Tonnage

Tonnage is a measurement used in shipping to describe the capacity or size of a vessel. It is used to calculate various fees and taxes related to the operation of the vessel. There are different types of tonnage measurements, including gross tonnage, net tonnage, and deadweight tonnage. 

Gross tonnage (GT) is the total internal volume of the vessel, including all enclosed spaces. Net tonnage (NT) is the measurement of the space available for cargo and passengers, after deducting the space taken up by the crew, machinery, and other items. Deadweight tonnage (DWT) is the maximum weight of cargo and fuel that a ship can carry.