Watertight doors on ships
Subdividing ships and consequently watertight doors predate the *Titanic* and have roots going back around 1,000 years. The development of modern watertight doors that can be automatically closed obviously required electrical and mechanical systems to be possible.
The gravity operated doors on the *Titanic* had an electric release system that could not be reversed once operated. Much of the modern development was related to warships and shortly after the *Titanic* sinking a huge amount of operational experience was gained during the 1914-18 war. One of the failings identified was that crew would leave doors open for ease of movement but this had disastrous effects if the ship was torpedoed. Given that many casualties through to the modern day have occurred precisely because of doors being left open it would appear that human nature puts more importance on saving a few seconds when moving around the vessel than on saving lives if an incident occurs.
Certainly that was true of the *Costa Concordia* as a report by the Italian said that after the hull was opened by contact with rocks, water immediately flooded compartments number 5 propulsion electric motor and number 6 (aft generators) and soon spread to number 7 (forward generators) and number 4 (galley compressors).
Soon after the incident, the P&I club Gard released an in-depth examination of the role watertight doors may have played in other incidents that raised longstanding issues over their use. Going back as far as 1982, when the ro-ro ferry *European Gateway* collided with a vessel at the entrance to thePort of Harwich in the UK), an investigation found that watertight doors to machinery spaces were open at the time of the collision.
“The doors complied with the regulations in force at the time but could only be closed manually,” noted Gard. “Attempts had been made to close two of the doors without success.”
After the *Herald of Free Enterprise* disaster in 1987, the UK authorities proposed new regulations at the IMO resulting in, among other things, 1988 amendments to SOLAS requiring indicators on the bridge for all doors that could lead to major flooding if left open. Further amendments were adopted in 1989, all coming into force on 1 February 1992. The most important were changes in regulations for openings in watertight bulkheads in passenger ships. The report also looked at the issue of power-operated sliding doors capable of being closed from the bridge. While most accept that the safety of the ship is improved, the danger to crew members has increased because they can be trapped behind doors or if too slow in moving through they can be crushed. The report also mentioned lack of standards as being an issue.
In 1994 the Ro-Ro passenger ferry *Estonia* sank in the Baltic Sea with the loss of 852 lives. In addition to the official report, there were different views concerning the sequence of events that led to the sinking. In 2003, Anders Bjørkman of Heiwa Co stated that the vessel had 22 doors in watertight bulkheads below the superstructure, and that those doors could be opened and kept open from the bridge. There may have been confusion about the colour of signalling lights)on the bridge panel for doors open or doors closed. It was international practice to use green lights for doors closed and red lights for doors open, but there were indications that it was the opposite on board the Estonia.
In 2000 Greek ro-ro ferry *Express Samina* hit a rocky island and sank in 45 minutes. Water ingress caused the electrical supply to fail. The ship had 11 watertight doors in subdivision bulkheads, nine of which were open and could not be closed because of the power failure. In 2007 the cruise vessel Sea Diamond ran aground on a reef near the Greek island of Santorini. Water entered the vessel, which took a list of 12° before watertight doors were reportedly closed. Following massive ingress of water, the vessel sank. There was a dispute later as to whether the watertight doors had been closed, and if so, at what time. Given the long list of incidents it should be no surprise that the issue of watertight doors was being discussed and regulations revised at the IMO well before the *Costa Concordia* incident.
Safety under pressure
Watertight doors come in a variety of types with variants suited to specific applications. Most watertight doors are of the horizontal sliding type and are hydraulically operated. The hydraulic rams keep closed doors pressed firmly shut against rubber gaskets that prevent leaks. Although designed to be operated automatically, they can also be operated manually to both open and close as necessary.
When doors are operated automatically, light and sound alarms will be activated warning crew of the hazard. Assuming that power is available and a closed door needs to be negotiated, the procedure may require the use of both hands making transport of any heavy or bulky items a two-man job. If power is not available, (link: /ancillary-machinery/pump-technology-on-ships text: a manual pump) is provided to operate the hydraulics but again this is not a single-handed operation.
Maintenance of doors consists of observation and checking the mechanisms to their full operation. The rubber gaskets must be check for damage and hydraulic hoses and connections checked for chaffing and tightness. Guides must be obstacle free and moving parts checked for easy operation. The hydraulic ram should be checked for leaks, these can be caused by a damaged cylinder ram. Manual pumps must have an adequate fluid level with all pipes and connections intact and leak-free and importantly the removable handle must be readily to hand. Finally the manual operating switches on each side must be operational.
Some doors are not powered and are always operated manually. These are hinged doors with locking bars or latching dogs located around the perimeter that can be operated individually or with a control lever that is connected by chains or gears to all the latching arms. Any moving parts on these doors need to be maintained so as to operate freely when required.
Some of the cargo doors on ro-ro decks may be top or side hinged with a sliding element at the end. This allows the door to be opened to its full width when handling cargo but with restricted width for opening the door at sea for crew to pass.
An open door is clearly not watertight but while SOLAS can regulate their presence, it is the flag state that determines which if any can be left open during voyages. At MSC.88 the IMO approved MSC.1/Circ.1380 which gives guidance on the issue. The default position is that doors must be kept closed but shipowners can apply to the flag state for dispensation for certain doors. The circular describes the following categories.
* Type A - a door that is kept open, OR
* Type B - a door that shall be closed, but may be left opened for the length of time that personnel are working in the adjacent compartment. In the case of the crew accommodation area, the presence of a competent person, in the adjacent compartment will satisfy this requirement, OR
* Type C - a door that shall be closed, but may be opened to permit passage.
* Type D – a door that shall be closed BEFORE the voyage commences and shall be kept closed during Navigation.**
The final decision as to category will rest with the flag state and owners will be expected to make a reasoned case for any requested exemption.