I'm sorry folks but I gotta get my sailing fix for the day. This question came up recently, names are witheld to protect the innocent.

Two boats on starboard tack. A F16 is finishing downwind (under spinnaker). Can he legally head up, preventing an A cat (or any other type) from finishing. By heading up he will sail faster and improve his portsmouth score, so he is not sailing above proper course.

I say this is one of those execptions. He must allow the other boat to finish.