Port Tack Boat (P) approaches a Starboard Tack Boat (S). Both boats are close hauled..The wind is moderate, but shifty. P is getting lifted nicely and decides to cross ahead of S. There appears to be adequate time for a safe crossing and P proceeds across the bow of S.
As P is part way across the bow of S, the wind shifts suddenly 20 degrees to the right. P is headed and has no time to tack. P bears down quickly to keep up speed and to complete the cross.
As the shift occurs to the right, S is lifted quickly to the right and is now on a new course. Collision is now apparent. S continues on this new course and then strikes the back stay of P.
S protests P ( port/starboard).
P protests S ( failure to avoid collision)
Neither boat accepts the other's protest and the protests go to committee..
As Judge...how do you rule?

Where any hails made?
Would S have cleared P if S had not changed [u]compass[/u] course?
What was the wind speed. Boats were easily controlled?

No hails were made.
S would have cleared P if S had not changed compass course.
Wind was moderate, although the change in wind direction was accompanied by a puff.
Boats were under control.

S could have avoided BUT P took a chance and lost.
S was ROW and seems did not "hunt" P
S wins.
Great discussion.

I will disagree.
DSQ S

P was going to cross S.
S changed compass course following the lift such that P was unable to keep clear.
S broke rules 16.1 and 14 by failing to avoid contact.

Welllllll.... I love you Doc, but it depends on where and when S changed course. Wind shifts are not part of the equation. S is allowed to follow the wind and so may change course to stay in the best wind, but when she changes course she MUST give room an opportunity to P to keep clear.. If P was sailing a course to keep clear of S and would have crossed S without any worries and then S changed course close enough to P that P had to make a major change of course to avoid contact, then S would have broken rule 16.1.

16 CHANGING COURSE
16.1 When a right-of-way boat changes course, she shall give the other
boat room to keep clear.
16.2 In addition, when after the starting signal a port-tack boat is keeping
clear by sailing to pass astern of a starboard-tack boat, the starboard-
tack boat shall not change course if as a result the port-tack
boat would immediately need to change course to continue keeping
clear.

So the question is, Did S give P room to keep clear? More information might be needed.
If P was clearly going to cross S before the wind shift and S's change of course was so close to P that P could not avoid, then S was at fault.
If S gave room for P to avoid and P could not due to the wind shift, then P is at fault.

It is not so cut and dry. I think a good judge would ask more questions before deciding.

It is a good discussion. My guess is the judge will lean towards S if there are no witnesses to back P.

Illustration from Perry book on rule 16.1. page 117 in the 2012 Edition but I believe still included in that section on the current book.

Good Job Joe and Tom P. They covered the question correctly!

Dick additionally asked how the judge/protest committee would rule. In the absence of any further information and presuming that both parties agreed to the basic facts-

P's protest of Starboard would be upheld.
S's protest of Port would be dismissed.

Witnesses could be critical.