17.—(1) The number of openings in the boundaries of watertight compartments shall be the minimum compatible with the design and proper working of the ship. Where penetration of watertight bulkheads and internal decks is necessary for access, piping, ventilation, electrical cables, or for any other purpose, arrangements shall be made to maintain watertight integrity at each such point of penetration. The Certifying Authority may permit openings in compartment boundaries above the freeboard deck to be weathertight rather than watertight where it is demonstrated that any progressive flooding resulting therefrom can be easily controlled and the safety of the ship would not be impaired.
(2) Doors provided to ensure the watertight integrity of internal openings which are used while the ship is at sea shall be of the sliding watertight type and capable of being remotely closed from the bridge and capable also of being operated locally from each side of the door without the door closing automatically. Indicators shall be provided at the bridge position showing whether the doors are open or closed, and an audible alarm shall be provided when the door closes. The power for operating and controlling the doors, indicators and alarms shall be supplied from the emergency switchboard required by regulation 49. The control system shall be so designed that if the system fails, closure by hand will not be prevented or impeded. Each power-operated sliding watertight door shall be provided with an individual hand-operated opening and closing mechanism. Means shall be provided at the door itself to open and close the door safely by hand from both sides and from an accessible position above the bulkhead deck.
(3) Access doors and access hatch covers normally closed at sea and intended to ensure the watertight integrity of internal openings, shall be provided locally and on the bridge, with indicators to show whether these doors or hatch covers are open or closed. A notice shall be affixed to each such door or hatch cover stating that it is not to be left open at sea. Such doors and hatch covers shall not be used except where access is necessary and is authorised by the officer of the watch.
(4) Watertight doors or ramps of satisfactory construction may be fitted to subdivide large cargo spaces internally where the Certifying Authority is satisfied that such doors or ramps are essential. These watertight doors or ramps may be of the hinged, rolling or sliding type, but shall not be remotely controlled. They shall be closed before the voyage commences and shall be kept closed throughout the voyage. The time of opening such doors or ramps when the voyage has ended and of closing them before the voyage commences shall be entered in the log book. Any doors or ramps which may be accessible during the voyage shall be fitted with a device which prevents unauthorised opening.
(5) Every closing appliance which is required to be kept permanently closed at sea to ensure the watertight integrity of a compartment shall be provided with a notice affixed to it stating that it is to be kept closed, except that manholes secured by closely bolted covers need not be so marked.