A "multiple contact situation" is a special circumstances situation, by definition. The Rules apply to the conduct between two vessels only.
Rule 5, the lookout rule, requires each vessel to ascertain to the fullest extent possible the risk of collision. That means that one is not only required to make a determination of approximate course and speed of other vessels but to also divine their intent. As Yamsailor posited, a large ship headed for a narrow channel a few miles distant should probably trigger the thought process in the minds of other vessel's master the thought that he's probably heading for the Kill van Kull, or some similar thought.
All decision making is based upon the presumption of rational actions. The lack of those rational actions, particularly in the cases of small boats and aircraft carriers, is what makes navigating in their presence a bit nerve wracking.(!)
If you're out fishing off Ambrose Light Ship amidst thirty similar sport fishermen and the Bremen Express heaves clear of the eastern horizon headed towards the light ship you can make certain preliminary assumptions about her likely future actions. And you can take early actions based upon those assumptions. But you cannot assume that the Bremen Express will regard thirtyone sport fishermen as anything other than a special circumstances situation, to which the rules of burdened and privileged do not apply. And the logical action on board the Bremen Express will be to proceed towards Ambrose Light Ship and the pilot station in the most direct fashion. Were her master to treat each fishing boat encounter as other than special circumstances, making a nice 30-45 degree course change for the first one, there would be justified and wide-spread panic among the fishing fleet. And by the time the master got done manoeuvering he'd probably be somewhere off the eastern end of Long Island as well.
The
VHF is all well and good. I'm in favor of it's use. But the idea that the Bremen Express is going to communicate with very many of those fishing boats is not practicable. Her master has no practical way of telling the white hulled-blue cabined "Dolly Anne" from the white hulled-teal cabined "Annie B", much less which one is calling him on the
radio. And even if communication is established, it's not reasonable to expect to exchange specific passing information based upon one 5 ton fishing vessel trolling and a 50,000 ton containership. Anotherwords, the ship can't run all over the ocean for one fishing boat without throwing the whole fishing boat fleet into a situation of doubt as to intentions. The most important role of the
VHF in that situation would be to confirm to the fishing fleet that they should be expecting to see a big ship appearing shortly because he just spoke to the pilot boat and said he'd be there in an hour.
What used to be known as the General Prudential Rule is now Rule 2 (b)
"In construing and complying with these Rules due regard shall be had to all dangers of navigation and collision and to any special circumstances, including the limitations of the vessels involved, which may make a departure from these Rules necessary to avoid immediate danger."
Now we know that the Rules only apply to the conduct of two vessels within sight of one another. What makes for a special circumstance? I'll rely on my 1969 edition of
Farwell's Rules of the Nautical Road for a summary of what the courts have found to be special circumstances.
"These may be said to fall into five groups: (1) where the situation is
in extremis; (2) where other apparent physical conditions make obedience to the ordinary rules impracticable; (3) where the ordinary rules must be modified because of the presence of a third, or additional vessels; (4) where the situation is not specifically covered by the rules; (5) where one of two vessels proposes a departure from the rules and the other assents."
Later on Falwell writes, "In all such cases, special circumstances may be deemed to exist the moment any of the vessels is prevented from obeying the usual rules." This in regard to more than two vessels.
Earlier on he details what are not considered special circumstances and I'll try to summarize some of the lengthy explanations.
...if an impending danger is too distant to be considered immediate.
...action by the privileged vessel while it is still possible for the burdened vessel to carry out her obligation and give way. (that being the situation where if you have not taken early and substantial action, readily apparent, you're required to stand on until the pucker factor goes rather higher than confortable!)
...steaming in restricted visibility where a certain amount of headway must be maintained to maintain steerage but that amount of headway makes it impossible to stop the vessel as required. (think maybe Cape Cod canal or other swift moving currents)
...an interesting example of a sailing vessel drifting in a very light wind insufficient to provide steerageway and not keeping a proper lookout subsequently struck by a tug and tow. "the tug was obviously at fault for failing to keep clear of the sailing vessel; but the court held the yacht also at fault, refusing to excuse her situation on the grounds of special circumstance and holding that she should have anchored near the shore instead of allowing herself to drift into mid-stream and into the regular path of moving vessels."
As can be seen there's rather more to the Rules than a cursory reading will reveal and many of the ideas of hard and fast rules are not always quite so. I well recall thinking I had a firm grasp of the Rules and all their concepts only to be confronted with court case examples that required me to go back and re-study the Rules, this time integrating all of them into a cohesive body of work in my mind. For instance, I'd blithely overlooked the fact that the Rules only apply to two ships in sight of one another (assuming that accurately derived
radar information was as valid as visual information) and assumed also that, where more than one vessel was present, you dealt with each as they appeared via the Rules for two ship situations ( special circumstances to me at that time was an ephemeral concept!).
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