What advice would you give for this question?
"I am also thinking about the laminated cedar bottom that is used in the WoodenBoat version and wondering if I would pay a very big weight penalty if I used 3 layers of 3mm Sapalli instead?"
Sapele (this is the correct spelling) is an African Hardwood. It's quite beautiful when finished in layers of spar varnish but it has a density of 39 pounds per cubic foot. Northern White Cedar is 21 pounds per cubic foot, and Western Red Cedar is 23 pounds per cubic foot. In answer to your question: Yes, you will pay a substantial weight penalty if you use Sapele instead of Northern White or Western Red Cedar.
Paul J. Bennett
Marine Engineer, Naval Architect
Bennett Marine Enterprises