Sorry for the long delay. If the model is built at 1:12 then the entire model including batteries and motors etc. has to weigh under 20lb. Mine comes in at 18.5 lb. although it is 51"x11". The mould is probably in the region of 25lb.
The reason the boat has to be light is due to the fact there is no draught to speak of. The "skeg" contributes nothing to the buoyancy so the effective draught aft is only about 1.5", and although the forward draught may be 3" or so, the hull form is such that little buoyancy is created. If you would still like a CD of my build and a full set of plans (although segmented) please PM me via the "profiles" button. I was going to offer to use my mould to make you a hull, but present cicumstances make that a no-no. BY.