Last month we started the discussion of luffing rights. To summarize, we say that leeward boats have “luffing rights” unless rule 17 says they don’t. This month we will look at those rights, and what can be done with them. The basic concept comes from rule 11, which gives right-of-way to the leeward overlapped boat. Rule 16.1 then restricts any right-of-way boat when that right-of-way boat alters course. This restriction applies to leeward boats, clear-ahead boats and starboard-tack boats (there are additional restrictions on some starboard-tack boats in Rule 16.2, but that is a subject for another article). As long as the leeward boat complies with rule 16.1, it can luff as much as it wants.
11 ON THE SAME TACK, OVERLAPPED
When boats are on the same tack and overlapped, a windward boat shall keep clear of a leeward boat.
16 CHANGING COURSE
16.1 When a right-of-way boat changes course, she shall give the other boat room to keep clear.
17 ON THE SAME TACK; PROPER COURSE
If a boat clear astern becomes overlapped within two of her hull lengths to leeward of a boat on the same tack, she shall not sail above her proper course while they remain on the same tack and overlapped within that distance, unless in doing so she promptly sails astern of the other boat. This rule does not apply if the overlap begins while the windward boat is required by rule 13 to keep clear.
Proper Course
A course a boat would sail to finish as soon as possible in the absence of the other boats referred to in the rule using the term. A boat has no proper course before her starting signal.
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(click on the diagram to see a larger cleaner version)
In the diagram, the Yellow and Blue boats are beam reaching on a course to the next mark. We will assume that this is their proper course. Yellow is sailing faster and gets an overlap on Blue, to windward, from clear astern at position 2. Since Blue did not establish the overlap from clear astern, she is not restricted by rule 17. We therefore say that she has luffing rights. At position 2, Blue starts to alter course to windward (or luff) toward Yellow . Yellow is able to keep clear, so Blue is not breaking rule 16.1. Blue continues to luff Yellow, until at position 6, Yellow , who is sailing slightly faster, is able to get clear ahead. Blue is now clear astern and the give-way boat. There is no rule preventing her from continuing to sail this course.
At position 7, Yellow bears away and becomes overlapped with Blue. This time Blue established the overlap from clear astern and is subject to rule 17. Blue is not allowed to sail above her proper course, so she immediately bears away to that proper course. For those of you who learned their rules before 1997, this is the new equivalent of getting “mast abeam.” For those of you who never learned that concept, please ignore this comment.
(click on the diagram to see a larger cleaner version)
In the second diagram, we find that you can be luffed by a boat without “luffing rights”. The Red boat is flying a symmetrical spinnaker and has a proper course square to the wind or near to it. On the other hand, the White boat is flying an asymmetrical spinnaker and so has a proper course that is a reach. At position 1, White is clear astern. At position 2, she establishes an overlap from clear astern, making her subject to rule 17. Although White is constrained by rule 17, she is the leeward boat, she has right-of-way, and as long as White does not sail above her proper course, Red must keep clear, even though this means she must sail far above her own proper course. Since the rule makes no mention of forcing a windward boat like Red to sail above her proper course, and as long as White steers her own proper course, White is complying with rule 17, and Red must bear it..
In these two situations, White and Blue both took quite legal approaches. They may or may not have been the best approaches – White would probably have done better to go slightly higher and sail above Red – but they are legal nonetheless.
© Copyright 2012 Andrew Alberti