The Plimsoll line
The Plimsoll line or International Load line is placed mid-way between the forward and after perpendiculars of the ship and give the draft of the ship that is the legal limit to which a ship may be loaded for specific water density and temperature so that the ship will have sufficient reserve buoyancy to safely deal with any unforeseeable sea conditions. Temperature can influence the draft of a ship because warm water provides less buoyancy as it is less dense than cold water but this factor is not really taken into account in cargo calculations except by the use of Load line Zones of areas that have been defined in the International Load line Convention. The factor that is taken into account before every ships sail and must be entered in the ships official log book so that it can be inspected by the ship’s Administration is the density of the water. Saltwater has a density of 1025 kg/m3 and fresh water 1000 kg/m3 (MariEMS 2017).