Hi Gross tonnage (GT) is a complex volumetric calculation for a...

Hi

Gross tonnage (GT) is a complex volumetric calculation for a vessel based on internal cargo volume capacity and is used for determining safety regulations, manning levels, port dues and registration fees. GT is not a cargo capacity weight.

Gross registered tonnage (GRT) is a measure of the volume inside a vessel that may be available to stow cargo and historically was a tax calculation relating to the number of port alcohol barrels that sailing ships could theoretically carry from Portugal to England. Space volume in this calculation includes any possible barrel storage including accommodation etc. GRT is also not a cargo capacity weight.

Gross tonnage given on marine traffic is provided by the person (not always the ship agent or owner) who enters the vessel's photos and data on the website and is static information not automatically updated to reflect the actual tonnage carried on the current voyage.

Deadweight tonnage (DWT) as given on marine traffic is the weight a ship can carry. Again, data displayed is not updated for each voyage and may not be a reflection of the current voyage cargo weight.

Finally, ship measurements given on marine traffic sometimes appear to be generated by the computer and differ from actual vessel dimensions.