Draft (nautical)

In nautical parlance, draft is the depth below water's surface of the lowest part of a ship or boat. Draft is usually determined for a fully-laden vessel. It determines the minimum depth of water that the vessel may pass through. Riverboats are often purposely designed with a shallow draft to avoid sandbars and other obstacles.

Also in nautical parlance, the draft of a sail is a degree of curvature in a horizontal cross-section. Any sail experiences a force from the pervailing wind just because it impedes the air's passage. A sail with draft also functions as an airfoil when set at an angle slightly greater than the angle of the wind, producing lift which then propels.