Waterline

The line traced by the water level around the sides of a floating hull, or a drawing of the same outline. The length on the waterline (LWL) is the straight-line length from stem to stern in the plane of the waterline, also called the Waterplane. The actual waterline of a vessel may be higher or lower than the designed waterline (DWL) to the extent that she is heavier or lighter than the designer intended. For the purpose of design, the hull is deemed to be sliced fore and aft in planes parallel to the real waterplane – but above and below – and the outlines of these sections are also known as ‘waterlines’ to naval architects. They are in effect the waterlines that would occur if the boat were loaded much above or below the normal – assuming she did not sink or capsize. (See also: Lines).