It looks like my stringers were made by having plywood style walls, then filled with foam, and then topped with plywood. As I poked a hole in one of the stringers to see if they were solid wood, come to find out that they are filled with foam. Now since theres three of them, I need to figure out how am I going to replace the rotted sections, and what kind of foam do I need. Going to start ripping the floor apart Monday.

Initially, the wood provided the stiffness. The glass was just to keep them in place. Eventually it became evident that wood was not the way to go, and they started using foam, which was only used to give the fiberglass beam its shape. The glass was then made thick enough to provide the stiffness and strength of the former wood components. That eliminated the rot and degradation of structural wood parts.

There really isnt that much glass holding the wood in, in fact, the only glass I noticed was the layer they put over the flooring. Im gonna cut into it more and see how they secured the wood to the hull.