RRS question, tacking at the leeward mark

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Steve Landeau
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Post by Steve Landeau » 13 Jul 2006, 19:03

Ok, all.
I've done a bit of homework, and I have it here straight from ISAF, Case 81.
Quote in full:
"When two boats on the same tack are about to round a mark, rule 18 applies even if the boats are on a beat. When one boat enters the two-length zone clear ahead of another boat on the same tack, rule 18.2(c) applies. When the boat clear ahead then tacks, rule 18 ceases to apply and she becomes subject to rule 13 after passing head to wind and rule 10 after she has completed her tack."
Steve Landeau
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Lester
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Post by Lester » 13 Jul 2006, 20:03

Steve Landeau wrote:I've done a bit of homework, and I have it here straight from ISAF, Case 81
Hi Steve

Way to go! My quote is slightly different (smile):
ISAF Case 81, 2005-2008 wrote:When two boats on the same tack are about to round a mark, rule 18 applies even if the boats are on a beat. When one boat enters the two-length zone clear ahead of another boat on the same tack, rule 18.2(c) applies. If the boat clear ahead passes head to wind, rule 18.2(c) ceases to apply and she becomes subject to rule 13 and, after she is on a close-hauled course on port tack, rule 10.
Thing is, I'm not sure it helps our scenario too much. Case 81 deals with a windward mark, and when the clear ahead boat tacks onto port. Our scenario deals with a leeward mark, and when the clear ahead boat tacks onto starboard...

I think ISAF updated the case book for 2005-2008, and case 81 now notes only that 18.2(c) ceases to apply to the boat that tacked, rather than the whole of 18 ceases to apply. This makes quite a difference!
Lester Gilbert
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Marko Majic
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Post by Marko Majic » 13 Jul 2006, 22:10

Lester wrote:I think ISAF updated the case book for 2005-2008, and case 81 now notes only that 18.2(c) ceases to apply to the boat that tacked, rather than the whole of 18 ceases to apply. This makes quite a difference!
I looked up the case in the ISAF (05-08 ) case book and, while you're right that it now says only that "18.2(c) ceases to apply" it would be equally valid to say that rule 18 ceases to apply altogether as it did in the older case book Steve quoted (but only under 2005-08 rules).

The reason, of course, is that following A's tack (from the ISAF diagram) - her proper course around the mark is to sail on and B's is to tack and hence rule 18 does not apply.

Either way - quite different from our discussion (since my prior contention under 18.1(a) was already labeled "weak" and rejected). :lol:

Marko
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Steve Landeau
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Post by Steve Landeau » 13 Jul 2006, 23:31

Lester wrote: Way to go! My quote is slightly different (smile):
I think ISAF updated the case book for 2005-2008, and case 81 now notes only that 18.2(c) ceases to apply to the boat that tacked, rather than the whole of 18 ceases to apply. This makes quite a difference!
Yes, It does.
I'd expect that since they used to only show "18", and now specifically point out "18.2(c)", they are showing 18 to stay "on" for Green.
I don't have the newer case book (guess I'd better get it). I did not know that they went back and changed them as the rule changed, but it makes sense that they do.
Steve Landeau
AMYA 10859
IOM USA 112
Finn USA 112
Cal 25 #548

Hiljoball
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Post by Hiljoball » 15 Jul 2006, 01:52

I think the important issue is what can we learn from this scenario. When I started to learn the racing rules, I read that there are two kinds of ‘protest’ situation; win-no-win, and win-lose. If there is no contact, then you may win the protest, or it may be disallowed…ie win or no-win. However if the situation is pushed to contact, then someone will be DSQ…and it might be you…a win-lose.

Before blue begins to tack, the onus for any perceived infringement would be on green to show why she was in the right. Once blue begins to tack, the ‘onus of proof’ moves to blue. Now blue has to show why she was in the right. When you have the onus of proof and you cannot satisfy the committee with your argument, then you will be the one who gets the DSQ.

In this situation, green sails between blue and the mark at her peril…until blue starts to tack. From this transitional moment for a number of seconds, blue has to manoeuvre such that green is not impacted.

With the diagram as presented, I think that blue would be dsq for tacking too close. To win the protest, blue would have to show that the tack was completed and that green had time to keep clear. Note that the onus is on blue, even though the contact occurred when she was on stbd and green was on port.
John Ball
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kure
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Post by kure » 18 Jul 2006, 23:21

I copied the diagram to an international judge.
I forgot to tell him that this was r/c so he said the boats where outside the two- boat circle....I am waiting to here if my added info changes anything.

He said that in this picture he would rule that blue tacked too close to green.
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kure
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Post by kure » 19 Jul 2006, 08:35

He further said; the fact that the incident is inside the "circle" doesn't change anything, because the boats are so far apart all the time.

I don't have the possibility to discuss this further with him, but I think he means that the boats are not rounding together, so the rules dealing with two boats rounding together is not usable here. So we are left with a port/starboard situation, where blue looks in the drawing to tack to close to green....

he refers to rule 13 and 15
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Lester
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Post by Lester » 19 Jul 2006, 08:52

Hi Kure

Yes, in the drawing I think we can all agree that Blue is probably at fault. It is unfair on your IJ to consider opinion without him being involved in the discussion. After discussion, I am confident he would agree that the rule which was broken by Blue was 18.2(a), and not 13 or 15... (smile)
Lester Gilbert
http://www.onemetre.net/

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