Tuesday, 17 November 2009

LTW Readers Q&A | 034; Tacking /\2

A good number of LTW-Readers are racing in a virtual world using simulators. I’ve been tracking some of what they’re doing on several forums. Apart from never have to deal with injury, I guess the rules play out pretty much the same.

In this readers-Q&A, one of those virtual wizards is asking a question about a situation at the windward mark. He even included a Boats Scenario gif to illustrate. Thanks for sending this in, Thorsten, I hope I haven’t kept you waiting too long.


Hi Jos,

While playing virtual skipper (an online regatta simulator), the following situation at the windward mark arose in a fleet race.

Since I had similar situations with H-Boats from time to time on our lake at home, I think the situation would also be possible in real life. I wondered what rules apply here, given the fact that both boats are head to wind simultaneously in position 3 and both overturn about 5 or 10 degrees.

(I can’t seem to get the animation running at the moment, so here’s the jpg)

In position 1 and 2 rules 11 and 18.2(a) apply, ok. But what rules apply in position 3, 4 and 5? Both boats are under rule 13 in position 3 and 4, yellow being obliged to keep clear.

Rule 18.3 does not seem to apply, since the boats are not on opposite tacks and there is no boat under rule 13 while the other one can fetch the mark. Since no other rule switches off rule 18.2, to me it seems that rule 18.2(a) is still on. After overturning 5 to 10 degrees, both boats are now on port tack, though not on a close-hauled course. Yellow would be entitled to mark-room including room to tack. In position 5, Blue ignores Yellow, turns to round the mark and pushes Yellow onto the mark.

Without Blues maneuver and the contact, Yellow would have been able to round the mark. Slowly, but still.

So it seems to me that Blue breaks rules 16.1 and 18.2(a).

I searched the RRS, the case book and the Q&A Service for similar cases,
but that was to no avail. I’m wondering if my conclusion is correct, especially the interpretation of rule 18.2(a) and 18.3.

Maybe you can help me out?

Thanks in advance and best regards from Germany,


Well Thorsten, after discussing this with some others and having a look at the casebook myself, I’m coming to the conclusion that you are pretty much ‘on the ball’. I think you got it right, almost. I differ only in some or the applicable rules.

In position one rule 11 applies, so Blue is keep clear boat.

In position two rule 11 still applies, but now in addition to having to keep clear, Blue also has to give mark-room to Yellow, according to rule 18.2(b).
They enter the zone overlapped on the same tack, with Yellow as inside boat.

In position three Yellow luffs in order to get to the mark and even if he should have established a leeward overlap from clear astern and was under a rule 17 restriction, he may do so. For Yellow ‘shooting the mark’ is her proper course. She would also do this if Blue wasn’t there.

Rule 18.2(c) states that rule 18.2(b) is switched off, when either of the boats passes head to wind. They both do that, just before position 4. So rule 18.2(b) is off, rule 11 is off and rule 13 switches on. Both are tacking boats and rule 13 states that in that case Blue is right of way boat.

They are now both also on port tack and still overlapped. They are in the zone and rule 18.2(b) no longer applies. None of the exceptions in rule 18.1 are applicable. That means rule 18.2(a) is the rule to follow.

In position four Blue still has to give mark-room and that mark-room indeed includes room for her to tack. In position four Yellow is overlapped to windward and on the inside of Blue who has to give mark-room. The fact that that happens while tacking, does not alter that.

In position five Yellow breaks rule 13 by not keeping clear of Blue, but she’s exonerated because Blue fails to give her mark-room (RRS 18.5(b)). She also breaks rule 31, but is again exonerated, now under 64.1(c). Because Blue forced her to break that rule by breaking rule 18.2(a) and yes, also rule 16.1. Blue is NOT the boat with mark-room, so she has to change course, as right of way boat, within the restrictions of rule 16.1.

Now, where are the critical point(s)?

In position three Yellow is entitled to mark-room, but that mark-room does not include room to tack. She’s not overlapped to windward but overlapped to leeward. If Yellow tacks first, forcing Blue to tack as well, she breaks rule 13 and will not be exonerated.

If Blue tacks first, Yellow can follow instantly and is ‘protected’ by the rules mentioned above. A PC handling a protest will need to find as fact which boat tacked first. In case they do it simultaneously, I would give Yellow the benefit of the doubt.

At first I dismissed rule 18.3, like you. Neither of the boats is fetching the mark. But upon looking at you diagram, I started to think. If you take away Yellow, Blue might be able to fetch the mark, she might be able to shoot the mark without ever passing head to wind….

The definition of fetching however, does not have the “absence of the other boats referred to in the rule” - clause. Like in the definition of ‘Proper Course’. In order to fetch the mark, Blue must be in a position to do so, INCLUDING Yellow. That is not the case, so on that grounds 18.3 is not applicable.

What if is was. What if Blue COULD fetch the mark? Would that make rule 18.3 applicable?

The rule begins by stating another provision; Boats must be approaching the mark on opposite tacks. They do not, they approach on the same tack. In position three, four and five they are no longer approaching. They are already in the zone. Because of that rule 18.3 never is applicable, even if Blue could fetch the mark, in my opinion.



Leave a comment if you have an (different) opinion

1 comment:

  1. When both boats are tacking at position 4 does the room to be given by Blue include room for Yellow to complete her tack onto port and then room to tack to round the mark as well?
    The definition of mark room says a boat has to be given room to sail her proper course while 'at' the mark and if she is going too slowly to turn back onto stbd then her proper course might be to complete on port and then tack back onto stbd.
    The best manoeuver for Blue is NOT to pass head to wind at position 3, then Yellow beaks 13 and she would not be exonerated as 18 would not apply as the boats would be on different tacks.


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