Ship construction Ship dimensions

Mohd. Hanif Dewan, Chief Engineer and Maritime Lecturer & Trainer, Bangladesh.

SHIP CONSTRUCTION-

SHIP DIMENSIONS

Definitions and

ShipS DimenSionS Hull: The structural body of a ship including shell plating, framing, decks and bulkheads. Afterbody : That portion of a ships hull abaft midships. Forebody: That portion of a ships hull forward midships. Bow : The forward of the ship Stern : The after end of the ship

8/23/2014 2 Mohd. Hanif Dewan, Chief Engineer and

Maritime Lecturer & Trainer, Bangladesh.

Length Overall

STARBOARD

Beam

PORT

bow midships bridge stern



starboard bow

starboard beam

starboard quarter

Dead ahead Dead Stern

Port bow

Port beam

port quarter



Port : The left side of the ship when looking forward

Starboard : The right side of the ship when looking forward



Length between perpendicular (LBP) Length on waterline (LWL)

Length overall (LOA)

freeboard

Amidships

Aft perpendicular Fwd perpendicular

Sheer aft Sheer fwd

Summer load line

SHIP DIMENSIONS

Camber Tumble home

Depth

Moulded beam

Rise of floor Half siding of keel

Base line

Draft



After Perpendicular (A.P.): A perpendicular drawn to the waterline at the point where the aft side of the rudder post meets the summer load line. Where no rudder post is fitted it is taken as the centre line of the rudder stock.

Forward Perpendicular (F.P.): A perpendicular drawn to the waterline at the point where the foreside of the stem meets the summer load line.

Length Between Perpendicular (L.P.P. / L.B.P.): The length between the forward and the aft perpendiculars measured along the summer load line.



Amidships: A point midway between the after and forward perpendiculars

Length Overall (L.O.A.): Length of the vessel taken over all extremities.

Base line: A horizontal line drawn at the top of the keel plate. All vertical moulded dimensions are measured relative to this line

Moulded beam: Measured at the midship section is the maximum moulded breadth of the ship



Moulded Draft/ Draught: The distance from the bottom of the keel to the waterline. The load draft is the maximum draft to which a vessel may be loaded

Moulded Depth: Measured from the base line to the heel of the upper deck beam at the ships side aidships.

Sheer: Curvature of decks in the longitudinal direction. Measured as the height of deck at side at any point above the height of deck at side amidships



Camber / Round of Beam: Curvature of decks in the transverse direction. Measured as the height of deck above the height of deck at side

Rise of floor / Deadrise: The rise of the bottom shell plating line above the base line. This rise is measured at the line of moulded beam

Half sliding of keel: The horizontal flat portion of the bottom shell measured to port or staoad of the ships logitudial ete line. This is useful dimension to know when dry-docking.



Tumble home: The inward curvature of the side shell above the summer load line.

Freeboard: the vertical distance measured from the waterline to the top of the deck plating at the side of the deck amidships. Normally exposed to weather and sea.

Flare: The outward curvature of the side shell above the waterline. It promotes dryness and is therefore associated with the fore end of ship



Extreme Beam:

The maximum beam taken over all extremities.

Extreme Draft:

Taken from the lowest point of keel to the summer load line.

Draft marks represent extreme drafts.

Extreme Depth:

Depth of essel at ships side fo uppe dek to loest poit of keel.

Half Breadth:

Sie a ships hull is syetial aout the logitudial centre line, often only the half beam or half breadth at any

section is given.



SCANTLING The dimensions of the structural items of a ship, e.g. frames, girders, plating , etc.

INTERCOSTAL Composed of separate parts, non-continuous



CENTER OF FLOATATION

It is the center of the waterplane area and is the

axis about which a ship changes trim.

CENTER OF BUOYANCY

It is the center of the underwater volume of the

ship where the force of buoyancy acts.

CENTER OF GRAVITY

It is the point at which the whole weight of the

object may be regarded as acting. If the object is

suspended from this point, it will remain balanced and

not tilt.

8/23/2014 14

Mohd. Hanif Dewan, Chief Engineer and


TONNAGE MEASUREMENT

This is often referred to when the size of the vessel is discussed, and the gross toage is uoted fo Lloyds egiste.

Tonnage is a measure of the enclosed internal volume of the vessel, 100 cubic feet representing one ton

Its normally divided into categories as follow:-



1. Displacement Tonnage

A ships displaeet is the su of the ships atual eight lighteight ad its otets (deadweight).

The metric unit of measurement is 1 tonne (= 1000 Kg).

The displacement represents the amount of water displaced by the ship expressed in tonnes.

The weight of water displaced therefore equals the weight of the ship



TONNE PER CENTIMETRE (TPC) It is the mass required to increase the mean draught by 1 centimetre.

LOAD DISPLACEMENT The weight of the ship and its content, measured in tonne. The value will vary according to the ships draught.

DEADWEIGHT SCALE It is a scale diagram indicating the deadweight of the ship at various draughts.

FORM COEFFICIENT It is devised to show the relationship between the form of the ship and the dimension of the ship.



2. Lightweight Tonnage (LWT)

The lightweight is the weight of the ship as built (hull, machinery) including boiler water, lubricating oil and the cooling water system.

Lightweight like displacement is expressed in units of tones.

It assumes importance in a commercial sense only when considering the value of the vessel which is to be broken up for scrape.



3. Deadweight tonnage (DWT)

Deadweight is the weight of the cargo which a ship carries plus weights of fuel,

stores, water ballast, fresh water, crew

and passengers and baggage.

It is the difference between the loaded ship displacement and the lightweight.



4. Gross Tonnage (GT)

Measurement of total internal volume of a vessel and includes all under deck

tonnage and all enclosed spaces above

tonnage deck.

100 cubic feet of space being considered as 1 ton



5. Nett Tonnage (NT)

Ship measurement derived from gross tonnage by deducting spaces allowed for crew

and propelling power.

100 cubic feet of space being reckoned as 1 ton



Ship side markings

LOAD LINE The marking on the ship side that relate to the loading

condition of the ship termed as the load line mark. Load line mark

consists of a ring 300 mm in outside diameter and 25 mm thick which is

intersected by a horizontal line 450 mm in length and 25 mm thick, the upper edge of which passes

through the centre of the ring. The centre of the ring is placed amidships and at a distance equal to the assigned summer freeboard measured vertically below the upper edge of the deck line.



Sailing ship



ANY QUESTION?

THANK YOU! 8/23/2014

Mohd. Hanif Dewan, Chief Engineer and

Maritime Lecturer & Trainer, Bangladesh. 26

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Ship construction Ship dimensions