So...it was the rating? Did they regularly race as one fleet, alone, or were the being scored with all the other boats you mentioned?
Single catamaran start on Sundays ranging from Dart 16's to Nacra 20's, doesn't seem to matter as most cats are pretty nifty off the line, . Wednesdays eves is fun racing, it can be 30+ boats ranging from lasers to Nacra 20's and Tornados. It can be entertaining to say the least on the start line with the 10 slowest boats all lined across the start line at 0 speed ready to go with the other 20 all baring down on the line at speed, yes we do have some shouting and whinging about tactics at the time, but its all done with great aplomb and little bickering afterwards as we tuck into a good supper and a beer, its a good night out and more should try the social racing.