[BigMike8o9]

Hey Edloh, Both West and system three are good fugusides. If you have a solid transom with just localized rot, soak the inside of the hole with one of the slow cure mixes. Then drill small holes 1/8 in. and get some seringes from the place you buy your epoxy from.
Radiate outward in circle till you hit fresh wood. The holes only have to be about 1- 1 1/2 in apart.
Soak all the holes out a couple of times with a slow cure mix. Then push some small wooden dowles in the holes. make sure the dowles are shorter then the hole. and don't go through the transom. Also make sure that no air is behind them. Tap in slowly. That will force the epoxy into the surounding wood.
The layers of glue on the ply wood stop the epoxy from getting through, so you have to get the right depth.
Then fill the holes and cover.
I have made about fifty repairs that way that were suposed to be temporary that became permanent.
Even saved a motor mount on a stringer in a big hatteras. just to get through the season, but so far has lasted fifteen years.
I did a demonstration in a wooden boat repaire course one time for a club of restorers. I took a severly rotted board and soaked it with west. I junped on the board (350lbs) and it wouldn't even bend. When the board was hardened after a week, a file could hardly get through the surface.
One thing to remember. Fresh water causes dryrot, saltwater kills it. Rain and washing are the biggest causes. Everybody protects the wood from the water side. Protect from standing water first. Also do not park or moore next to a rotted boat because the fungus spores will travle boat to boat. Ever notice the boat that gets taken out more has less rot problems then a boat that stays parked in a yard for years. Boats stored in doors stay rot free.
BigMike