Wet but solid stringers.

Hello from Chicago. My newest project is a 1967 24' Piranha deep vee (I have never seen another Piranha). I started out to replace the transom, which was delaminating; and am, as it turns out, replacing all the flooring and foam as well. The floor was replaced around 10 years ago with treated 3/4" plywood and coated with polyester resin on both sides and cloth at the seams. It seems to have soaked up water; but can't dry out. It is still solid; but HEAVY! The foam too- it may have been closed cell in 1967; but it is more like a sponge now and was saturated- and HEAVY.
Now, This gets me curious about the condition of the stringers. I drilled a 1" hole through the fiberglass encasement in several places after the foam was removed. The 2x material (8" in the back- around 14" in front) under the fiberglass is very wet; but also extremely solid in the several test locations. I couldn't identify the species of wood used - though from the little bit I saw, it seems to resemble pine. The fiberglass encasement is approximately 1/8" heavy weave cloth - and it doesn't seem to be bound to the wood stringer anymore, for I can press it in a little.
Do I just leave good enough alone? Or could I beef up the fiberglass encasement for added insurance? I don't want to get into stringer replacement if not necessary. After all, it could have been this wet for 30+ years now. Any advice would be appreciated.
Thanks,
Tom

 

I've built boats with fiberglass stringers filled with foam with good results. 5 mats and 2 rovings (more for larger boat) of an appropriate weight for the size of vessel. You could cut the glass at the base of the stringer and pop it off the wood, remove the wood, glass the shell back down, and tie it in with a few more mat/rovings (or stitchback), then fill it in with foam. I've repaired a few bay skiffs this way with great results.