Well, that is not an easy question to answer. Look at the situation from this perspective.

Making predictions of the F16 performance compared to the F18's, I-20's and even the Nacra 17's/FX-ones/iCat is easy as all of these boats are very similar in their setup. They use sails with very compareble aspect ratio's, their weight-to-power ratio's and heeling-to-power are very similar. The same with length to width etc. They all use spinnakers and require very similar sailing skills for optimal performance. As a result, wind and sea-state conditions as well as sailed courses impact the same on all of these designs with only a rather small set of (small) exceptions. This means that performance differences are largely determined by a few equalities or inequalities in key ratio's/parameters.

The A-cat however is not very similar to the group of boats named above. Its ratio's lie far away from those of the others and different conditions or courses impact differently on the A-cat design then they do to the other designs. It is hard if not impossible to summerize the relative performances in one simple statement or even one simple number. The situation is just too multifacetted to be condensed to such a simple (1-dimensional) benchmark.

It is my experience and opinion that the F16's are at least as fast as the A's on a windward-leeward course in medium conditions. In the light stuff it all dependents on whether the wind is just strong enough to fill the spi. If it doesn't then the A's are faster. In the rough stuff it all comes down whether the conditions allow the spi to be set and douced without capsizing. It is also my opinion that the A's can be fast downwind but only with sufficiently developped windthing skills and these are harder to learn then riding the spinnaker. So for most recreational sailors and racers the F16 will be faster over a significant range of conditions. Partly because the skills to effectively fly the spi are relatively easy to learn.

Personally, I don't think F16 to A = 63.0 to 64.5 is a large difference. It is about a minute per 45 minute bouy race. Even if that ratio is wrong, I still don't believe it is far of the mark. I think, by crude averaging, that the A's are properly placed just a tad slower then the F18's (and F16's) while recognizing that they have convincing sweet spots like sub-spinnaker light winds where they are simply outperformaning nearly all others.

Whether the difference of 3.4% that currently exists between the F18's and A's under USPN is right is something that future results must prood or disproof.

Wouter