Draught
The vertical distance from the waterline to the bottom of the keel — how deep the ship sits in the water.
Draught (also spelled draft) is the depth of a vessel below the waterline. It increases as the ship loads cargo, ballast or bunkers, and it must stay within the limits marked by the load line for the relevant zone and season.
Draught governs which ports, berths and canals a ship can use; many size classes — such as Kamsarmax and Aframax — are defined partly by the draught restrictions of key terminals. The design (summer) draught corresponds to the ship’s maximum deadweight.
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Also known as: draft, laden draught.
Related terms
Deadweight TonnageDWT
The total weight a ship can carry — cargo plus fuel, stores, crew and water — at her load line, in metric tonnes.
Ballast
Seawater carried in tanks to keep an unladen ship stable and properly trimmed — and the term for a non-revenue, empty leg.
Load Line
The marks on a ship’s hull showing the maximum permitted loading draught for different water densities and seasons.
Air Draught
The vertical distance from the waterline to the highest point of the ship — what must clear under bridges and cranes.
Plain-English reference definition — our own explanation of a standard shipping concept, not a licensed source or legal advice. See the full glossary or the broader maritime dictionary.
Last reviewed: June 2026.