Tuesday, 16 March 2010

ISAF Q&A 2010 - 011 and 012; Overlapped and rule 18.3

Two new Q&A's were published by the ISAF Q&A panel:

Q&A 2010 -011 about how to interpret overlap with one of the boats having a bowsprit overhanging the stern of the other boat.
Q&A 2010-012 about rule 18.3. One boat forcing the fetching boat above close hauled, after having been subject to rule 13 in the zone. 

The principle in Q&A 2010-011 is used for umpiring. The point of last certainty dictates the decision. And that does not change until a next certainty is reached. The rule-book also uses the same principle in rule 18.2(d).

Now for those of you who want to do a little digging:
Suppose the boat with the bowsprit establishes an overlap to windward, then swings the bowsprit over the stern of the other boat until it has an overlap to leeward. Does the leeward boat have a rule 17 restriction? Can she sail above her proper course?

Q&A 2010-012 is pretty straightforward. The crucial words in the rule are: "causing the other boat to sail above close hauled". If that is the case it does not matter that the fetching boat already had to do that to round the mark or not. If the tacking boat was the cause, she breaks rule 18.3.


  1. 'Digging' Question
    Rule 17 never switches on. The boat astern remains technically overlapped throughout and is never clear astern.

  2. @Brass: cf Call UMP 28

    On a downwind course Yellow establishes an overlap to windward of Blue with
    her spinnaker. Yellow bears away, without breaking the overlap, and overlaps to
    Do rules 15 and 17 apply?

    Yes. At the moment Yellow becomes right of way as the leeward boat, rules 15
    and 17 begin to apply.

    However I don't know how they justify this (for rule 17) since, as you noted, the boat astern remains technically overlapped and is never clear astern...

  3. So much for a technial overlap with a spinnaker.

    I always thought the main purpose of calling technical overlaps was to decide whether rule 17 would come on.

    "Technically" Ump 28 does not apply to overlaps involving bowsprits/overhangs.

  4. No need to justify it. The call is to give certainty in how this sort of case will be umpired in match racing.
    Just learn to live with it.

  5. Q&As are specifically for fleet race
    (unless mentioned) and where match race has a call on a subject, then that call applies for match race. Like for instance this Q&A 2010-011
    versus 'technical overlap'

  6. Call UMP 28 might be a bit surprising (in the way that rules 15 and 17 actually begin to apply).
    On the other hand, if this call were written in a way that rules 15 and 17 did not apply, this might have opened the door to funny techniques of establishing an overlap from clear astern.
    The trailing boat could just intentionally establish a technical overlap to windward, "swing" to leeward and then enjoy not being bound by rules 15 and 17.

  7. Q&A 2010-12 does not apply to Match Racing, as Rule C 2.6(b) changes rule 18.3.
    So this situation would have a different outcome in Match Racing. Call MR 34 illustrates this.


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