To avoid ships being overloaded, a British politician, Samuel Plimsoll, introduced a law in Britain whereby every ship had to have a special marking on both sides of the ship. This marking had to be positioned at a prescribed measurement from the main deck. The marking is now compulsory on all ships and was called the Plimsoll Line, but is generally referred to now as the loadline. (See the key below for the meaning of each black letter. The yellow lines and the letters in the yellow arrows are only labels for the diagram – see their meaning below.)

load_line_1A          Deck Line

B          Summer freeboard (The measurement from the Summer mark S to the main deck of the ship.)

         These show the Classification Society (Lloyd’s Register) that “classes” the ship. Other ships may have the letters A B (American Bureau of Shipping) or N V (Det Norske Veritas) or the initials of other Classification Societies here. Classification Societies will be covered during your Maritime Economics course in Grade 12.

The black letters shown in this diagram indicate levels to which the ship may be loaded when operating in specified areas. These are internationally agreed areas that are fixed according to either  water density or the general weather conditions in each area. Seasonal weather is also taken into account, especially in those area where conditions experienced in summer are very different to those in winter or in a cyclone season.

TF        Tropical Fresh : Tropical areas where the water is fresh (e.g. the Amazon River.)

F          Fresh Water : Areas where the water is fresh (e.g. parts of the St Lawrence Seaway and the Great Lakes of North America.)

T          Tropical Water  : Any area inside the tropics (e.g. a ship going from Nigeria to the Caribbean Sea will pass through tropical water.)

         Summer : Summer zones are marked on a special map of the world according to the general weather conditions experienced. The entire South African coast is a designated Summer Zone, even during winter!

W         Winter :  Winter zones are marked on a special map of the world. These are zones where stormy conditions can occur at particular times of the year.

WNA    Winter North Atlantic : The northern part of the North Atlantic Ocean in winter and in some areas of the Southern Ocean. These are areas where severe stormy conditions are experienced regularly.