Ventucky,

Yep, original Nacra 20. I owned one for a time and have a Tybee 500 under my belt on the boat so am aware of the rear beam slap. It would be a good mod to our fleet to race the rear beam a few inches, but honestly it wasn't usually that bad if you kept one hull out of the water. In the race I'm talking about we were on the Chesapeake Bay in some of the nastiest sea state I've been in; the waves were spaced about 8-10' apart. This was driven by 3 kts of current plus wind driven through a fairly narrow channel (4-5 minutes to gybe across at 17kts of ground speed under jib+main). We had rear beam slap on the Infusion a few times as well even with the extra stern volume and raised rear beam. In that particular set of circumstances the extra 2' of hull length was noticeably faster. Usually this isn't a problem for the 20's as the bay is generally lighter air and flat which suits this design quite nicely.

Of the F18's I've sailed the Scorpion and Falcon are the least likely to have this issue. The Cirrus probably fits that category as well; all are relatively high volume designs and the Scorpion has hulls 4" taller than the Infusion PLUS an elevated rear beam. Very comfortable and fast in breeze.

My experience is generally speaking the Atlantic doesn't have a lot of what I call short chop, mostly rollers. There are places this isn't true-Jacksonville at the St. John's River inlet, Cape Fear, Hatteras, Hyannis, St. Barths, approximately 1400nm east of Newport, RI in a deep low with sustained 40 and gusts to 50. In these spots you have chop/breakers on top of rollers and it can get nasty.

I'm sure even the free range organic Pacific can deliver similar in some spots..