by GreenLake » Wed May 30, 2012 10:01 am
You got the right idea with the sandwich.
In this case the meat, i.e. the wood is rotten, and to get at it, you need to take one of the slices of bread off.
I think, in this case, one usually cuts the fiberglass on the inside, it's a bit harder to get to, but marks from the repair will be less visible.
If you have the wooden floor and shelves, those have to come out, but there's no need in trying to take the deck off.
A Fein Multimaster would seem the ideal tool to neatly slice the fiberglass along the line where it meets the hull at the bottom and sides, and then in a line across at the top - as high as you can reach.
Once youv've made that cut, it should pry off the wood more or less easily. You are then free to dig and chisel out the damaged wood. I haven't done that particular repair myself - so I don't know how easy it is to get at the wood and how much you can expect to be affected.
You could always start by cutting a simple square around the leaking fittings, to check whether the damage is localized, but if things got to the point where these leak, I would expect the whole transom, or at least it's bottom part saturated and rotting.
After digging out all the rotten wood (and then some), I would treat any wet but firm wood with a generous application of borax. A commercial preparation is available from SystemThree as RotFix. Their kit includes instructions and a very thin (like water) epoxy which can be used to seal the wood after it has dried out thoroughly(!).
The same stuff is useful around the house, when you have a localized spot of rot and want to treat and restore the wood rather than tearing things apart to replace it.
Back to the transom. Once you have removed all questionable wood, treated, dried and sealed all salvageable wood, you need to cut and fit a replacement piece - from marine plywood. A gap of up to 1/8" in a few places isn't an issue, because you can fill that with epoxy without loosing too much strength.
Then you seal you new piece and glue it in place. You can use an epoxy formulated as glue, such as SystemThree's GelMagic, or mix your own by following some other vendor's instructions on thickening epoxy. Gelmagic or thickened epoxy would be nice because it doesn't "run", like pure laminating epoxy would.
You're then ready to glass over the wood (no need to wait for the glue to fully cure). Instructions for that can be found online. Finally paint (to protect from UV) and you are done - except for drilling holes for the fittings (and be sure to make sure any holes are properly sealed).
~ green ~ lake ~ ~