Ajay Kumar at 17:11, 24 August 2023

2023-08-24T17:11:53Z

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{{Short description|Measure of how much weight a ship can carry}}
{{hatnote|Not to be confused with [[displacement (ship)|vessel displacement]].}}
[[Image:Draft scale at the ship bow (PIC00110).jpg|right|thumb|The more heavily loaded a ship is, the lower it sits in the water. Maximum DWT is the amount of weight a ship can carry without riding dangerously low in the water.]]
[[Image:Echelle Port en lourd.jpg|right|thumb|Scale for a 6,000 tonne DWT ship.]]

'''Deadweight tonnage''' (also known as '''deadweight'''; abbreviated to '''DWT''', '''D.W.T.''', '''d.w.t.''', or '''dwt''') or '''tons deadweight''' (DWT) is a measure of how much [[weight]] a ship can carry.<ref name="tm">{{cite book | last =Turpin | first = Edward A. |author2=William A. McEwen | title =Merchant Marine Officers' Handbook | edition = 4th | year = 1980 | publisher =Cornell Maritime Press | location =Centreville, Maryland | isbn =0-87033-056-X | pages = 14–21 }}</ref><ref name="hm">{{cite book |last=Hayler |first=William B. |title=American Merchant Seaman's Manual |edition=7th |year=2003 |publisher=Cornell Maritime Press |location=Centreville, Maryland |isbn= 0-87033-549-9 | page=G-10}}</ref><ref
name="msd">{{cite book |last=Gilmer |first=Thomas C. |title=Modern Ship Design |edition=2nd |year=1975 |publisher=Naval Institute Press |isbn= 0-87021-388-1 |page=25 }}</ref> It is the sum of the weights of [[cargo]], fuel, [[fresh water]], [[Sailing ballast#Water ballast|ballast water]], provisions, passengers, and [[crew]].<ref name="tm" />

DWT is often used to specify a ship's maximum permissible deadweight (i.e. when it is fully loaded so that its [[Plimsoll line]] is at water level), although it may also denote the actual DWT of a ship not loaded to capacity.

==Definition==
Deadweight tonnage is a measure of a vessel's weight carrying capacity, not including the empty weight of the ship. It is distinct from the [[displacement (ship)|displacement]] (weight of water displaced), which includes the ship's own weight, or the volumetric measures of [[gross tonnage]] or [[net tonnage]] (and the legacy measures [[gross register tonnage]] and [[net register tonnage]]).

Deadweight tonnage was historically expressed in [[long ton]]s<ref group=note>One long ton (LT) is {{convert|2240|lbs|kg|0|abbr=out}}</ref> but is now usually given internationally in [[tonne]]s (metric tons).<ref>{{cite book |last=McNicholas |first=Michael |date=2011-08-29 |title=Maritime Security: An Introduction |url=https://books.google.com/books?id=4ZIzff8gzi8C |publisher=Butterworth-Heinemann |page=30 |isbn=9780080919539 |access-date=2014-08-25 }}</ref> In modern international shipping conventions such as the [[SOLAS Convention|International Convention for the Safety of Life at Sea]] and the [[MARPOL 73/78|International Convention for the Prevention of Pollution From Ships]], deadweight is explicitly defined as the difference in tonnes between the displacement of a ship in water of a [[specific gravity]] of 1.025 (corresponding to average density of [[sea water]] of 1025 kg/m<sup>3</sup>) at the [[draft (hull)|draft]] corresponding to the assigned [[summer draft|summer freeboard]] and the [[light displacement]] (lightweight) of the ship.<ref>{{cite book |author= |title=SOLAS Consolidated Edition 2009 |location=London |publisher=International Maritime Organization |page=33 |year=2009 |isbn=978-92-801-1505-5 }}</ref><ref>{{cite book |author= |title=MARPOL Consolidated Edition 2011 |location=London |publisher=International Maritime Organization |page=44 |year=2011 |isbn=978-92-801-1532-1 }}</ref>

== See also ==
* {{Portal-inline|Transport}}

==Notes==
{{Reflist|group=note}}

==References==
{{Reflist}}

{{Ship measurements}}

{{DEFAULTSORT:Deadweight Tonnage}}
[[Category:Nautical terminology]]
[[Category:Ship measurements]]
[[Category:Shipbuilding]]

Deadweight tonnage - Revision history

Ajay Kumar at 17:11, 24 August 2023