Sunday, 18 February 2018 11:58

Port-Starboard and a Wind Shift

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Port-Starboard Crossing with Wind Shift Port-Starboard Crossing with Wind Shift Boat Scenario

Rules Quiz - Port Starboard with a windshift

Boats S (blue, on starboard tack) and P (yellow, on port tack) are both sailing close-hauled and are converging on a beat.  P will safely cross S.  However, when they are less than 2 boat-lengths apart, the wind shifts to the right ten degrees.  S heads up (changes her course) in response to the windshift such that P is unable to keep clear.  There is minor contact with no damage or injury, and both boats protest.  You are on the protest committee.  How would you decide this and why?

The answer will be provided in the comments in a few days after we've had a chance to discuss.  Hint - its not as clear-cut as it may seem ;).

Here we can see that without the windshift, boat P is able to cleanly cross (keep clear) of boat S

However, with the windshift occuring, the angles change and P is no longer able to keep clear.

This quiz comes from Dave Perry's 100 Best Racing Rules Quizzes (Quiz #6)  Answers to Dave Perry's 100 Best Racing Rules Quizzes are based on The Racing Rules of Sailing for 2017-2020.  For a comprehensive explanation of the rules, read Dave Perry's Understanding the Racing Rules of Sailing through 2020, which is available through US Sailing: 1(800) 877-2451 or .  Permission to reprint this quiz for non-commercial use is granted by the author.
Read 909 times Last modified on Monday, 19 February 2018 10:03
Jeff Rehm



  • Comment Link Jeff Rehm Wednesday, 21 February 2018 19:05 posted by Jeff Rehm

    OK - so here is the long-awaited conclusion:

    Boat S (Blue) is penalized under rule 16.1, Changing course. Rule 16.1 states "When a right-of-way boat changes course, she shall give the other boat room to keep clear." S changes course when so close to P (Yellow) that P is unable to keep clear and there is contact. Therefore, S failed to give P room to keep clear, thereby breaking rule 16.1 The fact that S's change of course is in response to a windshift is not relevant to the application of rule 16.1

    Boat P breaks rule 10, on Opposite Tacks, but is exonerated (not penalized) under rule 21, Exoneration, or rule 64.1(a), Decisions: Penalties and Exoneration because she is compelled to break rule 10 by S's breach of rule 16.1.

    Boat S also breaks rule 14, Avoiding Contact; but as the right-of-way boat, she is exonerated (not penalized) as the contact does not cause damage or injury (see rule 14(b)). P does not break rule 14, because S changes course so close to P that it is not possible for P to avoid the contact.

    Referenced Rules:

    So both Jeff Dusek (on Facebook) and Roger (on the comment section) are 100% correct!

    Ron - you had the right idea, but not 100% for the right reason :)

  • Comment Link Ron Wednesday, 21 February 2018 08:35 posted by Ron

    I know nothing of rules = ( - but I suspect blue is at fault, over taking boat is to keep clear? Though he was starboard, he's now over taking and leeward. Love that you're doing these!

  • Comment Link Roger Cochran Sunday, 18 February 2018 16:34 posted by Roger Cochran

    Rule 10 says: ON OPPOSITE TACKS
    When boats are on opposite tacks, a port-tack boat shall keep clear of a starboard-tack boat.


    Rule 16.1 says: When a right-of-way boat changes course, she shall give the other boat room to keep clear.

    Since the boat was crossing, the starboard boat is required to keep clear and not make contact.

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