While I have no knowledge of the detailed circumstances of last night’s Sydney Harbour collision tragedy, I have long been considering the tendency of the single decked government catamaran ferries to become involved in collisions with small vessels.
There have been many. On the other hand, I am not aware of any situations in which either River Cats or Harbour Cats have been involved in collisions with (visually) larger vessels.
I specifically rule out collisions with wharves or other structures in which situation the matter may also involve mechanical failure. Such mechanical failure can be more dramatic because of the fact that one of the two hulls will be unpowered while the other is still under power. The resultant unbalance of power can, in some situations, overpower any possible rudder effect.
The key to last night’s accident may well have been visibility.
Pam Burridge: The ferry which collided with a private boat on Sydney Harbour last night.
Any vessel that has the wheelhouse on the second deck or higher provides the Master with a position in which he or she is looking down on the water ahead, perhaps at an angle of 50 or more degrees. In effect he/she is looking at a black area on which there may or not be another vessel. If that vessel is light coloured or well lit it is not too hard to work out what it is doing and what it may be likely to do.
This situation applies equally in daylight as at night but the possibilities for confusion are greater at night. Should a small craft be one of the many whose Masters do not have the correct navigation lights or who do not understand their responsibilities as Master of vessel, concerning the Rules of Road, it becomes much harder for the operator of another vessel to make a decision.
I noticed this particularly when I moved from large vessels into skippering small fast craft.
The Master of one of the River Cats/Harbour Cats is at best one deck height above the water. Most of these craft have car-type sloping wheelhouse front windows and some have a curved surface. There is a natural tendency for such surfaces to produce varying reflections. This was recognised in the 1969 Lady Cutler class of Sydney ferries in which the original name ship had her windscreen set up like a car windscreen. The other four of the class plus two larger vessels were given reverse screens to reduce reflections.
I would like to see examinations of this theory carried out by competent people as I feel that the low, flat angle of vision from the Harbour and River Cats may be exacerbated by the windscreen setup.
In these vessels the Master’s angle of view forward across the water may be something around 10-15 degrees of angle which provides only a small clear area of water that is not overshadowed by background.
Thus, another vessel instead of being clearly ”in” a patch of water, may in part be blending into the lights of the shoreline behind, thus reducing the visual information available to the Master.
I emphasise that I have noted this situation at night and by day when operating vessels ranging from 10 knots to 35 knots and in commercial and private craft ranging from 8m to 60m odd (from one tonne to 500 plus).
More recently I have spoken to ferry masters who have commented on the vision problems of the River and Harbour Cats when compared the bigger and, importantly, vertically higher ferries.