Draught

The vertical distance between the waterline and the lowest point of the hull, typically the keel, indicating how deep the vessel sits in the water.

The draught (also spelled “draft” in American English) is a measurement in the design, operation, and navigation of boats and ships. It represents the depth of water a vessel requires to float without touching the seabed. This measurement is taken from the waterline (the point where the hull meets the water’s surface) down to the lowest part of the vessel, which is usually the keel. The draught is an important factor in determining where a vessel can safely navigate, especially in shallow waters, harbours, or when approaching shorelines.

For example, a vessel with a deep draught may not be able to enter certain ports or navigate through shallow channels, while a vessel with a shallow draught can access more restricted areas. The draught also affects the vessel’s stability and handling. A deeper draught can provide better stability in rough seas, as the vessel’s centre of gravity is lower, but it may also increase drag, reducing speed and fuel efficiency.

The draught can vary depending on the vessel’s load. A fully loaded ship will have a deeper draught than when it is empty or lightly loaded, a concept known as “loaded draught” versus “light draught.” Understanding a vessel’s draught is essential for safe navigation, ensuring that the vessel does not run aground or encounter underwater obstacles.