Lawrence James wrote:

I suggest you take a look at some standard floor joist simple span tables
and see just what it takes to span 10 feet. Conventional wood is not very
resistant to flexing. A lot of other things are stronger.

I suggest you educte yourself about wood boat construction.

http://www.westsystem.com/webpages/u.../composite.htm

Floor joists notwithstanding, wood is one of the best boatbuilding materials.
It's only in the past ten years (or a bit less actually) that carbon fiber has
become predominant over cold molded wood.

Boats are not built like houses.

Fresh Breezes- Doug King