ALL fiberglass boats with wood sub-structure rot.
ALL fiberglass boats with engineered sub-structure suffer joint failure after about 15-20 years
All fiberglass boats have a 15-20 year design life
yes, the wood covered stringers and the transom in older fiberglass boats is prone to rotting.
post pictures.
also go to the hull restoration forum, 4th sticky down is the DIY restoration links. read links 14, 15, 18, 2, 3, 4a, and 4b in their entirety. look at every video. that will arm you with the knowledge to move forward with your hull restoration.