January 2010 - When Does Mark-Room End?

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January 2010 - When Does Mark-Room End?

I had a question sent to me during last summer about the new mark-room rule. The question was when does mark-room end. There are really two answers, a legal one and a practical one. 

(click on the diagram to see a larger cleaner version)

If we look at the diagram, we see a scenario where the question applies. The two boats are approaching a gybe mark on starboard tack. There are probably other boats around, but showing them would make the diagram too crowded. The yellow boat reaches “the zone” (three of her hull lengths from the mark) just after position 1. She is overlapped inside the blue boat so according to 18.2(b) she is entitled to “mark-room”. She is also the right of way boat as the leeward boat. She makes a fairly close rounding of the mark at position 4. If there are no other boats around, this is probably not a good move, she should have gone wider. She was probably forced to this by the presence of other boats. Since she cannot turn on a dime, by the time she gets around the mark at position 5 there is a gap between her and the mark.   The blue boat hung back and swung wide. At position 5 the blue boat stuck her nose in and became a windward boat.   Yellow knowing that she was entitled to mark-room and the blue was not, and not wanting to be passed to windward, luffs up at position 6 trying to squeeze blue out (and probably yelling “no room, no room” or words to that effect). 
Let’s look at the rules that apply. 

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

18.1     When Rule 18 Applies
Rule 18 applies between boats when they are required to leave a mark on the same side and at least one of them is in the zone. ….

18.2     Giving Mark-Room
(b)               If boats are overlapped when the first of them reaches the zone, the outside boat at that moment shall thereafter give the inside boat mark-room. If a boat is clear ahead when she reaches the zone, the boat clear astern at that moment shall thereafter give her mark-room.

18.5     Exoneration
When a boat is taking mark-room to which she is entitled, she shall be exonerated
(b)               if, by rounding the mark on her proper course, she breaks a rule of Section A or rule 15 or 16.

From position 5 to 6 the yellow boat is the right of way boat as the leeward boat. She is altering course quickly by luffing.   According to rule 16 she must do it in a way that gives the blue boat room to keep clear.   If yellow is subject to rule 16 this limits how quickly she can luff. 
Normally rule 18 overrides rule 16. A boat is entitled to alter course while rounding a mark. This is covered in 18.5(b). “she shall be exonerated…if…she breaks…rule 16”.

The yellow boat was overlapped on the inside when she got to the mark so blue has to give her mark-room (see rule 18.2(b).)   Blue saw a space and went inside. There is no rule that says that she can’t go inside, but yellow does not have to give her room to do it. While rule 18 applies Yellow is, as we have just seen, entitled to alter course without having to give room for blue to keep clear since she would be exonerated from breaking rule 16. Rule 18.1 says that rule 18 applies as long as one of them is in the zone. Both boats are still in the zone so legally rule 18 applies.   However if look more carefully at rule 18.5 we see that the right to be exonerated for altering course too quickly (breaking rule 16) applies while “rounding the mark on her proper course”. At some point after reaching the course to the next mark, yellow stopped rounding on her proper course and started to luff just to block blue. She is no longer exonerated for breaking rule 16.   She is still right of way boat but can only luff in a way that gives blue room to keep clear.  

This is just one of many examples that can lead to the question of “when does mark-room end?”   While the legal answer is often that it lasts until the boats have left the zone, the power of the rule ends when mark-room stops having a function which is usually much earlier.  

© Copyright 2010 Andrew Alberti
Posted: 1/1/2010 3:09:24 PM by Andrew Alberti

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This page provides links to a set of articles original published in Kwasind magazine. The versions here include animated diagrams. The original articles can be found within the original magazines which are available online back to January 2007. 

Articles before December 2016 are based on the Racing Rules of Sailing 2009-12 or 2013-2016 and have not been updated to reflect the changes that apply as of January 2017 with the publication of the Racing Rules of Sailing 2017-20. A copy of the new rules can be found on sailing.org.
Andrew Alberti has been writing these monthly articles in the Kwasind since early 1997.  They explain the Racing Rules of Sailing. Andrew is a National Judge and National Umpire. He is a member of the Sail Canada Rules and Appeals Committees. The interpretation of the rules contained in the articles is Andrew's and not that of the RCYC or any of the committees he sits on. 

Send your questions to Andrew at kyrules@alberti.ca.


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