Hull Construction Regulations — 16
16 (1) Where in a ship not required by section 9 of Schedule I to have a factor of subdivision of 0.5 or less, any sliding watertight door in a bulkhead, other than a door at the entrance to a tunnel, is in a position that may require it to be opened at sea and the sill thereof is below the deepest subdivision load water line, the following provisions apply: (a) if the number of such doors exceeds five, all such doors and all tunnel doors shall be operated by power and shall be capable of being simultaneously closed from a central control situated on the bridge; and (b) if the number of such doors does not exceed five, (i) if the criterion numeral of the ship does not exceed 30, such doors and tunnel doors shall not be required to be operated by power, and (ii) if the criterion numeral of the ship exceeds 30, all such doors and all tunnel doors shall be operated by power and shall be capable of being simultaneously closed from a central control situated on the bridge, provided that, if there is only one such door and one tunnel door in the ship, both of which are in the machinery space, they shall not be required to be operated by power. (2) In every ship, other than ships of Class I, required by section 9 of Schedule I to have a factor of subdivision not over 0.5, all sliding watertight doors shall be operated by power and shall be capable of being simultaneously closed from a central control situated on the bridge, provided that, if there is only one such door and it is in the machinery space, it shall not be required to be operated by power. (3) Where a sliding watertight door that may be opened at sea for the purpose of trimming coal is fitted between bunkers in the between decks below the bulkhead deck, such door shall be operated by power. (4) Where a trunkway that is part of a refrigeration, ventilation or forced draught system, is carried through more than one transverse watertight bulkhead and the sill of the opening of such trunkway is less than 2.13 m above the deepest subdivision load water line, the sliding watertight door at the opening shall be operated by power. (5) Where a sliding watertight door is required to be operated by power from a central control, the power system shall be so arranged that the door can also be operated by power at the door itself; the arrangement shall be such that the door will close automatically if opened at the door itself after being closed from the central control, and will be capable of being kept closed at the door itself notwithstanding that an attempt may be made to open it from the central control; handles for controlling the power system shall be provided at both sides of the bulkhead in which the door is situated and shall be so arranged that any person passing through the doorway will be able to hold both handles in the open position simultaneously. (6) Where these Regulations require that the opening and closing of the sliding watertight doors of a ship be operated by power, (a) there shall be at least two sources of power for opening and closing all such doors simultaneously; (b) an indicator shall be fitted at the central control site for such doors, to show whether there is any disruption in the power available to operate them; (c) any fluid used for the purpose of operating such doors shall be incapable of freezing at the temperatures likely to be encountered on the voyages the ship makes; (d) there shall, in the case of an electro-hydraulic operating system, be two sources of hydraulic power fitted, consisting of two pumps or their equivalent, in addition to the main and emergency sources of power. (7) Every sliding watertight door that is operated by power shall be provided with efficient hand-operating gear that can be operated both at the door itself and at an accessible position above the bulkhead deck; at the position above the bulkhead deck the hand-operating gear shall be operated with an all-round crank motion. (8) Where a sliding watertight door is not requ