Pink beaks rule 11 (on same tack: overlapped) and possibly rule 2 (fair sailing) when green has to alter course to avoid contact. 

 1. Yes, Pink is windward boat and must keep clear.   From the time the overlap was established sometime before position 1, until after position 2, Pink has taken no action to use the room she was given to keep clear of Green.   Pink infringes Rule 11.  Because Green does not change course until she is required to avoid Pink, rule 16 does not apply.

2. As Mark has stated, the infringement occurs when Green can no longer sail her course and must take avoiding action. 

To answer your original question, changing speed (acceleration) is not changing course.  I agree completely with Mark.  

Thanks all, very helpful. I believed as much, but happy to confirm.  It seems to me that boats are in position 2 very regularly, often working it out such that the leeward boat gets a good start regardless of the foul.

Mark T, I'm interested by the fair sailing question. I tried to create a situation where Pink (W) made every effort to keep clear once the boats were approaching each other. It's clear to you and me that they should have begun avoiding earlier, but that's not always obvious to the 10/20-times-a-summer racer while the gap is still 2.5 boat-widths. Again, no disagreement there's a foul, but I'm just trying to understand the fair sailing part.

Sportsmanship and the Rules states “Competitors in the sport of sailing are governed by a body of rules that they are expected to follow and enforce.” Rule 2 (Fair Sailing) refers to the recognized principles of sportsmanship and fair play. Breaches of this principle include: 

 

Five seconds before the start Pink is less than a hulls width from the starting line. When she fails to luff to keep clear is she deliberately breaking a rule to avoid being OCS?

Ahh, understood, Mark. My intention was to describe a situation where Pink made every effort to luff and keep clear, beginning at position 2.2ish, a heartbeat after Green trims to accelerate.
See bullets 4, 5 and 7.
Thanks, Niko

Pink is the keep clear boat from before position 1. Green, the right-of-way boat, was unable to sail her course with no need to take
avoiding action. The question that should be asked is did Pink do enough, soon enough? Probably not because Green needed to take avoiding action. Why didn't Pink sheet in earlier and luff? Was it to avoid being over the line?   

Hi,
I personally think it really depends on timing here.
Case 92 describes the obligation to keep clear as follows:
“A keep-clear boat is required to act only in response to what a right-of-way boat is doing at the time, not what the right-of-way boat might do subsequently. “

When pink could have crossed if green did not accelerate then she was not in breach of 10 prior situation 3. And if she did everything to keep clear at this point she was sailing in her room to keep clear. Only real question is if green needed to give this room, or did she change course.
To this I would argue, yes, a sailing dinghy has a different drift factor with different speeds and therefore is essentially changing course with different speeds. 

Fair Sailing

I would suggest that Match Racing has a very useful approach to fair sailing in these sorts of situations.

RRS C8.3 clearly distinguishes between deliberately breaking a rule and a breach of sportsmanship which may be particularly applicable where an intention to gain an advantage cannot be 'clearly established'.

C8.3 When the umpires decide that a boat has
(a) gained an advantage by breaking a rule after allowing for
a penalty,
(b) deliberately broken a rule, or
(c) committed a breach of sportsmanship,
she shall be penalized under rule C5.2, C5.3 or C5.4.

Penalties under C5.2, C5.3 and C5.4 are:  A 1 Turn penalty, or Double or repeated 1 Turn penalties, a Red Flag, immediate penalty, and Black Flag Disqualification.

The WS MR Umpires Manual 2.4.2 amplifies this (emphasis added)

2.4.2
Sometimes breaking a rule and getting penalized leaves a boat in a better position than she would have
been if she had not broken a rule. In such cases the umpires have several options (rule C8.3):
1. To give an additional, umpire-initiated penalty (rule C5.2).
2. To give the penalty as a red-flag penalty (rule C5.3).
3. To display a black flag (rule C5.4).
The additional, umpire-initiated penalty is meant to take away an advantage gained by a boat that broke
a rule, especially if that advantage was gained through a deliberate breaking of a rule at a critical time
e.g. breaking a rule to avoid being OCS, barging at the start and denying an inside boat room at the
mark. It may also be given to a boat that commits a breach of sportsmanship, and in such a case, the
umpires may initiate the penalty without any flag Y from a competitor. (rule C8.3 and MR Call M2)

If a boat breaks a rule and it is not clearly established that she deliberately broke the rule and did to with the intention of gaining an advantage, I suggest that RRS 2 is not applicable and a disqualification on valid protest is quite sufficient.

Maybe if we want to make scenario for a distinction, might it be a clearer breach of Rule 2 if Pink altered course toward Green between 2-3  ... or no alteration at all to windward (possibly thinking she was too close for comfort at 1 and 2)?

I continue to be surprised that judges think an ILCA is knowingly breaking a rule when two boats are both:

Don't get me wrong. I am frustrated when this happens (often enough) and obviously Pink was too close, but that an amateur sailor would know that such that she is breaching a rule of fair sailing is asking a lot IMO. This seems like a misjudgement of time, distance, and the boat-handling of a better sailor, not an attempt to game the system, but Ill also admit that I often overhear new racers saying afterwards, "sorry, I was too focused on not being OCS."

Questions:

(Also, to be clear, this is not a specific incident I saw, but is similar to many incidents that I see in many fleets on a near-weekly basis.)

Niko, in general Judges are there to enforce RRS 42, but in doing so can witness other rules infractions.  Often, there is an agreed upon "policy" between the judges prior to racing for what and when they may protest boats for other rules, and these are typically in the realm of gross violations or rule breaches where no other boat was in a position to see/witness the rules breach. In this instance, they would rely upon Green or another boat who saw the incident protesting Pink ...

So ... Judges aren't "throwing RRS2 at people on the start line". This might be a consideration in deliberation while hearing a valid protest, based upon the evidence heard and facts found.   

For a Rule 2 in this circumstance, IMO knowledge, awareness and intent are key. 

Niko, Hopefully the following will help you understand what the protest committee might be considering. Assuming that the incident you described is the subject of a hearing request how does the protest committee decide who broke a rule. How do they determine if it was "misjudgment of time and distance," or "an attempt to game the system." Normally the protest committee shall make its decision based on a balance of probabilities. (rule 64.1(a)) However, rule 2 requires the protest committee to clearly establish that the principles of sportsmanship and fair play have violated.

Mark re: "Why didn't Pink anticipate that Green would sheet in to start? .... WS Case 27 says that  "A boat is not required to anticipate that another boat will break a rule." Green did not break a rule, so WS Case 27 does not apply."

Mark that's a really insightful application of that case.  Thanks for that. 

Mark, " Did Green hail, "up, up, up" or "windward boat" during that time."

Given that RRS 14 says that Green is not required to take any action to avoid contact before it is clear that Pink is not keeping clear, and there is no prospect of Green breaking any rule, why is any hail by Green relevant?

John, I agree with your comment. WS Case 107 says that hailing is one way that a boat may 'act to avoid contact.' If Green was hailing before she altered course Pink doesn't have many good arguments she can make.