Introduction to ship draughts and tonnages

Draft: The vertical distance from the upper edge of the plate keel to the surface of the water. Plus the thickness of the flat keel, for the actual draught.

Weight ton: Indicates the weight of the ship, but also indicates the shipping capacity of the ship. Can be divided into displacement and load.

Displacement: refers to the weight of the same volume of water that the ship is displacing in the water.

Full-load displacement: The amount of water discharged when the ship is loaded with cargo, passengers, fuel, fresh water and supplies, and has the specified safety freeboard, usually the displacement of the ship when it reaches the summer load line in seawater.

Empty boat displacement: The amount of water discharged when the ship is not loaded with cargo, passengers, fuel, fresh water and supplies.

Load capacity: The total load, which means the ship's load capacity. Namely: Load = Full-load Displacement - Empty Ship Displacement Net Load: This represents the actual tonnage of the cargo that can be loaded. It varies with the amount of stock required for the particular voyage.

Net load = total load - weight, volume, tonnage of fuel, fresh water, supplies, stocks, etc. Tonnage: It is the tonnage obtained after the ship's displacement has been measured. It represents the size of the ship's space, also known as the registered tonnage. .

Gross tonnage grossstonnage: A general statistical unit representing the scale of the construction of a ship, and is one of the benchmarks for calculating maritime claims.

The navigation work spaces above the upper deck, navigation equipment spaces, safety equipment spaces, ventilated lighting spaces, mechanical spaces, anchor equipment spaces, lift ports and access hatches, kitchens, and toilets shall be deducted from the volume of all fixed enclosed spaces on board. The total tonnage of the ship is divided by 2.83 after the volume occupied by the workshop, storage room, ballast water tank, etc. The specific provisions for its measurement can be found in the "Ship Tonnage Measurement Specification".

Nettonnage: The volume that cannot be used for passenger and cargo transportation, such as the engine room, material cabin, and crew accommodation, is deducted from the total volume, and then divided by the tonnage obtained after 2.83. The net tonnage is the basis for calculating taxation, port fees, parking fees, pilotage fees, and tugboat fees.

The calculation of volume tonnage is:

1 volume tons = 2.83m3 = 100ft3