# Thread: Material Comparisons

1. ## Material Comparisons

Can any one steer me to a page that shows various boat building materials and their weights? I would much prefer to build in plywood or cold molded wood. But I need to get a comparison on weights of building materials. What is a cubic ft. of ply weigh vs. a cubic foot of foam and glass? I don't care about steel or alu. as this is for a multihull.

3. ## Re: Material Comparisons

The WOOD HANDBOOK contains properties of most woods.

Plywood is marginally heavier than the wood it's made from.
The structural core (foam and balsa) manufacturers document the properties of their products.

I work up the weight of a glass or carbon composite layup from the weight of the glass or carbon. It's described in oz./yd^2. Multiply by .007 to get lbs./ft^2. The weight of the epoxy will be about the same as the weight of the glass. So, a composite of 3 layers of 12 oz glass will weigh 3 * 12 * .007 * 2 = 0.5 lbs./ft^2.
The foam manufacturers and Dave Gerr's Boat Strength book can provide guidance on scantlings.

There's some data in the Gougeon book on the amount of epoxy used in laminating, cold molding, coating, etc.
Last edited by JimConlin; 01-03-2010 at 10:22 AM.

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