Of course I have no first hand knowledge of the Infusion F18, but I can tell you that the other Flyer A-cat inspired boats like the Capricorn F18, Blade F18 and Blade F16 are all reported to be sailed best under spinnaker with the bow out of the water. This appears to make them faster. It was not expected, nor envisioned during the design stages, but in real life testing it proved to work well. Some people think it has something to do with the "reduced volume in the wvepiercer bows", but actually the bouyancy was never reduced here; if anything it was increased. The explanations are still various. Some say the wide keels allow planing others say that it reduces pitching even more because the wave contact the hulls rather away from the bows. There is no concensus apart from the fact that these new hulls like to be sailed out of the water with their bows when sailing at speed under their spinnaker.

Maybe it is just a way to reduce wetted surface area because the new hullshapes depress their sterns much less than the older shapes and thus suffer only a mild penalty in wave-making drag. More testing and theorizing is required

Wouter