almost pointless question

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pintobest

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It's pouring with rain, I've a day off work and WILL get lumbered with DIY. I'm bored, so I thought I'd pose a question which a yachtmaster-examiner mate of mine put to me just for interest's sake over a pint.
(I'm new to this, so if it's already been done please accept my apologies in advance!)
The problem to be solved as he put it to me is :-
Three vessels are in sight of each other and on a steady bearing and all three are on a converging course. There is a risk of collision.
One vessel is showing a black cylinder, the second is showing two black balls and the third is showing ball-diamond-ball.
Who gives way to whom ?



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I would suggest everyone stays clear of the two black balls because this vessel, in theory can take no avoiding action (not under command). Both the others have some ability to manoeuvre. I would then suggest the Ball/diamond/ball cedes to the cylinder because she may have more scope for manoeuvring, but this would depend on circumstances. In a very narrow channel it may be that the ball/diamond/ball, with shallow draught, may be able to move outside the channel. Alternatively it may be that the cylinder can at least slow down or speed up while the ball/diamond/ball is committed to a course and speed (refuelling, for example though it's unlikely this would be done in a narrow channel).

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Your yachtmaster examiner mate forgot to introduce the seaplane which was about to start its take off run. A careful study of Rule 18 (d) (i) and (e) will answer all your questions, assuming you know the daylight signals being displayed by the various vessels. If not see Rules 27 and 28

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And the vessel with a blue and white diver flag. What's he doing there? He's down investigating the wrecked vessel of the last bloke who got confused by this sort of tosh.

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I know the answer, I thought the question might be a bit of fun - that's all.
I do realise that the situation is unlikely to arise.
I'll be more circumspect in future .

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Pointless but interesting

Not quite. Rule 18(d)(i) certainly helps, but only by implication. It requires every vessel except those not under command (NUC) or restricted in ability to manoeuvre (RIAM) to avoid impeding the passage of a vessel constrained by draught (CD); by implication, therefore, a CD vessel should give way to NUC or RIAM vessels. But nowhere in Colregs does it specifically say so. The list of vessels given in 18(a) appears to suggest that NUC vessel have a higher priority, but only by the implication of position on the list; nowhere in Colregs are the relative priorities of NUC and RIAM vessels specifically given.

Rules 3(g)(ii) and 27(d)&(e) make it clear that a vessel engaged in diving operations is a sub-class of RIAM vessels, and flag 'A' (which should actually be "a rigid replica of flag 'A'") is only shown when the size of the vessel makes it inappropriate to show the full set of lights or shapes.

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Re: Pointless but interesting

I agree, but CD is also required to navigate with particular caution having full regard to her special condition (makes her sound as if she is pregnant) under Rule 18 d (ii). Beyond that she is a power driven vessel and should give way to RIAM and NUC in the same manner as a vessel engaged in fishing is required to do.

There are NO relative priorities between NUC and RIAM vessels because each is "unable to manoeuvre as required by these Rules and therefore cannot keep out of the way of another vessel".

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