tonnage

tonnage A measure of the volume or cargo-carrying capacity of a ship. The gross register tonnage (GRT) is the volume of a ship below the upper deck measured in shipping tons of 100 cubic feet. The net register tonnage (NRT) is the GRT less the space occupied by engines, fuel, stores, and accommodation for crew and passengers. Harbour and port dues are usually based on the NRT and dry dock dues are usually based on the GRT. In the UK it is now mandatory to measure tonnage in either GRT or NRT, rather than in any of the various alternative ways sometimes used formerly.

Since 2000 a UK shipowning company may elect to pay corporation tax on the basis of the NRT of its shipping, rather than on the basis of the profit or loss made.