321. (1) The master of every ship other than a Bangladesh ship, being a passenger ship or being any other ship of five hundred tons gross or upwards, belonging to a country to which the Safety Convention applies, shall produce a valid Safety Convention Certificate to the Collector of Customs from whom a port clearance for the ship is sought in respect of a voyage from a port or place in Bangladesh to a port or place outside Bangladesh, and port clearance shall not be granted and the ship may be detained until such a certificate is so produced. (2) Where any such ship, other than a passenger ship, as is referred to in sub-section (1), is of less than five hundred but not less than three hundred tons gross, the master shall be required to produce only a valid Safety Convention Certificate equivalent to those issued under section 311 and the other provisions of sub section (1) shall apply accordingly. (3) Where a valid Safety Convention Certificate is produced in respect of a ship other than a Bangladesh ship, the ship shall not be deemed to be unsafe for the purposes of section 359, by reason of the defective condition of her hull, equipment or machinery unless it appears that the ship cannot proceed to sea without danger to the passengers or crew owing to the fact that the actual condition of the ship does not correspond substantially with the particulars stated in the certificate.