Ship`s tonnage was determined by calculating the number of wine barrel in the middle age. As the volume of wine trade increased, the tax tunnage was imposed on the wine barrel. The term ton have been used as the unit of ship`s size since the 15th cent...
Ship`s tonnage was determined by calculating the number of wine barrel in the middle age. As the volume of wine trade increased, the tax tunnage was imposed on the wine barrel. The term ton have been used as the unit of ship`s size since the 15th century. English people had kept on trying to calculate the tonnage by using 3 components of ship`s dimension, that is the length, the breath, and the depth. At last tonnage was calculated by the following form; tonnage = (L×B×D) ÷ divisor Tonnage measurement introduced in 1582 by Baker had been modified with the time and finally George Moorsom invented the concept of gross and net tonnage respectively in 1854. Moorsom`s Measurement was spreaded to many countries such as USA, France, Netherlands, Germany, Norway, Japan and etc. Many governments used the net tonnage as the basis of taxation. But Moorsom`s Measurement had defects to measure net tonnage, because it used not real volume but fixed ratio volume to deduct the space of engine room. For example, in case of vessels propelled by paddle-wheels, in which the tonnage of the space occupied by the machinery is above 20 per cent. and under 30 per cent. of the gross tonnage, the deduction shall be 37 per cent. of the gross tonnage. Many shipping countries had proposed to rationalize the tonnage measurement meanwhile. Finally UN adopted International Convention on Tonnage Measurement of Ships in 1969 and it came into effect 1980.