Stephen,

By that line of thinking the Taipan 4.9 counts as well as it too was first launched (tried) with a spinnaker although that was quickly dropped after the first races with it. And it is a succesful F16 design although the newer designs are better.

The T4.9 hull is very similar to the Mark 3 and 4 AHPC A-cats. But I wouldn't not call either the T4.9 or T5.7 a dedicated spinnaker boat as the Formula boats and M20 etc are. Back in the days of the T4.9 and T5.7 the spinnaker was very much an after thought without making specific changes to the hull to carry a spinnaker better. Same with respect to the Tornado and Hurricanes. That pretty much changed with the introduction of the F18 class in 1994. From then onwards the spinnaker feature became a integral part of the hull design. But the designs began really to diverge a little after 2000 as is my original statement.

(To Matt) I'm really at pains to recognize the (strong) similarities between the A2/A3 and the Infusion, apart from both being of the same length. It may be that some distributed set of percentages relate the two hulls, but then the design part is only redefined as finding the right set of those. And where do we stop ? Some one commented that the Nacra 20 hulls look much like the old clippers of yore ! High V-shaped bow and fat and wide behind that. I imagine a similar relation exist between a super bike (road) and a dirt bike (of road). In the end both are motor cycles and there is only so much that can be different within such a framework. Still doesn't mean that the best frame for off the road is also the best frame for road races.

(To everybody) But I grant that that is a personal opinion.

What I can however state as fact is the following.

Using a single percentage to scale the Infusion hull to F16 size will produce a quite reasonable F16 hull without any modifications (and the factor is 90.58% or simply the ratio of hull lengths). This rescaled hull with have the exact same waterline when a crew of 138 kg is sailing it (against 150 kg on the Infusion). Doing the same to any A-cat hull (young or old) will result in awful F16 platform (will carry on a 6 kg crew on the same waterline ! yes less then 10 kg). You'll need at least several different scaling factors to even get an acceptable F16 hull that way. And we only know one of those factors, the other needs to be found somehow (experimentally)

Wouter