Tuesday, 2 October 2012

LTW Readers Q&A (63); Tacking at the Finish?

A Q&A from David and Vernice about a situation close to the finishline:

A couple of months ago David was a member of a protest committee which heard the following case:

Two one-design boats (Blue and Red) were approaching the upwind finish line in one of several races in a multi-class regatta. Both boats were on port tack near the port (left) end of the line, looking upwind.There were about 2 1/2 boat lengths separating the two boats, gunnel to gunnel.
Both boats were well within the 3-boat-length zone and had entered the zone almost simultaneously, with the windward Blue boat being slightly closer to the finish line than the leeward Red boat.
The leeward (right hand) Red boat suddenly tacked onto starboard. The windward Blue boat, which was slightly closer to the finish line, crash-tacked to avoid a collision.
After her tack, the Blue boat was outside the lay-line, to the left-hand end of the finish line, and had to execute a jibe to circle around and finish after the Red boat had crossed the line.

The Blue boat hailed "protest" and raised a red flag immediately. She filed a protest within the time limit. She alleged, citing Rule 18, that she should have been given mark-room as the inside boat and allowed to finish on her port-tack course.

The facts found that both boats were overlapped on port tack on their approach to the finish line, with 2 1/2 boat lengths of separation, well within the three-boat-length circle. Both boats were within the port-tack layline to the finish, and the Blue boat would have finished first if they both remained on port tack.

Even though both boats entered the zone on the same tack, the P.C. ruled that the last sentence in the preamble to Rule 18 and Rule 18a indicated that Rule 18 did not apply in this situation because: after the leeward boat (Red) tacked, "both boats were on opposite tacks on a beat to windward." Therefore Blue was not entitled to mark-room (since Rule 18 was shut off). Red was within her rights to tack onto starboard within the zone, becoming the Right-of-Way Boat and forcing Blue as the Give-Way Boat (Rule 10) to tack away onto starboard and be unable to fetch the line.

The questions are:
1.) Did the rule-makers intend that the last statement of the Rule 18 Preamble, along with Rule 18a, would allow the outside leeward port (Red) boat to have such a powerful weapon of being able to tack onto starboard and force the windward port boat (Blue) to tack away and be unable to fetch or to claim mark-room, even though both boats entered the zone overlapped on the same (port) tack and with the windward port boat closer to the mark? Was the Blue boat in that situation unable to invoke Rule 18?

2.) Can the last part of the Preamble, along with Rule 18b, be construed to mean that the proper course for the leeward port boat (Red) should always be to tack in this situation, so that she would be able to shut off Rule 18 and finish before the Blue boat?

I have a question of my own: You mention a crash-tack by Blue. Did she have to respond before Red was on a close hauled course? According to my animation of the incident that is almost unavoidable.  I’m assuming the PC did not find that as fact, otherwise they would have DSQ-ed Red for not keeping clear while tacking. And a crash tack is not seaman-like. If that was the only way Blue could keep clear, Red possibly broke rule 15.

Answer 1: YES. As soon as Red tacks to starboard, both boats are on a different tack and rule 18 is switched off per 18.1(a). Have a look at case 95 in the casebook

Answer 2: Proper Course? Maybe you can call it a good tactic, but not proper course. The definition proper course does not take into account whether a boat finishes before or after.
It is only the fastest way to the finish.
But if Blue ‘allows’ this manoeuvre it is a good way for Red to make sure she finishes before Blue.

There is an affective tactic to defend against such a manoeuvre. If Blue makes sure that Red can never complete her tack without keeping clear, she is effectively blocked and Blue wins.
In order to do this she must bear off and close the gap between her and Red. Not too close, she’s still keep clear boat (and has no protection from her mark-room, because she’s not sailing directly TO the mark) but close enough so that Red cannot tack.

David and Vernice came back to me, with an answer to my question and additional questions. Watch this space for part 2 of LTW Readers Q&A (63).


  1. I get the point of the post: Blue has an option of falling off closer to Red to deter/prevent the latter's tack. However, assuming these are one-design boats, in the first animation, Blue has won the race: all she has to do is maintain her way. She can clear Red whose progress is slowed by a tack. Good move by Red, but close only counts in horse shoes.

  2. So apparently the word "thereafter" in Rule 18.2(b) doesn't mean much more than "as long as Rule 18 applies".

    1. Yes. If rule 18 is switched off by 18.1 the thereafter in 18.2(b) looses its meaning.

  3. Since January 1, 2010 18.2(c) was changed leading to a different result:

    "Rule 18.2(c):
    (c) When a boat is required to give mark-room by rule 18.2(b), she shall continue to do so even if later an overlap is broken or a new overlap begins. However, if the boat entitled to mark-room passes head to wind or leaves the zone, rule 18.2(b) ceases
    to apply."

    Therefore, even though on starboard, red was required to give blue mark room. Red should be disqualified.


    1. If rule 18.2(b) ceases to apply we go back to 18.2(a); Inside boat gets markroom. But 18.2(b) is not switched by the boat that has markroom passing head-to-wind, it is switched off because both boats are on a beat to windward on different tacks. As dictated by 18.1. Red may tack there as long as she complies with RRS 13 and 15.

  4. Sylvie Harlé (FRA)15 October 2012 at 18:18

    I think (as Trevor Lewis states in his book page 69) that the change from January 2010 only affects leeward marks. "A change of tack by either blue or red will switch off RRS 18.2(b) not because of RRS 18/2(c) but because of RRS 18.1(a) or 18.1(b) will now disapply all RRS 18 once they are on opposite tacks".
    Do we aggree?


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