Deadweight tonnage (also known as deadweight abbreviated to DWT, D.W.T., d.w.t., or dwt) is a measure of how much weight a ship is carrying or can safely carry. It is the sum of the weights of cargo, fuel, fresh water, ballast water, provisions, passengers, and crew. The term is often used to specify a ship's maximum permissible deadweight, the DWT when the ship is fully loaded so that its Plimsoll line is at the point of submersion, although it may also denote the actual DWT of a ship not loaded to capacity.
Deadweight tonnage was historically expressed in long tons but is now usually given internationally in tonnes. Deadweight tonnage is not a measure of the ship's displacement and should not be confused with gross tonnage or net tonnage (or their more archaic forms gross register tonnage or net register tonnage).
- Turpin and McEwen (1980), pages 14–21.
- Hayler and Keever (2004) page G-10.
- Gilmer (1975) page 25.
- One long ton is 2240 pounds (1016.05 kg), and one tonne or metric ton (tonne isn't used in the U.S.) is 1,000 kg.
- Gilmer, Thomas C. (1975). Modern Ship Design (2nd ed.). Naval Institute Press. ISBN 0-87021-388-1.
- Hayler, William B. (2003). American Merchant Seaman's Manual (7th ed.). Centreville, Maryland: Cornell Maritime Press. ISBN 0-87033-549-9.
- Turpin, Edward A.; William A. McEwen (1980). Merchant Marine Officers' Handbook (4th ed.). Centreville, Maryland: Cornell Maritime Press. ISBN 0-87033-056-X.