What does "draft" measure on a ship?

The term "draft" specifically refers to the vertical distance from the waterline of a ship to the lowest point of the keel. This measurement is crucial because it determines how much water a ship requires to float safely. The draft indicates the depth of water required to navigate without running aground, meaning that a ship's draft is an essential factor in harbor entrances, navigation channels, and various maneuvers in different water conditions.

Understanding draft is vital for ship operation and planning, as it can affect the vessel's stability and handling characteristics. Adhering to draft limits helps prevent grounding and allows safe passage through various waterways, which may have depth restrictions.

The other measurements mentioned—weight, length, and width—are distinct from draft and serve different purposes in naval architecture and ship operation. Weight pertains to the overall mass of the vessel, length relates to the distance from the bow to the stern, and width (or beam) describes the widest part of the ship. These dimensions are important for overall ship design and capability, but do not define the draft measurement specifically.