At each of the ports of Bombay, Calcutta and Madras, the principal officer of the Mercantile Marine Department, and at any other port such authority as the Central Government may, by notification in the Official Gazette, appoint, shall be the registrar of Indian ships at that port:
     ¹[Provided that subject to such order as the Central Government may issue in this behalf when the office of registrar of Indian ships at any port is vacant or the holder of such office is on leave or is not available, for any reason at the port to exercise and discharge the powers, duties and functions of the office the senior most surveyor at that port may act as and exercise and discharge the powers' duties and functions of the registrar of Indian ships at that port.]