First of all, great work ! Having some time today, I think that another possibility in example 1 could be the following: as you say "It was not reasonably possible for W, a boat entitled to mark-room, to avoid contact with L when it was clear that L was not giving mark-room" then we can also conclude that W did not infringe rule 14. In that case, with that conclusion, I think that we don't need to exonerate W, as she did not break the rule. Manolo

I realize you’re focused on rule 21, but there are some broader rule issues that are causing a problem with the write-up.

First the small issue. I think you have a typo between 18.2(a) in your conclusion and 18.2(b) in your Result (Decision). As is, you do not have enough facts to shown that rule 18 applies, or support your conclusion that L is required to give W mark-room and W is sailing within mark-room she is entitled to.

 In this incident, when W makes contact with L, W breaks rule 11 (a Part 2, Section A rule), and, when W touches the mark, she breaks rule 31.

It looks to me like the result (Decision) you want supported by Conclusions and Facts is:
(a) L DSQed rule 18.2(d) (See applying rule 14 below)

The necessary Conclusions for that decision are:

(a) L, outside and overlapped of W, failed to give W mark-room breaking rule 18.2(b).
(b) W made contact with L, breaking rule 11, and touched the mark breaking rule 31.
(c) W is exonerated. That can be done two ways.
(c1).1 When W broke rules 11 and 31 she was sailing within the mark-room she was entitled to, and
(c1).2 W is exonerated by rule 21(a) and 21(b).
or
(c2) W was compelled to break rules 11 and 31 by L when L broke rule 18.2(a) and is exonerated by rule 64.1(a).

[whether adding rule 21 was a good idea when introduced in 2008 and rule 64.1(a) had been working for decades; and, whether it is better to use one or the other, would be a good discussion for a this forum or a round table – or to follow the RRS's example, both :-) ]

Checking if all the needed Facts are there to support the conclusions is now pretty straight forward.
-- You have a fact defining where the boats were at the collisions and the resultant damage.
-- You need a fact about when and where the overlap was established to apply 18.2.
-- You need a fact describing how W was sailing within the mark-room she was entitled to.

Rule 14.

Conclusion 2 says, “It was not reasonably possible for W … to avoid contact with L.”

Rule 14 is therefore not broken because W does not get past the initial condition.

Because W is not disqualified she does not qualify for the 14(b) exoneration.

 Assuming there are facts that lead to the conclusion that L is an outside, overlapped boat that owes W mark-room, L is also a right-of-way boat. Your fact that there was no damage or injury means L shall be exoneration by 14(b). L cannot be DSQed under rule 14.

I think you’ve got a logic error in example 2.

You have S finishing her tack within one boat length of P, then bore away to avoid contact.

The first conclusion the protest committee needs is whether P kept clear when S finished her tack - can the r-o-w boat sail her course with no need to take avoiding action?

My conclusion is that P broke rule 10. When S was less than a boat length apart she bore away to avoid contact. (A fact about wind speed is necessary.)

Then, was P compelled to break rule 10 by S breaking rule 15 and initially failing to give P room to keep clear — the space P needed, in the conditions and when manoeuvering promptly, to comply with her obligation to keep clear?

(I disagree with your conclusion that S gave P room, but let’s leave that match racing vs fleet racing discussion to another time.)

1. P is eligible for rule 21 exoneration because she is owed room by S. 
   
2. If S gives her that room, then P either keeps clear (No rules broken by P or S), or ,S does not giver her the room. S breaks rule 15, P breaks rule 10 and is exonerated by rule 21(a). 
   
3. If S gives her that room and P does not keep clear then P is no longer sailing within the mark room she is entitled to and rule 21 does not apply. P breaks rule 10.
   

Finally circling back to this (a month later!).

There was a fact regarding wind speed (light air).

For sake of argument, it was determined (fact) that when S completed her tack (acquired right of way), she was less than a 1/2 BL (about 1.5 m) away from P with her bow pointed aft of P's midship.  P's only way to keep clear was to keep sailing her course.

Scenario 2a:
S bears away behind P, no contact.
S gave P room to keep clear and complies with 15, P keeps clear (no contact) - no rules broken, therefore no exoneration required.

Scenario 2b:
S bears away behind P and clips P's stern quarter.  No damage or injury.
S did not give room for P to keep clear, and breaks 15.
S breaks 14, but is exonerated by 14(b) [right of way boat]
P breaks 10 but is exonerated by 21 [in an incident with a boat required to give her room]
P does not break 14, [not reasonably possible to avoid contact]

I'm still trying to wrap my head around the use of 21 in situations other than at marks.

  

Interesting discussion.

Note that Section B is "General Limitations."

Rule 15 provides that "when a boat acquires ROW she shall initially give the other boat room to keep clear."  It seems to me that if S is required to give P room to keep clear, P did not break rule 10 if she did not keep clear of S during the time S was required to give her room. In any event, P is entitled to exoneration under 21 if she did break rule 10.

I am interested in the implications of this perspective on the events and decision.