plywood thickness (daggerboards, etc)

Got around to doing the calculation. Looks like if face ply grain is
perpendicualr to inner plies, then each face ply should be 1/8 of
total thickness (.123 or so, actually) for equal strength in each
direction. For equal stiffness, face plies would have to be thinner.
Any of you other engineering types want to double check me? This
means
that for a 1/4 sheet, the usual luan with the very thin face sheets
is
close to correct, but that if you put two sheets together the face
plies are inadequate.