Ship ConstructionShip Construction

Framing Systems

Double Bottom Construction

Stem & Stern Construction

Transverse Framing:Transverse Framing:

Deck Beams tie upper ends of frames

Fewer, deeper & more widely spaced Longitudinals …

Support Inner Bottom & give longitudinal strength

Longitudinals supporting Decks are called(Deck) Girders

Additional Decks (supported byBeams & Girders) increase Transverse & Longitudinal strength

Many, closely-spaced Frames

Transverse Bulkheads provide watertight boundaries, contribute significantly to transverse strength, and provide vertical support for Decks

Advantages Open, nearly rectangular interior space Ideal for stowing large, irregular, break-bulk

items, or Vehicles (Ro-Ro’s)

Disadvantages Vertical support for decks requires more

closely spaced transverse bulkheads (hence smaller compartments) or

Pillars (stanchions) or Longitudinal bulkheads

Transverse Framing:Transverse Framing:Many, closely-spaced Frames

Longitudinal Framing:Longitudinal Framing: Deep (Web)Transverse Frames

Few & widely spaced

Smaller, closely-spaced Longitud-nals support shell plating

Side shell longitudinals call stringers

Inner Bottom givesadditional longitudinal &transverse strength

Girders in high-stress areas:Double bottom spaces and …

Under main deck

Advantages Widely spaced transverse bulkheads allow for

large (i.e., long) continuous cargo spaces (“tanks”)

Ideal for stowing liquids (reduced free surface effects)

Disadvantages No large, open interior spaces Difficult to load or unload break-bulk items Difficult to stow large, irregular shaped items

Longitudinal FramingLongitudinal Framing::Deep (Web)Transverse Frames

Framing Systems:Framing Systems:

Typically, most ships have some combination of transverse & longitudinal framing

T T

T T

T T

T T

T T

T T

T T

T T

T

CL CL

SECTION VIEW

PLAN VIEW

TypicalTransverseFrames

Web Frame

L L L L L L L L L L

FLOOR

UPPER TWEEN DECK

LOWER TWEEN DECK

(LOWER) HOLD

Bulkhead STIFFENERS

Stringer

Double Bottom details:Double Bottom details:

RiderPlate

Inner Bottom(Tank Top)

Air-hole

MarginPlate

Center Vertical Keel

KeelPlate

Outer Bottom

Lighteninghole

Limberhole

Longitudinal

Bilge

Frame

“SOLID” FLOOR

Reverse Frame “OPEN” FLOOR

Frame Longitudinal Strut

Bilgewell

Shell Plating details:Shell Plating details:

KeelStrake

Garboard Strake(“A” strake)

“B”Strake

“C”Strake

“D”Strake

“E”Strake

“G”Strake

“F” Strake(Bilge Strake)

(Longitudinal) Rows of plating are called “strakes” The Keel Plates form the “Keel strake” The strakes outboard (P&S) of the Keel are the “A” Strakes

or “Garboard Strakes” Strakes are consecutively lettered moving outboard and

up the side shell

Shell Plating details:Shell Plating details: (Longitudinal) Rows of plating are called “strakes” Welded horizontal joints between strakes are called seams Welded vertical joints between plates in a given strake are

called butts Strakes that do not run the entire ship length (as the hull

surface area decreases at the ends) are drop strakes

Bilge (“F”) Strake“G” Strake

“H” Strake drop

“J” Strake Through

“K” Strake Sheer Strake

Strakes running stem to stern are called through strakes An oversized plate merging a drop & through strake is a

stealer plate The strake at the deck edge is the sheer strake and is

heavier than typical side shell plating

Openings in shell plating must:Openings in shell plating must:*have rounded corners *be reinforced to make up for missing material

portholes

Watertight doors

Hatch openings below decks

… and on weather deck -- COAMINGS

Stem ConstructionStem Construction

Wrapper Plate Stem

BreastHooks

Vertical Stem Post

DeepFloors

Forward CollisionBulkhead

Rider Plate

C.V. Keel

Keel Plate

Decks

Stringers

Wrapper Plate Stem

Stern ConstructionStern Construction

Stern Frame

PropellerPost

UNBALANCED RUDDER

Rudder Stock

Rudder Post

Stern Tube

Steering Gear RoomDeck

Mach’yRm

Rope Locker

AfterPeak

Tank

AfterCollisionBulkhead

Stern Frame

Cant Frames

SEMI-BALANCED RUDDER

Lug

Pintle

Gudgeon