
Originally Posted by
Rojo
Respectfully speaking in a core laminate the integrity of the laminate is directly related to the integrity of it's core material. Divinity Cell is one type of core you see in decks, floors, consoles, cabins, etc where compression is not a big factor. Glass Reinforced Plastic, GRP, or fiberglass is a flexible composite regardless of how it is molded. Add a core between the laminate or a substrate to use a different name, the integrity of that substrate or core directly effects the spine or stiffness of the finished laminate. Coosa Bluewater 20 is a lighter material per cubic foot but also compresses easier, fractures easier, and is used mainly for flooring like Divinity Cell. Coosa Bluewater 26 on the other hand is a much tougher core composite, much harder to crush, crack, compress, etc so when you bed a Coosa 26 core in it is usually in a transom or in a much larger boat 40ft+ you may find it as the core in a Cleat base, davit base, in a deck where the Tuna Tower is intended to be bolted, etc. In my Blazer build, when I'm laminating the new deck to epoxy to the stringers that is a 1/2 Coosa Bluewater 20 core. We are walking on it not bolting a engine to it. The cost difference between Coosa Bluewater 20 & 26 is there for a reason, it is two Different Materials to be used in different applications. I hope this explanation of the differences in application is helpful. You could have left the rotten wood in the stringer (almost) if using Coosa 20. Now that being said 4 layers of 1708 would certainly make up the difference but at a much higher laminating cost.
P.S. be sure you stringer was 1/2 in and not 5/8in. I have never removed 1/2 plywood in a stringer system. Coosa 26 is available in 4x8 sheets 5/8in thick. That was my number one go to on a multilaminate transom. Multilaminate transoms are much stronger, I did those on Offshore Center Consoles.