How much is enough? In rebuilding my 15' tri-hull w/ 85hp V4, I have come upon an interesting question. How thich shoiuld I make the glass on teh stringers? I currently have 2 layers of heavily resined 1.5oz mat. Is this sufficient? It seems very solid, but I don't want to ever do this job again. I thought ablout a layer of 18oz woven roving. I know that is probably overkill. Is what I have enough or would you add more?