One of the most important regulations to be complied with during the design of watertight bulkheads and doors are that of SOLAS, and some important ones are discussed below:
· The number of openings for pipes and access should be kept to minimum in order to retain the strength of the bulkhead. In case such openings are provided, proper reinforcement must be provided so as to prevent stress concentration, and retain water tightness of the structure. Proper flanging must be incorporated in openings for pipelines and cables.
· Not more than one watertight door is allowed per watertight bulkhead. However, in case of ships having twin shafts, there may be two watertight doors, each providing access to the two shaft tunnels on either side. The mechanical gears required for manual operation of these doors must be located outside the machinery spaces.
· The time required to close or open any watertight door when triggered from the control room or navigation deck should not exceed 60 seconds when the ship is in upright condition.
· The transverse location of the watertight doors should be such that they must be easily operable even when the damage to the ship is within one fifth of the ship’s breadth from its side shell.
· Every watertight door should be equipped with an audible alarm distinct from all other alarms in the area. In case the door is being operated remotely, the alarm should start sounding at least 5 seconds before the door begins to slide either way, and must continue till it has completely opened or closed. However, if operated in situ, the alarm must sound only when the door is sliding. In case of passenger ships, the audible alarm must be accompanied by a visual alarm.
· All watertight doors that are accessible during voyage must be locked via an authorised unlocking system.
· Access doors and hatches on watertight bulkheads must remain closed when the ship is at sea. Visual indicators must be provided for every access hatch to indicate their status at the location and the navigation bridge.
