# Draft (draught)

> The vertical distance between the waterline and the bottom of a ship's keel.

## Record

- Record type: Encyclopedia entry
- Canonical page: https://admiralsatlas.com/en/ship-technical/draft/
- Last updated: 2026-08-31

## Article

A ship’s draft (British spelling: draught) is the vertical distance from the waterline to the lowest point of the keel — in effect, how deep the ship sits in the water. Draft increases as cargo is loaded and is the key constraint that determines which ports, berths, channels, and canals a vessel can use.

Draft marks are painted on the hull at the bow, stern, and midships, and reading them before and after loading is the basis of the draft survey, a standard method of determining the weight of bulk cargo loaded.

Maximum permitted draft is set by the vessel’s load lines (Plimsoll marks), which vary by season and zone — summer, winter, tropical, and fresh water. Deep-draft chokepoints shape trade: the Suez Canal, the Malacca Strait (“Malaccamax”), and individual port approach channels each impose their own draft limits, and terms like “Suezmax” derive from them.

## Related records

- [Ballast](/en/operations/ballast/index.md)
- [Deadweight tonnage (DWT)](/en/maritime-units/deadweight-tonnage/index.md)
- [Freeboard](/en/ship-technical/freeboard/index.md)