Racing Rules (again) - Windward/Leeward

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Racing Rules (again) - Windward/Leeward

Postby M1sha Dallin » Sun Sep 07, 2008 8:50 am

There have been many words on the subject of the windward/leeward rule over the last few days. I offer the following in an attempt to clarify the situation for people who are now confused. Errors and omissions gratefully received. I may add diagrams at a later point and use the material in a future sailing class.

Whilst racing the conduct of yachts towards other yachts who are racing is governed by the racing rules as notified in the notice of
race. Otherwise the conduct of yachts (and other vessels) in sight each other is governed by the Collision Regulations.

The rules identified in the notice of race generally reference the ISAF racing rules, though additional rules may also be included
(e.g no luffing between sunset and sunrise is quite common).

The racing rules of sailing notified for the more formal regattas within SL are given in:
http://www.slsailing.org/forum/viewtopic.php?t=2226&highlight=rules

These are a subset of the full ISAF rule set in acknowledgement of the fact that situational awareness is not complete within SL.

There is however an expectation that a sailor that knows of a rule that is omitted shall not exploit the situation that the rule was
intended to cover. To do so is considered 'gaming'.

Now most sailors are happy with the operation of Rule 10 (the port and starboard rule) as long as everyone is using the same
windsetter :-) but there does appear to be some confusion about the operation of Rule 11 - the windward/leeward rule.

This article is intended to address what is meant by the rule and the further implications of rules 12 and 17.1. Note that rule 17.1 is
not included in the SL Sailing subset of the ISAF rules. There are however important implications of the rule, without which there
are opportunities for 'gaming'. So once you know what the rule is trying to prevent you will understand the limits of what a sailor
can do without falling foul of race guideline 7.

Statement of rule: Rule 11 - ON THE SAME TACK, OVERLAPPED
When boats are on the same tack and overlapped, a windward boat shall keep clear of a leeward boat.

In its most obvious application between racers who are on different legs of the same course as would occur on a windward/leeward race course it is self evident who has the right of way - the boat sailing downwind is more manoeuvrable and gives way.

What happens between boats who are on the same leg of a course that are converging because of different boat haracteristics (e.g. Tako and Fizz); or where one sailor has better control (Takos under spinnaker near 90 degrees wind angle); or even between two yachts who are converging on the same tack but are part of different races (a common occurrence at events such as Cowes week in the UK)?

The SAME! - With one exception (which I'll cover later) the windward boat always has to keep clear of the leeward boat. In a normal crossing situation this is simply a case of situational awareness and it may be necessary to bear away a degree or two. Where two boats are fighting for position it can result in either the bear away, a luffing contest or the windward boat tacking away. The response of the windward boat and the legal manoeuvres from the leeward boat are governed by rules 12 and 17. As ever in yacht racing it is not just where the boats are, but also how they got there.

The simplest to consider is Rule 12.
Statement of rule: RULE 12 - ON THE SAME TACK, NOT OVERLAPPED
When boats are on the same tack and not overlapped, a boat clear astern shall keep clear of a boat clear ahead.

Definitions are needed here:

Clear Astern and Clear Ahead; Overlap - One boat is clear astern of another when her hull and equipment in normal position are behind a line abeam from the aftermost point of the other boat’s hull and equipment in their normal position. The other boat is clear ahead. They overlap when neither is clear astern. However, they also overlap when a boat between them overlaps both.

This essentially means that a faster boat approaching from clear astern cannot require the boat ahead to get out of the way. The boat that was astern has to manoeuvre (to windward or leeward) in an attempt to get into a position where a passing manoeuvre is possible.

This is when it starts to get more complex. A passing manoeuvre can be considered as started when an overlap is established. The
subsequent manoeuvres allowed by both the windward and leeward yachts depend on (a) whether the overlap was established to windward or leeward; and (b) whether the overlap was caused by the yacht being overtaken.

(1) Passing to Windward

Passing to windward the leeward boat has all the rights and can luff (head up) as far as head to wind. If the windward boat does not respond fast enough and there is contact then the windward boat is penalised.

(2) Passing to Leeward - Overlap caused by the yacht astern

Passing to leeward and gaining the overlap just by sailing faster - then both the leeward and windward yachts have some rights.

Another definition:
Proper Course - a yachts proper course is that course she would optimally sail in the event that there were no other yachts to prevent it

If the windward yacht heads up or tacks immediately, and then makes contact with the leeward yacht, then the leeward yacht did not leave enough room and would be penalised. The leeward yacht is constrained to not sail above her proper course (Rule 17.1), e.g. if the leeward yacht is sailing close hauled then it is not allowed to luff unless in doing so it would pass astern of the windward yacht. If the windward yacht delays its response to the overlap and subsequently makes contact whilst tacking (or by making no attempt to manoeuvre) then the windward yacht would be penalised for not keeping clear. This is where 'gaming' could occur; since Rule 17.1 is not included in the SL ruleset it might be thought legal to luff in this situation. Rule 17.1 also includes references to two hull lengths to leeward. This again is not practicable in SL - AN ACA is 23m long.

(3) Passing to Leeward - Overlap caused by the ahead yacht

Passing to leeward and gaining the overlap as a consequence of an action by the windward yacht (e.g. bearing away) then all rights
revert to the leeward yacht - including the right to luff.

The above refers to the fairly straightforward situation where both yachts are on the same tack and one catches the other. A similar
situation applies when two yachts are heading towards the same point (maybe a buoy) and one is on Starboard and one on Port. The Starboard yacht may think that things are straightforward (Rule 10 Port, Starboard applies), and so it would be if the intent of the Port yacht is to cross the Starboard yacht. If however that is not the intent, then the Port yacht may tack in the lee of the
starboard yacht. In this case the lee yacht (with the exception I mentioned earlier) has the same rights as in case (3) above. This
is very useful when rounding a windward mark to Port - position can be gained and other yachts forced to take action to give you room. The one exception is if the tack is completed within two boat lengths of the buoy. In this case there is no need for the windward yacht to give any room.
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Re: Racing Rules (again) - Windward/Leeward

Postby Jane Fossett » Thu Sep 11, 2008 10:00 am

Thank you M1sha for a great discussion!
My understanding is there is no 'proper course' in SL Sailing. It keeps coming up in explanations of the RL rules, but it's my understanding we agree Rule 17 is hard to enforce here.

My understanding in SL is: If two boats are on the same tack and the leeward boat establishes an overlap, the skipper can call "UP!" and force the windward boat to luff to keep clear, to a maximum of zero apparent.

Of course, the windward boat needs to have room to tack.
Assuming the windward boat has such room, in SL Sailing it makes no difference how the leeward boat established the overlap. The leeward boat has luffing rights over the windward boat.

This issue comes up repeatedly in several contexts. One is the Prestart. I raised it as a question here to get people's views, since often people argue 'proper course' at the raceline. MTW's reply to that article I thought was pretty definitive, and I think consistent with the lack of 'proper course' in SL Sailing.
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Postby M1sha Dallin » Thu Sep 11, 2008 11:27 am

Two points, one easy, one not so easy :?

Pre-start there is no thing as a proper course (RL or SL) - so the leeward yacht has rights. No issue

On the racecourse (RL) there is a proper course, so the leeward yacht has to be careful. In SL we don't declare the proper course rule but we do require skippers to not 'game' the rules. Ignoring proper course gives an overtaking leeward boat an unfair advantage. So in my opinion (fwiw) the leeward yacht who wouldn't have rights (because of rule 17) should not behave as though it has. If it does then it could be open to a protest under SL race guideline 7.

Having had a quick read of MTW's response to the slsailing.com article - the Tako Cup races between Hans and Armchair (that I remember) had Hans as an overtaking Windward yacht. Proper Course does not apply in that situation, and Armchair had all the rights.

I would argue (for racing) that the lack of realism permitted due to the inability to easily assess sailing characteristics (like proper course) is more important than adding additional features like waves.

Note the above only applies where you want to apply rules - if you don't then life is simpler. The race director's choice to apply, and the skipper's choice to compete using the rules as declared.
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Postby Jane Fossett » Thu Sep 11, 2008 12:24 pm

M1sha Dallin wrote: ... On the racecourse (RL) there is a proper course, so the leeward yacht has to be careful. In SL we don't declare the proper course rule but we do require skippers to not 'game' the rules. Ignoring proper course gives an overtaking leeward boat an unfair advantage. So in my opinion (fwiw) the leeward yacht who wouldn't have rights (because of rule 17) should not behave as though it has. If it does then it could be open to a protest under SL race guideline 7.
Having had a quick read of MTW's response to the slsailing.com article - the Tako Cup races between Hans and Armchair (that I remember) had Hans as an overtaking Windward yacht. Proper Course does not apply in that situation, and Armchair had all the rights.
I would argue (for racing) that the lack of realism permitted due to the inability to easily assess sailing characteristics (like proper course) is more important than adding additional features like waves. ...

I think 'gaming' is trying to win a race by taking advantage of script bugs or SL anomalies that have nothing to do with sailing in RL (or even SL as I understand it).
Bouncing off the EOW in Z-40 races, 'paddling' the Fizz2.0 in the Fizz Cup, or making your raceboat 'phantom' are all different examples of what I'd call 'gaming' and should be illegal.
If you use the Rules to gain advantage... that's called "strategy and tactics," I think.
Grin... As usual, I could be wrong.
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Postby M1sha Dallin » Thu Sep 11, 2008 12:34 pm

From the rules:

Gaming the rules is loosely defined as using the ruleset to violate the fundamental purpose of the ruleset, which is to create an environment where The purpose of rules are to keep boats sailing competitively and "safely", not provide opportunities to win by other means than excellence in sailing skills.


I would argue that this also covers exploiting the 'gaps' created by not implementing the full ISAF rule set. But it will only apply where a 'full' (as in SL full) ruleset has been declared.
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Postby Jane Fossett » Thu Sep 11, 2008 4:22 pm

M1sha Dallin wrote:From the rules:

Gaming the rules is loosely defined as using the ruleset to violate the fundamental purpose of the ruleset, which is to create an environment where The purpose of rules are to keep boats sailing competitively and "safely", not provide opportunities to win by other means than excellence in sailing skills.

I would argue that this also covers exploiting the 'gaps' created by not implementing the full ISAF rule set. But it will only apply where a 'full' (as in SL full) ruleset has been declared.


I agree with M1sha on this and most stuff.

In her 12:30 irregular Sailing Skills time slot today, M1sha lead a wonderful, well attended discussion at NYC on the topic of ISF Rules and how to apply them in SL. The group covered many issues, but no surprise, we really only scratched the surface with regard to people's interests and concerns.
Hopefully M1sha will have more meetings in the near future so we can evolve a group consensus about a variety of different SL Racing issues.

The issue of 'gaming' came up today. I personally think of that term in a very restricted way, having to do with the SL interface and script bugs.
For example, in many Trudeau boats, you can use the chat command 'pp' to make your boat phantom. That change provides a skipper with a big tactical advantage racing, since she/he doesn't have to worry about grounding on a sandbar, hitting a buoy with the boom, or having enough room to pass another boat in a tight channel.
In RL sailing, and I suspect in the vision of nearly all SL Sailors and developers here, a phantom boat violates the whole idea of sailboat racing.
Setting your race boat to 'phantom,' in my opinion, isn't SL Racing; it's GAMING.

M1sha made the strong point that "GAMING" could go beyond that. In some situations, SL Racing Rules might also be 'gamed.' Here's my understanding of her argument (I'm sure it is not completely accurate, but I'm also sure M1sha will correct me):

We all agree that the RL ISAF Rules are the Holy Grail, and in 'a perfect sailing emulation' we would encourage all race directors to use as many of the ISF rules as they deemed practical.
Unfortunately... guess what? SL is not perfect.
We are limited to an abbreviated ruleset. We agree that some ISF Rules can't be consistently applied in SL. Rule 17 (about proper course) is frequently brought up as an example.
I think M1sha makes the point that the ISF ruleset is a system. If you remove one rule or modify others, it makes it possible for a sailor to take inappropriate advantage. M1sha (and many other experienced sailors) thinks that "gaming" should include instances where a sailor takes advantage of the limited SL ruleset to subvert the basic idea of an SL Sailing Race emulation.

I appreciate that opinion, and I guess in theory I agree with it.

I have to admit it will take more discussion for me to feel comfortable with that view, however. I mean, what constitutes an unfair rules advantage? I worry that kind of judging call could prove very subjective and inconsistent.
I know we'd all agree being 'phantom' give a boat an unfair advantage, but does the lack of 'Rule 17 proper course' really give a leeward boat unfair 'gaming' advantage over a windward boat, particularly one that's about to flatten it with a windshadow hammer? I think that sounds tactically even...

Actually? I don't know, but I love the discussion, and thank you M1sha for leading it, both on the NYC dock and in the Forum here.

Please do more!
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Postby M1sha Dallin » Sat Sep 13, 2008 2:43 am

I think Jane has captured my comments. One thing to consider in response to Janes's last point.

but does the lack of 'Rule 17 proper course' really give a leeward boat unfair 'gaming' advantage over a windward boat, particularly one that's about to flatten it with a windshadow hammer? I think that sounds tactically even...


A leeward boat claiming luffing rights in SL (when they would not be permitted to do so in RL due to rule 17) could be used to avoid being hit by that windshadow.
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