Shell Plating

Shellplating

• purpose:– keeps water out– ties together ship’s framework– plays important part in resisting longitudinal

bending stresses• needs to be stronger amidships than at the ends

– particularly at the deck and bottom

Shellplating is…

• stiffened by frames

• supported by frames

• composed mostly of rectangular steel plates

• arranged longitudinally

Shellplating

• strake– shell plating arranged longitudinally

• one plate after another

• a row

• a course

3 Types of Shell Plating

• flat plate

• rolled plate

• furnaced plate

Flat Plates

• doesn’t have to be “worked” into shape– therefore, most economical

• because of this…– majority of plates are flat plates

Rolled Plates

• curvature in only one direction

• most often found at the turn of the bilge

Furnaced Plates

• curvature in two direction• must be heated and pressed into desired

shape by placing heated plate over a form• most expensive

– avoided as much as possible because of expensive

• developed by a yard in Germany– builders of the battleship “Bismarck”

• built entirely of flat surfaces

Layout of Shell Plates

• greater Girth mid-ship then at ends– Girth: distance around the hull

• results in excess plating at the ends– therefore, certain strakes (rows) are dropped as

bow and stern are approached

Drop Strake

• dropped strake, top strake of the two involved, is called the Drop Strake

Through Strake

• the other strake, the bottom of the two involved, that runs through in continuous line from stem to stern is called the Through Strake– see expansion plan

Stealer Plate

• The “new” single plate that butts up against the two strakes involved, is called the Stealer Plate– it is necessary due to the reduction in girth

Butts and Seams

• Butts– transverse joints between the plates

• Seams– longitudinal joints between the plates

Names and Letters of Strakes

Thickened Plates…

• certain plates are thickened in areas of higher stress– sheer strake– keel plates– plates on the bottom forward (pounding)– bottom and bilge – margin plate (provides more substantial material for

connection of outboard ends of floors and for the frames, also protect against more rapid corrosion in this area)

– (deck stringer) outboard most strake on deck

Thickened Flat Plate Keel

notice: molded surface in the same plane

• Reference pg. 201 Steel Merchant Ships

Numbering and Lettering

• Shell Expansion Plan

• notice:– lettering from

keel strake and up

– numbering: from aft forward

aft FWD

Plan of Deck Plating

• Deck Stringer Strake– outer most

strakes on deck

aftStringer Strake