balsa core material

[FishStretcher]

I would expect it would be much better than the fir, pound for pound. The 1/2" end grain balsa in my 25 is still holding up well at 42 years old, except where holes were drilled into it and left open to the elements. Even at that, the grain is vertical, so water doesn't migrate far. I am continually surprised by the relative lack of water damage where holes were drilled. Plywood grain is lateral, so it would let the water travel along the panel quickly- I suspect delaminating and soaking up water more quickly. There is a little bit of genius in using end grain balsa.