What works best IMHO is to just ask them directly by waving or do "the stare".
Rofl. Let me rephrase my story then:
Funny, I was in the exact opposite situation last Wednesday: A 29er was in front of me, I was a couple of boat length behind and to windward. But my layline is further than their layline as a 29er points better than my Stealth.
I saw the skipper looking at me, looking at the mark, finally realizing he was screwed and that he would have to go further, to my layline.
So he gave me the evil stare, one of those long frightening look. His piercing eyes seemed to be looking into the inside of my skull. I heard myself studder "You tack, I'll avoid you". My hand, by its own accord, pulled the tiler to avoid his stern while he was tacking, still looking at me with his frightening glance. When he was sure to be clear he looked away and a weight seems to be lifting from my shoulders. I regained control of my arm. I avoided getting to close of his black sail for the rest of the regatta and made sure to land on the opposite side of the beach.
Anyway, I find the f18 crews generally more aggressive. In my experience there are more skippers there willing to push the rules a little bit to gain any advantage, especially if it is just fouling an irrelevant boat from some other class they are not directly competing against. To make matter worse, due to their minimum weight, those boats are overbuild and build like tanks. A side sweep by one of those is going to cut any F16 in two. I would not take the risk.
