Ms. MAK 20SF

[FishStretcher]

Originally Posted by flyingfrizzle

coosa blue water 26 is a great product for transoms, it has better compressive strength than most other foams but I would go with two 3/4" pieces bonded together or just one 1 1/2 piece. I would think one single 1" piece will be thin unless you built it up real thick on both sides with cloth biax but then to would be way to heavy.

I thought about this a little. I would agree that 1-1/2" foam is better. But the specific gravity of fiberglass in resin at 40% glass content is something like 1.5. And decent plywood about half that. 0.7 If Coosa is 26 lb/cubic foot, that's a specific gravity of ~0.4.

So if the old plywood weighed 50 lb, replacing it with glass would be a bit over 100 lb. But an additional 1/2" of glass would be about 35 lb. Plus the inch of foam another 17ish lb. For about 50 lb again.

So I think the weight would wash out versus *dry* plywood. But you would have another 1/2 of glass in the transom. And a foam core. Not as light as 1-1/2" of foam, but not a terrible tradeoff.

Check my math, though. I am running out the door to work.