After discovering that my boat had wet rot in the wood within the hull, a small job, turned into completely ripping the wood from everywhere in the boat (almost.) I took the opportunity to add some hull reinforcements along with all pressure treated marine plywood, which I obtained from Mirage. Pressure treated marine plywood or boat panel is chemically treaded and then dried so that it may be laminated with and bond to fiberglass. The hardest job was ripping everything out. My favorite tool was a skill saw with the blade set very shallow to cut through only the glass. I cut out little square sections and then pried the remainder out with a chisel or flat bar. Removing the foam was a pain as well :o)

I would recommend a full quality respirator and full coveralls with several sets of disposable coveralls, eye protection, hoods to cover your hair and head, if you plan on taking this on. 

I read a lot about boat repair and decided to try and avoid hard spots where plywood cross-members or stringers meet the hull in a small area or point. I prefabricated  the stringer assembly in my garage and made it so that there was a gap in between the hull and the framework. Later I filled the gap with spray expanding foam, then sculpted off the excess. After the system was in place, I glassed everything to the hull.