My deck, cabin side and cabin top are of 2 layers of 1/2" ply and I glassed
mine using a fab-mat that had a chopped strand on the face of the roving.

I would recommend that you lay a layer of CSM at the same time you lay your
18WR as a binder. Much the same as when you doing a glass lay up. The 18WR
being rather course weave.


--
My opinion and experience. FWIW

Steve
s/v Good Intentions (Ingrid 38)