Load Line
The set of marks on a ship’s hull showing the maximum permitted loading draught for different water densities and seasons.
- Category
- Vessel Size and Tonnage
- Last reviewed
How it works
The load line (or Plimsoll line) is a set of marks amidships indicating the deepest a vessel may legally be loaded in different zones and seasons (tropical, summer, winter, and fresh versus salt water) to preserve adequate reserve buoyancy.
Load lines are regulated under the International Convention on Load Lines. Loading beyond the applicable mark is a serious safety and legal breach.
Where it shows up on The Maritime
Also known as: plimsoll line, plimsoll mark, freeboard mark.
Related terms
Draught
The vertical distance from the waterline to the bottom of the keel: how deep the ship sits in the water.
Deadweight Tonnage (DWT)
The total weight a ship can carry (cargo plus fuel, stores, crew and water) at her load line, in metric tonnes.
More vessel size and tonnage terms
A 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: .