Thanks for noting rule 16.1 Mark.  I did miss that.  
Rule 16.1 really muddies the water.  16.1 is in direct conflict with rule 14.  Rule 16.1 allows a make-way boat to maneuver to restrict a right-of-way boat by staying close enough to invoke rule 16.1 and thus put the burden on the right-of-way boat.   Rule 16.1 could be applied in this case and I think this is a major flaw.  Note that I was present on the yellow boat.  This may not have been the intent of the helmsman, but the maneuvers of the yellow boat did restrict the maneuvers of the blue boat.  The yellow boat did put itself in a position from which it could not keep clear and rule 16.1 could apply, but yellow could have prevented this situation had it taken the traditional approach of keeping a good space to the leeward boat.  If rule 16.1 allows the windward boat to maneuver in these ways, then the prestart/start is going to be much different.  A weather boat can just squeeze a leeward boat, especially taking advantage of the "initially" part of rule 15 to extend initially to continuously by means of rule 16.1, or, as was the case here, reestablish limitations on the leeward boat.  In my experience it is much better to race under clear rules that remove the ambiguity produced by 16.1 and just stick with rule 14 for avoiding contact.  Clear cut responsibilities result in fairer, better and safer racing.  

Second talk about the rules changes for 2021 with John Doerr, Ana Sanchez , Nelson Ilha, Ricardo Lobato and special guest. We will quick review the main questions from the first program and we will present the changes related to the Appendices. https://youtu.be/gD1voeQFqO0

Good point. Thanks Tim

A touch late to the party here, but a question- The World Cup and other WS events display Class, starting penalty, and other (e.g. O) flags prior to the 5 minute signal. As the sound system is intended to keep Signal Boat personnel smaller in number with less to do at any given moment, does it make sense to 1) display Orange at Start minus 6 (minimum) minutes (with sound), Class and Starting Protocol (P, I, Z, U, or Black) (with the meanings associated in Race Signals (P) or RRS 30) at S - 5mins, then at 3 mins go with the Appendix U sequence? AP and 1st repeater drop 1 min prior to Appendix U Warning.

Thanks!

to me, this is a tempest in a glass of water. It's all in the book.

Port tack boat has to "keep clear". First for RRS 10, then for RRS 13 if taking, and if she ends up overlapped WW, for RRS 11, or, if overlapped downwind, "room"  for RRS 15.

"Keep clear" and "room"   are rather well described in the "Definitions", And applies to all boats,  in all conditions. 
Of course different boats and different conditions  will makes different speed, distance, timing  etc, to match the requirements of  "Keep clear" and "room" , but in principle,  the Keep clear and room are, well, rather "clear"