Checking of plywood, what about birch plywood ?
 

On Wed, 12 Oct 2005 09:09:50 -0400, Jim Conlin wrote:

Alas, birch ply is a poor material for boatbuilding.
Birch is not the least bit decay resistant and i've never seen a birch ply
made with water resistant glue.
Save it for furniture and cabinets.

In 1989 I built cross-beams for my cat
http://hem.bredband.net/b262106/

Carbon was way outside my budget and I didn't have the
equipment or skills needed to create really good glass
laminates. After some research I opted for a combination
of (Scandinavian) Birch plywood and Sitka Spruce. Having
looked up structural data for these I am not surprised
these were many times the materials of choice for aircraft
in the pre-aluminium era. I use epoxy for protection.
I have had no problems with these beams.
http://hem.bredband.net/b262106/Boat/beams.html

/Martin