MEANS: Boats p.1

Calculating Displacement of a hull:


The displacement of an object is essentially its weight in a given medium. This is not to be confused with the mass of the object itself rather it has to do with density. It is calculated by multiplying the volume of the object by the weight of the same volume of the liquid in which it will (hopefully) float. Imagine a swimming pool filled to the very top. When a body, say a human, floats in the water, the volume of water that spills out of the pool to allow for the body to float at rest is the body’s displacement. If the person were a boat the weight of the water would be referred to as the boat's displacement.


If a hull is lighter than a volume of liquid equal to that of the boat it will float -- assuming it is made in a shape that does not allow the liquid to enter the displaced volume -- by tipping or flipping, etc. The amount a hull is designed to displace is referred to as its weight, tonnage, diplacement and many other specific terms depending on conditions such as load, cargo, fuel levels, etch. Notice this is related to but not identical to the weight of the boat in conventional terms.


To calculate the total displacement of a hull in fresh water:
Multiply the volume in cubic feet of an object by 62.4 lbs (the weight 1 ft^3 of fresh water)


To calculate the total displacement of a hull in sea water:
Multiply the volume in cubic feet of an object by 64.1 lbs (the weight 1 ft^3 of sea water)