(a)  the tonnage of a ship shall be determined in accordance with the valid certificate indicating its tonnage;

(b)  "valid certificate" means,—

  (i)  in case of ships registered in India—

(a)  having a length of less than twenty-four metres, a certificate issued under the Merchant Shipping (Tonnage Measurement of Ship) Rules, 1987 made under the Merchant Shipping Act, 1958 (44 of 1958);

(b)  having a length of twenty-four metres or more, an international tonnage certificate issued under the provisions of the Convention on Tonnage Measurement of Ships, 1969, as specified in the Merchant Shipping (Tonnage Measurement of Ship) Rules, 1987 made under the Merchant Shipping Act, 1958 (44 of 1958);

 (ii)  in case of ships registered outside India, a licence issued by the Director-General of Shipping under section 406 or section 407 of the Merchant Shipping Act, 1958 (44 of 1958) specifying the net tonnage on the basis of Tonnage Certificate issued by the Flag State Administration where the ship is registered or any other evidence acceptable to the Director-General of Shipping produced by the ship owner while seeking permission for chartering in the ship.