Ship Construction
Framing Systems
Double Bottom Construction
Stem & Stern Construction
Transverse Framing:
Many, closelyspaced Frames
 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 by
Beams & Girders) increase
Transverse & Longitudinal strength
 Transverse Bulkheads provide watertight boundaries, contribute significantly to
transverse strength, and provide vertical support for Decks
Transverse Framing:
Many, closelyspaced Frames
 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
Longitudinal Framing:
Deep (Web)
Transverse Frames
 Few & widely
spaced
 Smaller,
closelyspaced
Longitudnals support
shell plating
 Side shell
longitudinals
call stringers
 Inner Bottom gives
additional longitudinal &
transverse strength
 Girders in high-stress areas:
Double bottom spaces and …
 Under main deck
Longitudinal Framing:
Deep (Web)
Transverse Frames
 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
Framing Systems:
 Typically, most ships have some combination
of transverse & longitudinal framing
L
TTTTT
UPPER TWEEN DECK
(LOWER) HOLD
SECTION
VIEW
L
L
L
L
L
L
L
L
Bulkhead STIFFENERS
TTTTTTTTTTTT
LOWER TWEEN DECK
L
Stringer
Web Frame
Typical
Transverse
Frames
FLOOR
CL
PLAN VIEW
CL
Double Bottom details:
Inner Bottom
(Tank Top)
Rider
Plate
Airhole
Margin
Plate
Frame
Center
Vertical Keel
Keel
Plate
Outer
Bottom
Longitudinal
Bilge
“SOLID” FLOOR
Lightening
hole
Reverse Frame
Frame
Longitudinal
Limber
hole
Bilge
well
“OPEN” FLOOR
Strut
Shell Plating details:
 (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
“G”
Strake
“B”
Strake
Keel
Strake
Garboard Strake
(“A” strake)
“C”
Strake
“D”
Strake
“E”
Strake
“F” Strake
(Bilge Strake)
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
“K” Strake
“J” Strake
Sheer Strake
Through 
“H” Strake
drop 
“G” Strake
Bilge (“F”) 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:
*have rounded corners
*be reinforced to make up for missing material
… and on weather deck -- COAMINGS
portholes
Hatch openings
below decks
Watertight doors
Stem Construction
Wrapper
Plate Stem
Decks
Forward
Collision
Bulkhead
Wrapper
Plate Stem
Stringers
Vertical
Stem Post
Rider Plate
Deep
Floors
C.V. Keel
Keel Plate
Breast
Hooks
Stern Construction
After
Collision
Bulkhead
Stern
Frame
Steering Gear Room
Rudder
Stock
Deck
Mach’y
Rm
Cant
Frames
Rope
Locker
After
Peak
Lug
Stern
Tube
Tank
Rudder
Post
Propeller
Post
Stern
Frame
UNBALANCED
RUDDER
Pintle
Gudgeon
SEMI-BALANCED RUDDER