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Ship Structure Exam 3
N/A
54
Other
Undergraduate 4
12/06/2011

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Term
What are the purpose of cant frames in steel vessels?
Definition
provide strength to shell plating at stern
Term
what is a stanchion?
Definition
a vertical strength member
Term
what are the synonyms for pillar?
Definition
post
stanchion
column
Term
why should pillars always be fitted in a vertical line?
Definition
To transmit load directly down to the keel, and not onto beams and deck plates.
Term
why is a pillar fitted under the windlass?
Definition
to absorb the stress, vibration, and weight of the windlass
Term
what is a partial bulkhead
Definition
bulkhead that does not extend across a compartment; used to strengthen the structure
Term
what three things does the size of a pillar depend on?
Definition
load, location, and length
Term
How does acceleration affect the size of the pillar?
Definition
dynamic load can be double the static load
Term
what is the purpose of deck girders?
Definition
support deck beams by reducing span
Term
why should pillars be well protected when cargo is loaded/unloaded?
Definition
to prevent damage, bent pillars provide little to no vertical support
Term
what is the purpose of wood sheathing
Definition
insulates - wood has low heat transmission
absorbs damage and protects deck
keeps outer decks cool for passengers
prevents sweating due to rapid temp change under deck
add aesthetic value to appearance of ship
Term
what is the purpose of the stringer plate?
Definition
thicker outboard plating to prevent racking and provide support for cargo hatchess
Term
why should corners of all hulls cut into the strength deck be rounded, doubled, or both?
Definition
to prevent cracks and notches from forming due to stress
Term
differentiate between side stringer, girder, and longitudinal
Definition
side stringer: longitudinal strength member inside deck plating
longitudinal: fore and aft strength members in bottom structure
girder: fore and aft longitudinal strength members supporting decks
Term
functions of bulkheads?
Definition
provide additional vertical support & act as structural diaphragms to resist racking
create fire & flooding boundaries
Term
what is a 2 compartment ship?
Definition
A ship that can be flooded in 2 compartments and stay afloat
Term
max number of passengers a merchant ship can carry without being considered a passenger vessel?
Definition
12
Term
what is the maximum distance the collision bulkhead can be from the stem?
Definition
1/20th the vessel length at summer load line
Term
what are the functions of the stem?
Definition
vertical extension of the keel
gives strength and rigidity to hull along center-line
ties shell plating
gives rigidity to entire bow
Term
advantages of a clipper bow?
Definition
additional space and buoyancy
flare throws water away from bow when headed into heavy seas
Term
what is the function of the stern frame?
Definition
vertical extension of the keel
provides strength for rudder and single prop
ties shell plating together at stern
Term
pillars give vertical support to...
Definition
girders
deck beams
decks
heavy concentrated loads: ground tackle, anchor windlass, line handling winches, capstains
Term
why place pillar under deck beam or girder?
Definition
redices deflection by reducing span
relieves stress on beam brackets & transverse frames
Term
top/bottom of pillar (names)?
Definition
top: head
bottom: heel
Term
purpose of doubling plate at bottom of pillars?
Definition
to spread the load over larger portion of deck plating
Term
ideal depth of beam brackets
Definition
2.5 times depth of beam
Term
purpose of upper deck?
Definition
increases seaworthiness by forming watertight top of hull and contributes strength by acting as upper flange of hull girder
Term
purpose of lower deck?
Definition
working platforms for operation of machinery and loading of cargo
living spaces for passengers and crew
Term
Additional purpose of all decks
Definition
serve as horizontal diaphram, keeping the ship in shape longitudinally
Term
Girder stress concentration?
Definition
amidships and outboard
Term
2 methods of insulation on ships?
Definition
insulation bats fixed to underside of deck via wire studs
spray on insulation applied directly to steel deck
Term
purpose of insulation?
Definition
insulate space
prevent sweating
noise barrier in engine room decks and bulkheads on passenger vessels
Term
deck coverings
Definition
paint
cement composite that flexes with deck
carpet, tile or linoleum over top of cement composite
Term
bulkhead construction
Definition
flat plate steel
or
corrugated (adds strength, reduces need for additional framing)
Term
collision bulkhead
Definition
acts as auxiliary watertight bow in event actual bow is punctured in collision
Term
afterpeak bulkhead
Definition
encloses shaft in watertight compartment
required on all screw type vessels
prevents broken prop shaft from flooding aft section of vessel
Term
machinery space bulkheads
Definition
enclose machinery spaces - watertight
regulatory requirement due to large through-hulls in engine rooms
Term
3 bulkheads required by regulation
Definition
collision bulkhead
afterpeak bulkhead
machinery space bulkhead
Term
Bulkheads are usually plated...
Definition
horizontally
Term
plate thickness thicker towards the bottom of the ship..
Definition
due to increased water pressure
Term
Why are longitudinal bulkheads avoided
Definition
danger of capsizing due to collision and flooding of one side of the ship
but they are seen in tankers
Term
longitudinal bulkheads in tankers
Definition
single hull: port and starboard longitudinal bulkheads form boundaries between port, center, and stbd tanks
double hull: usually only centerline longitudinal bulkhead
Term
3 major types of bows?
Definition
plumb
clipper
spoon
Term
plumb bow
Definition
straight up and down
classic passenger ship, aided with riveted construction
Term
clipper bow
Definition
flared bow, extra space and buoyancy, throws water when headed into seas
Term
spoon bow
Definition
ice breaker, allows bow to ride up on ice and break it with the weight of the vessel
Term
forefoot
Definition
curved connection between stem and keel
sometimes cast
Term
solid stem bar
Definition
lower stem section joining forefoot to upper stem
Term
rolled plate
Definition
plate heated and rolled to form plating around upper stem
Term
breasthook
Definition
triangular plate that joins plating and reinforces the solid stem bar
Term
peak tank/forepeak tank
Definition
located forward of collision bulkhead
serves as forwardmost ballast tank
exerts greatest moment for trim changes, good for lessening sag
Term
components of forepeak tank
Definition
valves and piping
reach rods to open and close valves
swash bulkheads reduce wave motion, can be longitudinally or transverse (generally longitudinal)
Term
Bulbous bow - what vessel speed?
Definition
higher vessel speed - improves vessel flow through water, overcomes wave making resistance
acts to fill in trough of bow wave = less power needed to reach medium/high speed
Term
two primary types of sterns
Definition
cruiser: rounded, requires cant frames and beams to make curve. older construction
transom: flat, modern construction cuz its cheaper, and waterline is carried further aft
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