Waterline

For other uses, see Waterline (disambiguation).
Waterline of a ship. The mark above the waterline indicates the Plimsoll line

The waterline is the line where the hull of a ship meets the surface of the water.

A waterline can also refer to any line on a ship's hull that is parallel to the water's surface when the ship is afloat in a level trimmed position. Hence, waterlines are a class of "ships lines" used to denote the shape of a hull in naval architecture lines plans.[1]

The load line (also known as Plimsoll line) is the waterline which indicates the legal limit to which a ship may be loaded for specific water types and temperatures in order to safely maintain buoyancy.[2]

For vessels with displacement hulls, the hull speed is defined by, among other things, the waterline length. In a sailing boat, the waterline length can change significantly as the boat heels, and can dynamically affect the speed of the boat.

  1. ^ Kerchove 1961, p. 901, Waterlines.
  2. ^ Kerchove 1961, pp. 464–465, Load Waterline.