Ships’ Tonnage

“Tonnage” is the measure of a ship’s volume or capacity, described in cubic feet. Gross registered tonnage ( grt ) is the measure of total internal volume of a ship, in units of one hundred cubic feet, excluding machinery spaces, bridge and navigation spaces, and other minor spaces essential to the operation of the ship. This measure is applied only to merchant vessels. Net registered tonnage ( nrt ) is tonnage frequently shown on merchant ship registration papers. It represents the internal volume available for cargo and for passengers. Set at one hundred cubic feet per ton, it is used by port and canal authorities as a basis for tolls and charges.