> I have also run across 'aircraft birch' plywood. Does anybody have any
> opinions on its suitability as a marine building material?

Klepper uses Baltic (Finnish) birch plywood as their material of choice for frames and bracing on their ash stringers. They have been making kayaks for about 90 years and seem to have settled on these materials.

On their web page (www.klepper.com) they list the life expectancy of the wood frames (birch and ash, mind you) as about 2 generations, or 50 years.

I'd call that durable.

My friends who have a Klepper (now on the second generation) cracked a brace 4 years ago and simply patched it with a layer of fiberglass cloth and epoxy resin. Certainly easy to fix.

As I understand, aircraft birch is a very high quality product that is certified to meet certain standards set by the FAA, and/or other aviation agencies. A similar, high quality plywood that is not certified might be less expensive, if you can find it. I'm not sure if the plywood makers have their entire output manufactured to meet certification rules, or if they just produce certain batches for certification. Aircraft Spruce (www.aircraft-spruce.com) has this to say about their regular aircraft plywood specs:

>

I seems to me that if the stuff holds together after being boiled for three hours it should hold together for the typical kayak jaunt.

I wonder if you could contact a plywood manufacturing plant and get the unlaminated plys that they cut from the logs. If there is a market for them, I suppose these guys would sell them. After all, they are in business to make money, and if they are already making a salable product, but not marketing it, someone might nudge the marketing department or convince them to fill a special order.

Hope this helps.

Paul G. Jacobson