In either scenario, as you said, Orange didn't change course. No breach of 16.1.
And nothing she could do to avoir contact, when it's obvious that Blue doesn't keep clear, which is at position 3.5. No breach of 14

Maybe we need to ask which quad?  Here is RRS 14 in 2025 ...

Notice, the "however" clause only applies to 14(a) ... not (b) or (c). 

Letting one's sails out to stop the boat is an "act" by that boat, that one could argue caused contact between the boats, and there is no "however" escape-hatch for 14(b)'s "cause contact" for the ROW boat. 

'Luff' is usually taken to mean 'change course to windward'.  In this case, I take it you mean 'starts or eases sails'.

Yes, B breaks RRS 10.

I don't think O has not broken RRS 14.

Case 87

A right-of-way boat need not act to avoid contact until it is clear that the other boat is not keeping clear.

IF the protest committee finds as a fact that O changed course, then O broke RRS 16.1.

If what O was doing was aggressive, repeated sculling intended to reduce speed (permitted by RRS 42.3(f)) that may or may not have changed her course, then the protest committee might find that she did not change course.

Let's see what you are keeping back.

Ang,

Good get on 2025 RRS.  I agree with 'cause'.

You may wish to consider:
Team Racing Calls L1, A4
WS Case 73

Did I say that in scenario Beta?

My follow up question per JA's request, is effectively the title: I'm trying to get at whether we can ever say "didn't change course", and whether changing course slightly (1 or 2 degrees, or a wiggle up and down a degree or two) matters in a scenario where the contact was mostly caused by a change in speed, rather than a change in course.

To be clear, I've never seen this protest, but I've definitely been the ducking boat when I suddenly had to duck harder, and also been in scenarios similar to my question last month, which is somewhat related. I do think this question could be particularly valuable in a team-racing scenario.

I had forgotten about (or didn't know about) RRS 14b, and I think it's pretty applicable here as Ang says. (Note that for the life of me I can't tell from JA's double negative if he agrees.)

"Note that for the life of me I can't tell from JA's double negative if he agrees."

He's wily that one. :-) 

That's an interesting aspect  of the change. AIUI previously if orange let sails fly in front of blue who was narrowly keeping clear and thus made it difficult or impossible for blue to avoid a collision orange would I think have been in the clear.

My interpretation of 14b and 14c, looked at together, is that if As actions cause B, perhaps taking avoiding action, to hit third party C or  an obstruction, then A has broken a rule, and I think that is an improvement. 

 Here Angelo seems to me to be interpreting 14b so that orange can be penalised for shall we say provoking contact between her and blue. Is that what the revised rule intends? In that situation should a PC be considering penalising both boats, one for failing to keep clear and the other for causing contact? 

Jim ... so are saying there is an implied "other" in 14(b)?

PS: that certainly isn't obvious ... that the boat itself is excluded in the word "boats" ... term: "boat" does not make that distinction or exclusion ... it is still "A sailboat and the crew on board."

Well, the way I was thinking was that 
14a - A touches B,  
14b - A causes B to touch C
14c - A causes B to touch obstruction
I agree that without 'other' in the clause your interpretation that 14b also covers A touching B is not unreasonable, but if that is the case 14a seems redundant. The alternative interpretation is that the phrase 'causes contact between boats' only covers the situation where the causative boat does not make contact. 

On the water, though, is there a practical difference? 

I don't know ... I'm just reading the words as they are written.  If the intent was "other" ... then they should put "other" in there. 

Another interesting discussion!
Not for me to discuss what is intended but I think we should interpret what is written.
In the scenario below Blue breaks rule 16 by luffing hard and there is contact between Yellow and Green.
Yellow and Green are boats.
Blue has 'caused contact' between Yellow and Green so breaks 14(b). If there was damage, I do not believe she should be exonerated under 43.1(c).

Jim, Ang,

i don't disagree with Ang.

I could swear there was a similar question recently about changing course and speed but can't find it. I'm sure the conclusion was speed is not course.

As for Rule  14

I'm assuming orange in the protest room will say they were waiting for blue to avoid them, then tried to slow down to allow them to pass clear ahead, this attempting to comply with 14 (per the 2020-24 rules as we aren't in 2025 yet).

(my emphasis)
Did Blue respond to a starboard call etc? If Blue replies that they've seen orange is is unreasonable that orange delays taking avoiding action until he is convinced blue is not doing enough (in oranges opinion) to stay clear? Then the question is did orange do sufficient to try and avoid contact.

If this was in January, 

Then I think orange is going to claim by slowing down he was attempting to comply with 14(a). But I suspect the hearing will determine that in attempting to comply with 14(a) he failed to comply with 14(b) and as the statements are joined with 'and' he therefore failed to avoid contact.

But as notes by others, the RoW boat doesn't need to act to avoid contact until clear other boat is not keeping clear, exactly as before. However, 14(b) is not ACTING TO AVOID it is CAUSING. And as 14(b) is breached, the RoW is irrelevant next year.  Which seems appropriate.  The RoW boat needs to maintain course and speed. But you can't write that because a boat can't manufacture speed if the wind dies... 

You can't have a situation where a starboard boat slows down to force the port boat to tack/make a massive duck etc. 

I agree with John S.

I think the case he illustrates is what was intended by the change in RRS 14.

Adding 'cause' to RRS 14 is a pretty big deal.

I think the 2025 RRS 14 does also apply to the 2 boat case where one causes contact.

Exoneration where there is no damage or injury still applies.

14(b).

I'm not sure I agree with Ang.

14(a) covers boat-on-boat like it always did.

Rule 14 still allows the right of way/room/mark-room boat to sail within her rights, which include sailing at which ever speed she chooses (so long as she complies with her limitation of other rules).  When another boat was required to afford her the right to sail as she pleases, ROW/R/MR can't be said to have 'caused' a contact when she does so.

But notably, I agree with JohnS, and think this is exactly why 14(b-c) was included.  To handle the long-standing question of when a boat luffs a boat above her into a boat above her (or into the committee boat)!

Let's clear up some language here.

Luff(v) - To steer a boat on a course too close to the wind such that her sails are not properly trimmed.  This almost always involves a course change.

Course - A boat changes course when she changes her compass bearing. Leaning out, slowing, and heeling the boat are not changing course.
(Wording from TRCBA4)

(Changing speed is not 'changing course'.)

-------------------------------------
On OPs Post

Scenario Alpha - Rule 16 not broken, since slowing down (by easing sails) is not a 'course change'.(TRCBA4)
Rule 14 is not broken, since Rule 14 still allows a right of way boat or one entitled to room or mark room to sail within her rights, which includes sailing at whatever speed she chooses.
The RoW does not have to maintain her course and speed. (That's a IRPCAS approach.)
Rule 2 may be broken if it is found with comfortable satisfaction that the reason why Orange eased her sails was only to 'checkmate' Blue (WS Case 73).

Blue breaks rule 10.

Scenario Beta - The question is whether the slight wiggle broke rule 16.

A course change may be so infinitely small that it's physical effect on the overall scenario is imperceivable.  It seems that Orange's 'slight wiggle' was effectively the same as 'no course change'.  Blue had failed to keep clear regardless of this wiggle.

Blue breaks rule 10.

To address the question in the OP.

There is no rule that requires Orange to maintain or to try and maintain her speed.  Rule 16 is about changing compass course not speed.  As far as 1 or 2 degrees of change in her that course, we don't refine things to that level when interpreting the rules.  We accept the reality that a boat is generally progressing in a straight line, even though when looked at instant to instant, her absolute compass course is constantly changing at some level of precision.  In heavy seas, we accept that the boat may be changing compass course quite a bit as they work through and are pushed around by waves and decide that she was not changing course for the purposes of rule 16.

No doubt the application of the revised RRS14 will become a little clearer when we have a case or two. 

John Robson's mention of Case 73 is apposite. If orange aggressively slows in a manner that can only be intended to cause contact then under the same principle as Case 73 is she breaking rule 2 even under current rules? Presumably the opposite situation of speeding up doesn't apply since (at least outside team/match) a boat will always be expected to be sailing as fast as she can. 

Calum re: "I'm assuming orange in the protest room will say they were waiting for blue to avoid them, then tried to slow down to allow them to pass clear ahead, this attempting to comply with 14"

It seems clear that if O did not slow, it would have taken a minor course change if any) to leeward for B to tuck. Simply place O-4 bow to stern with O-3.   Given the diagram, that's a hard sell IMO.  Now, O could have had equipment failure ... or maybe O's main trimmer didn't fully cleat the sheet while adjusting and it slipped ... or kicked it out with their foot .... etc, etc, etc.

In the OP case, both the main and jib are let loose at the same time, which seems to remove the idea of happenstance and bring forth the question of intention as others have raised.

---------

Ben re: "I'm not sure I agree with Ang."

To be clear .. i don't fully agree with me either!

I think it is very likely that the Rule-writers intended it to be interpreted as "[other] boats ...", but that is not what is written.

There are 2 different action verbs .. "avoid" and "cause".   Avoiding a punch (ducking) is different than punching (causing contact). 

The structure of the sentence doesn't make it clear either.  As structured, each (a)-(c) stand as their own statement, which can be read independently joined with "If reasonably possible, a boat shall ...".

PS: [Think the 10 Commandments ... and regrouping them such that all the individual "Thall shall not"'s are put together in one sentence (a), (b) .. etc.  Each statement when re-expanded stands as its own independent statement like they started.]

Adding "other" in (b) and (c) is a simple fix for clarity .. just as they did with "another" in 14(a)

To use your boxing analogy.

I can avoid a punch by ducking out of the way.
I can cause contact by punching.
What if I punch someone as a block? (Is that causing someone to be punched... sounds like it?) What if I grab someone else and use them as a shield - Im.causimg them to be punched...

The only thing other means is not myself.  So adding other means I can't punch myself. In the context of boats that means I can't cause myself to crash into myself so seems a moot point. But likewise, I can't crash into the committee boat and say it was necessary to avoid another boat.

I am with Jim Champ on this.  If there was no reason for O to slow down other than to force contact with B, then I also think that violates Rule 2.  We don't know why O slowed from the information given so far.  If it was equipment failure etc. then no violation, but if it was tactical,  then O should be disqualified both for breaking Rule 2 and for having too much money (who wants to collide with another boat?).  

David,
I agree, but think you need to be careful here with use fo the word 'tactical' being the infringement. Perhaps 'malicious' is a better word in your summary.

O slowing 'maliciously' to cause B to break a rule or worse, cause contact (as I say, 'checkmating') breaks Rule 2.
O slowing for tactical reasons to force B to tack or duck is OK.

Let's not imply that O must hold her course and speed under RRS.
-----------
Ang, I see where you're coming from with the literal interpretation not seeming to make clear the scope of (b).  I have a few counter approaches typed up, but not sure which to post!

Ben ... since they use "another" in 14(a) (which sort of sets a standard for setting the "scope" in the sentence)... and how the sentence is structured, and thus how the elements expand into individual statements,  I think we are saying RRS2025 14 was very likely intended to be interpreted as ... [mods added]

If reasonably possible, a boat shall
(a) avoid contact with another boat,
(b) not cause contact between [other] boats, and
(c) not cause contact between a [another] boat and an object that should be avoided.

Given the following scenario, how does rule 14 apply

Three ILCAs on starboard tack are approaching the starting line to start. Blue, Green, and Red are overlapped with the signal vessel and are above close-hauled. Ten seconds before the start, the leeward boat, Blue, luffs head to wind. Green and Red respond. Blue makes contact with Green, Green makes contact with Red, and Red makes contact with the signal vessel. All boats hail protest.

 Blue is the leeward right of way boat. When a right-of-way boat changes course, she shall give the other boat room to keep clear. Room includes space to
comply with her obligations under the rules of Part 2 and rule 31, while manoeuvring promptly in a seamanlike way.   

Under the 2025-2028 rules does Blue break 14(a), 14(b), and 14(c)?

1. Blue did not avoid contact when it was reasonably possible, and broke RRS 14(a).

2. Blue caused contact between Green and Red and broke RRS 14(b).

3. Blue caused contact between Red and the race committee signal vessel and broke RRS 14(c)

Maybe we need a new thread 2025-2028 RRS Rule 14.

Mark re: "Maybe we need a new thread 2025-2028 RRS Rule 14."

Sounds good. Wanna frame that up and get it rolling?