Stringers,foam,pourable no brains ect...

The problem rotten wood.
The fix - get rid of it -
I'm thinking about a composite stringer that could be fitted in the original fibergla$$ shell that housed the stringer. Like the pourable stuff ,grind off the top,hog out all the wood & now we have a mold.
The pourable stuff is heavy and not as strong as we would like to think.
The foam is light and fairly stiff, but the new boats are a different design so it really doesn't apply.   
Now the club sandwitch -
A composite 2x8(ish)could be layed-up in a mold or in the bottom of the boat .
2 layers of heavy gla$$, 3/4 thick "general plastic's" closed cell foam sheet, 2 layers heavy gla$$, 2 layers of roving in the center, 2 gla$$ ,foam,& 2 gla$$ on the other side.
The foam is tough it stands up to 100 psi & 350* F auto-clave cure cycles on military aircraft parts. The 4x8 sheets can be had in any thickness.       
A molded stringer could be just under size width wise, buttered with adhesive and slipped into the original fibergla$$ form.
In the boat it could be built up in the fibergla$$ shell on each side with pourable foam in the center.

             Anyway it's a start - fire away
                      - waterdog -

Skibum, Use epoxy resin to replace the floor. It doesn't absorb water like polyester resin does. Pete

Consider pool noodles instead of foam. Airflow is better to prevent rot and they are lighter, and it will never soak up again.

Is'nt this fun?
Epoxy it is more expensive than polyester. Additionally, epoxy will stick to poylester but polyester will not adhere to epoxy. To me it is like getting chocolate in my peanut butter.

Hasbeenskier-
     Location is a big plus for leaving the gla$$ stringer shells in place. Building the laminant on the inside will make a clean factory look.It will be much stronger than the wood stringer & won't rot. I'm tempted to build a mold & fab up a couple stringers that could be bedded in place with foaming epoxy adhesive. There seems to be a need to repair our antique-fiberglss boats with modern    technology. I'd like to have a phone con if we could. I slept thuogh my high school typing cla$$ ! Typin - i dont need no stikin typen!!!
               w/d

My thoughts:

The wood stringers are not necessary in the boat for structural reasons. The purpose is to maintain the shape of the hull and prvent oil canning. But, the main purpose of the wood in the main stringer is to provide a firm mounting point for the engine and transmission. With that said, the fibergla$$ shell around the wood stringers should do the job (this is why you never see a broken in half boat that has rotten stringers). But, you need to come up with a suitable mounting system for the drive train. These are just my thoughts, do not bet your life on them.

BJ; Keep on practicing man. I agree with the Lake, our day is coming and I could never tackle this job alone. Maybe we can get you some side work. Of-course the Lake will have to tow his boat here to central Florida to get her done.

john

Having recently removed the floor, foam, and observer side stringer from my 87 SN I now have a much better understanding.

In my case, the majority of rot on the main stringers was forward of the engine cradle. The old stringer was very heavy compared to a new 2"x8"x16' Fir plank cut to size. Even after multiple coats of epoxy resin and gla$$. Replacing the old with wood is very difficult. It it hard to remove them. It is harder to cut them to the approximate right size. Then, it is painful to trim them to just the right fit. Once correctly installed, the boat will be ready to stand up to another 20 years of the course.

It would have been easier to cut and care out the stringers, leaving a form that could be filled with something...Seacast, 16lb foam, a mix of gla$$, foam, and moon dust, or whatever. In the case of Seacast it is tested and proven, just much heavier.

As for the secondary stringers that are made of 1/2" wood and in some cases with foam as a filler, rot is a serious problem almost everywhere. These have to be totally replaced. Hopefully much easier than the main stringers.

Bottom line, may as well stick with the wood. It is by no means easy. But, it is tested and proven, for more than 20 years on my boat.