When does rule 18 turn off?

A question I hear often is "When does rule 18 turn off?"  At the simplest level, the answer is given by rule 18.1:

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.

If rule 18 does apply at some point during a mark rounding, part (d) clearly never applied.  Condition (b) is really just an extension of (a) for situations where there might be disagreement about whether boats are on a beat to windward, so we get the following summary: "Rule 18 turns off when either boat tacks at a mark to be rounded on its windward side, and when the leading boat leaves the mark while the other boat is still approaching it."

However, that's not the whole story.  The real question is, "When does the obligation to give mark-room end?"  And while that seems like the first question, it's actually quite different.  Basically, the obligation to give mark-room ends when the boat entitled to mark-room no longer needs it to pass or round the mark. 

Consider ISAF Q&A 2013-017.The animation at the left was used to draw the scenario in that Q&A; it shows two catamarans rounding a port-rounding offset mark, with the next leg directly downwind, in 10-12 knots of wind, no current.  At position 4 Yellow has passed the mark and both boats are on their downwind courses (which, they being catamarans, is not straight downwind).  Yellow jibes directly in front of Blue, breaking rule 10 (Port/Starboard).

Blue is required to give Yellow mark-room at this mark because Yellow is clear ahead at the zone.  According to the definition Mark-room, Blue has to give Yellow three things:

1. Room to sail to the mark if her proper course is close to it;
2. Room to round the mark as required to sail the course; and
3. Room to leave the mark on its required side.

(I've changed the order of the requirements in the definition Mark-room so that they appear in time order, making them easier to discuss here.)

Consider the situation at position 4 of the animation.   Yellow's proper course is no longer close to the mark, so she no longer has the right to room to sail to it.  She is on her downwind starboard-tack course, so she has rounded the mark as required to sail the course.  And Blue has clearly given her room to leave the mark on its required side. Thus, Blue's obligation to give Yellow mark-room has been discharged and she is no longer obliged to do so.

That conclusion is particularly important because of rule 18.2(c)(2), which says:

(c) When a boat is required to give mark-room by rule 18.2(b),
      (1) she shall continue to do so even if later an overlap is broken or a new overlap begins;
      (2) if she becomes overlapped inside the boat entitled to mark-room, she shall also give
            that boat room to sail her proper course while they remain overlapped.

At position 4, Blue has become overlapped inside Yellow.  But because Blue has discharged her obligation to give Yellow mark-room, she is no longer required to do so and the initial phrase in rule 18.2(c) does not apply to her.  Therefore rule 18.2(c)(2) does not apply.  Yellow's breach of rule 10 is not exonerated under rule 21 and she should do her turns.

 Now consider a situation at a port-rounding leeward mark, with the next leg a beam reach (as with Mark 3 in a standard digital-N course in team racing). Blue is overlapped when she enters the zone, so she is required to give Yellow mark-room.  By luffing Yellow at positions 3-4, does she break rule 18?

I think the answer is no.  Refer again to the list of requirements from the definition Mark-room.  Blue has certainly given Yellow room to sail to the mark, and just after position 3 Yellow is on her course to the next mark, so she has been given room to round it.  At position 4 Yellow  has not yet passed the mark on its required side, but Blue is not preventing her from doing so.  Thus unless Blue luffs Yellow into the mark she has given mark-room as defined and has no further obligations.  

Note that this isn't as clear-cut as the previous example because not all the conditions of the definition Mark-room have been met when Blue luffs Yellow above her course to the next mark: Blue still has to allow Yellow to leave the mark on its required side.   So one could argue that until all the parts of the definition have been met, Blue has no right to interfere with Yellow.  But I don't think that conclusion is supported by the wording of rule 18 and the definition Mark-room.

If I'm right, this has an interesting consequence for team-racing: it essentially allows the outside boat to set a "post-mark trap" at Mark 3.  Suppose Blue has a team-mate close astern; then this play allows that team-mate to pass while Blue holds up Yellow.  You might say, Blue could have accomplished this by luffing later, along the leg, and that may be true -- but it may not, because if Blue allows Yellow to trim in and reach along the next leg, she may lose any real opportunity to luff Yellow above close-hauled, which she needs to do if she wants to hold Yellow up.  It's only the presence of the mark that forced Yellow to come down into the vulnerable position she's in at position 4. 

Clarification of "Changes to the RRS 2013-2016"

On November 3, 2012, I gave a 45-minute presentation at the US Sailing Annual General Meeting (AGM) in San Francisco, entitled "Changes to the RRS 2013-2016".  This presentation is posted on the US Sailing website; you can find it and download it at http://raceadmin.ussailing.org/Rules.htm. 

Before I discuss that presentation any further, I have to tell you that the opinions expressed there are mine and mine alone.  I did not consult the US Sailing Racing Rules Committee before preparing it, nor did any committee of US Sailing review it before it was posted.  Having said that, I think the overall message of the presentation is correct, and the presentation could form the basis for a club or regional clinic on changes to the Racing Rules of Sailing.  If you agree, please feel free to download it and use it.  All I ask is that you not edit it or change it in any way (other than to skip over slides).

But that's not what I want to write about here.  The subject of this posting is Slide  8, entitled 'Implication of “Proper Course” in Rule 18.2(c)(2)', which features the following animation:

On the right of this animation I wrote, "Here, Blue breaks rule 16.1, Changing Course, and is not exonerated because she is not taking mark-room under rule 18.2(b), nor room to sail her proper course under rule 18.2(c)(2)."

At the time, I thought this was clear; but several e-mails from sailors have convinced me that it's not.  Here's what I was trying to say and to illustrate in the animation.

First, we all agree that Blue is entitled to mark-room under rule 18.2(b) because she was clear ahead when she entered the zone.  This means she is entitled to room to leave the mark on its required side (in this case, to port), room to sail to the mark as long as her proper course is to sail close to it and room to round the mark as necessary to sail the course (see Definition Mark-room at the beginning of the 2013-2016 rulebook).   

Just after position 3, Yellow becomes overlapped inside Blue, so rule 18.2(c)(2) kicks in.  That rule says, "When [Yellow] is required to give [Blue] mark-room by rule 18.2(b), ... if she becomes overlapped inside [Blue], she shall also give [Blue] room to sail her proper course while they remain overlapped."

Note that this right is additional to the those Blue already has from from the definition of mark-room.  Also, new rule 21 Exoneration says that as long as she's sailing within the mark-room or room to which she's entitled, if she breaks a rule of Section A (Right of Way), rule 15 (Aquiring Right of Way), 16 (Changing Course) or 31 (Touching a Mark) because the other boat failed to give her that room, she is exonerated for her breach.  

Now let's look at position 4 in the animation.  What is Blue's proper course from that point on?  To answer that question we need to remove Yellow from the diagram (see Definition Proper Course).  In the absence of Yellow, what course would Blue take to finish the race as quickly as possible?  Well, there may be other boats in the fleet, and Blue might want to take a high line so maybe she would luff up as shown in the animation -- but I don't think so.  Starting from her deep position 4, she has no hope of luffing up high enough to get above the line of other boats rounding the mark -- after all, they will have luffed up slightly, too, and starting from a position much further to windward.  If Blue luffs up as shown, all she will accomplish is to bring herself almost to a stop and then be in the backwind of all the boats who have already rounded the mark ahead of her.  So in my opinion Blue's proper course is to trim in onto a closehauled course and make the best of her poor rounding.

At least, that's what I hoped I had conveyed in the animation, but apparently not.   I concede it's not obvious.  Dick Rose, in his rules column in Sailing World, says, "[The boat entitled to room]  can luff, even above closehauled on port tack, to shut the door on [the other boat]."  If I were to do the presentation again, I would picture Blue head-to-wind at position 5 to emphasize that she is clearly not on her proper course.

   

Suppose you concede that Blue is not sailing her proper course between positions 4 and 5. What is she entitled to do under rule 18, that Yellow is not allowing her to do?  Blue had the opportunity to sail to the mark and chose not to do so, and at position 4 she has already rounded the mark as required to sail the course (i.e., turned to a close-hauled course).  So Yellow only needs to allow Blue to leave the mark astern on her port side, and although that hasn't happened yet at position 5, it's clear that Yellow is complying with that requirement -- instead of luffing up, Blue could trim in and quickly leave the mark astern.  

Therefore, the events between positions 4 and 5 are governed entirely by rules 11 (Windward/Leeward) and 16, Changing Course.  

Blue has right of way, and clearly Yellow fails to keep clear of her.  So, why not penalize Yellow under rule 11?  Well, rule 16.1 says, "When a right-of-way boat changes course, she shall give the other boat room to keep clear." New Definition Room says that room includes "space to comply with her obligations under the rules of Part 2 and rule 31 ...".  Because Blue's change of course forces Yellow to hit the mark, Blue did not give Yellow room to comply with her obligations under rule 31.  Therefore Blue breaks rule 16.1 and Yellow is exonerated for breaking rules 11 and 31 because Blue's illegal change of course caused her to do so.

So Blue should take her turns. 

I hope this clears up the issues sailors may have with Slide 8 of my presentation at the AGM.