1989 SEA RAY 210 BOWRUNNER Does it matter when the original wood substrate rots -- originally serving as the form on which the fiberglass hull was overlaid? In my case, this rotten wood that concerns me is in the transom, beginning low at the drainplug fitting. The fiberglass hull shows no signs of cracking or distress and there is no engine mounted on the transom or significant engine load transferred into it -- the inboard block and transmission are all anchored and supported on engine mounts secured to interior structure that appears solid. Do I understand correctly? Sea Ray constructors laid up the original glass and epoxy resin hull over the wood substrate, but after the fiberglass cured it became the structure and developed sufficient strength to serve as a hull without any dependency on the wood formwork temporarily needed to support the fiberglass during construction. Does that wood, an artifact of the construction process, serve any useful -- that is, structural -- purpose? The Details 1989 Sea Ray 210 Bowrunner with GMC 4.3L V-6 Inboard and Mercruiser Alpha 1 -- Mechanically flawless and utterly dependable. First project boat: Great fiberglass hull and great mechanicals -- except, beneath the hood, the interior plywood forms beneath the floor were no longer reliable -- originally installed to retain floatation foam during construction -- and provide mechanical attachment points for floor deck and other items. In mine, the floor deck was spongy and all that under-deck wood was rotten; so I cut it all out and replaced it with treated plywood this time and installed new carpet throughout. Good and solid, if a tad heavier than original. And this spring, completed the interior upholstery job replacing all the seat and vinyl trim pieces. Looking good and fit, we enjoyed the fruit of this labor this summer -- until i discovered that the transom is apparently rotted inside, beneath the fiberglass hull. Localized at the drainplug area, where it apparently leaked around that fitting. Am now faced with major service to the Mercruiser lower end -- pump impeller and lubrication, boots, etc. and contemplating whether the rot issue undermines further investment in this boat? Thanks for your thoughts.