Thanks very much for everyones input. Making female moulds would be great if my friends were the same weight and experience level (they're not), we could make half a dozen and have a ball! And making a male foam mould to an exact CAD designed shape might be almost as time consuming as stripping. The tried and true methods are indeed usually the best but we still gotta think outside the square. I dont think hot air bubbles would be a problem if the craft was painted white, especially where I live - exceptionally hot is 30 dgrees C. "Why not S&G" is a very good question, my original concern was the compromise in hull speed, but unless I'm aiming for a placing in a race the difference might not be enough to worry about. Maybe balsa would be a nice light easily shaped wood for a strip surfski.