Reserve Buoyancy
The volume of the watertight portion of the ship
above the waterline is known as the ship’s reserve
buoyancy. Expressed as a percentage, reserve
buoyancy is the ratio of the volume of the above-water
body to the volume of the underwater body. Thus
reserve buoyancy may be stated as a volume in cubic
feet, as a ratio or percentage, or as an equivalent weight
of seawater in tons. (In tons it is 1/35 of the volume in
cubic feet of the above-water body.)