by Gene Rosson » Wed Jan 04, 2006 7:31 pm
Charlie;
Deck construction is a hot topic about which you can get numerous opinions. I'll describe my position as follows.
The deck <b>is</b> a structural member. The rigidity of the deck is not quite as important on a light boat, say a US one meter. In fact some boats use Monocoat, the stuff model plane wings are covered with. Some marbleheads for example. A heavy boat like a 12 needs more stiffness.
You can add stiffness with deck beams. Several of them, especially where the hatch perimeters are located. The deck beams will not weigh much if you use cedar or spruce or some other light weight wood. I dont think balsa is appropiate here.
Yes, veneer is made in more than one thickness. The thin stuff is going to need some glass on both sides. If I was using thin veneer
I'd probably put sixteenth inch balsa on the bottom and glass both sides. That will make a four ply laminate. The trick in controlling weight is to be sure the glass laminate is not resin rich. Use one and one half ounce glass on the bottom and three quarter ounce glass on the top. Try to persuade yourself not to use teak. Teak is likely to be oily, heavy, and tends to dull cutting tools. Don't give polyester resin a second thought. Use a good epoxy and the whole thing will stay together with more certainty than polyester.
I have seen some very nice decks made from balsa without a top veneer. It still has glass both sides. If you select the balsa carefully you can find some with pleasing grain patterns. It looks good thhrough the top layer of glass. If you intend to paint the deck, then grain pattern does not matter.
The strength of a plate structure such as a deck is determined by two basic things. First by thickness, not necessarily the strength of the core material, and next by the strength of the inner and outer surface. Glass over balsa will do that very nicely. Extra core thickness increases stiffness exponentially. By the third power actually. So three thirty second balsa core is way more than one and one half times stiffer than sixteenth balsa.
Your questions are by no means simpleton.
I expect several others to jump on this , so you'll have plenty of input. I think Jim Linville and perhaps other builders use foam sheet for decks...Light, strong, nice.