January 2011 - Tacking Too Close - At The Mark II

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January 2011 - Tacking Too Close - At The Mark II

In October we started to talk about tacking too close.   In November we continued with one boat tacking at the mark. This month we will continue with two boats, both tacking within the zone. The rules here will get a little complex. If you don’t want to follow the complex rules, I recommend a simple rule of thumb “don’t tack within three boat lengths of the mark”.  

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

In the diagram both boats approached the windward mark on port tack. When they get to the zone (position 1) they are overlapped.   If we look at rule 18.1 we can see that at this time none of the exclusions in rule 18.1 apply so rule 18 does apply. The boats are on the same tack (so rule 18.1(a) doesn’t apply). The proper course for both of them is to tack (so 18.1(b) doesn’t apply).

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. However, it does not apply
(a) between boats on opposite tacks on a beat to windward,
(b) between boats on opposite tacks when the proper course at the mark for one but not both of them is to tack,
(c) between a boat approaching a mark and one leaving it, or
(d) if the mark is a continuing obstruction, in which case rule 19 applies.

18.2 Giving Mark-Room
(a) When boats are overlapped the outside boat shall give the inside boat mark-room, unless rule 18.2(b) applies.
(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.
(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 either boat passes head to wind or if the boat entitled to mark-room leaves the zone, rule 18.2(b) ceases to apply.
(d) If there is reasonable doubt that a boat obtained or broke an overlap in time, it shall be presumed that she did not.

Room for a boat to sail to the mark, and then room to sail her proper course while at the mark. However, mark-room does not include room to tack unless the boat is overlapped to windward and on the inside of the boat required to give mark-room.

Yellow is the right of way boat as the leeward boat but she has to give blue boat mark-room. She has to give blue room to sail to the mark and room to sail her proper course while at the mark.   Since blue the inside boat is overlapped to windward, yellow does have to give room to tack.

At position 4 yellow gets to head to wind. Until she gets to a close-hauled course she is required to keep clear as a tacking boat (rule 13). At position 5 yellow has completed her tack and is on starboard tack. Blue is still on port tack. Yellow has become right-of-way so she initially has to give blue room to keep clear. Blue has room to take yellow’s stern.   If we now look at rule 18.1 again, we see that with the two boats on opposite tacks the rest of rule 18 no longer applies. Yellow is no longer required to give mark-room to blue. Instead of taking yellow’s stern blue tries to tack. During the tack she makes contact with yellow and breaks rule 13.
After a boat passes head to wind, she shall keep clear of other boats until she is on a close-hauled course. During that time rules 10, 11 and 12 do not apply. If two boats are subject to this rule at the same time, the one on the other’s port side or the one astern shall keep clear.

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

In the second diagram again both boats approach the mark on port tack. Green is clear ahead when she gets to the zone. She is therefore entitled to mark-room according to 18.2(b). At position 4 she heads up towards the mark. She is entitled to head up as the leeward boat and as the boat entitled to mark-room. She is not however entitled to room to tack. The definition of mark-room gives room to tack only to an inside windward boat. She is the outside leeward boat. After that she makes a mistake. At position 5 she crossed head to wind. Rule 18.2(c) says once she crosses head to wind 18.2(b) doesn’t apply anymore so she is not entitled to mark-room. They are now on opposite tacks on a beat to windward so 18.1(a) says that the whole mark-room rule doesn’t apply. Green is tacking so rule 13 does apply and she is required to keep clear which she doesn’t do. She should now take a penalty or risk being protested and disqualified.

What green should have done is continue on port tack on the course shown in position 4 until red who is the give way boat bears off and goes behind her. At that time green can tack.

© Copyright 2010 Andrew Alberti
Posted: 1/30/2011 2:23:08 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.


166 Years of Tradition | World-Class Sailing | Toronto Island & City Clubhouse
Sailing Rules: Mark Room - When Can You Gybe?
Mark Room at a Gybe Mark
Penalties – When and How to Take Them
New Rule Changes III
Mark Room at a Gybe Mark
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