22.—(1) The following closing appliances are to be securely closed before the ship proceeds on any voyage and are to be kept closed until the ship has been secured at a berth or anchorage—
(a)watertight doors below the margin line fitted in bulkheads which are required to be watertight and which separate cargo spaces;
(b)sidescuttles which can be opened and which are situated below the margin line;
(c)deadlights of any sidescuttles which are situated below the margin line and which—
(i)will not be accessible whilst the ship is at sea; or
(ii)are situated in spaces appropriated for use sometimes for the carriage of cargo and sometimes for use by passengers, while such spaces are being used for the carriage of cargo; and
(d)gangway and cargo loading doors below the margin line.
(2) No closing appliance described in paragraph (1) shall be considered as being securely closed unless it is locked.
(3) Watertight doors below the bulkhead deck fitted in bulkheads which are required to be watertight, other than those doors described in paragraph (1), shall be kept closed whilst the ship is on any voyage except—
(a)when opened in accordance with the procedures laid down in written operational instructions;
(b)when opened for the purpose of drill required by regulation 24; or
(c)when any such door is opened on the express authority of the master for a specific purpose, for no longer than a specific period of time and on condition that all other watertight doors below the margin line, except those opened in accordance with the provisions of sub-paragraph (a), are closed during that period.
(4) The operational instructions referred to in paragraph (3)(a) shall be kept on board the ship at all times in the custody of the master.
(5) Any watertight door which may be opened in accordance with the requirements of paragraph (3) shall be kept clear of obstructions which might prevent its rapid closure.
(6) Notwithstanding the requirements of this regulation, in an emergency situation the master may authorise the opening or closing of any watertight door, provided he is satisfied that such action is essential for the overall safety of the ship.
(7) Every portable plate closing an opening below the bulkhead deck in any portion of the internal structure of the ship which is required to be watertight shall be fitted in place before the ship proceeds on any voyage and shall be kept in place, except in case of urgent necessity, until the ship has been secured at a berth or anchorage. In replacing any such plate all reasonable precautions shall be taken to ensure that the joints are watertight.
(8) Both the watertight cover and the automatic non-return valve of a chute or other similar device on the ship having its inboard opening below the margin line shall be kept closed and secured when such device is not in use.