I had the same probles a few years ago. I went ahead and fixed it myself.... it's an old Bumblee so I figured I couldnt screw it up to bad. I wasnt able to refloor the entire cockpit floor. (that would have reqired lifting the whole top of the boat. I basically stripped the carpet off, set the skillsaw shallow and cut a square out where the soft spot was.
I bought a sheet of marine grade plywoood ($$$) and used about half of it. The stringers were still in good shape so I feft them alone, and replaced the old soft section of floor with the new marine plywood. I sealed it with matting and marine epoxy from Boaters World (Iv'e heard fiberglass resin isn't completey water resisitant)... about 2-3 layers of matting and resin overlapping new and existing wood. I went ahead and installed new (cheap) carpet through the rest of the boat (big pain in the a$$).
It's been over a year now and still solid as a rock... knock on wood. lol. Just to let you know, I'm not much of a mechanic or carpenter, but I'm fairly handy with power tools and folllowing instruction... with that being said it was still a challenging job but worked out in the end. It sure beat the estimates I was getting. Good luck and feel free to ask any more questions.
