Displacement (ship)
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The displacement or displacement tonnage of a ship is its weight. As the term indicates, it is measured indirectly, using Archimedes' principle, by first calculating the volume of water displaced by t
Draft marks, by showing how low a ship is sitting in the water, make it possible to determine displacement.
Shipboard stability computer programs can be used to calculate a vessel's displacement.
In this 1940 photo, USS Aaron Ward, left, and USS Abel P. Upshur are destroyers of comparable size, but because the latter is more heavily loaded, it sits lower, displacing more water.
Greek philosopher Archimedes having his famous bath, the birth of the theory of displacement
Tonnage
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Tonnage is a measure of the capacity of a ship, and is commonly used to assess fees on commercial shipping. The term derives from the taxation paid on tuns or casks of wine. In modern maritime usage,
Traditional English wine cask units