Originally Posted by fud
I have to confess that I know zero about ISAF racing rules . . .
Nor do I. Nor would the powerboat captain involved. Nor most likely would either sailboat captain. That's why they would have zero bearing, except by coincedence, in a meeting situation as originally described unless it was during a race in which all parties had been informed that those rules would apply.
In U.S. waters I'd say the Rules of the Road as published by the U.S. Coast Guard would be the prime authority - in which case all vessels are obligated to avoid a collision, right or not, so I'd go with fud's earlier response.