ship structure and stability Flashcards
keel
bottom
bow
front
stern
back
hull
outer shell
stanchion
vertical support
longitudinal frame
bow to stern
transverse frame
side to side
compartment numbering
deck-frame-compartment-use
“A” usage
stowage
“C” usage
control
“E” usage
engineering
“F” usage
fuel tank
“G” usage
gas
“L” usage
Living
“M” usage
ammo
“Q” usage
miscellaneous
“V” usage
void
Archimedes’ principle
an object submerged in a fluid is buoyed up by a force equal to the weigth of fluid it displaces
Weight (W)
total weight of all equipment stores and personnel. Acts vertically downward through the ship’s center of gravity Also known as displacement
buoyancy (B)
weight of the ship is equal to that of displaced water. Displaced water exerts a pressure on all submerged surfaces of the ship opposing the weight (gravity) of the ship. Acts vertically upward through the ship’s center of buoyancy (B)
Free board
the distance between the waterline and ships main deck
draft
the distance between the waterline and the keel of a ship
seaworthiness
a measure of a ship’s fitness for a sea voyage
draft vs free board
as draft changes, free board changes by an equal opposite amount
center of gravity (G)
determined by ship’s mass, applied at the geometric center of object, stays constant as ship moves
center of buoyancy (B)
applied at the geometric center of a ship’s body underwater (submerged portion), varies as the ship moves
unconditionally stable
center of gravity is BELOW center of buoyancy. regardless of the ship’s heel angle the ship always wants to right itself
metastable
center of gravity is ABOVE center of buoyancy. almost all ships built fall into this category
stability aids
increase resistance to rotation in water, bilge keels, fin stabilizers
titanium hull
Advantages: deeper operation (stronger) lighter (more agile) Disadvantages: costly to manufacture, shortened lifespan because of less flexibility of metal causing more fatigue
aluminum melting point
1220 degrees F
steel melting point
2500 degrees F
