Thanks for both your responses Jonathan and Reg. Will sure look into the scantling reference you gave me. As for the thickness a bit over an ich could well be right. The traditionally built dragons here in Thailand are built out of 3 or 5 massive boards of tropical hard wood and then carved to leave just a bit over an inch on thickness. Was thinking there must be a way in the construction to beat that weight. going from about an inch thickness I guess if I would build a hollow hull of two sheets of 0.25 inch strips with half an inch ribs inbetween them I would almost reduce the weight by half. The thus created box frame would possibly be stronger than a solid board of the same thickness. There is no possible gain in the choice of a lighter wood, because one of the few standards of construction in this racing class is the use of only this species called Takian here. The closest I came to that name was Iron Wood, which is a fine and long grained hard wood with hardly any knots in it, A bit like teak but not as oily as teak is.

regards
Arthur
: Arthur