of all the resins used in
maritime applications. However epoxy is not commonly applied in maritime structures because it is not
easy to handle and expensive. Epoxies degrade fast when they are exposed to ultaviolet (UV) light. (Eric
Green Associates, 1999, p. 71).
2.1.1.4 Phenolic resin
The last possible thermoplastic material is a phenolic resin. An important feature of phenolic resin is the
mechanical property of it, which is between 10 to 20% lower compared to polyester, such as flexural
strength and elastic modulus (Chalmers, 1991). Using phenolic resins thus results in a heavier
construction with the same properties regarding to stiffness, shock, buckling and so on. However,
phenolic resins have excellent properties regarding to fire resistance (Chalmers, 1988). Fire resistance is
another important feature of a naval ship. Phenolic resin has good thermal properties, therefore is it
applied for products, which are in service in a tropical climate (Anon., 1996). The material cost are lower
compared to isopthalic resins however the production cost are higher due to higher material cost (Smith,
1990).
2.1.1.5 Conclusion resin
Based on the description of the resin, above one can conclude that vinylester should be applied for the
construction of composite vessels. It has relatively good properties compared with polyester and
Production of composite ship hulls 16 2. Production of composite ship hulls
benefits in production compared with epoxy resin. However, depending on the mission area phenolic
resin can have advantages due the thermal properties.
2.1.2 Reinforcement
The reinforcement gives the strength to the composite. Fibres are used to provide this strength. Several
materials may be used as reinforcement: glass, carbon and aramid (Smith, 1990). Glass fibre is used for
low performances applications. Several glass fibres are available as reinforcement. E-glass (lime
aluminium borosilicate) is the most commonly applied material. S-glass (silicon dioxide aluminium and
magnesium oxides) has better strength performance, but is more expensive (Eric Green Associates,
1999).
Carbon and aramid are used for high performance applications. An example of a high performance
application is the use of carbon fibre in the Visby class. The advantage of carbon and aramids fibres is the
strength of these materials. However, carbon and aramid fibres are not generally used because of their
high price (Eric Green Associates, 1999). Another advantage of the use of carbon fibre are the good radar
absorption properties of these fibres (Galanis, 2002). Making the superstructure in carbon fibre is thus a
manner to improve the stealth properties of a ship. A side effect is an improvement in stability when
carbon fibre is used, because carbon fibre structures have a lower weight and the KG is thus reduced.
A disadvantage of the use of aramid reinforcement is that aramids have low compressive properties. An
advantage is the high wear resistance (Departement of defense, 2002).
Different types of reinforcement are used for maritime applications. They can be distinguished into two
categories: continuous and non-continuous. Continuous fibres have better strength properties. The low
strength non-continuous properties are mostly used for fibreglass reinforced structures, this is due to
processing restrictions and economic reasons (Eric Green Associates, 1999). Different reinforcement
types will be treated in the next paragraphs.
2.1.2.1 Chopped strand mats
Chopped strand mats (CSM) are mats of short, up to 50 mm, randomly oriented fibres (Chalmers, 1988).
CSM is thus a non-continuous fibre. CSM has low strength properties, however it is easy to handle and it
has good wet-out properties. Production manners for CSM are hand lay-up, spray lay-up and automated
lay-up (Eric Green Associates, 1999).
A big advantage when spray lay-up is used is that it can sprayed directly on a mould together with the
resin (Smith, 1990). The production rate is thus higher. However, more material is necessary due to the
lower material properties.
A combination of woven roving (see 2.1.2.2) and CSM is for instance used for the hull of the Royal
Australian Navy mine hunter of the Bay class (Thomson, et al., 1998).
2.1.2.2 Woven roving fabric
The woven roving fabric reinforcements or woven fabric reinforcements are the most applied
reinforcement types used in maritime applications. Bundles reinforcement are woven to each other. The
materials properties depend on the weave pattern. The weave pattern has effect on materials properties
like deformability and strength (Fibreglas developments corporation, sd). Out-plane-stiffness, strength
and toughness are influenced by the weave pattern (Huang, 2000).
Production of composite ship hulls 17 2. Production of composite ship hulls
2.1.2.3 Prepreg
Prepreg is a resin already containing reinforcement. Prepregs are thin sheet materials, which can be
placed on a mould. A freezer is necessary to store the prepregs. Prepregs are used in high performance
vessel such as high-speed vessels and sail boats. The reason for that is the high production cost for
prepregs. For most applications are the costs to high compared to the benefits of the use of prepregs.
Prepreg has good strength properties.
Prepregs are cured in an autoclave or in an oven. An oven is applied in maritime applications due to the
big structures (Eric Green Associates, 1999, pp. 272-273). Difficulties occur for structures above 40-50m
due to the curing (Galanis, 2002).The difficulties arise due to size of the oven that has to be used for the
production of the ship. The product has to be put in the oven as a whole. Prepreg can thus not be used
for the construction of an MCMV because an MCMV is a big structure.
2.1.2.4 Unidirectional reinforcements
Unidirectional reinforcement has fibres only in one direction. The material is very strong in the direction
of the reinforcement, but has much less strength properties in the transverse direction of the fibres.
Typical applications for unidirectional reinforcements are stem and centreline stiffening and tops of
stiffeners. Entire hulls are seldom produced in unidirectional reinforcements, only if ultra-high
performance is required for instance if an extreme light structure is required for a race boat (Eric Green
Associates, 1999).
2.1.3 Core materials for sandwich
The reason why constructors choose a sandwich construction is the possible achievement in hull weight
reduction. The reduction in weight can be used for higher payload, increasing speed or range. A core
material has a low weight and strength properties. A sandwich construction has thin composites layers
with thick core materials between those layers (Galanis, 2002). Several structures types can be used for
making a sandwich, among these are foam core sandwich (figure 3a.), honeycomb core sandwich (figure
3b.), web core sandwich (figure 3c.) and truss core sandwich (figure 3d.). Cores can be PVC’s, plywood
and balsa wood.
One of the features of a honeycomb sandwich constructions are the good absorbing properties regarding
to mechanical and sound energy (Vinson, 1999). Given that it is important for a MCMV to reduce the
signatures, the use of a honeycomb sandwich structure could be preferred. However honeycomb
sandwich structures have big downsides: curved geometries are hard to make and the possible
absorption of water is high (Eric Green Associates, 1999). In addition, vacuum infusion and transfer
methods cannot be used because the liquid resin goes into the honeycombs. The costs for foams are
Figure 2. Most used weave patterns (Xu, sd).
Production of composite ship hulls 18 2. Production of composite ship hulls
lower than the cost for honeycomb structures. Foams are mostly applied in structures for the
automotive industry and transport, honeycomb is used in aerospace structures (Biron, 2014).
2.2 Joints In the construction of ships joints are important. Loads have to be transferred from one part to another.
Therefore joining of the different members of the construction is crucial in the design of a marine
structure. This section treats different type of joining.
2.2.1 Adhesive bonding
Adhesive bonding is used to transfer the loads between the core and laminate. The tensile strength and
the shear strength of the bonding should be at least the tensile strength and the shear strength of core.
(Gullberg & Olsson, 1990). The quality of the adhesive bond is determined by the resin type, size of the
reinforcement, processing techniques and laminate void content. This type of bonding is important for
sandwich constructions. It is the most common type of failure for these structures. Therefore, it is
necessary to take care of the changes from the core to the laminate (Eric Green Associates, 1999).
2.2.2 Secondary bonding
Secondary bindings are bonds, which attach a structural part to another already cured structural part
(Simpson & Burchill, 2004). Primary bonds are the bonds, which are made before the material is cured.
The difference between the secondary bonds and the primary bonds is that the primary bond is both
chemical and physical linked and the secondary bond is only physical linked. The secondary bond can
Figure 3. Different sandwich structures (Vinson, 1999).
Production of composite ship hulls 19 2. Production of composite ship hulls
withstand less stress because the absence of the chemical linking. Preferably, the linking to the part
takes places before the curing. However, that is not always possible (Murphy, 2014).
Examples of secondary bonding are the connection of stiffeners to panels, decks and skin and bulkheads.
These connections cause stress concentrations. Secondary bindings are the reason for many structural
failures (Eric Green Associates, 1999). If stiffeners are used in the design of the secondary bonding it is
important to prevent these failure types.
The function of these bindings is to carry shear stress and local bending stress. Especially in a MCMV hull
the design of these bondings is important. Stiffeners are sensitive for debonding if they are exposed to
shock loads.
2.2.3 Butt joints
Butt joints are connections between two construction parts in the same plane. These connections can for
instance be used to connect different parts of prefabricated decks. Their main function is to transfer
membrane tension, compression and shear from one part to the other. Several connection types have
been developed to make these butt joints, some of these can be found in figure 4. (Smith, 1990).
Figure 4. Examples of butt joints (Smith, 1990).
2.3 Production methods Composite products can be produced in a variety of ways, which are all variations of a few basic
processes (Owen, et al., 2000, p. 5). The production methods can be divided in contact moulding and
closed moulding. Although the methods may vary, the production of composites always follows the
same key steps (Owen, et al., 2000). These key steps are:
Mould preparation
Placing reinforcement
Production of composite ship hulls 20 2. Production of composite ship hulls
Introduction of the resin matrix
Wet out and wet trough of the reinforcement
Matrix cure
Removal of the cured material from the mould
Trimming
Post curing if required
Mould cleaning (only if the mould is used again)
The exact building process for the Alkmaar class AMBV will be described in chapter 5.
Some general remarks have to be made before diving into the details of the different production
methods, reinforcements and resins.
First of all, the ratio between the matrix and the resin is very important for the strength of the material.
The higher the content of reinforcement, the larger the strength of the composite (Chalmers, 1991). The
fact that higher content of reinforcement gives a higher strength is important with regard to types of
reinforcement. Unidirectional rovings have the highest possible ratio 0.5-0.65, for woven fabrics this is
between 0.4 and 0.55. Random mats have a fibre content between 0.23 and 0.33 (Shenoi & Dodkins,
2000). The production manner also influences the fibre content.
In most cases, moulds are used to produce composite product. The two types of moulds that are used
here are called male moulds and female moulds. Female moulds can also be called negative moulds or
cavity moulds and male moulds can also be referred to as positive moulds. The difference between the
two moulding methods is related to the side of the construction that is on the mould. The side, which
has to be smooth is always on the mould (Lee,
1993). The sides of the vessel for instance, which
have to be in the water, because a smooth side
reduces the resistance of the vessel. The closed
moulding techniques combine a male and a
female mould. The advantage of a closed
moulding technique is that both surfaces are
smooth.
The choice for a moulding type does not depend only on the required smoothness of the side of the
construction. Often it also depends on the costs of the production. If a product has to be produced five
to ten times or fewer, the male mould would be the cheapest way of producing. It would also be the
least time consuming. The use of the more expensive female moulds can be justified if more than 5-10
products are produced (Fibre glast developments corporation, sd).
Bulkheads, decks and stiffeners are produced elsewhere. They can be bound onto the hull when the
production is in the stage where the bulkheads and decks need to be installed. (Karlsson & Aström,
1996).
Some environmental conditions should be controlled during the fifth step of the process, the curing.
Figure 5. Male en female mould (Empire West Inc., sd).
Production of composite ship hulls 21 2. Production of composite ship hulls
2.3.1 Contact moulding
2.3.1.1.1 Hand lay-up
The first production technique for composite materials was the hand lay-up method or wet lay-up
method (Marsh, 2006). It is also the easiest way in terms of equipment to produce a marine structure. A
part of the reinforcement is placed on the mould. Resin is applied with the use of hand-held rollers. Air
bubbles possible present in the material are removed due to the pressure applied with the rollers.
However, the void content is high compared with other techniques. The required thickness can be
reached by repeating the process (Dharmawan, 2008).
Hand lay-up is a good production method for large products with a low production rate. However, hand
lay-up has several disadvantages. The content of the fibre is low. As a result, the strength of the material
is also low, resulting in a thicker construction compared with other production methods in order to get a
product with the same strength and stiffness. Furthermore, the manufacturing time is high and the
biggest part of the work is manual work. As a result are the man-hour costs high. However tooling cost is
low for hand lay-up. The reproducibility of the materials is poor (Drechsler, 1999), due to the high
percentage hand labour, it is difficult to produce identic products.
The advantage of hand lay-up is the curing at room temperature and the absence of pressure beside the
atmospheric pressure (Owen, et al., 2000). As a result, a product can be made without major
investments in tooling.
Hand lay-up is hardly any used due to regulatory requirements. During the curing of the material styrene
will release. Other production techniques do not have this disadvantage due to sealing or a closed mould
(Shenoi & Dodkins, 2000). These techniques are described in 2.3.1.1.3, 2.3.1.1.4 and 2.3.2.
2.3.1.1.2 Spray-up
During the 1960s other methods were developed. Due to the labour intensive hand lay-up process,
possibilities to reduce the labour part in the production process investigated. Mechanisation was the key
factor in developing less labour intensive methods. The first developed method beside hand lay-up is the
spray lay-up method. Spray lay-up uses a chopper gun to spray the material onto the mould.
Reinforcement as well as fibres are sprayed together onto the mould (Owen, et al., 2000).
Chopped strand mats are mostly used for the spray lay-up method. A disadvantage of the spray lay-up
methods is the poor quality of the product. Hand lay-up products have a better quality compared with
spray lay-up methods. (Owen, et al., 2000). The reinforcement can also be placed on the mould
manually. This gives better strength properties, however the work and thereby the cost are increased.
(Biron, 2014).
The advantage of the spray-up method is the speed compared to hand lay-up method and the extent to
which the process can be automated. Disadvantages are the control of thickness of the material, losses
of resin due to the spraying and the need for experienced workers (Biron, 2014).
2.3.1.1.3 Vacuum bag moulding
This method was applied for the first time in a marine application at the end of the 1970s (Reuterlöv,
2002). Vacuum bag moulding or vacuum-assisted resin injection (VARI) requires more tooling compared
with the hand lay-up and spray-up method. The reinforcements are placed on the mould and if
applicable the core material. The reinforcements and core material are sealed with plastic, this creates
Production of composite ship hulls 22 2. Production of composite ship hulls
an airtight bag, called vacuum bag. Vacuum is applied and the resin is sucked into the vacuum bag. The
construction is held vacuum until all the material is cured (Owen, 2000). Air bubbles in the material are
reduced due to the vacuum applied (Biron, 2014).
The vacuum bag moulding has many advantages over the hand lay-up method and the spay-up methods,
among these are less styrene emissions, independent set-up time and better mechanical properties.
Disadvantage of the vacuum bag moulding process are a mat necessary for the distribution of the resin
and peel ply layer. These two increase the cost and production time. (Reuterlöv, 2002). The lay-up is
expensive part of the production when vacuum bag moulding is used, the reinforcement is laid up by
hand, resulting in high production times (Judy, et al., 1994). Automation of the lay-up could possible save
a lot of money. The surface, which is not on the mould, is more smooth compared with spray-up or hand
lay-up although a single side mould is used. The vacuum bag takes care of the finishing the outer surface
(Biron, 2014).
Vacuum bag moulding is called dry bag moulding if a core is bonded to an already cured laminate. It is
called wet bag moulding if a laminate is made with the vacuum bag moulding technique (Eric Green
Associates, 1999).
The reinforcements and if applicable the cores are placed dry on the mould. This results in better
controllable quality of the structures because visible inspection can take places without any time limit.
(Eric Green Associates, 1999, p. 269).
2.3.1.1.3.1 SCRIMP
Seemann Composites Resin Infusion Moulding process (SCRIMP) is a process similar to the vacuum bag
moulding technique. This technique is developed by the Seemann composites company. Advantage of
the SCRIMP process are the high ratio between reinforcement and resin. Weight fraction up to 80%
reinforcement has been achieved for unidirectional reinforcement and up to 75% percent for woven
rovings. (Eric Green Associates, 1999).
The difference between the SCRIMP method and the ‘normal’ vacuum bag moulding is the point in time
where the reinforcements are place on the mould. For the vacuum bag moulding first some resin has to
be cured before the reinforcement can be laid-up. This is not necessary with the SCRIMP process.
Reinforcements and cores are being pressed together by the applied vacuum. The resin is sucked into
the reinforcements and cores. As a result of this type of injection of the resin no void content is present
in the construction (Eric Green Associates, 1999).
The SCRIMP process has been used for the production of the superstructure and some internal
structures of the RN Sandown class mine hunters (Naval technology, sd). Yachts have also been built
using the SCRIMP process. The biggest vessel made with this technique is a yacht produced by Horizon
yachts. This vessel has a displacement of 211 ton and is almost 40 metres long (TPI composites, 2006).
2.3.1.1.3.2 SPRINT
This method is developed by the company SP high modulus, currently named Gurit (Gurit, 2013). SP resin
infusion technology (SPRINT) is method which uses advance prepreg to make construction with.. SPRINT
uses a vacuum bag, but instead of adding the resin after the reinforcement is placed on the mould and a
vacuum is applied, are prefabricated resin films placed on both sides of the reinforcement. The
reinforcement melts and goes in to the reinforcement. A big advantage of the SPRINT method is that
Production of composite ship hulls 23 2. Production of composite ship hulls
that it ensures that the resin takes up all void space. The resin is near the reinforcement and does not
have to flow through the mould to reach every place (Ness & Jones, 2000).
An example of the use of the SPRINT technique in shipbuilding is the M67 RS, a 20 m long yacht, built by
Murti yachts (Murtic yachts, sd).
2.3.1.1.4 Impregnation
Impregnation is an technique to automate the lay-up of the
reinforcement. Normally, the lay-up is a costly process, reducing the
amount of work necessary to place the reinforcement on the mould
can result in tremendous cost savings. Big rolls of reinforcement are
feed onto a platform of a gantry crane. Rollers are on this platform
where the reinforcement is wetted. The gantry crane is positioned
transversely with respect to the mould, see figure 7. The
reinforcement is placed on the mould due to horizontal and vertically
movement of the gantry. This method has been used for the
production of a GRP minehunter of the Royal Navy (Smith, 1990). The
advantages of impregnation are higher output, higher efficiency of
materials and a constant quality of the material. Only reinforcement
that can be handled when wetted can be used for this method
(Chalmers, 1991). A disadvantage of the impregnation is the constant
output of impregnated mats. An impregnator is used during the production of the AMBV class vessels.
The occupation of the impregnator was only 15 weeks a year. The other part of the year the impregnator
could not be used because of the constant output. (Lohuizen, 1985).
2.3.2 Closed moulding
Closed moulding uses two mould sides to close the mould. This paragraph describes two methods of
closed moulding.
2.3.2.1 RTM
Resin transfer moulding (RTM) is a closed moulding
process. The fibres are placed on one side of the
mould. The other side of the mould is placed on top
of the mould when all the reinforcement is placed.
This creates a closed mould. Pressure is applied and
the mould will be filled with the matrix.
RTM is expensive for small series due to the
expensive tooling used for the process. Another
disadvantage of RTM is the production difficulties for
parts over five to six meters in length (Reuterlöv,
2002). There is a risk of moving reinforcement if RTM
is used (Biron, 2014). Therefore is it hard to control
the quality of the construction.
Figure 6. Impregnation (MagnumVenusPlastech, sd).
Figure 7. Gantry crane for the construction of a GRP minehunter for the Royal Navy (Smith, 1990).
Production of composite ship hulls 24 2. Production of composite ship hulls
2.3.2.2 VARTM
The difference between VARTM (vacuum assisted resin transfer method) and RTM is the use of vacuum
instead of pressure to transport the resin into the mould. Another difference between VARTM and RTM
is that VARTM can either use closed or open mould or RTM only closed mould. VARTM closed moulding
technique has been used for the production of the Landing Craft Utilities (LCU) for the RNLN. (Judy, et al.,
1994). If an open mould is used the process is the vacuum bag moulding as described in 2.3.1.1.3.
2.4 Structure design ‘philosophy’ Several main structure ‘philosophies’ can be distinguished for GRP MCMV’s. Three structure
‘philosophies’ are already applied for operational MCMVs, which are framed single skin, sandwich
composite and monocoque or single skin construction. Vessels of the MCMV-classes listed in table 2 are
in service or under construction at 1999-12-31 (Mouritz, et al., 2001). Each of the structure types is thus
feasible to construct MCMV’s. Other aspects, such as construction costs, LCC, material properties and
construction restraints, also have an influence on the choice for the composite materials.
Framed single skin Sandwich composite Monocoque
Hunt (UK) Landsort (SW) Lerici (IT, MA, SK, NI)
Sandown (UK) Stryso (SW) Gatea (IT ,TH, USA, AU)
Tripartite (NL, FR, BE, IN, PA) Flyvevisken (DM)
KMV (BE) Alta (NO)
Bay (AU)
Table 2. GRP MCMV's in service at 1999-12-03
2.4.1 Framed single skin structure ‘philosophy’
The framed single skin method is a structure ‘philosophy’ comparable with normal steel ships. Stiffeners
are bound on the shell. These stiffeners are either transverse or longitudinal stiffeners depending on the
size of the ship and the construction ‘philosophy’ used. A combination of the two stiffeners can be used
as well. Bulkheads and frames are used
as secondary stiffeners. The framed
single skin method is labour intensive
because each stiffener has to be bound
separately to the hull (Shenoi & Dodkins,
2000). The structure of the current
Alkmaar class AMBV’s is a framed single
skin. The connection between the
stiffeners and the skin are important for
this structure ‘philosophy’, because they
are sensitive for shock loads (Smith,
1990). The AMBV has hat stiffeners,
other stiffener types may be used as well.
Examples of connection for between the
skin and the hull can be found in figure 8
Figure 8. Connection types hat stiffeners.
Production of composite ship hulls 25 2. Production of composite ship hulls
2.4.2 Monocoque
The monocoque or single skin method is a structure ‘philosophy’, which does not use any stiffeners on
the hull. The shell of the hull is very thick in order to compensate for the absence of stiffeners. The result
is a heavier hull because a stiffened skin requires less material. The effect of a heavier hull are higher
material costs. The mine hunter of the Italian Navy has for instance a 150 mm thick construction at the
keel and 50 mm at the deck (Rusell, 2005). The difference with the skin of the Alkmaar class vessels is
huge. The shell thickness of the Alkmaar Class vessels is up to 34 mm at the keel.
However, the higher material costs are compensated by less man-hour costs, as there are no stiffeners
which, have to be bound to the shell. Since the bonding of stiffeners is labour intensive work and thus
costly (Smith, 1990), constructing hulls without stiffeners means that man-hour costs can be cut.
A disadvantage of the monocoque structure ‘philosophy’ is the cost of the mould, which tends to be high
especially for large vessels. As the MCMV counter measure will be a large vessel, the construction costs
for the mould are expected to be high. The higher cost for the mould can be justified if a series of six to
ten hulls has to be produced (Chalmers, 1991).
2.4.3 Sandwich structure
The third structure ‘philosophy’ is a sandwich structure. A sandwich structure has three parts: two
‘normal’ composite layers on the outside of the construction and a core of a light and cheap material in
between those layers (Chalmers, 1991). These three parts are produced in a certain order: first, one of
the outside layers is being produced. Then the core material is positioned on that outside layer, after
which at last the other outside layer is produced.
The main advantage of sandwich structures is that it gives a light construction at a reasonable price. A
sandwich construction is mostly used together with carbon as a matrix to benefit optimally from the low
weight of sandwich structures (Karlsson & Aström, 1996).
Sandwich structures can be produced without the use of an additional mould, because the core is used
as a mould. First one side of the reinforcement is placed on the core and that reinforcement is
laminated, after which the reinforcement is placed on the other side of the core and is laminated
afterwards (Biron, 2014).
2.4.4 Corrugated hull
A completely different manner to obtain a stiff hull is the use of corrugation in the material. Corrugation
has several advantages compared to the other construction ‘philosophies’. The first advantage is the
absence of the costs for the stiffeners bound onto the structures after the construction of the shell. The
second advantage is the shock resistance, which is much better compared to a structure where the
stiffeners are bound to the hull as described earlier.
Mine counter measure vessels with a corrugated hull are not produced yet. However, research has been
carried out on corrugated hulls. A corrugated hull is produced and tested for different conditions. It was
found that the total weight of a corrugated hull is 15% lighter compared to a conventional hull and the
production costs are 25% lower compared to a conventional transversely framed hull (Smith, 1990).
Production of composite ship hulls 26 2. Production of composite ship hulls
2.4.5 Possible construction methods
Sandwich structures can be used in combination with stiffeners or in combination with the monocoque
structures (Ship structure committee, 1997). Four construction philosophies can be used to design the
construction for a MCMV:
1. Monocoque single skin constructiion
2. Framed single skin construction
3. Monocoque sandwich single skin construction
4. Framed sandwich single skin construction
Three of these structure methods have previously been used for MCMV designs as mentioned in
paragraph 2.4. A monocoque sandwich single skin structures has not yet been applied for a MCMV
construction.
A fifth option is the use of corrugation to obtain the stiffness. This structure method is only used for
research projects.
Production of composite ship hulls 27 3. Why a production model?
3. Why a production model? The solution for solving the problem of the unknown production cost of a c0mpsite ship hull with a
production cost model is chosen for several reasons. The reasons include cost aspects, model aspects
and production aspect.
3.1 Cost aspects The choice for the production model is made because it is relatively cheap to make a production model.
Other solutions to solve the problem would be more expensive: one could for instance make a cost
estimation by producing prototype parts of the ship. However, that would cost more than making a
production model and model the production with production techniques used before.
A production model can be used for the budget aspects of the project. The Dutch government decides
about the budget for the MCMV’s. The developed the design has to fit within this budget. The model can
be used to determine the influence of change in the design on the price of the ship and whether the ship
is affordable or not.
3.2 Model aspects The production cost model can also be used to perform a sensitivity analysis of the estimators. The cost
prices estimation will be done for producing a hull in the (nearby) future. Meanwhile changes, which
have influence on the production cost, can happen. The future cannot be predicted; however, the effect
of possible change can be determined with a sensitivity analysis.
Models can easily handle change in the production. The effect of a change can be shown by comparing
the outcome before and after a change.
3.3 Production aspects The production model will be developed to get more insight in the steps necessary to come to a
composite ship hull. Due the nature of the production model, each required step has to be determined
to come to a good estimation of the production costs.
More detailed information will be known due the production model. The possible bottle necks can be
determined, expensive parts of the production can be determined. Also the consequences of some
structural choices can be found with the production model. The best way to produce composite ship
hulls can be calculated in this way.
It is easy to adapt the model after the use of the model to predict the cost and build a hull in a certain
way. The model can be adapted to review the consequences of the change in production if it becomes
clear that the production cost can be lowered in a certain way.
Production of composite ship hulls 28 4. Requirements model
4. Requirements model Requirements are important to measure whether the model does what it should do. The aim is to
develop a model, which is able to make cost estimations for a composite ship hull. The requirements for
the model can be divided in several groups. These groups are: requirements related to the model type to
be developed, requirements concerning the hull to be estimated, requirements regarding the use of the
model during a project. The requirements of the model will be described in this chapter.
4.1 Model type The model type to be developed determines several requirements for the model. This is the first group
of the requirements. The requirements in this group are: the model has to result in a production cost
estimation, a cost price estimation, should be production process oriented and it should have a certain
accuracy.
4.1.1 Production cost estimation
The model should be able to produce estimations for the production of composite ship hulls. Three main
parts can be distinguished in the cost estimation. The material cost should be part of the cost estimation,
the second parts are the man hour costs and the third part of the calculations should be the costs of the
production, which are not directly related to the man hour cost or material costs. The three main parts
of the cost estimation can be broken down further during the development of the model. However, that
will be described in chapter concerning the development of the model.
4.1.2 Cost price estimation
The model has to produce a cost price estimation for the production of a composite ship hull. The model
will be developed to give the ship owner insight in the production process, to provide information
regarding the affordability of the project and to support the DMO in the acquisition process. As a result,
no commercial information will be implemented or estimated. Profit and risk factors are not part of a
cost price estimation.
4.1.3 Production process oriented
The cost price estimations developed at DMO are product oriented price estimations. That means that
the cost price estimation is based on data from previous projects. Based on the production of previous
vessels estimates are made for the next vessels. The number of man-hours for certain parts of the
construction are used to determine the required work per kg construction. This data can be used to
determine the production rate for the construction of the vessel to be built. The data is used to make
cost price calculations for the project. However, this method cannot be used for the cost price
estimation of ships built in materials rarely used in Dutch naval projects. The data necessary for a
product oriented price estimation is simply not available or outdated due to developments and
improvements in the production process.
Due to the considerations described above, it is necessary to investigate the production steps necessary
to come to a good product. The production has to be split up in smaller production steps to estimate the
time necessary to make a certain part of the product.
Production of composite ship hulls 29 4. Requirements model
4.1.4 Accuracy
The accuracy of the model has to be an improvement compared with the current method used at DMO.
With accuracy is meant the deviation due to the uncertainties, unknowns in the model, deviation as
consequences of the modelling of the production as well as the accuracy of the estimators used.
The requirement regarding accuracy is that the model to be developed should have a better accuracy
compared with the models now used at the DMO. It is hard to compare the accuracy of the model used
at the DMO and the model to be developed, because the two models are not the same type of models,
as described in 4.1.3. However if the accuracy of both models will be investigated, it will be possible to
compare the accuracy of the models.
4.2 Requirements regarding hull to be estimated The model does not have to be able to develop cost price estimation for every ship and construction
type. This part will describe the features and requirements for the ships for which the model can be
used. The first requirement in this part will be the requirement concerning the hull type and dimensions
of the ship. Another requirement in this part is a requirement regarding the structure philosophies of the
ship.
4.2.1 Hull type and dimensions
The model will be developed for the production of monohull vessels. The hull form should not matter as
long as the vessel is a monohull. The model will have constraints regarding the maximum main
dimensions of the hull to evaluate. At least it should be able to give estimations for all vessels between
the AMBV-class vessels and the concepts in the new project.
It has to be possible to change the position of the bulkheads and the decks as well as the number of
decks and bulkheads and the deck height of the vessel.
4.2.2 ‘Structure philosophies’
As described in 2.4 the structure of composite hull can have different forms. Each form has its own
features and a different production process. The main processes are the same however, some
construction philosophies has production steps others do not have. The model should thus have a
structure such that it is easy to switch production steps on and off.
Strength calculations have to be performed to make equivalent structures. It could be that not the whole
construction is known already if a cost estimation is necessary. Therefore, strength calculations should
be part of the cost estimation model. However, it is too much work to design the whole structure. Two
types of loading will be investigated, the first one is the global bending and the second one is the local
pressure caused by the water. Whether a construction can withstand the global bending moment is
determined by the dimensions of the midship section and the moment of inertia of the midship section.
Whether a construction can withstand the local pressure caused by the water is determined by the
thickness of the hull and the dimension of stiffeners if applicable.
4.3 Use during a project The aim of the model to be developed is to use in a project of the DMO. Some requirements are
connected with a project in which the model could be used. These requirements are: the applicability of
Production of composite ship hulls 30 4. Requirements model
the model, the possibility of the model to evaluate multiple products of the same hull type, the
possibility to compare different concepts within a project and to evaluate improvements in the
production process.
4.3.1 Applicability
In the beginning of a project, little is known about the constructions and details of a ship hull. A cost
estimation has already to be made in that stage to evaluate the affordability of the project. The model
should be able to generate a cost estimation based on this few information. However, during the project
more and more will be known about the construction and details of a ship. The model should be able to
cope with these developments within a project. A consequence of this requirement is that the
estimation model could be made more and more detailed.
4.3.2 Multiple production of the same hull
The model should be able to evaluate the effect of more ships in one series. The ability to evaluate series
of ships has two main reasons: non-recurrent cost and learning curve.
The production of ships can be separated in non-recurrent and recurrent cost. The recurrent cost occurs
at every produced ship. The non-recurrent costs are costs that occur ones in a project, independent on
the number of ships produced as a result of the project. The first ship of the project is relatively
expensive because the non-recurrent costs have to be paid. Every next ship is cheaper due to the
absence of the non-recurrent cost.
The other factor is the effect of the learning curve. The production of a hull takes less time when the hull
is produced several times. The personnel learn how to produce the ship. This effect is expected to have a
big influence of the price of each next vessel in a series.
4.3.3 Compare different concepts
Different design concepts are mostly developed in a project to get more insight in the product to be
developed and to determine the affordability of a concept. The importance of this requirement for the
model to deal with different concepts depends highly on the required computing power to generate a
cost price estimation for one of the concepts. If the required computing power is high, this needs
attention.
It needs at least attention to create the possibility to compare different concepts within a project easily
and to assess the change in the concepts rapidly.
4.3.4 Evaluation improvements production
The aim of this project is to indicate possible improvements in the production of composite hull
constructions. The model should be able to cope with these improvements. Proposals for improvements
have to be assessed easily on their impact on the production cost. Promising improvements should be
implemented easily to investigate the effect of the improvement more thoroughly.
These improvements could by either organizational improvements or improvement in the production
process. The improvement in the production process could vary between a total new production
technique and just an improvement in one of the steps of the production.
Production of composite ship hulls 31 5. Production process AMBV
5. Production process AMBV This chapter will describe the production of the AMBV class vessels. The production process of this vessel
is used as benchmark during the development and testing of the production model. The production of
the Alkmaar class vessel has been done in a special developed production hall in Alblasserdam. Giessen-
de Noord Marinebouw (GNM) has made the ships in this hall. The description of the production hall will
be the first part of the description of the production process. Only a part of the yard is relevant for the
production of the composite hull. However, this chapter will describe the whole process of the
production to create insight in the total the production of an AMBV and the consequences of the whole
production for the production of the hull. The second part will be the rough description of the steps
necessary for the production process and the third part will be a more detailed description of the
different steps and sub steps in the production. Several documents are used to describe the production
process of an AMBV (Hage, 1984), (GNM Naval construction, 1985) and (Giessen, 1977).
5.1 Lay out production yard GNM naval construction had to take a decision regarding the yard of the AMBV. After investigation, they
came to the following conclusions: the existing locations were not suitable for the production of an
AMBV and the production of the facility has to be two or three ships per year. So GNM decided to design
a total new yard to produce the fifteen AMBV’s for the RNLN. The production hall is designed based on
these conclusions (GNM Naval construction, 1985). Thus, major investments were necessary for the
production of the AMBV’s. The processes that could be done in facilities already available would not be
done in the production facility (GNM Naval construction, 1985).. The facility to be designed is thus an
assembly facility. That meant that storage place was necessary to store half products such as bulkheads,
and decks.
The advantage of the yard is that it is
specifically designed for the production of
this type of vessels. The designers of the
production location concluded that the
ideal situation for the production was a
production line. The production hall has to
be arranged like a production line, such as
the production of cars. The production cost
would be lower as a result of this choice.
The cost for producing the whole ship
simultaneously would be much more
expensive compared to production line
(GNM Naval construction, 1985). If the
whole ships are produced simultaneously,
the amount of tooling has to be twice or
thrice as much. The learning curve for the
Figure 9. Layout GNM yard (GNM Naval construction, 1985).
Production of composite ship hulls 32 5. Production process AMBV
production will also be higher in this situation.
This yard has been built in Alblasserdam. The layout of the yard can be found in figure 9. The design of
the yard is made for the production of ships up to a length of 75 meter and a lightweight of 1500 ton.
The costs to build the yard, initial tools and moulds were about 45 DG. 7 million of this was used for the
GRP production equipment and 6 million for the future use of the production facility (GNM Naval
construction, 1985).
The dimensions of the hall are 144 * 68 *23 metres. Along both sides are offices, stores and workplaces.
The yard has three main parts. The first part is the construction building. The ship will be built in this
building. The next parts are the facilities for launching of the ship. The ship is launched by the use of a
ships lift after completing the work in the main construction building. Once the ship is in the water, it is
brought to the quay where the mast is installed. The berth is also used for test and trials (GNM Naval
construction, 1985).
The main construction building consists of four different building stations. These stations can be found in
figure 10. In each of these building stations, the same production steps are executed for the production
of a ship. A flowchart of the building stations and a major description of the tasks in each station are
given later in this chapter. The production of a vessel starts in station 1, after a while the vessel is
transported to the next station.
The mould is located in station 1 and the production of the vessel is started if the required tasks on the
mould are finished. After 22 weeks, the production in the first station is finished and the hull will move
to the next station. The rest of the production processes related to the production of the composite
Figure 10. Layout van der Giessen-de Noord marinebouw (GNM Naval construction, 1985)
Production of composite ship hulls 33 5. Production process AMBV
parts of the vessel are executed in that station. The vessel moves to third station after completing these
proceedings. The outfitting of the vessel starts in the third station and at the end, the vessel will move to
the fourth station of the production. The main construction building is divided in to parts, separated with
a door. The outfitting takes places at the last two station of the production line. At these two stations,
not much composite work has to be done. The composite work of the hull is performed in the first two
station of the yard. This part of the building is air-conditioned. The temperature is between 19 °C and 23
°C and the relative humidity is 65%. The air-conditioners can maintain these values if the outdoor
temperature is between -12 °C and 30 °C. The allowed styrene concentration is 50 ppm, this is
maintained by the use of a ventilation system (GNM Naval construction, 1985).
The yard is equipped with four cranes. One travelling crane with a capacity of 2*10 ton for the first two
stations and two cranes, one 2.5-ton crane and one 10-ton crane, for station 3 and 4(GNM Naval
construction, 1985).
The transport between the different stations is done with air cushions. By using this transport systems
GNM was able to transport four ships to the next station in a single weekend (GNM Naval construction,
1985).
The last two stations are thus not relevant for the scope of this project. However they put a constraint
on the production in station 1 and station 2 because the hulls has to move to next station before one is
able to start up the production of a next vessel. So the time in the stations has to be the same time.
The organisation of GNM has been divided in three disciplines. One of these disciplines was the GRP-
work. At this part of the organisation, 115 people were employed (GNM Naval construction, 1985)..
5.1.1 Station 1
In station 1 starts the production of the ships. The skin and its stiffeners are made in this station. Also are
some of the decks and the bulkheads. The starboard side of the mould is mounted to the floor and the
portside can be moved. The hull can be moved to the next station if the portside of the mould is
separated from the starboard side. Four moveable platforms can be used for the production of the hull.
The production starts in the middle of the ship and moves in both directions. The production is
cascading. Layers are made to reach the required laminate thickness. The production of the centre girder
and the sider girder can start if the required laminate thickness is reached. If the girder are produced the
transverse stiffeners can be brought on the hull. The production of the skin, girders and the stiffeners
can be done simultaneously in this way.
Important to note for the production are the different layers in the skin. The skin consists of a so-called
buffer layer and a so-called strength layer. The buffer layer is to maintain the water tightness of the ship,
it gives some strength but its main goal is keep the water outside. The strength layer is meant to gain the
strength and stiffness of the hull structure (Van Der Giessen-de Noord, 1984). The difference in layer
type has consequences for the production because the fibre content of the strength layer is higher as the
fibre content of the buffer layer. The fibre content of the layers differs but also the type of woven
rovings used for the layers differs.
A loop system is used to bring the resin into the hull. Buckets are used to transport the resin to the place
where it has to be applied.
Production of composite ship hulls 34 5. Production process AMBV
5.1.2 Station 2
The remaining composite work will be done in the second station. The remaining decks and bulkheads
are placed in this area. The composite work is finished with exception of the superstructure which will be
placed in the third station.
5.1.3 Station 3
The vessel is moved to the other part of the production hall. This part of the production hall is meant for
the outfitting of the vessel. The two parts of the building are separated with big doors. The outfitting
part of the hall does not require the same stringent climate control as the other part. So separating the
two parts leads to fewer costs.
Some composite work is done there as well. The superstructure is placed in the third station. The
superstructure is largely build in sandwich composite material. Only the wheelhouse is made from
another material, namely aluminium. The panels for the sandwich are made at another company and
placed on the ship by GNM.
5.1.4 Station 4
Station 4 is the other station for the outfitting of the vessels. No structural composite work is done in this
station. Parts have to be connected to the structural components of the hull. Some embedding is
necessary to make the connection between a part and the hull. However, this work is only a small part.
5.2 Production steps The steps necessary for the production of a hull for an AMBV are described in this part of this chapter.
The steps described are the processes that take place in station 1 and station 2. The production of the
superstructure, done in station 3, will also be described.
Each type of production step is necessary for the production of the hull and has to be repeated if a next
hull has to be produced. An indication for a measure to estimate the amount of man-hours related to the
production steps is also given in the description of the processes. The order of the production steps as
described in this chapter does not necessarily reflect the order in the actual production of an AMBV.
Most of the processes are done several times during the production of a composite hull.
5.2.1 Make mould ready
The mould consist of different parts which has to be put together to make the total mould. The mould
has to be cleaned and build together before the actual production of the hull can start. The cleaning can
be done with water or toluene depending on which material is used for the mould.
The production can start if the dimensions are put on the mould. The amount of hours necessary to
make the mould ready depends on the size of the mould and the number of parts to be assembled.
The measure are hours per time that the mould has to be made ready thus, a fixed number of hours for
the production of each ship.
5.2.2 Apply release-/separation agent
A release-/ separation agent has to be brought on the mould to prevent that the materials bonds to the
mould. This agent has to be brought on the mould to ensure that the mould and the structure will be
Production of composite ship hulls 35 5. Production process AMBV
separated if the product has to leave the mould. This step is necessary for the mould of the decks,
bulkheads and hull.
A metric for the production time for the application of the release- /separation agent are the amount of
square meters a worker is able to treat in one hour.
5.2.3 Lay-up fibres
The fibres have to be brought on the mould or the already existing structure. The fibre mats are laid
down and one has to be fasten it to ensure that the will not move when the lamination starts. These
mats have a weight of 580 gram/m2. These mats are applied dry and fixed such that they not can move.
Each layer of fibres has to be laid down separately. Included in this task is the customisation of the fibre
mats if necessary. The lay-up of the fibre includes the required work for the transportation of the fibres
from the storage to the production side. The fibres have to be laid up for the stiffeners and for the skin.
It might be that the production rate for these two differs.
A metric for the performance indicator of the lay-up of the fibre is the amount of square meters that can
be laid down in one hour.
5.2.4 Lamination
The resin has to be applied to produce the composite structure. Each fibre layer has to be laminate
separately. The lamination includes also the work to be done for the transport from the dosing unit to
the place where the resin has to be applied. The lamination includes also the work necessary preparing
the resin for the production by adding the accelerator and the catalyst. The resin is applied by using paint
rollers. The speed of the lamination depends on which part of the structure will be laminated. The
lamination of large areas such as deck or skin goes faster than the lamination of much smaller areas as
the stiffeners and knees.
A metric for the performance of the lamination of the fibre is the amount of square meters that can be
laminated in one hour.
5.2.5 Scour surface
Sometimes it might be necessary to scour surface before going to the next step in the production
process. For instance if the stiffeners has to be made on the skin, the skin has to be scoured before the
production of the stiffeners can take place. However, scouring is also necessary if a laminate is made on
a laminate that has cured for more than eight days. (Van der Giessen - de Noord Marinebouw BV, 85)
A metric for the scouring of material is the amount of square meters that can be scoured in one hour.
5.2.6 Make water courses holes
Some parts of the structure, which are not watertight, contain watercourses holes. Each of these holes
has to be made separately. The holes are half circle which have to be laminated on the structure.
A metric for production is the number of watercourse holes, which can be made in one hour.
Production of composite ship hulls 36 5. Production process AMBV
5.2.7 Make foam core
The stiffeners on the decks, skin and bulkheads are made on a foam core. These foam cores are the
inside dimensions of the stiffeners. These foam cores are made from blocks and have to be sawn to the
right dimensions. Foam cores are also applied for the production of the knees.
A metric for the production of the foam core is meter per hour for the stiffeners and number per hour
for the foam cores for the knees. It also important to distinguish whether a foam core has to be made
underhand or overhand.
5.2.8 Glue foam cores
If the foam cores are made they have to be made fixed on the surface. This is doing by gluing the foam
cores to the underlying surface.
A metric for gluing the foam cores is the length of foam blocks that can be glued in one hour or the
number of foam core for the knees that can be made in one hour.
5.2.9 Apply rubber emulsion
A rubber emulsion is applied on the foam cores before the fibres are laid down on the foam core. The
rubber emulsion has to be applied to prevent that the resin draws into the material. The rubber
emulsion is brought on the foam core with a spatula.
A metric for how much rubber emulsion can be treated is the amount of area that can be done in one
hour.
5.2.10 Drilling holes
Glass pens are used to prevent the stiffeners releasing the surface. The glass pens are place in holes.
These holes have to be made before. So, holes have to be drilled and to be cleaned after the drilling of
the holes.
A metric for the drilling of the holes is the number of holes that can be made in one hour.
5.2.11 Glue glas pens
When the holes have been made, the glass pens can be placed in the holes. These glass pens are glued
into the hole. The glues have to be put in the hole and one has to press the pen in the hole. The glass
pens have to be controlled a few minutes after they are placed. The have to be pressed in the hole again.
This activity contains also the mixing of the glue, the resin and harder has to be put together.
A metric for gluing of the pens is the number of pens that can be placed in one hour.
5.2.12 Positioning of the components of the ship
The decks and the bulkheads are made separately. GNM has outsourced the production of these
components. The deck and bulkheads are transported to the production facility of the AMBV. The decks
and bulkheads are placed in the ship by the cranes in the production hall.
A metric for the positioning of the components is the amount of man-hours necessary for the positioning
of one component.
Production of composite ship hulls 37 5. Production process AMBV
5.2.13 Making angle connection deck/bulkheads/skin
A laminate is made at the connection between the decks, bulkheads and skin to ensure the stiffness of
the structure. This laminate is a so-called angle lamination. The laminate is made with glass mats and
resin.
5.2.14 Production sandwich panel
The panels for the superstructure are basically two laminates with are core between these laminates.
The extra work compared to a normal laminate is thus only the connection between the core and the
laminates. The production rate can thus be deduced from the production parameters for the laying of
the fibres and the lamination of the fibres with the resin.
5.2.15 Placing sandwich panel
After the production of a sandwich panel, they have to be placed on the ship. The panel has to be
connected to the deck and some other panels. The sandwich panels have to be brought to the right
position and afterwards the connection can be made.
A metric for speed of the placing of the sandwich panels is the connection length, which can be made in
one hour.
5.2.16 Remove release-/separation agent
The release-/ separation agent has to be removed when the mould has to be prepared for the next hull.
This has to be done before the mould for the decks, bulkheads and the hull. The release-/separation
agent is removed by washing the moulds with water or toluene, depending on the material used on the
mould.
A metric for the production rate of the removing of the release-/separation agent is the amount of
square meters cleaned in one hour.
5.2.17 Break off mould
The mould has to be broken off if the production of the hull is complete to a phase where the hull can
leave the mould. The different parts have to be removed in order to prepare the transport from the first
production station to the next one.
The estimator for the production is the amount of man-hours for removing one part of the mould.
5.3 Production order AMBV As described before, the production hall for the AMBV has four stations for the production of AMBV’s. A
flowchart of the process can be found in figure 11. The aim of the cost price estimation is to estimate the
cost for the production of a composite hull. The first two station are the station where the main part of
the composite work for the hull of an AMBV. The main focus will thus be on this station. The third station
contains the installation of the superstructure on the ship. This is also incorporated in the research
because it is composite work to be done. The superstructure is only a small part of the work done in
station 3.
Production of composite ship hulls 38 5. Production process AMBV
Each station contains one AMBV under construction. The four ships under construction move to the next
station simultaneously when they have been 22 weeks in a station. This is important to consider because
when the stations are not ready simultaneously, the shift cannot take place. In that case, only a few
people are able to work and the others not. A delay at one station costs a lot of money. For the
description of the process as described, it is assumed that if the stations are always ready at the same
time.
Flowcharts for the production of the composite work in station 1 and station 2 can be found in figure 12
and figure 13.
A figure of the first two station in the building hall is shown in figure 15. The vessel on the left is the
vessel in the first building station, the vessel on the right is in the second building station. Figure 16
shows the last two building stations. The vessel in the front of the photo is in the third station and the
vessel in the back is in the fourth production stations.
Main scope investigation
SSc Station 1 Station 2
Station 3
Station 4
Figure 11. Flowchart production process AMBV.
Production of composite ship hulls 39 5. Production process AMBV
Figure 12. Flowchart station 1.
Production of composite ship hulls 40 5. Production process AMBV
Figure 13. Flowchart station 2.
Production of composite ship hulls 41 5. Production process AMBV
The production of the hull starts with the preparation of the building for the production of a new AMBV. The materials for the production have to be available, everything has to be ready. Both station 1 and 2 have their own preparations for the production. 5.3.1 Station 1 production order
The next step is to prepare the mould for the production of a new ship. The mould has to be cleaned and the parts of the mould have to be assembled. When the mould is assembled, the dimensioning can be put on the mould to ensure that the hull will be build according to the drawings. The release-/ separation agent can be applied on the mould. The moulds of the decks and bulkheads have also to be prepared for the production. The same process as for the mould of the hull is necessary. The production of a hull can the start if the mould is ready. The production of the hull starts in the middle of the mould. This has the advantage that one is able to work in two directions, the front direction and the back direction. The first step is lay-up of the fibres mats. The lamination of the fibres can start if the fibres are laid on their place. The process of lay-up of the fibres and lamination of the fibres has to be repeated until the required thickness has been achieved. The production is done butt wise as can be seen in figure 14 in that way the production propagates along the mould (Giessen, 1977). At a certain time, the skin reaches the required thickness at the start of the production point. Each following step a bigger area reaches the required thickness. If the area is big enough the production of the transverse stiffeners can start. The foam cores are glued to the skin and the stiffener is laminated on that foam core. The production of the transverse stiffeners can start after the production of the transverse stiffener. The longitudinal stiffeners are produced in the same way as the transverse stiffeners. The decks and the bulkheads are produced while the skin and the stiffeners are produced. The production of these components is outsourced and they are transported to the storage to be installed on the vessel if the production reaches the stage where the components have to be installed. The bulkheads are installed if the longitudinal stiffeners are completed. The decks are put in the vessel after the bulkheads. Not all decks and bulkheads are installed in the first station. The hull moves to the next station if the stiffness is high enough to move the structure to the next station. The structure and the mould are separated if the production in the first station is finished. The mould can be demounted if the structure and the mould are separated. The hull is moved to the next station by means of air cushions. 5.3.2 Station 2 production order
The production in the second station contains the installation of the decks and the bulkheads not yet
installed. The knees between the skin and the bulkheads can be made if the bulkheads are made.
When all bulkheads are in the vessel, the decks are placed in the vessel. The knees between the skin
and the deck and the deck and the bulkheads can be made when the decks are placed. The angle
laminates are made when the knees are finished.
Figure 14. Butt wise built laminate.
Production of composite ship hulls 42 5. Production process AMBV
5.3.3 Station 3 production order
The superstructure is placed on this vessel in this station. The production of the sandwich panels is
outsourced to another company. The panels are produced on the foam core. The laminate is made
on one side first, then the foam will be turned and the laminate on the other side will be made.
The panels are placed on the vessel with a crane. If the sandwich panel is on the right position, the
connection to the hull or other materials has to be made. Stiffeners are not made on the panels
because the core gives the stiffness to the materials and the panels have a corrugated form.
Figure 15. First two stations.
Figure 16. Last two stations
Production of composite ship hulls 43 6. Conceptual model
6. Conceptual model The model will be developed to make an estimation for the production costs for a composite ship
hull. The AMBV class is thus used as benchmark for the model. The set up for the concept model can
be found in figure 17. The concept model starts, if necessary, with the determination of the
structure. This part determines the dimensions of the structure. The second part is the actual cost
price estimation model. The first step is the translation of the main dimensions and the structure
dimensions into production dimensions. The production dimensions can be used for the
determination of the overhead cost, the material cost and the man-hour cost. These parts can be
used for the calculation of the cost for a series of ships. This chapter describes all the aspects of the
concept model.
6.1 Structure model The model should be able to make cost estimations for different ships hulls. The idea is to be able to
compare different production techniques and structure philosophies. The ship hulls should be
comparable to each other. One structure is known, in this case the structure for the AMBV class
vessel. This is a single skin stiffened construction. The other structures to be calculated have to be
reviewed and designed to same criteria as the AMBV class vessel. Two types of loading will be
reviewed. The first one is the global bending moment and the other is the local stresses due to the
water pressure. These types of loadings are assessed to be the loadings determining the
construction. Important to keep in mind is that the aim of the structure models is not to design a
structure but to be a step between a concept design and the cost price estimation model.
The structure models are used to generate the information necessary to make a cost price
estimation. The structure model generates the dimensions of the construction. If a construction is
already known, it is no longer necessary to use the structure model. The structure model will only be
used in the beginning of project when not much is known about the structure. During the project, the
information of the structure becomes more and more and the structure model is no longer
necessary.
6.1.1 Global bending moment
Global bending moment is the moment caused due to the distribution of the weight of the ship and
the buoyancy. The stresses cause by the global bending moment can be calculated with the section
modulus of the midship section. If the proposed structure has the same material as the old structure,
the section modulus has to be same. If a proposed structure has another material, the maximum
allowable global bending moment has to be the same.
6.1.2 Local water pressure
The pressure on the skin caused by the water pressure has to be evaluated as well. Finite element
calculations to design a comparable structure will be used. Two terms of the water pressure will be
used for the calculations of the stresses. The first one is the static water pressure. This is the pressure
on the skin if the vessel is in flat water, see figure 18 . The second term is the dynamic water pressure
as a result of the relative motion, see figure 19. This model will give the local stresses and local
displacements cause by the water pressure.
Production of composite ship hulls 44 6. Conceptual model
Figure 17. Schematic overview cost price estimation model.
Production of composite ship hulls 45 6. Conceptual model
Figure 18. Static water pressure (Van der Giessen - de Noord marinebouw BV, 1988)
Figure 19. Dynamic pressure caused by the relative motion.
Production of composite ship hulls 46 6. Conceptual model
6.2 Cost price estimation model The information from the structure model, if necessary or the information already available can be
used for the cost price estimation. The cost price estimation model will be divided in several parts to
calculate the price for the production of a hull properly.
6.2.1 Dimensions
Some dimensions are important for the production. In the first part of the model the user will be able
to provide the dimensions of the vessel. Important dimension for the production process are the
main dimensions, stiffener spacing, place of decks and bulkheads. The dimension of the construction
at the midship section and the dimensions of the stiffener. The ship will be divided in three parts to
deal with the possibility of changes in stiffener spacing. The length at which the stiffener spacing has
to change has to be determined.
The aim of the model is to give a price estimation for the production of monohull ships. It should be
able to give a price estimation for different hull forms. Therefore, it is important to develop the
model such that the calculations are independent of the input value of the hull form. In the concept
phase of a project, the hull form is globally known. This geometrical form can be used as input for the
model. The geometrical form of the ship can be used to calculate the area of the skin and cross
section of the ship, circumferences of the cross section and so on. The input of these values should
be separated from calculations. To calculate the effect of a change in hull form one should be able to
change the input of the hull form and immediately get a new cost price estimation.
The combination of the information of the hull form and the dimensions of the ship can be used to
calculated areas of the decks, bulkheads and skin; total stiffener length, volume of the materials and
all other information necessary for the cost price estimation.
This part of the model contains the relevant production metric generator. This is the transformation
form structural dimensions to relevant production metrics, see figure 17.
6.2.2 Production parameters
The second part of the price estimation model are the production parameters. These parameters
determine the final cost price. The will be put together to create an overview and to be able to see
the effects of change in the parameters easily.
The production steps has been described in chapter 5. For each of these steps the production rate
will be determined. This part of the production model contains also some other production
parameters such as the mass percentage fibre in the different layers, the composition of the resin for
the different layers and the costs of the material.
6.2.3 Production process en man-hours
The third part of the model is the production process and the calculations of the man-hours. The
production process for an AMBV class vessel has been described in chapter 5. These process steps
have been incorporated in the model, this is the man-hour calculator, see figure 17. The production
process will be described such that it is possible to look at the production speed for each process and
for different parts of the vessel. This is important to be able determine which processes are the
bottlenecks of the production and to calculate the effect of change in the production process.
Another aspect is the planning of the production in a latter stadium of the project. The production
process can be planned easily with a detailed calculated production process and the required sub
steps.
Production of composite ship hulls 47 6. Conceptual model
The information about the dimensions (see 6.2.1), the production parameters (see 6.2.2) and the
process model leads to the man-hours necessary for the production of a certain item.
Two aspects are important to be able to assess changes in the production process. The first one is the
calculations of different sub steps in two processes. The production of stiffeners for instance has
several sub steps. To assess the effect of stiffeners in the structure it is important to determine the
total time of the production of the stiffeners easily. A second aspect is the total time for a certain
activity. For instance, the total time required for the layup of fibres. The lay-up of fibres takes place
at different stage in the production, first on the skin, on the decks, on the bulkheads and on the
stiffeners. Therefore, a quick overview of main processes in the production is necessary to assess the
impact of possible changes in the production process. The output of this part of the model is the
required number of man-hours to build a ship.
6.2.4 Material cost
The material costs are another part of the calculations. The weight of the material can be determined
with the part of the model where the dimensions are given.
The amount of volume necessary for each material can easily be determined with the known
dimensions. The density of the materials has to be known and the total weight for each material can
be determined. This is the weight calculator, see figure 17. The total amount of material is an
estimation for the lightweight of the ship.
For the production of composite materials, different materials are necessary. The main materials are
the fibres and the resin. Other materials are the foam to make the stiffeners and the balsa, which is
the core of the material. The cost for the material can be determined with the cost/kg. This is the
material costs calculator, see figure 17.
6.2.5 Non man-hour related costs
The fifth part of the model are the non man-hour related costs. Different costs aspect cannot be
caught with man-hour or material costs for a single ship. These are the so-called not man-hour
related costs. Among these costs are the costs for the investments, the investment for the yard, the
overhead, assurances, transportation cost, stock, mould and so on. Most of these costs are fixed
either in yearly production or for a series of ships. Some of them could be fixed cost per ship. This is
the overhead cost calculator, see figure 17.
6.2.6 Learning curve
The learning curve is the vital element of the series cost calculator, see figure 17. The not man-hour
related cost are independent on the number of ships to be produced. The material costs are linear
with the number of ships to be build. However, the man-hours necessary to produce a series of ships
are not linear. A learning curve is a model for the effect of producing a single structure several times.
The production of the parts will become faster if more than one structure is made. Learning can take
place on two aspects, the first one is the labour learning. The second one is the organizational
learning (NATO NG/6 Specialist Team on Ship Costing, 2001). NATO gives a mathematical relation for
the learning curve, see Eq. 6.1 (NATO NG/6 Specialist Team on Ship Costing, 2001). DMO uses a
somewhat different mathematical relation, Eq. 6.2. Important to mention is the difference in the two
formulas. NATO gives a formula with an average building time for a series. DMO uses a formula,
which gives a building time for a certain ship produced as part of a series. To compare those formulas
the average building time for the DMO has to be determined. The difference between the two
Production of composite ship hulls 48 6. Conceptual model
formulas is shown in figure 20. This figure shows that there is very little difference in the formula
used by DMO and the formula of NATO. The metric of learning for the graph in figure 20 is 90%. A
learning curve between 90% and 95% for labour learning is not uncommon for naval shipbuilding
(NATO NG/6 Specialist Team on Ship Costing, 2001).
Production of composite ship hulls 49 6. Conceptual model
( )
( )
Eq. 6.1
( )
( )
( )
Eq. 6.2
Figure 20. Difference between NATA formula and the DMO formula for the learning curve.
75,0%
80,0%
85,0%
90,0%
95,0%
100,0%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Ave
rage
bu
ildin
g ti
me
of
the
sh
ip t
o b
e b
uild
ed
Number of ships to be build
NATO formula vs DMO formula
NATO formula
DMO-formula
Production of composite ship hulls 50 7. Parameters production model
7. Parameters production model Important for the model are the parameters. The accuracy of the parameters in the production
model is important for the final result of the model. The parameters will be described in this model.
7.1 Process parameters The steps necessary for the production of a composite vessel can be found in chapter 5.2. These
production steps are used in the model and the production rate has to be estimated. Two documents
are used to estimate these parameters. The first one is a report concerning the production in the first
station of the yard of GNM (Lohuizen, 1985). The second one is a GNM calculation (Van der Giessen -
De Noord Marinebouw BV, 1983).
7.1.1 Preparatory work
Before the production of the hull can start, several preparations have to be made. The assembly,
disassembly of the mall and the move to station 2 takes 2820 hours (Van der Giessen - De Noord
Marinebouw BV, 1983). This is including the building of the scaffolding necessary to make the GRP
hull. The assumption is made that half of the time is necessary for the assembly and half of it for the
disassembly. Another assumption is that the mould consists of six parts. So the assembly and
disassembly of one part of the mould needs 235 hours.
A separation medium has to be brought on the mould. GNM calculates that it take 600 hours (Van
der Giessen - De Noord Marinebouw BV, 1983) to apply that medium on the mould, resulting in a
production speed of 1,33 m2/h.
The measurements dimensioning has to be brought on the mould. The production speed is 2,34
m2/h.
7.1.2 Producing laminate
Different parts in the vessel have different production characteristics. The skin, stiffeners, girders and
the decks/bulkheads has their own production speed. The value for this speed can be found in table
3 (Lohuizen, 1985). A ratio between these production speeds can be found in the last column of that
table. This ratio is introduced to have one production speed in the model and to correct the
production of the other parts with the ratio.
Part of the ship Production speed (kg/h) Ratio
Skin 3,8 1,00 Stiffeners 1,8 0,47 Girders 1,2 0,32 Decks/bulkheads 3,0 0,79
Table 3. Production speed several part of the ship.
The GNM calculations gives value for the weight of the skin and the production time of the skin (Van
der Giessen - De Noord Marinebouw BV, 1983), see table 4 there is a remarkable difference between
the production speed of Lohuizen and the GNM calculation. But one has to keep in mind that during
the production of the skin several parts has to be cured when the previous layer is made more than
eight days ago, as described in 5.2.5.
According to Lohuizen the ratio between scouring of the material and the lamination of the material
is 0,36 (Lohuizen, 1985). Lohuizen takes the lamination as both the lay-up of the material and the
Production of composite ship hulls 51 7. Parameters production model
impregnation of the material. Based on the total amount for 17.900 hours necessary for the
production of the skin according to GNM (Van der Giessen - De Noord Marinebouw BV, 1983), the
amount of hours necessary for the production lay-up and lamination of the skin is 13.162 hour and
for the scouring 4.738 hours.
The total area of all the layers required to create the skin can be calculated. This area is 13.386 m2.
This has to be laid down and laminated in 13.162 hours resulting in a production speed of the
lamination and the lay-up of the material of 1,017 m2/hour. The weight of the skin is 40.049 kg (Van
der Giessen - De Noord Marinebouw BV, 1983). The weight per square meter is thus 2,99 kg.
Resulting in a production speed of 3,04 kg/hour for the lay-up and lamination of the material. There
is a difference with the production speed as presented in table 3. However, it is believed that the
GNM calculations have to be preferred in the calculations due to the measure of the production of
the first ship. The higher production speed in table 3 could be the result of a learning curve. Lohuizen
presented his report in 1985 while the production started in 1983. The ratio between the production
speed of the skin, stiffeners, girders and decks/bulkheads is maintained because the learning effect
does not affect the ratio between these values.
The next step to investigate is to determine the production of the lay-up and the lamination
separately. Lohuizen does not give values for the lay-up and lamination separately. However GNM
has given separated values for the production of the buffer layer and the strength layer (Van der
Giessen - De Noord Marinebouw BV, 1983), see table 4. The difference in fibre content, and thus the
difference in production speed between the lay-up of the fibres and the lamination, could be an
explanatory parameter for the difference in production speed of the buffer layer and strength layer.
A negative coefficient is necessary to solve that problem. The difference in lay-up speed and
lamination can thus not declare the difference between the production speed in the buffer layer and
the strength layer. The difference might be explained by the difference in vertical distance to keel. It
is easier to produce the composite close to the keel compared to composite further away from the
keel. The buffer layer has a constant thickness of 5 mm along the skin. The thickness of the strength
layer differs from 29 mm at the bottom of the ship to 13 mm in the sides of the ship, see appendix 1.
The strength layer has thus relative much volume close to the keel. This can explain the difference in
production speed. However, in the model this difference will be neglected due to the small weight of
the buffer layer compared to the strength layer and due to the few data available. It is assumed that
the time necessary for the lay-up of one square meter and the lamination of one square meter is the
same. Resulting in a production speed for lay-up of 2,03 m2, as well as for the lamination.
Buffer layer Strength layer
Fibre content (%) 25 50
Weight (kg) 3.222 36.827
Production (h) 2.400 15.500
Production speed (kg/h) 1,3425 2,3759
Table 4. Characteristics buffer layer and strength layer.
7.1.3 Scouring
The total time necessary for the scouring of the material is known based on the result of the product.
If a certain part has cured for eight days, it is necessary to scour the material as described in 5.2.5.
The assumption is made that half of the layers requires scouring before the lay-up of the material can
Production of composite ship hulls 52 7. Parameters production model
take place. Based on this assumption, 6.693 m2 has to be scoured in 4.738 hours, see 7.1.2. The
production speed for the scouring is thus 1,41 m2/h.
7.1.4 Making stiffeners
Before the production of the stiffeners on the skin and the stern can start the surface below the
stiffeners has to be scoured. Based on photos available of the production of the AMBV it was
estimated that the area to be scoured is 0,2m plus the breadth of the stiffeners including the flange.
Resulting in an area with a width of 0,5m that has to be scoured.
The estimated time for the production of the stiffeners on the skin is 15.170 hours (Van der Giessen -
De Noord Marinebouw BV, 1983). Based on the data described in 7.1.2 and 7.1.3 1864 hours are still
available for remaining steps in the production of the stiffeners. The assumption for the work
necessary for the scouring while making the stiffeners is that 1 out of 4 layers has to be scoured.
The 1953 hours has to be divided of the making the foam core, gluing the foam cores to the skin,
drilling the holes, applying the rubber emulsion on the foam core and for the glass pens and place
the glass pens and producing the angle laminate. The assumption is made that the same amount of
time is necessary to make the cores, to make the angle laminate and to place the glass pens, thus
650 hours for each of them.
The assumption for the production of the foam core is that the process of making the foam core
takes ½ of the time and the gluing of the foam core ¼ and ¼ for applying the rubber emulsion on the
foam core. Resulting in a production speed for making the foam core of 6,17 m/h, gluing the foam
core with 12,34 m/h and applying the rubber with 3,47 m2/h.
The assumption for the glass pens is that it takes the same time to drill a hole and to place a hole in
the hole. Both of them can take 325 hours in total for the production of the stiffeners on the skin.
The production speed is drilling 123 holes per hour and placing 123 pens per hour.
The total length of the angle laminate to be produced for the stiffeners is 2005,7 m. Resulting in a
production of the angle laminate 3,1 m/h.
7.1.5 Placing decks and bulkheads
The assumption is made that the placing of the decks and bulkheads takes a certain amount of time
for the decks and de bulkheads. GNM accounts 3.270 hours for the placing of the bulkheads,
approximately 250 hour per bulkhead and 16.570 for the placing of the decks, approximately 1.000
hours per part of the deck (Van der Giessen - De Noord Marinebouw BV, 1983).
Seams are filled when the decks and bulkheads are place. The filling of the seams is assumed to have
the same production as the angle laminate.
7.1.6 Super structure
The total production the placing of the superstructure is 7000 hours (Van der Giessen - De Noord
Marinebouw BV, 1983), approximately 1750 hours for each of the four panels. The area of the
sandwich panels is estimated to be 200 m2. The assumption is that it takes 10 hours to customize the
balsa. The balsa has to be glued to the laminates. The assumption that the production speed is the
same as applying the rubber emulsion to the stiffeners 3,47 m2/h.
7.1.7 Overview process parameter
A short overview of the process parameters related to the production of the hull can be found in
table 5.
Production of composite ship hulls 53 7. Parameters production model
Parameter Value
Hand lay-up 2,03 m2/h
Lamination 2,03 m2/h
Scouring 1,41 m2/h
Make foam core stiffener 6,17 m/h
Applying rubber emulsion 3,47 m2/h
Drill holes 123
Place pens 123
Glue balsawood 3,47 m2/h
Make angle laminate 3,1 m/h
Make measurements dimensioning 2,34 m2/h
Glue foam core 12,34
Filling seams 3,1 m/h
Place bulkhead 250 h/part
Place deck 1000 h/part
Make balsa wood 10 m2/h
Place sandwich panel 1750 h/part
Table 5. Overview process parameters.
7.2 Structure and material parameters Several parameters to be used in the production are related to the structure and material to be used
for the production of the hull. This paragraph gives an overview of these parameters.
7.2.1 Number of layers
The number of layers necessary to reach a certain thickness depends on the thickness and whether
the part to be made is a stiffener or a simple surface. The value for a certain thicknesses can be
found in table 6. These values are used for a regression analysis of the relation between the thickness
and the required number of layers. This analysis can be found in figure 21. The equations can be
found in eq. 7.1 and eq. 7.2.
Thickness (mm) Layers skin layers stiffeners
16 9 12
18 11 14
20 12 15
24 15 18
25 16 19
27 17 20
30 20 23
34 22 25
41 27 30
52 36 39
60 41 44
Table 6. Thickness vs. layers
Production of composite ship hulls 54 7. Parameters production model
Figure 21. Graph thickness vs. layers.
Eq. 7.1
Eq. 7.2
7.2.2 Buffer layer and strength layer
The skins consist of two types of material. The first one is the so-called buffer layer. This layer has
better water immersion properties and is on the outside of the skin. The other layer is the so-called
strength layer. This layer takes caries the most of the load on the skin. The buffer layer and the
strength layer differ in composition, fibre content and strength properties. The thickness and mass
percentage fibre content can be found in table 7. The weight of the matrix and the fibre can be found
in table 8. The mixing ratio of the different components of the matrix can be found in table 9.
Material Weight (ton/m3)
Matrix 1,166
Fibre 2,54
Strength layer 1,853
0
5
10
15
20
25
30
35
40
45
50
0 10 20 30 40 50 60 70
Laye
rs
Thickness
Thickness vs. layers
Skin
Stiffener
Linear (Skin)
Linear (Stiffener)
Mass percentage fibre strength layer 50%
Mass percentage fibre buffer layer 25%
Thickness buffer layer 5
Table 7. Mass percentage fibre and thickness buffer layer
Production of composite ship hulls 55 7. Parameters production model
Buffer layer 1,51
Table 8. Weight composite material
Component Strength layer
Buffer layer
Resin 100 100
Catalyst 2 3
accelerator 0,25 0,5
Total 102,25 103,5
Table 9. Mixing ratio matrix
7.2.3 Glass pins
Important for the amount of glass pens to be put in the structure depends on distance between the
glass pins. GNM has specified that the distance between the glass pins is 0,05m. The assumption for
the cost of a glass pin is €0,10
7.3 Cost parameters 7.3.1 Inflation rate
Some of the prices are known for the past. These prices have to be corrected for the price today. This
can be done with an inflation rate. DMO uses a 2.5% inflation rate. This rate is used also in the
model.
7.3.2 Material prices
To determine the total cost price, data regarding the price of material and the cost of man-hour is necessary to determine. Information from different source is found to define the price of the material. The price found in the source is converted to prices nowadays with the inflation rate and it is also converted to euros. An overview of some price found is given in table 10. The sources are numbered. The first source is a paper published in 2001 (Das, 2001). The second are data published in 1993. The third are data from 2000 (Shenoi & Dodkins, 2000). The fourth are data from 1988 (Smith, 1990) and the fifth from 1995 (Eric Green Associates, 1999).
E-glass fibre (€/kg)
S-glass fibre (€/kg)
Carbon fibre (€/kg)
Epoxy resin (€/kg)
Polyester resin (€/kg)
Vinyl ester resin (€/kg)
1 2,28 --- 18,12 --- --- --- 2 2,52 17,64 88,18 7,56 3,02 5,04 3 --- --- --- 7,06 2,12 3,89 4 1,82 22,80 142,52 8,79 2,43 6,89 5 3,01 13,22 31,73 10,31 3,15 4,60 Average 2,41 16,77 70,17 8,43 2,68 5,10 Table 10. Cost price different material to be used.
Production of composite ship hulls 56 7. Parameters production model
7.3.3 Investment
For the investment, it is important to know the cost of the yard and the mould. For the model the
cost for the yard including the equipment is taken as whole. The second part is the mould to be used
for the production of the hulls. Both of them are assumed to be dependent on the length of the ship.
The total investment for the yard and the mould was 45 million Dutch Guilder (DG) for GNM,
including 6 million DG for invested for future use of the facility (GNM Naval construction, 1985). The
cost of 6 million DG for the future use of the production facility will not be implemented in the cost
price model, because the cost are not related to the production of the Alkmaar class vessels. The
costs for a mould were 7- 15 million DG for a vessel of 140m long in 1982 (Brüggemann, 1984). Using
10 million DG, the cost for each meter of the ship is 70.000 DG, which is approximately €32.000/m.
The remaining investments cost are 36 million DG or 707.000 per meter ship, which is approximately
€321.000/m. However, one has to keep in mind that parts of the production are done on location
other than the production facility in Alblasserdam. Therefore, the investment costs per meter are
increased with 10%, becoming thus €353.000/m.
Production of composite ship hulls 57 8. Experimental model
8. Experimental model
This chapter gives a description of the developed production model. The aim of the model is to
estimate the cost of the production of composite vessels. The model shall be able to estimate the
cost for different structure philosophies as well as different production techniques. The model has
several parts. The first part is the characteristics of the ship to be estimated. The second parts are the
production parameters. The third part is actual building process of the ship. The fourth parts contains
the calculations to predict the material cost and the last one are the not man-hour related cost. Each
of these parts will be described separately.
The model is developed to be able to estimate the cost for a general composite ship. However, the
description of the model will be given with reference to the AMBV.
Some parts are modelled with the use of macros in Microsoft Excel 2010. The macro will not be
described in detail. However, a short description of the most important macro’s are given.
8.1 Dimensions ship In this part of the model the most important dimensions can be filled in. This part of the model has
basically two parts. The first part is the part where the information of the hull form has to filled in.
The second one is the more specific characteristics of the ship. These two parts are used to be able to
do the calculations for different hull forms and sizes of the ship.
8.1.1 Hull form
Several characteristics of the hull are used to describe the
hull. The Rhino model of the AMBV is used to obtain this
data.
The distribution in transverse and longitudinal direction of
the ship can be found in figure 22. The subdivision in the
transverse direction is done every 5 meter. For the
subdivision longitudinal direction are chosen some
waterlines. Waterline 5, 10 and 15 are used. The height of
the waterlines related to the keel of the ship can be found in
table 11. This subdivision result in several areas as can be
seen in figure 22. The area of these surfaces is the input for
the model. They can be found in fifth, sixth, seventh and
eight column of appendix 2. The first rows of that table are
the lower and upper value of the range. The other value in
the table is based on the lower value of the range.
The width of the ship can also be obtained from the Rhino
model of the AMBV. The width of the ship is measured at the
height of the tween decks, the main deck and the forecastle
deck, see figure 23. The widths can be found in the ninth,
tenth and eleventh column of table 26.
In the Rhino model is made an area every five meter.
These areas, see figure 23, represent the cross section at that
point. This cross section can be used to calculate the area for
the bulkheads. The part of the circumference directly on the
Figure 23. Width decks
Figure 22. Division ship
Figure 24. Cross sections
Production of composite ship hulls 58 8. Experimental model
skin of the vessel can be used to calculate the stiffener length on the skin. That circumference can be
found in the third column of appendix 2. The cross section can be found in the fourth column of
appendix 2. The dimensions of the ship are translated to parameters, which can be used for
determining the amount of man-hours. These parameters can be found in appendix 3.
Waterline Height (m)
0 0
5 1,225
10 2,45
15 3,675
Table 11. Height waterlines
8.1.2 Macro’s dimensions ship
Several macros are used to calculate the dimensions of the ship. These macro’s are important to
name, because they explain how important aspect of the calculations haven been done.
8.1.2.1 Area_length_stiffener_bulkhead
This macro calculates the area of the bulkhead. The position of the bulkhead is not always on the
same position as the cross section shown in figure 23. Interpolation is used to determine the area of
the bullheads if it is not at such a position. Some of the bulkheads do not continue to fore castle deck
or tween deck. A correction based on the width at those decks has used to calculate the area of the
bulkhead.
The stiffener length on the bulkheads is also calculated in this macro. The calculation of the stiffener
length is based on the equation given in eq. 8.1.
This macro has to be runned when the column ‘Area’ behind a bulkhead is selected.
Eq. 8.1
8.1.2.2 Area_length_stiffenere_decks
This macro does basically the same as the previous macro. It calculates the area and the stiffener
length for the decks. The calculation of the area of the decks is based on the width as described in
8.1.18.1. The calculation of the stiffener length is done on as given in eq. 8.2. This macro calculates
also the number of brackets that has to be produced for a deck.
This macro has to be when the column Area behind a deck is selected.
( ) ( )
Eq. 8.2
8.1.2.3 Stiffener _length_foreship/midship/aftship
These macro’s are used to determine the stiffener length of fore ship, mid ship and aft ship. The
circumference as described in 8.1.1 is used to calculated the stiffener length. The stiffener length is
calculated for each stiffener separately. The circumference is interpolated to calculate the stiffener
spacing if the current stiffener is between the cross sections. The macro checks whether the stiffener
Production of composite ship hulls 59 8. Experimental model
is at the place of a bulkhead or not. If not the stiffener length is calculated, if there is a bulkhead the
next stiffener is selected.
8.1.2.4 Determine_range_deckheight
This macro checks for each bulkhead to which deck it continues. A range is made for each deck and
when a bulkhead continues to a certain deck, it is put in that range. This macro is important for the
determination of the number brackets of the connection between the bulkheads and the skin.
8.2 Characteristics ship The other part of the necessary information is related to ship. It does not describe the hull form of
the ship but it is more specific information about the layout and construction of the ship.
8.2.1 Main dimensions
The first most important are the main dimensions of the ship. The required main dimensions can be
found in table 12.
Main dimensions (m)
Length oa 51,5
Length cwl 47,1
Breadth 8,9
Draft CWl 2,45
Depth to fore castle deck 6,55
Depth to main deck 4,25
Depth to tween deck 2,3
Table 12. Main dimensions
8.2.2 Stiffeners
The AMBV has different stiffener spacings at different parts of the ship. The ship is divided in three
parts to be able to handle to difference in stiffener spacings. The location of the division can be
found in figure 25. The locations of these transitions in stiffener spacing can be found in table 13.
Aft ship Fore ship Mid ship
Figure 25. Division ship
Production of composite ship hulls 60 8. Experimental model
Separation Relative to AP (m)
Aft / mid 15,15
Mid / fore 33,9
Table 13. Changes stiffener spacing
The places of the change in stiffener spacings are a input in the model. The spacings can be found in
table 14. The spacing of the stiffeners of the bulkheads can be found in that table as well. However
not only the stiffener spacing can be varied also can the size of the stiffeners. The stiffeners used in a
AMBV are hat stiffeners. The dimensions of the hat stiffeners are different for several plates fields.
Stiffeners for decks and skin/bulkheads can be distinguished as well as the centre girder and de side
girders. An example of one of these stiffeners can be found in table 15.
Stiffeners spacing (m)
Fore ship 0,7
Mid ship 0,75
Aft ship 0,6
Bulkheads 0,7
Table 14. Stiffener spacings
Stiffener deck girder
Width of flange (m) 0,06
Thickness of flange (mm) 12
Heigth of web (m) 0,3
Thickness of web (mm) 12
Widht of cap (m) 0,28
Thickness of cap (mm) 22
Table 15. Dimensions deck girder
The longitudinal stiffener on the decks and at the bottom of the ship does not continue to the bow of
the vessel. The point relative to AP where these stiffeners top can be found in table 16.
Stiffener End location relative to AP
Longitudinal deck stiffening to 44,4
Longitudinal side girders to 33,9
Table 16. Longtidunal stiffener end location.
8.2.3 Bulkheads
Bulkheads can be placed on different positions in the ship. Not all bulkheads continue to same deck.
The AMBV has three different decks. A tween deck, a main deck and a fore castle deck. The position
of these decks can be found in figure 27.
The position of the bulkheads in an AMBV can be found in figure 26. The bulkheads are numbered
from the stern to bow. The most left is bulkhead 1 and the most right is bulkhead 11. The exact
positions, the thickness and the deck to which a bulkhead continues can be found in table 17.
Production of composite ship hulls 61 8. Experimental model
Name Place bulkhead relative to AP (m)
To deck Thickness (mm)
Stern -0,95 Main deck 25
Bulkhead 1 3,75 Main deck 12
Bulkhead 2 10,35 Fore castle deck 12
Bulkhead 3 13,95 Tween deck 12
Bulkhead 4 15,15 Tween deck 18
Bulkhead 5 24,15 Fore castle deck 8
Bulkhead 6 26,4 Tween deck 8
Bulkhead 7 27,9 Main deck 8
Bulkhead 8 29,4 Main deck 8
Bulkhead 9 33,9 Fore castle deck 8
Bulkhead 10 43 Main deck 12
Bulkhead 11 44,4 Fore castle deck 12
Bulkhead sonar dome 36,7 Tween deck 12
Bulkhead bow thruster
40,2 Tween deck 12
Table 17. Bulkheads
Figure 26. Bulkheads in the ship
Production of composite ship hulls 62 8. Experimental model
8.2.4 Decks
The ship has three decks, a tween deck, the main deck and the fore castle deck. The depth to the decks
can be found in table 12. The fore castle deck starts not from the stern of the vessel, but somewhat later
as can be seen in figure 27. Therefore, the start point of the fore castle deck is one of the input
parameters in the model.
Each of the decks is divided in several sub parts. The bulkheads are place in the hull before the decks will
be place. The decks should thus be split in parts between bulkheads. The force castle deck is divided in
three parts due to the length of the deck. The thickness, start and end point of the decks can be found in
table 18. The tween deck does not exist over the whole length of the vessel. In table 18 can be found
where there is a tween deck and where not.
8.3 Production parameters The production parameters are important to determine the total man-hours necessary for the
production of an AMBV. The most important parameters will be described. Most of these parameters are
related to work people should do and how much they are able to do in a certain time period. However,
some of the production parameters have to do with the material and feature of design. The production
parameters can be changed in the tab used for the production parameters.
Figure 27. Decks in ship
Fore castle deck
Tween deck
Main deck
Production of composite ship hulls 63 8. Experimental model
8.4 Production process This is the combination of the first part of the model containing the dimensions ship and the second part
containing the production parameters. It combines the data of the dimension of the ship with the
production parameters. The man-hours required for the production of the ship can be calculated in this
way. The production is split up in several parts of the ship. The sub steps are described in paragraph 5.2.
The several parts with separated calculations can be found below:
1. Production of the skin, decks and bulkheads
2. Production of the transverse stiffeners on the item produced in step 1.
3. Production of the centre girder on the skin
4. Production of the side girders on the skin
5. Production of the longitudinal stiffeners of the decks and bulkheads.
The production time necessary for the production of each particular product can be calculated. The total
production time for each product is used to calculate the man-hour cost of each vessel.
8.5 Determination material cost This part is used to calculate the material cost for the production of an AMBV. However, it is also used to
estimate the weight of the AMBV. This can be used to verify the model. For each part in the production
process is the weight calculated.
The buffer and strength layer for the skin have been calculated separately. This has been done due to the
difference in weight fraction of the fibres. The input in the tab ‘dimensions ship’ has been used to make
an estimation of the material to be used. The volume can be calculated with that input. If this is
combined with the information concerning the material the weight can be calculated. The composite
material is split in the fibre and the matrix. For detailed information about the weight of the
constructions, see appendix 4.
Deck Start deck End deck Thickness
(mm)
Tween deck 1 10,35 15,15 34
Tween deck 2 24,15 33,9 34
Tween deck 3 33,9 43 34
Main deck 1 -0,95 10,35 14
Main deck 2 10,35 24,15 14
Main deck 3 24,15 33,9 14
Main deck 4 33,9 43 14
Main deck 5 43 44,4 14
Main deck 6 44,4 46,6 14
Fore castle deck 1 6,75 24,15 26
Fore castle deck 2 24,15 33,9 26
Fore castle deck 3 33,9 50,5 26
Table 18. Decks
Production of composite ship hulls 64 8. Experimental model
8.6 Total cost calculation series This part of the model is the final part of the model. Everything comes together in this tab. It is a
combination of the man-hour cost, material cost and the labour cost for the production of series of ship.
Series of ship has influence on the amount of work necessary for the production of the ship. This tab
calculates everything. The results are presented in 9.1 because they are an important part of the
research.
The material cost are assumed to be the same for each next ship. However, one can reason that the
costs of the material decrease if more ships has to be built. The costs for the investment are assumed to
be independent of the number of ship to be produced. The costs for the man-hour for each ship depend
on the learning curve. The learning curve is implemented in this part of the calculation.
8.7 Optional steps conceptual model Figure 17 shows optional steps to determine the parameters of the ship. These steps are not necessary
for the cost price estimation. During this graduation they are not uysed. However it is important to know
what the output is for the required steps of the cost price estimation.
One of these steps is the Ansys model. This model could be used to compare different structure types.
Other structures could be evaluatie for instance with the data known from the Alkmaar class vessels. The
structure and hull form of the Alkmaar class can be put in Anys. The deformation and maximum stresses
could be calcuated based on the loading described in 6.1.2.
The factor between the maximum allowable stress and the maximum stresses found during the
calcualtions could be used as a `safety factor´ in other designs. For instance if another material with
other maximum allowable stresses is used. Or to compare another structure ´philosophy´ with the
structure ´philosophy´ used for the Alkmaar class vessels. The deformation could be used to design
another structure with the more or less the same deformation. The Ansys model could also be used to
evaluatie other hull forms. A different only in length without a difference in the midschip section does
not effect the structure, because the draft and the depth remain the same.
The section modulus calculator is also an optional step. This calculator can be used to evaluate the
section modulus of a hull. The section modulus calculator could be used to compare the section modulus
of different hulls. The maximum global stress can be calculated with the definded maximum global
bending moment (for instance based on the rules) and the section modulus of the midship section. The
maximum allowable stress of the material can be used for determining the dimensions of the structure.
Production of composite ship hulls 65 9. Results and sensitivity analysis
9. Results and sensitivity analysis This chapter describes the result of the model. A sensitivity analysis will be performed to show the effect
of difference in the parameters on the final output of the model.
9.1 Results The price per ship depends on the number of ships produced. If a few ships are produced the ship is
more expensive than when lots of ships are produced. Originally, the current AMBV was built in a series
of 15 ships. The cost price per ship for series of different sizes can be found in figure 28. Clearly to see is
the effect of the decrease in cost due to dispersion of the cost of the investment over more vessels.
Included is also the effect of the learning curve. The effect of the learning curve can be found in figure
29. The cost price per kg for a series of fifteen ships is €81,80 and the cost price for a series of six ships is
€123,00.
Figure 28. Cost per ship for series of different sizes
Figure 29. Effect learning curve
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€ 70.000.000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Decomposition cost for a serie of ships
Labor cost
Material cost
Fixed cost
€ 5.000.000
€ 6.000.000
€ 7.000.000
€ 8.000.000
€ 9.000.000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Pri
ce (
€)
th ship
Influence learning curve
Production of composite ship hulls 66 9. Results and sensitivity analysis
The decomposition of the man-hour cost and material cost are also important. By using the
decomposition of these two the major cost drivers for these cost can be established. Improvements in
the production can focus on these aspects because an improvement will have the most effect on these
aspects. A decomposition for the material cost can be found in figure 30 and for the man-hour cost can
be found in figure 31. Important to notice is that the majority of the material cost are the costs for the
fibre. Two factors are the cause for that. The first one is the amount of material that is fibre. Around 50%
of the material used is fibre. The other cause is the price if the material. The fibres are per kg the most
expensive material.
Figure 30. Decomposition of the material cost.
The different processes have different characteristics. The determination of the parameters is explained
in 7.1. The parameters have been combined with the data of the form of the ship. The total time spent
for each of the processes can be determined. An overview of these times is given in figure 31. Four of the
processes are more than 90% of the total amount of work. These processes are the lay-up of the fibre,
the lamination of the fibre, the scouring of the material and the positioning of the decks, bulkheads and
sandwich panels of the superstructure. If one wants to improve the production rate of the vessels one
has to focus on these tasks. The lay-up and the lamination process are of main interest for the
production of composite products. Improvements in newer techniques could lower the production time
necessary for the production of composite vessels. An improvement of 10% in the lay-up the fibres saves
around 3.200 hours of working for the first ship, resulting in a saving of €210.000.
To get more insight of the production of the different components the production steps for these
components are grouped and represented as whole. The proportion of main parts of the construction
can be found in figure 32. One can see that quite a number of hours (59% of the total time) is necessary
for the production of the stiffeners on different locations. The production of the stiffeners is less fast
than the production of skin, due to the geometrical form of the construction. One of the focuses of the
production should be on the production of the stiffeners.
83,0%
2,1%
0,3%
13,5%
0,7% 0,5%
Cost material
Fiber
Catalyst
Accelerator
Resin
Pins
Foam
Production of composite ship hulls 67 9. Results and sensitivity analysis
The total cost of a project for series with different number of ship can be found in figure 33. It is clear
that adding an extra vessel to a series will have influence on the total cost of the project, but it lowers
the cost per vessel. Depending on the need the decision can be made to add an extra vessel to the series
without having to raise the budget for the vessel with the same portion.
Figure 31. Decomposition different processes.
29,76%
29,76%
11,48%
0,40%
0,20%
0,42%
0,81%
0,81%
1,80%
0,02%
0,10% 21,07%
0,23% 3,16%
Decomposition different processes Lay up fibers
Laminate
Scouring
Making foam core
Glue foam core
Applying rubber emulsie
Drilling holes
Places pens
Producing angle laminate
Make balsa core
Glue balsa core
Transport and positiondecks/bulkheads/sandwich panelsFilling seams
Production of composite ship hulls 68 9. Results and sensitivity analysis
Figure 32. Production parts of the construction.
Figure 33. Cost of a project.
9.2 Sensitivity analysis This part investigated the sensitivity of the model for several parameters. The sensitivity analysis will be
based on a series of six vessels. This is done because DMO is investigating the production of a series of
six vessels replacing the current AMBV class vessels.
One of the important parameters is the influence of the man-hour cost on the total price of the vessels.
Figure 34 shows the influence of the man-hour cost. The price of a man-hour is €65. Varying the price
between €57 and €71 leads to a difference in man-hour cost of 9,5 million. If the price for a man-hour is
€57, the man-hour costs are 41% of the total costs. For a price of €65 per man-hour are the man-hour
costs 46% of the total price.
20,2%
16,6%
5,3% 2,2%
2,6%
8,2%
14,3%
26,8%
3,6%
Production construction parts
Skin
Stiffeners skin
Center girder
Side girders
Bulkheads
Stiffeners bulkheads
Decks
Stiffener decks
Sandwich panels
€ 0,00
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€ 40.000.000,00
€ 60.000.000,00
€ 80.000.000,00
€ 100.000.000,00
€ 120.000.000,00
€ 140.000.000,00
€ 160.000.000,00
€ 180.000.000,00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Cost of project for a serie of # ships
Total cost project
Manhour cost
Material cost
Fixed cost
Production of composite ship hulls 69 9. Results and sensitivity analysis
Figure 34. Influence manhour cost.
Figure 30 shows the largest part of the material cost are the cost for the fibres. The influence of the price
of the fibres is shown in figure 35. The price found for glass fibre vary between €13,00 and €23 per kg.
The influence of the fibre is low. The increase of the fibre price with 77% percent (difference between 13
and 23) has an effect of an increase of only 4% on the total cost of the hull.
Figure 35. Influence of the price of the fibres.
The ratio between the production of the skin and the production of stiffeners, girders, bulkheads and
decks has to be examined. The ratio of the production of the stiffeners has the biggest influence because
the production of the stiffeners takes the most man-hours compared to the other two.
€ 35.000.000
€ 37.000.000
€ 39.000.000
€ 41.000.000
€ 43.000.000
€ 45.000.000
€ 47.000.000
€ 49.000.000
€ 57 € 58 € 59 € 60 € 61 € 62 € 63 € 64 € 65 € 66 € 67 € 68 € 69 € 70 € 71
Tota
l man
ho
ur
cost
Cost price manhour (€/hour)
Influence manhour cost
€ -
€ 2.000.000
€ 4.000.000
€ 6.000.000
€ 8.000.000
€ 10.000.000
€ 12.000.000
€ 14.000.000
€ 16.000.000
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Pro
du
ctio
n c
ost
Fiber cost (€/kg)
Influence fiber cost
Fixed cost and manhour cost
Material cost
Production of composite ship hulls 70 9. Results and sensitivity analysis
Figure 36. Influence production stiffeners ratio
An decrease from 250.998 (ratio 0,4) man-hours to 185.924 (ratio 0,54) or 26% of the ratio between the
production of the stiffeners and the production of the skin has an effect of 9,1% on the man-hours and
an effect of 4,1% on the total production cost of a series of six ships. The effect of the ratio factor can be
found in figure 36. Important to notice is that this is only the effect of the lay-up and the lamination of
the fibres. Changing the production ratio between the production of skin and bulkheads/decks from 0,72
to 0,86 has an effect of 16% on the lay-up and the lamination of the fibres, resulting in an decrease of
the total production cost of 0,8%.
9.2.1 Sensitivity other ship
The model could be used to determine the cost price for ships with other hull forms or other lengths.
The AMBV which is used as benchmark for the model is one of the biggest composite ships. The model
has been developed to give a price estimation for this type of ship. Change in the hull form and size of
the ship has to be handled carefully. One has to assure that the model could be applied for the
production of the desired hull form. For instance if one wants to estimate the cost price for a catamaran
one has to investigate how this can be applied in the model.
It is expected that the model can handle changes in size quite easy. Because as change in the hull form
does not lead to a change in the production of the vessel. However, the input parameters have to be
investigated for production of significant smaller or bigger ships.
9.2.2 Sensitivity other materials
The results presented before are based on the use of glass fibre and polyester resin. Changing the materials of the structures leads to change in the dimensions of the construction. Materials used for the production of composite vessels can be found in 2.1. Changing the materials used for the structure of the vessels does not necessarily affect the construction order and the processes required for the production of the ship. The same type of calculations have to
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0,4
0,4
1
0,4
2
0,4
3
0,4
4
0,4
5
0,4
6
0,4
7
0,4
8
0,4
9
0,5
0,5
1
0,5
2
0,5
3
0,5
4
Ratio production stiffeners
Influence ratio production stiffeners
Remaining manhour cost
Production stiffeners cost
Production of composite ship hulls 71 9. Results and sensitivity analysis
be used. However, the input parameters could change as a result of a change in material. For instance, the lay-up of the fibres could change as a result of a change in materials. Another change due to a change in material are the material cost. The material cost for the most used materials for composite hulls can be found in 7.3.2 Important if one applies other materials is the check of the input parameters for the used materials. Are the production rates the same for the new materials or has one to conclude that the input parameters should change as well.
9.3 Building other structure Producting of the stiffeners is one of the main parts of the production of the Alkmaar class vessels.
Removing the stiffeners on the skin of the Alkmaar class vessels and making the skin stiffeners could be
an effective way to reduce the manhour cost. Removing the stiffeners save 38.462 man-hours and
€309.316 material costs. The skin of the ship should be made thicker to have the same deformation and
stresses in the material. Important to notice is that only the tranverse stiffeners on the skin are removed
and replaced by a thicker skin. The price for the ship can be compared when the skin with stiffeners is
made 2,6 times thicker compared with the skin of the Alkmaar class vessels. The result for the ‘normal’
Alkmaar class vessel and the Alkmaar class vessel with a thicker skin can be found table 19. The
investments costs are assumed to be same for both cases. Interesting to see is the change in costs from
material costs to labour costs. The vessel with a thicker skin has a higher weight but needs less
production others.
The effect of this change should be investigated further. The ship is much heavier as can be seen in table
19. One have also to investigate which dimensions of the skin are necessary to withstand the loadings.
A monocoque is always heavier than a single skin stiffened skin. This is what the model also gives. A
thickness at the keel of the ship of 90 mm (2,6 times the thickness at the keel of the an Alkmaar class
ship) is quite normal for a monocoque structure. The Lerici class minehunters for instance have at the
keel at thickness of 114mm. (Smith, 1990).
‘Normal’ Alkmaar class
vessel
Thicker skin Alkmaar class vessels
Material cost € 1.308.426 € 1.829.571
Labour cost € 8.655.291 € 8.129.372
Weight (ton) 135,299 184,751
Table 19. 'Normal' Alkmaar class vessels and Alkmaar class vessel with thicker skin.
9.4 Using other process An important improvement in the production of composite hulls is the use of the vacuum bag moulding
tech nique instead of the traditional hand lay-up method, see 2.3.1.1.3. Vacuum bag moulding is used
because the labour costs are reduced considerably for large structural applications and the fiber content
is higher (Brouwer, et al., 2002). The assumption for this example is that the improvement of the
lamination speed due to the use of vacuum bag moulding is 15%. Thus instead of a lamination speed of
2,03 m2/h a speed of 2,34 m2/h. Every other process has the same production speed as described earlier.
The total amount of man-hours in this case is 115.191 hours, resulting in a reduction of 4.651 man-hours
or 3,9% of the total production time. The resulting in a saving of about €336.000 for the first ship. If more
Production of composite ship hulls 72 9. Results and sensitivity analysis
ship are produced the amount of money increases. Important to notice is that this is only the saving due
to a change in the process. This cases doesnot contain a change in the structure due to the higher fiber
content. The actual saving could be higher if the structures is redesigned. Weight savings of 15% has
been achieved with vacuum bag moulding (Shenoi & Dodkins, 2000). Another note is about the required
extra investments for the vacuum bag moulding. The cost for the investment are somewhat higher,
however not much. Vacuum bag moulding requires only small capital investments (Karlsson & Aström,
1996). Important to notice is that some other processes can be affected by the change in material. In this
case for instance the required amount of scouring will probably be lower. The amount of money save
when using vacuum bag moulding is thus probably bigger. However, that has to be investigated further.
Production of composite ship hulls 73 10. Verification and validation model
10. Verification and validation model Validation is the check of the model based on other data. The behaviour of the model has to be checked
with the production data of vessels produced elsewhere. Verification is the process of checking the
information in the situation used. In this case the production of the AMBV class vessels.
It is hard to validate the model and to verify the model with the available information. Validation is
difficult due to difficulties in obtaining information about the cost price for the production of composite
hulls. Companies do not want to give information about the production of such vessel because insight in
cost gives company information.
Verification is difficult based on the information available. The input parameters as described in chapter
7 are used to verify the model. The verification is done with a calculation of the cost. The information
that can be used for the verification of the model is a study to improvements in the first station of the
GNM production facility. The second part to verify the data is the GNM calculation (Van der Giessen - De
Noord Marinebouw BV, 1983). However, difficulties arise on several aspects of that calculation. The
model is a process-based estimation of the cost price. The GNM approach is a calculation of the cost.
Since the GNM approach of the production was to use existing production facilities as much as possible
as described in 5.1. GNM gives are total price for the items produced elsewhere. One does not know the
man-hour cost for GNM of these items. The total price of both calculations can thus not be compared.
However, there are certain parts that can be compared. The assumption is that if the model can be
verified for the parts representing all the processes done in the production the whole mode is verified.
The parts of the production that where outsourced are the decks and the bulkheads. The production of
the decks and the bulkheads does not differ much from the production of the skin.
Another difficulty with the verification of the model is that GNM gives not the calculations for the sub
processes defined in the model but for several of these sub steps. For instance, the production of the
stiffeners is taken as whole, but in the model it is divided in twelve sub steps. So it is impossible to verify
all the sub steps but the whole production of the stiffeners has to be compared.
10.1 Verification weight structure GNM calculates that the total amount fibre reinforced plastic used for one AMBV is 149.027 kg (Van der
Giessen - De Noord Marinebouw BV, 1983). The total weight of the hull calculated in the model is
135.299 kg. The difference between these two is 7,9%. The difference can be explained by the fact that
the model does not calculate the whole construction but only the GRP hull. For instance, the foundations
and the secondary bulkheads are not calculated.
The structure can be divided in several parts. The weights of the model and the difference between the
weights of the GNM calculation can be found in table 20. The difference between the different parts is
quite huge, however the different between the total weight is quite low.
Item GNM calculation (kg) Model (kg) Difference (%)
Skin total 40.049 37.361 -6,7
Buffer layer 3.222 5.454 69,3
Strength layer 36.827 31.907 -13,4
Production of composite ship hulls 74 10. Verification and validation model
Stiffeners skin 15.056 13.209 -12,3
Centre girder 3.536 3.336 -5,7
Side girder 3.431 1.901 -44,6
Decks 49.360 57.998 17,5
Bulkheads 16.050 18.365 14,4
Table 20. Weight different parts according to the model and to the GNM calculation
10.2 Verification production skin The differences in the production of the skin are given in table 21. Especially the production of the buffer
layer differs quite much with the GNM calculation.
GNM calculation Model Difference (%)
Buffer layer 2.400 4.402 83,4
Strength layer 15.500 13.742 -11,3
Table 21. Production skin.
10.3 Verification production stiffeners The values for the production of the stiffeners can be tested with the values for the centre girder and
side girders. The production times for the production of the centre girder and the side girders can be
found in table 22. Important to notice is the difference between the side girder and the GNM calculation.
An explanation for the difference could be that the production of the sider girder is more like the
production of the stiffeners on the skin. Another explanation can be the difference in the weight of both
calculations. Less weight results in less work.
GNM calculation Model Difference (%)
Stiffeners skin 15.170 14.915 - 1,7
Centre girder 4.820 4.784 - 0,7
Side girder 2190 2804 28,0
Side girder corrected 2190 1998 - 8,8
Table 22. Production times girder and stiffeners
In table 22 a correction is done for the production speed of the lay-up and the lamination of the fibres,
the ratio for stiffeners is used instead of the ratio for the side girders. The assumption for that correction
could be justified by the fact that the drawings show that the production of the centre girder is more
difficult compared to the side girder.
Important to notice is the amount of time that is used for the lay-up and lamination of the girders. The
percentage for the stiffeners can be found in table 23. The lay-up and lamination are thus a huge part of
the production of the stiffeners.
Stiffeners
skin
Side girders
(corrected)
Centre
girder
Bulkheads Decks Deck
longitudinal
% Lamination and 80,2 86,1 92,2 80,3 79,7 85,8
Production of composite ship hulls 75 10. Verification and validation model
lay up
Table 23. Percentage of the time used for the lay-up and lamination of the stiffeners.
40.000 glass pins are necessary for the production of the stiffeners on the skin (Lohuizen, 1985). The
model calculates that 39.824 glass pins are necessary for the production of stiffeners. The difference
between those is 0,44%.
10.4 Verification investment If the investment is not corrected for the inflation, the investment is in 1980 44.024.406 DG. This is near
the investment of 45 million DG done by GNM. The difference is 2,2%. It is lower due to the investment
of GNM for further use of the facility.
10.5 Verification other processes A few processes are not directly related to the GRP work to be done for the production. These processes are preparing or finishing works. An overview of this work and the difference between the GNM calculation and the model is given in table 24.
GNM calculation Model Difference (%)
Assembly and disassembly mould 2790 2820 1,1
Place sandwich panels 6870 7000 1,9
Measurements dimensioning 340 340 0,0
Make mould ready for production 600 596 -0,7
Build scaffoldings 30 30 0,0
Table 24. Overview production times processes not directly related to the GRP work.
10.6 Comparison decks and bulkheads The GNM has outsourced the production of the decks and the bulkheads to third parties. The costs for
these parts are given in the calculation (Van der Giessen - De Noord Marinebouw BV, 1983). The total
cost for both material and man-hours can be calculated with the model. The difference between the
GNM calculation and the model are given in table 25. Important to notice is the difference in costs for
the tween deck. An explanation for the difference is the absence of deck camber in the production of
this deck. The model is based on the production of the decks with deck camber. The parameters for the
processes should be different if a deck is produced without deck camber
Price GNM calculation 1983
(gulden)
Price GNM calculation
2014 (€)
Model (€) Difference
(%)
Main deck 969.250 945.630 1.087.793 15,1
Fore castle
deck
864.305 843.242 1.044.109 23,8
Tween deck 287.060 280.065 469.892 67,8
Bulkheads 783.070 763.987 802.879 5,1
Table 25. Production cost decks and bulkheads.
Production of composite ship hulls 76 11. Implementation in DMO estimation model
11. Implementation in DMO estimation model The implementation of the results of the model can be done easily. The model can be used to predict the
effect of the implementation of new production techniques or the effect of changing the way of the
production cost. The model can also be used to calculate the effect of changing the structure of the
vessels and changing the ‘structure philosophy’.
The cost estimation model currently used at DMO is based on product-based estimations. Therefore, it is
necessary to translate the results of the process oriented cost price estimation model to data, which can
be used in the product-based estimation. The DMO estimation model is based on a price per kilo
construction. That is the measure for the output of the developed model.
A disadvantage of the model used at DMO is that it is based on the production of AMBV-like vessels. The
effect of changing the geometry or changing the method of construction cannot be estimated. This
model developed is able to evaluate the effect in changes in the structure design ‘philosophy’ and the
hull form.
Also changes in stiffening spacing can be performed with the model. This model is thus able to establish
the stiffeners spacing with the lowest cost.
In fact, one can say that this model can be used to generate information for the cost price estimation
model of DMO. This model focuses only on a part of the cost price estimation model of DMO. However,
for that part more insight in the behaviour of the cost development can be obtained with the model
developed.
The part of the production costs of the whole costs of a project have to be known to say something
about the effect of changes in the production cost. However, in general can be concluded that when a
change in production process leads to lower construction costs leads to lower project costs.
Production of composite ship hulls 77 12. Conclusion and recommendations
12. Conclusion and recommendations
12.1 Conclusion In this study, the cost price estimation of a composite hull has been investigated. Two parts are
important in the estimation of a the cost price. The first one is the determination of the structure of the
vessels. This can be done already for other purpose. However sometimes it is necessary to establish the
dimensions of the structure. Possible structures types for the construction of composite ships are:
1. Monocoque single skin construction
2. Framed single skin construction
3. Monocoque sandwich single skin construction
4. Framed sandwich single skin construction
5. Corrugated hull
The structure can be built in different materials, this choice for the materials depend on the
requirements for the ship.
Different techniques may be used for the construction of composite vessels. The production technique
used for the production of the AMBV class vessels is hand lay-up. Other promising techniques are
vacuum injection and RTM.
The construction cost for ships with composite hulls are estimated by the use of the developed model.
The model is a process based cost price estimation model, which means that the model determines the
processes necessary for the production of such ships and determines the amount of work necessary to
produce the ship. Other aspects of the calculation are the material cost and the cost related to the
investment in the yard and the mould.
Improvements can be investigated with the model due to change in parameters. The model is developed
in such a way that the parameters can be changed and that the model is not dependent on one or a few
production methods.
The model is developed with the data of the AMBV class mine hunter. The ‘structure philosophy’ of a
AMBV class vessel is single skin stiffened vessel. The result for the production of this ship is €123/kg.
The fixed cost, the investment for the yard and the mould, are the substantial part of the production
cost. This effect is big especially for smaller series.
The glass fibre costs are 83% of the cost of the material. Fibres are the strength bearing parts of the
construction of the vessel. Improvements in the production of the should focus on the processes of the
lay-up of the fibres, the lamination of the fibres, the scouring of the material and the transportation and
position decks. Improvements in the production can also focus on certain parts of the structure of the
vessels. These structures are the stiffeners of the construction 63,6% of the production time is the
production of the stiffeners.
Improvements can be implemented easily in the production model. Parameters represented the
production process. The main parts of the processes are the same as used in the model. They are
independent of the production process.
DMO can use the results of the model to improve their estimations. Improvements in the production
could be evaluated with the model developed and implemented in the DMO-models. This can be done
by calculating the effect of a change in the structure, materials or production techniques on the price/kg
Production of composite ship hulls 78 12. Conclusion and recommendations
of the structure. The price/kg can be used for the estimation of DMO. The advantage of doing that in this
ways is that the effect has to be calculated ones and it can be applied for each calculation performed
with the model used at the DMO.
12.2 Recommendations The model can be improved in different manners and especially the input parameters can be improved
significantly.
The determination of the production parameters was based on the GNM calculation and based on a
report regarding improvements in the first station of the GNM production facility. This data is quite old
to make a cost price estimation for a ship build nowadays. Improvements in the production process can
be incorporated as long as the improvements have more or less the same productions steps. For
instance producing of the hull by using composite panels cannot be estimated with the current model.
The production speed of the different sub steps should be investigated more thoroughly. A further
investigation of the production speeds can lead to a higher accuracy of the model. Better data can for
instance be obtained due to measuring production times at a company, which produced sufficient big
ships such that the production can be compared with the production of a composite ship with more or
less the same length as an AMBV. Evaluation using other production processes is also an option for
further research.
One of the parts of the model was the calculation of the cost not directly related to material or man-
hours. This cost was split in cost for the mould and cost for the investment for a newly build yard. This
part of the model should be improved further. The model gives some consideration about the items that
are in this part of the model and it gives a consideration of the influence of each of this items. However,
the link between the size of the ship and the influence of the cost of this item should be established.
Another improvement part mentioned before is the influence of the use of a current existing production
place. The starting point of the model is a newly build yard. The consequence of that starting point is a
high investment with the advantage of an ideal production facility. Interesting is a research in the use of
an existing production facility and the consequences of using that facility on the cost for the investment
and the production time of the ship.
Also the effect of using totally different processes could be investigated. An example is a construction,
which consists of panels, used for the production of the Visby class corvettes of the Swedish Navy. The
production technique of this vessel was the infusion of panels up to 60m2. Resulting in a production
method comparable with the production of ‘normal’ steel vessels (Lindblom, 2003).
A recommendation which does not focus on the use of a model for the estimation of the cost price of the
ship is the production of test samples. One can use the production data of the test samples to estimate
the production price for the whole vessel. If the test samples are representative for the production of a
whole ship, one can assumed that the production data could be used for the production of the whole
ship.
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Production of composite ship hulls 83 Appendix 1. Midship section AMBV
Appendix 1. Midship section AMBV
Figure 37. Midship section AMBV
Production of composite ship hulls 84 Appendix 2. Description hull form
Appendix 2. Description hull form
Table 26. Description hull form
Are
a sk
in b
etw
een
wl 5
and
wl 1
0 (
m2)
14
,40
1
12
,97
4
7,7
25
7,0
31
6,8
68
7,0
95
7,6
15
7,8
81
7,1
37
1,8
81
Are
a sk
in b
etw
een
wl 0
an
d w
l 5 (
m2 )
0 12
,13
18
,98
1
20
,12
20
,52
9
18
,89
1
15
,25
2
10
,76
9
6,4
49
0,4
55
Are
a cr
oss
sec
tio
n
(m2 )
6,5
8
7,2
4
11
,06
14
,76
26
,97
27
,61
27
,14
25
,4
22
,15
17
,33
9,5
4
0,2
5
Cir
cum
fere
nce
(m)
4,7
6
4,9
4
5,9
4
6,4
4
9,3
2
9,6
6
9,5
5
9,1
8
8,6
4
8,1
7
7,4
4
0,9
Up
per
val
ue
ran
ge
rela
tive
to
AP
(m
)
0 5 10
15
20
25
30
35
40
45
50
,5
Low
er v
alu
e ra
nge
rela
tive
to
AP
(m
)
-0,9
5
0 5 10
15
20
25
30
35
40
45
50
Are
a sk
in b
etw
een
wl 1
5
and
fo
re c
astl
e d
eck
(m
2 )
0,9
88
4,5
03
5,9
92
14
,38
6
14
,37
7
14
,37
6
14
,39
5
14
,51
5
14
,94
15
,85
1
12
,33
3
Bre
adth
tw
een
de
ck (
m)
3,3
3,9
7
4,2
5
4,3
7
4,2
7
3,8
6
3,0
8
1,9
5
0,7
1
Bre
adth
mai
n
de
ck (
m)
3,5
2
3,5
9
3,9
6
4,2
3
4,4
4,4
6
4,4
3
4,3
3
3,7
6
2,8
9
1,3
8
Bre
adth
fo
re
cast
le d
eck
(m)
4,4
1
4,4
7
4,4
6
4,3
7
4,1
1
3,5
5
2,2
8
Are
a sk
in b
etw
een
wl 1
0
and
wl 1
5 (
m2)
3,9
2
8,6
86
6,3
72
6,1
98
6,1
5
6,1
46
6,1
99
6,4
05
6,7
83
6,9
15
3,0
48
Production of composite ship hulls 85 Appendix 3. Production parameters
Appendix 3. Production parameters
Area between wl 0 en wl 5 (m2)
Area between wl 5 en wl 10 (m2)
Area between wl 10 en wl 15 (m2)
aft 63,43 70,62 50,72
mid 141,67 53,45 46,61
fore 42,06 37,15 36,31
Total 247,152 161,216 133,644
Opp tussen wl 15 en FCD (m2)
Total Area (m2) Total area all strength layers (m2)
aft 52,60 237,37 3496
mid 108,08 349,80 4507
fore 92,63 208,15 2201
Total 253,312 795,32 10205
Table 27. Production parameters skin.
Plaatsen schotten relative to APP
(m) To deck Area (m2) Thickness (mm) Stiffener length (m)
Stern -0,95 Main deck 5,06 25 7,23
Bulkhead 1 3,75 Main deck 11,31 12 16,16
Bulkhead 2 10,35 Fore castle deck 31,23 12 44,61
Bulkhead 3 13,95 Tween deck 16,19 12 23,13
Bulkhead 4 15,15 Tween deck 52,32 18 74,75
Bulkhead 5 24,15 Fore castle deck 54,44 8 77,77
Bulkhead 6 26,4 Tween deck 16,80 8 24,00
Bulkhead 7 27,9 Main deck 32,07 8 45,81
Bulkhead 8 29,4 Main deck 31,16 8 44,51
Bulkhead 9 33,9 Fore castle deck 45,73 8 65,33
Bulkhead 10 43 Main deck 14,34 12 20,48
Bulkhead 11 44,4 Fore castle deck 20,95 12 29,93
bulkhead sonar dome 36,7 Tween deck 12,91 12 18,44
Bulkhead bow thruster 40,2 Tween deck 11,09 12 15,84
Table 28. Production parameters bulkheads.
Production of composite ship hulls 86 Appendix 3. Production parameters
Deck Start deck relative to APP (m)
End deck relative to APP (m)
Area (m2) Thickness (mm)
Tween deck 1
Tween deck 2 10,35 15,15 39,59 14
Tween deck 3 24,15 33,9 75,66 14
Tween deck 4 33,9 40,2 32,88 14
Tween deck 5
Tween deck 6
Main deck 1 -0,95 10,35 88,33 14
Main deck 2 10,35 24,15 121,03 14
Main deck 3 24,15 33,9 81,54 14
Main deck 4 33,9 43 53,46 14
Main deck 5 43 44,4 5,38 14
Main deck 6 44,4 46,6 4,47 14
Fore castle deck 1 6,75 24,15 116,55 26
Fore castle deck 2 24,15 33,9 83,04 26
Fore castle deck 3 33,9 50,5 80,46 26
Deck Stiffener length decks (transverse) (m)
Stiffener length decks (longitudinal) (m)
Breadth begin deck (m)
Breadth end deck (m)
Circumference deck (m)
Tween deck 1
Tween deck 2 65,98 14,4 3,99 4,25 44,28
Tween deck 3 100,88 29,25 4,29 3,25 55,86
Tween deck 4 43,85 18,9 3,25 1,90 85,94
Tween deck 5
Tween deck 6
Main deck 1 147,21 27,3 3,25 1,21 53,32
Main deck 2 161,37 41,4 4,24 4,44 87,15
Main deck 3 108,72 29,25 4,44 3,89 58,46
Main deck 4 76,37 27,3 3,89 1,98 90,72
Main deck 5 7,69 4,2 1,98 1,53 22,99
Main deck 6 5,96 0 1,56 0,98 25,83
Fore castle deck 1
147,29 52,2 4,14 4,46 94,09
Fore castle deck 2
110,72 29,25 4,46 4,17 59,49
Fore castle deck 3
107,28 0 4,17 0,00 143,37
Table 29. Production parameters deck.
Production of composite ship hulls 87 Appendix 4. Weight parts of the ship
Appendix 4. Weight parts of the ship
Volume (m3) Weight (ton) Weight fibre (ton) Weight matrix (ton)
Aft 1,11 1,68 0,42 0,84
Mid 1,59 2,41 1,20 1,20
Fore 0,91 1,37 0,69 0,69
Total 3,61 5,45 2,73 2,73
Table 30. Material buffer layer skin
Volume (m3) Weight (ton) Weight fibre (ton) Weight matrix (ton)
Aft skin 5,51 10,21 5,10 5,10
Mid skin 7,72 14,31 7,16 7,16
Fore skin 3,99 7,39 3,69 3,69
Aft stiffeners 2,39 4,43 2,22 2,22
Mid stiffeners 3,09 5,73 2,86 2,86
Fore stiffeners 1,64 3,05 1,52 1,52
Total 24,35 45,12 22,56 22,56
Table 31. Material strength layer skin
Material Volume (m3)
Weight (ton)
Weight fibre (ton)
Weight matrix (ton)
Material decks 19,39 35,94 17,97 17,97
Material bulkheads 3,93 7,28 3,64 3,64
Material stiffener decks transvers
14,38 26,65 13,32 13,32
Material stiffener deck longitudinal
3,81 7,06 3,53 3,53
Material stiffener bulkheads 5,98 11,09 5,54 5,54
Total 47,50 88,01 44,01 44,01
Table 32. Material decks and bulkheads
Volume (m3) Weight (ton) Weight fibre (ton) Weight matrix (ton)
Aft 1,11 1,68 0,42 0,84
Mid 1,59 2,41 1,20 1,20
Fore 0,91 1,37 0,69 0,69
Total 3,61 5,45 2,73 2,73
Table 33. Material buffer layer skin
Production of composite ship hulls 88 Appendix 4. Weight parts of the ship
Volume (m3) Weight (ton) Weight fibre (ton) Weight matrix (ton)
Aft skin 5,51 10,21 5,10 5,10
Mid skin 7,72 14,31 7,16 7,16
Fore skin 3,99 7,39 3,69 3,69
Aft stiffeners 2,39 4,43 2,22 2,22
Mid stiffeners 3,09 5,73 2,86 2,86
Fore stiffeners 1,64 3,05 1,52 1,52
Total 24,35 45,12 22,56 22,56
Table 34. Material strength layer skin
Material Volume (m3)
Weight (ton)
Weight fibre (ton)
Weight matrix (ton)
Material decks 19,39 35,94 17,97 17,97
Material bulkheads 3,93 7,28 3,64 3,64
Material stiffener decks transvers
14,38 26,65 13,32 13,32
Material stiffener deck longitudinal
3,81 7,06 3,53 3,53
Material stiffener bulkheads 5,98 11,09 5,54 5,54
Total 47,50 88,01 44,01 44,01
Table 35. Material decks and bulkheads
The matrix can be split further to catalyst, accelerator and resin. For the buffer layer this can be found in
table 36, for the strength layer in table 37, for the bulkheads and decks in table 39.
Weight catalyst (ton)
Weight accelerator (ton
Weight resin (ton)
Aft 0,024 0,004 0,81
Mid 0,035 0,006 1,16
Fore 0,020 0,003 0,66
Total 0,079 0,013 2,63
Table 36. Material matrix buffer layer skin
Weight catalyst (ton)
Weight accelerator (ton
Weight resin (ton)
Aft skin 0,10 0,01 4,99
Mid skin 0,14 0,02 7,00
Fore skin 0,07 0,01 3,61
Aft stiffeners 0,04 0,01 2,17
Mid stiffeners 0,06 0,01 2,80
Fore stiffeners 0,03 0,00 1,49
Production of composite ship hulls 89 Appendix 4. Weight parts of the ship
Total 0,44 0,06 22,06
Table 37. Material matrix buffer layer skin
The volume and the material for the different stiffeners are calculated as well, see table 38.
Foam core Volume (m3) Weight foam core
stiffeners deck 33,11 1,32
longitudinal stiffeners deck 2,62 0,10
stiffeners skin 27,88 1,12
stiffeners bulkhead 2,62 0,10
centre girder 5,77 0,23
side girders 4,88 0,20
Total 76,88 3,08
Table 38. Foam core.
Weight catalyst (ton)
Weight accelerator (ton
Weight resin (ton)
Material decks 0,35 0,04 17,57
Material
bulkheads
0,07 0,01 3,56
Material stiffener
decks transvers
0,26 0,03 13,03
Material stiffener
deck longitudinal
0,07 0,01 3,45
Material stiffener
bulkheads
0,11 0,01 5,42
Total 0,86 0,11 43,04
Table 39. Material matrix buffer layer skin