Section 3(1) in The Merchant Shipping (Tonnage Measurement Of Ships) Rules, 1960
(1)The gross tonnage of a ship shall be determined by the methods and in the circumstances specified below, namely :-(a)By method I, at the time of registration of a ship and in other cases to which that method is applicable;(b)By method II with the permission of the Central Government, where the ship has cargo on board and in other cases where method I is not applicable :Provided that the owner of any ship the tonnage of which was determined by method II may, at any subsequent time, apply to the Central Government for the determination of its tonnage by method I.The ship shall thereupon be re-measured and tonnage altered accordingly.(c)By method III, in the case of open ships.
