- Gross tonnage
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Gross Tonnage, along with Net Tonnage, was defined by "The International Convention on Tonnage Measurement of Ships, 1969", adopted by the International Maritime Organization in 1969, and came into force on

July 18 ,1982 . These two measurements replaced Gross Register Tonnage (GRT) and Net Register Tonnage (NRT). Gross Tonnage is calculated based on "the moulded volume of all enclosed spaces of the ship" and is used to determine things such as a ship's manning regulations, safety rules, registration fees and port dues, whereas the older Gross Register Tonnage is a measure of the volume of certain enclosed spaces.**History**The International Convention on Tonnage Measurement of Ships, 1969 was adopted by IMO in 1969.International Maritime Organization, 1982.] The Convention mandated a transition from the former measurements of

gross register tonnage (grt) andnet register tonnage (nrt) to Gross Tonnage (GT) and Net Tonnage (NT). It was the first successful attempt to introduce a universal tonnage measurement system.Various methods were previously used to calculate merchant ship tonnage, but they differed significantly and one single international system was needed. Previous methods traced back to

George Moorsom ofGreat Britain 'sBoard of Trade who devised one such method in 1854.The tonnage determination rules apply to all ships built on or after

July 18 ,1982 . Ships built before that date were given 12 years to migrate from their existing gross register tonnage (GRT) to use of GT and NT. The phase-in period was provided to allow ships time to adjust economically, since tonnage is the basis for satisfying manning regulations and safety rules. Tonnage is also the basis for calculating registration fees and port dues. One of the Convention's goals was to ensure that the new calculated tonnages "did not differ too greatly" from the traditional gross and net register tonnages.Both GT and NT are obtained by measuring ship's volume and then applying a mathematical formula. Gross Tonnage is based on "the moulded volume of all enclosed spaces of the ship" whereas Net Tonnage is based on "the moulded volume of all cargo spaces of the ship." In addition, a ship's net tonnage is constrained to be no less than 30% of her gross tonnage.

**Calculation**The Gross tonnage calculation is defined in Regulation 3 of Annex 1 of " [

*http://www.admiraltylawguide.com/conven/tonnage1969.html The International Convention on Tonnage Measurement of Ships, 1969*] ". It is based on two variables:* "V", the ship's total volume in cubic meters (m³), and

* "K", a multiplier based on the ship volume.The value of the multiplier "K" varies in accordance with a ship's total volume (in cubic metres) and is applied as a kind of reduction factor in determining the gross tonnage value - which does not have a unit such as cubic metres or tons. For smaller ships, "K" is smaller, for larger ships, "K" is larger. "K" ranges from 0.22 to 0.32 and is calculated with a formula which uses the common or base-10 logarithm:

:$K\; =\; 0.2\; +\; 0.02\; imes\; log\_\{10\}(V),$

Once "V" and "K" are known, Gross Tonnage is calculated using the formula, whereby GT is a function of V :

:$GT\; =\; K\; imes\; V,$

As an example, we can calculate the gross tonnage of a ship with 10,000 m³ total volume.:$K\; =\; 0.2\; +\; 0.02\; imes\; log\_\{10\}(V),$::$=\; 0.2\; +\; 0.02\; imes\; log\_\{10\}(10,000),$::$=\; 0.2\; +\; 0.02\; imes\; 4,$::$=\; 0.2\; +\; 0.08,$::$=\; 0.28,$

Then the gross tonnage is calculated:

:$GT\; =\; K\; imes\; V,$::$=\; 0.28\; imes\; 10,000,$::$=\; 2,800,$

**Notes****References***cite web

url= http://www.admiraltylawguide.com/conven/tonnage1969.html

title= International Convention on Tonnage Measurement of Ships, 1969

accessdate= 2008-03-23

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*cite web

url= http://www.imo.org/Conventions/contents.asp?topic_id=259&doc_id=685

title=International Convention on Tonnage Measurement of Ships, 1969

accessdate= 2008-03-23

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author=International Maritime Organization

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authorlink= International Maritime Organization

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* cite book

last = Turpin

first = Edward A.

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coauthors = McEwen, William A.

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title = Merchant Marine Officers' Handbook

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year = 1980

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publisher =Cornell Maritime Press

location = Centreville, MD

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isbn = 0-87038-056-X

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quote =**ee also***

Tonnage

*Gross Register Tonnage

*Ton

*Light ship displacement

*Wikimedia Foundation.
2010.*

### Look at other dictionaries:

**gross tonnage**— UK US noun [U] (ABBREVIATION Gro T, also G.T., or GT, or gt) TRANSPORT, MEASURES ► a ship s total volume (= the amount of space inside it): »The liner was built in 2007 and her gross … Financial and business terms**gross tonnage**— noun : tonnage 4a * * * Naut. the total volume of a vessel, expressed in units of 100 cubic feet (gross ton), with certain open structures, deckhouses, tanks, etc., exempted. Also called gross register tonnage. * * * gross tonnage The total space … Useful english dictionary**gross tonnage**— gross register tonnage See tonnage … Big dictionary of business and management**gross tonnage**— Naut. the total volume of a vessel, expressed in units of 100 cubic feet (gross ton), with certain open structures, deckhouses, tanks, etc., exempted. Also called gross register tonnage. * * * … Universalium**gross tonnage**— a measurement of ship volume; may be used with engine power as a measure of fishing capacity … Dictionary of ichthyology**gross tonnage**— /groʊs ˈtʌnɪdʒ / (say grohs tunij) noun a measure of the enclosed internal volume of a ship and its superstructure, with certain spaces exempted … Australian English dictionary**gross tonnage**— /grəυs tʌnɪdʒ/ noun the total amount of space in a ship … Dictionary of banking and finance**Compensated gross tonnage**— (CGT) is an indicator of the amount of work that is necessary to build a given ship and is calculated by multiplying the tonnage of a ship by a coefficient, which is determined according to type and size of a particular ship. The standard CGT… … Wikipedia**Tonnage**— Ton nage (?; 48), n. [From {Ton} a measure.] [1913 Webster] 1. The weight of goods carried in a boat or a ship. [1913 Webster] 2. The cubical content or burden of a vessel, or vessels, in tons; or, the amount of weight which one or several… … The Collaborative International Dictionary of English**tonnage gross**— Gross tonnage includes a ship s internal volume, excluding such spaces as the peak, double bottom, deep tanks used only for water ballast, bridge, forecastle, open ended poop, certain light and air spaces, skylights, anchor and steering gear… … Dictionary of automotive terms