Not all rules come out of the International Maritime Organization nor federally regulated maritime administrations. In this case there is a new survey requirement for shell and/or inner doors of both passenger and cargo roll on - roll off ships which comes from the International Association of Classification Societies in the form of a Unified Requirement.
IACS UR Z24 is the new survey requirement for Shell and Inner doors of roll on - roll off ships, both cargo and passenger. (You'll have to scroll down to page 711 of a rather large PDF to get to the details). When this UR first hit table in November 2010 it seemed to refer only to ships fitted with a self-stowed loading ramp. Then a member of the IACS pointed out that "some ro-ro ships are not fitted with a loading ramp, but rather utilize a shore-based ramp since these vessels are on a common trade route." In July 2011, the IACS amended UR Z24 to include all ro-ro and ropax ships with shell doors, (bow, side and stern), leading to a ro-ro deck or special category space.
Generally, this survey requirement is pretty typical although there are some points which might give some operators a few moments of pause:
Door structures, securing, supporting, locking device, welds and sockets are subject to non-destructive testing. The maximum wear allowed beyond as-built thickness is 15 percent.
Door seals will be inspected and water tested. (More on this below).
Hinges, bearings and thrust bearings will be measured and, if not accessible to a surveyor, dismantled to gain access.
Vehicle deck drainage systems with storm valves or non-return valves will have to be dismantled.
The other usual things will also be carried out:
Correct panel lights, including a panel lamp test on all door operating and indicator panels; closed-circuit TV cameras; water leak detection system (if fitted); and, system isolation when not in use.
The following couple of items are going to give a couple of different companies a few moments of grief:
Confirmation that the operating panels are inaccessible to unauthorized persons. (That means denying possible access to all operating panels by people who should not be anywhere near them, such as passengers and uninvolved crew).
Verification that a notice plate giving instructions to the effect that all securing devices are to be closed and locked before leaving harbour is placed at each operating panel and supplemented by warning indicator lights. (That should be self-explanatory but you'd be surprised at how many ropax ships have no such instructions posted).
Weathertight doors
This may be one of the most misunderstood definitions in the ro-ro community. Too often seafarers interpret weathertight to mean "rainproof", and that is simply not the case.
Weathertight doors are required to be able to withstand the most severe maritime conditions when the ship is at sea including pressure from wave action and prevent the ingress of water onto the cargo/vehicle deck. Even in a damaged state, if the door is partially submerged, it is expected to withstand water to a pressure of 0.35 bar (5 lbs per square inch) to a height of 3.5 meters measured from the bottom of the door.
This is where the door seals come into play and the water testing of doors may create some issues. Weathertight doors are expected to keep water off the ro-ro deck under even the most extreme conditions. If any water finds its way through the seals during a hose test there is a very good chance the door does not meet the standard.
Door movement
How many ways can inward opening ro-ro deck doors be described as dangerous?
Of course, you could be like Washington State Ferries and simply not bother with doors at all.
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