The total weight of materials on board the vessel that varies little from one voyage to another, including the weight of engine spares, spare propeller, spare anchor, spare tailshaft, stores, provisions, crew’s effects, lubricating oil and fresh water. (A 20, 000 dwt bulk carrier may have a constant weight of 350 tonnes or more. ) It is routinely determined at the start of draught surveys. It is sometimes called the dead weight constant.