The Rot Doctor


Subject: advice (stringer rot)
Date: Sun, 25 May 2003

Do you have any information specific to inboards? I have a 1987 Supra. I think that was a peak year for inboard sales, so there of a lot of that vintage in other brands. I really think my boat was well made; AME resins, thick hand layered glass and kevlar, but they used regular fir for the stringers and plywood for floors.

So far I have reattached the swim platform with steel plates behind the transom, I've rebuilt the captain's chair which basically disintegrated, replaced the small section of floor behind the engine well, and replaced all the loose lag bolts with larger sizes and 3m adhesive where they bolt the steel pylon to the stringers. I think maybe these are all symptoms of an ultimate stringer disaster. In fact I'm reluctant to really torque the engine mount lag bolts. I like the idea of less invasive preventative maintenance. Like injecting something into the stringer and floor. I don't want to pull the engine.
Can you advise?

A lot of guys with your situation will pull the lags from the stringers, hook-out as much of the deteriorated wood as possible, and then treat the wood that remains (if any does in fact remain) with a little of our CPES (Clear Penetrating Epoxy Sealer) to stop the rotting process. A week or so later they come back and pour-fill the holes with a soft mix of our Layup & Laminating Resin and sawdust. They then drill new pilot holes for the lags and reinstall.

It's important in doing this to use our Layup & Laminating Resin. This is a wood-derived resin that is much slower setting than standard epoxy resins, and also is a non-shattering resin, that is, under stress and impact loads it will not crack. Most epoxy resins will. Usually an initial pour is made of sufficient thinness to penetrate through and around any remaining wood, and which will spread laterally. Twenty-four hours later a second pour can be made with a slightly thicker mix that will build on the base layer. Finally, 24 hours after that a thick mix can be pushed into the holes to top the mass and provide the surface for the pilot-hole drill.

This method assumes that the fiberglass that encases the stringers/motor mount areas is around 1/8" or thicker to give the hold-down strength for the poured epoxy mass. Once done, this is a permanent repair, and is VERY strong.

Hope this is some help, and feel free to come back if you have additional questions.