What do gross tonnage, net tonnage, gross deadweight tonnage, net deadweight tonnage, full load displacement, and empty load displacement mean?

According to the International Convention on the Measurement of Tonnage of Ships, 1969, "gross tonnage" refers to the total volume of the ship measured and determined in accordance with the provisions of this Convention. 

In layman's terms, it is the sum of the internal space (or volume) of all enclosed places in the cabin and on the deck.

According to the International Convention on the Measurement of Tonnage of Ships, 1969, "gross tonnage" refers to the total volume of the ship measured and determined in accordance with the provisions of this Convention. 

In layman's terms, it is the sum of the internal space (or volume) of all enclosed places in the cabin and on the deck.

From the literal meaning, we can see the meaning of the two concepts, which refers to the weight of the water discharged when the ship is empty or fully loaded. 

Displacement refers to the weight of the same volume of water displaced by the ship. 

Displacement tonnage can be used to calculate the deadweight of the ship, that is, the deadweight of the ship = full load displacement - empty load displacement.

Gross deadweight tonnage is the maximum weight that a ship can carry according to the International Ship Load Line Convention (ILLC). Gross deadweight tonnage = full load displacement - empty load displacement = cargo + fuel + fresh water, etc.

Net deadweight tonnage is the maximum weight of the ship's cargo. Net deadweight tonnage = gross deadweight tonnage - (weight of fuel, fresh water, etc.).