"As for hailing protest; that is not required either. If you foul, you should do your turn(s)."

So what if you had no idea you fouled the other boat because a. you were not even aware of his presance or b. what his intended course was (he said it was a distance race, so "proper course" could be open to speculation)

Any jackass could walk up to you after a long distance race and say, "I am protesting you because you fouled me way back when..." Now you have no way to exonerate yourself, or maybe even no knowledge of the foul, or even if the protest was legitamate. I've seen it done.

When in doubt, you can ask him if you fouled him, if he has not hailed you, and if allowed, you do your 360 and press on.