Sakari says:

I do have a vague idea of doubling; in other words, using 12mm strips
instead of 6mm plywood, say.

You need to carefully assess how much of the plywood is providing strength in
the 90degree direction, and apply a similarly-strong layer of strips in that
direction, as well as the obvious similarly-thick strips in the zero-degree
direction to replace the outer lamina of the plywood.

Steve
Stephen C. Baker - Yacht Designer
http://members.aol.com/SailDesign/pr...cbweb/home.htm

you should be able to do your own stress testing on sample pieces if you
want. I've read that in one direction plywood is only 60% as strong as
wood (hardwood?, softwood? same wood?, I don't remember), in the other
direction its stronger.

to test place a length of material between two blocks and pile weights
on the middle until it cracks or breaks. do it three times to make sure
its consistent and average the weights. moisture content will have some
effect.

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