Posted: May 22, 2009 - 02:31 PM
The Nacra 5.5 Uni is an 18SQ with an 8'6" beam and less sail. It is supposed to be a scaled down version of the 18SQ, but it can still be a lot of boat when the wind gets up. I would expect the 18SQ to be similar to the 5.5, but the 18SQ is faster, so it is probably a little harder to depower. The 5.5 can be equiped with a jib for those occasions when you carry crew, the 18SQ cannot.
A boat with an 11 foot beam will require some technique to right when you are on your own. I believe that it also has two beams that run from the front beam to the aft beam and were specifically designed to cause pain.
Since the 18SQ uses the same hulls as the 5.5, you will have no trouble with additional people on board. The uni rig setup takes some getting used to, but works very well. The 18SQ has a reputation for pointing ability.
A-Cats are pretty, very fast, expensive and built for one.
If you have the budget for an A-cat, you have a huge selection of good boats to choose from.