Doors should generally open outwards to provide additional security against the impact of the sea. See also Bow doors, Flood control doors.
- Watertight doors – Watertight doors that are used while at sea are to be sliding doors capable of being remotely closed from the bridge and are also to be operable locally from each side of bulkhead. Access doors, normally closed at sea may be of hinged-type with gaskets and dogs spaced and designed to ensure watertight closing. These closing appliances are to be provided with means of indicating locally and on the bridge whether they are open or closed.