1. The depth to which a safely loaded ship will sink in salt water.
2. One of a set of graduated marks on the side of a ship, indicating the depth to which the ship can be loaded in varying waters (such as salt water or freshwater) and weather conditions. • Load lines must, by law in most maritime countries, be cut and painted amidships.
— Also termed (in sense 2) load-line marks; Plimsoll marks.
“The interest of shipowners led them, in early times, to load vessels to a point beyond safety; the greater the weight of the vessel’s load, of course, the lower she rides in the water, and the more vulnerable she is to heavy seas. Many seamen consequently lost their lives. Britain led the way in establishing standards of depth in the water believed to be safe; Samuel Plimsoll, M.P., was the moving spirit, and gave his name to the Plimsoll mark, now seen on the side of all large vessels, which marks the limits of safety for different seas and seasons. Since 1929, the United States has made mandatory the placing of and compliance with loadline marks ….” Grant Gilmore & Charles L. Black Jr., The Law of Admiralty § 11-12, at 987 (2d ed. 1975).
