I used standard material for isolating the fasade (the cheapest you can get). Should have built adjustible rockertable years ago and the whole thing would be much easyer!
Bottom, top same layer 2*200g glass+1*200g carbon+1*200g glass. completely enaught!
The layers detached from core quite quickly, it was already predicted by more expirienced builders. Balsa wood should be right, and it will defenetly reduce to 3 layers of glass. Put first 2 and check the stiffness.
p.note: Hesitated long time and finaly went for no strap inserts, would be a crime!
I tried one homemade skim with concave (woody), different. afterwords i was sure to bult one strapless board every winter.
Just looking around for hybride boards to copy this year, as the waves don't get big on local spots!
(maybe someone knows rocker on the freestylefish (north))