what size of mat to use

[fishweed]

I have cut out the widows on a Roughwater 36 Pilot house and replace the plywood with 3/4 douglas fir, I want to glass over and fair I was wondering what weight of mat to use, I will be using epoxy , as I have already repaired the deck,the old windows were the cause of the rot.

[KnottyBuoyz]

Hard to say. Can you post a pic? Are they large holes? Do you have to replace some structural integrity where the repairs are made? CSM probably won't cut it. Biaxial fabrics might be a better choice.