The Rot Doctor


Subject: (Transom Wetness)
Date: Tue, 17 Apr 2001

I was installing trim tabs and when I drilled into the bottom of the transom to install the actual tabs a few drops of water came out of the drill holes, and the material on the drill bit was wet (the wood/foam behind the gelcoat). It was a milky color. I bought the boat last year and the hull was in perfect condition and was never bottom painted. There is no sign of blistering on the entire transom and I believe I may have found a problem before it got out of hand.

I've done a bit of research and found your website. The boat has been pretty much been a trailer boat for the last 3 years and/or for most of its life, I went to high school with the guy who I bought it from, and he bought it new in 1986 and the hull was in perfect condition when I bought it last year. After I bought it, I bottom painted it and left it in the water for 1 season (6 months).

This leads me to believe that the leak occurred last season. I think it came from the drain plug or the speedometer mount at the base of the transom. Pardon my optimism but I think I may have found the problem before it became one.

I think that because when I drilled the holes for the top of the pistons used for the trim tabs, the wood was slightly damp Not "wet". I think the majority of the water is at the base of the transom. I think the leak has been coming from the plug or the speedometer mount. It was never an issue because the boat was not left in the water for a full season until I owned it.

In a nut shell, my idea is this:

1. Drill out the Transom Plug and let the lower transom area drain and dry 2. Fill the semi dried area with your epoxy
3. Replace transom plug with a larger plug

Is this a pipe dream or a possibility,

Please respond


Jay R.


I think your analysis of the situation is a correct one. Wood can be wet without rotting, as all us old wood boat owners know. Generally speaking, if you notice no particular flex in the transom exterior, and if you tap on it and notice no definitely hollow sounds, the wood is okay.

I think your solution is also a good one. Get the transom plug out...however... and allow the transom to drain, and then take a hair dryer set on low heat/high fan and blow dry it for several hours. Just prop the dryer in place and leave it. I would also pull the fastenings on all other underwater fittings, such as the speedo mount and even the trim tabs, give as much dry time as possible, and then inject CPES (Clear Penetrating Epoxy Sealer) into all the holes. For the drain plug area I would slosh that with as much CPES as you can get the wood to absorb. Based on what you describe, I would guess than a 2-pint kit of the CPES would be sufficient. A 2-quart unit is a better buy, but I think will be more than you will need.

I would bed all the underwater equipment in a polyurethane sealant. Put down the sealant, screw the base down to about 80%, wait for a couple of days (or longer), and then go back and screw down to reasonably tight. This will give you a watertight seal, and the CPES in the wood should give you good protection against that wood rotting in the future, at least on the areas to which it was applied.

For the sealant use the 3M™ 4200 (not the 5200), or an identical product we sell them both (you can get info on these products at the Products section of our website). Either product will work just fine.
The Rot Doctor