Hum, I guess I needed to read-on before replying ! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
Chris, very respectable of you to identify yourself.
Airex foam (slightly more expensive than most foams but great for first time builders due to its increased flexibility.
I'm much less experienced then you Chris, but my advice here is to use foam that has sufficient resistance against denting. I've seen to many parties try to use a foam that is less "strong" then the basic 80kg/m^3 variety and they all came up wishing they didn't. Structural wise lighter foams are no problem, the problem has always been knees, elbows, buckles/trapezehooks, and protrusions on the trailer. Even with 80kg/m^3 denting can occur, just much less easily then with lighter foams.
Probably you already know this but it is certain a thing to get right straight of the bad as it is impossible to correct afterwards.
Hull shape is not for public display yet but has been developed through a typical design spiral including detailed weight estimate, resistance anaylysis and analysis of prefered coeffecients.
If the design is an F16 then allow me to advice you to give special attention to dive resistance and dive recovery. This behaviour is a special and therefor seperate analysis then the hull resistance and prefered coefficients analysis. It is however very important on F16 craft, because the rig can be quite powerful and the large squaretop sails can really press down the bows during gusts. Apart from being a control issue this can also be slow because bow down attitudes create alot of drag. Basically a less low drag hull design may well be faster as it is easier to keep it on its intended waterline. Again I know because I have modified an older design (Taipan) into a F16 myself and have sailed the newer designs like the Stealth and Blade several times. The difference is quite significant. The other aspect is freeboard, with the speeds the F16's travels at you really want ample freeboard, see also a similar trend in the F18's. Beam slap is deadly. So these are hull shape issues.
Pretty much all the other stuff can be modified or corrected at a later time.
Best of luck with the project and it is great to see different people designing their own boats.
I'm looking forward to the first pics and results.
Wouter
