transom help

[bradleymc]

I just purchased a 1976 Starcraft and the transom is a little warped. It appears to be a combination of the motor being too heavy and most likely getting rained on. The guy I bought it from just had caulk everywhere but I removed it all so I can try and reinforce it if possible. In the pictures you can see the transom slightly pulling away from the aluminum. But my question is what would be the best way to reinforce it, or would I just have to rebuild it? I'm attaching pictures, any help is greatly appreciated. FYI the transom is chipping slightly on the outside but there are no long cracks or anything. I'm not the experienced boater so a somewhat elaborate answer would be helpful. Thanks.

[PAR]

That transom is done, spent, kaput, toast . . .

It's a common problem and you need to replace the plywood transom core. Who ever sold you the boat knew the transom was shot, even going as far as to install extra plywood on the outside, to reinforce the rotten core. This doesn't work, at least not for long. I have a boat here in the yard (for transom replacement) where a guy used a piece of 3" angle iron across the bottom bolts, to reinforce the distorted transom.

The problem is the core is shot and no bandaid other then core replacement will truly fix it. It's a nasty job, like most things with 'glass boats, but doable in the driveway at home if you're reasonably handy with tools.

Preform a "transom core" search on this sight and you'll find hundreds of previous threads about the various processes, techniques, etc. It's been covered dozens of times. You'll need to do this "research" first so you can familiarize yourself with what's involved. After which you'll have specific questions about them, which will narrow down your focus.

[bradleymc]

the boat is aluminum

[bradleymc]

shouldn't i just be able to either chisel out the rotten areas of the plywood and use epoxy to repair...or even completely remove the plywood and replace?

[judgegage]

Replace the whole transom. Use marine plywood and seal the wood. It's that hard on an aluminum boat.

One last note, do not use regular silicon/RTV look for a noncorrosive silicon/RTV.

[bradleymc]

so basically since it's an aluminium boat its a simple removal of the plywood and putting a new one in?

[PAR]

Yep, it's that simple, remove the plywood, clean the surface (sand it), then immediately apply unthickened epoxy to the surface to prevent oxidation on the aluminum (two coats). Pre-coat the plywood with 3 coats of unthickened epoxy with special attention to the edges, as this is where the plywood is most vulnerable. When the epoxy is all cured, scuff the side that faces the transom with a 100 grit pad, then apply 3M-101 with a notched trowel as a bedding compound and clamp/wedge/bolt the core into place. Let this sit for several days (ideal) before use, to give the polysulfide a chance to cure up good. The polysulfide is easy to remove if you have to do this again. One last thing, to prevent future issues, "bond" the engine mount (and any other) holes with thickened epoxy. This will prevent moisture from getting into these and rotting out the transom. Don't rely on bedding (goo in a tube) alone, as it just doesn't last very long.