Michael, I can't see where Case 50 makes it clear that S's perception of reasonable apprehension governs anything. I think we agree it depends on the facts confirming that apprehension was reasonable, which means the facts might also show it was not reasonable. The conclusion of "reasonable" can only come from the jury in the answer to the second of 3 tests:
1. S changed course
2. There was reasonable doubt that P could have crossed ahead
3. S was justified in taking avoiding action by bearing away.

Note the conditional nature of "could" in the second test. "P could have crossed ahead" means the possibility existed of P crossing ahead. It is much weaker than "There was reasonable doubt the P would have passed ahead." As the boats get farther and farther apart, the possibilities multiply: wind gusts, shifts, steering issues, slight course changes, sail handling for two boats. Therefore, It's only when boats get close ("When Boats Meet") that it begins to be possible to project their course over a short period time with a great deal of certainty.
Your interpretation is plausible, but I think it creates unnecessary confusion about the standard of reasonability. Which is why Robert asked the question.

Can you expand on this?

John, I am glad that the WASZP rules are working in practice.  I think that the wingfoils will go a different direction, with little or no limitations, at least in part because they are always in the standing position.  I think that should be up to the fleet decide and adopt in their class rules so we shall see as the class matures.

I'm with Phillip, in the definition its a measure, and that measure should be consistent. A less than competent crew is not entitled to more room than an expert one, and would be breaking a rule if they require it (lets leave room made freely available out of it for now).  Similarlty an expert crew is allowed the same room as a competent one, even though they may not need it,

John, I agree with you about reasonable apprehension and skill level, but I think its a red herring in the context of Room and Case 103.

The world sailing judges manual changes on improper act or ommission in each version, each seeming giving judges more room for interpretation. Just track the change next time, it may be what gordon and i may expect.
The old bad race management hidden behind the word may not shall,, may not be tolerated.
A time of change perhaps! I believe for the better if we are to improve standards and improve the sport.