Let me be blunt. Don't put Kevlar on the outside of a core composite. It is likely to fail.

In general, near worst case, for a catamaran the outter layer of a core composite is in compression and the inner layer is in tension. Kevlar is strong in tension and weak in compression. Look at what happened to the Kevlar/foam core Tornados. The Kevlar failed in compression. This also applies to similar materials like Specta/dynema/Vectran/etc

I hate to keep this thread alive BUT I don't want anyone to spend time building something that may fail.