DISPLACEMENT TONNAGE - is the actual weightof the entire vessel and evey thing aboard her measured in long tons in long tons (2240 lbs.). The displacement tonnage is equal to the weight of the water displaced by the vessel and varies with the draft of the vessel. Displacement tonnage may be qualified as Light, indicating the weight of the vessel without cargo, fuel or stores; or Heavy indicating the weight of the vessel fully loaded with cargo, fuel and stores.
DEAD WEIGHT TONNAGE - is the actual carrying capacity of a vessel and is equal to the difference between the Light 'displacement tonnage and the Heavy displacement tonnage.
Gross tonnage - is the internal capacity of a vessel measured in units of 100 cubic feet.
NET REGISTERED TONNAGE - is also the internal capacity of a vessel measured in units of 100 cubic feet but does not include the space occupied by boilers, engines, shaft alleys, chain lockers, officers
