The Rot Doctor


Subject: How often....(transom problems)
Date: Wed, 10 Mar 1999

Hey There!! The friend that I spoke about has a 1992 Chris Craft Seahawk that sits beside his house (dry) and is probably only used once or twice every couple of months. To make a long story short, his transom has rotted out so bad the last time he went out, he almost lost the outboard. The scuppers are plastic and in two pieces. Obviously it would take quite a few years, sitting beside his house, for the transom to rot out that bad. Have you had any other complaints of this sort? We are thinking that maybe there could be a manufacturers defect in the way the scuppers were installed. Any ideas?? Thanks for all of your help! Larry & Bobbi

A common occurance even among very reputable builders is improper bedding (in our opinion) of fittings. We've seen portholes with less than 20% bedding compound between hull/deck and the fitting. Even if the bedding is fully applied, many workers will immediately fasten the fitting tight, squeezing 95% of the bedding compound out. In our opinion, the proper way to bed a fitting is to first completely bed the fitting, then screw/bolt the fitting to 90% tightness, then allowing the bedding compound to fully cure before tightening completely. This allows the bedding compound to act as an o-ring, providing a compressive seal. If you run the fitting tight with uncured bedding compound, there is no pressure between the fitting/hull and the bedding compound.

If the rot seems worse at or near the scuppers, they are the most likely source of the water. I would think that dye in a water solution, applied to the fittings would be the best way to test the fitting's integrity. You could also check any bracket holes or other through-hull fittings for signs of water intrusion. Of course, finding the source of the problem, and proving culpability in a court of law can be two different things. Corporate lawyers are well paid for a reason. If you've already removed the scuppers, the lawyers could say that you removed some of the bedding compound. If you haven't ever removed them, I'd probably set up a video camera, pour dye water around the scuppers, then remove them, showing the dyed wood inside the transom in one "take". Alternately, and possibly better, you could test the bedding integrity on a random number of new boats from the factory.

If it turns out to be a defect from the factory, good luck! If not, rotting transoms are one of our specialties, we can advise you on the best methods and materials for the repair. Many older boats have the same problem that your friend is experiencing. Time decays bedding compounds, and stress cracks allow water to get into the wood, and then it is only a matter of time before the rot starts.