epoxy on aluminum hull

[andy2774]

I have two 24' aluminum pontoons that are real solid except that they have some small holes from corrosion along the waterline. I would like to repair them to build my own pontoon boat and would like to use epoxy and epoxy matting, covering the entire hulls. I have been told it can be hard to do right and that aluminum doesn't take to epoxy or fiberglass well. I assume I will have to take them down to bare clean metal and then etch the aluminum but that is about all I have gathered so far. I'm wondering what type etching? What type resin, hardener and cloth? And, is there an easier way?
Andy

[skipperG]

hey, saw a pontoon painted with pickup bed linner material, looked good, they have different colors, seals pin holes

[alan white]

Good idea. At least do a six inch stripe. Far cheaper.

A.

[stonebreaker]

Depends on what epoxy you use, I guess. I coated my aluminum intake manifold on my impala with industrial epoxy, and it's been in there for 5 years and is doing fine, despite the gasoline vapors from the fuel injectors and the oil vapors from the PCV valve. This particular formula is designed as a potting compound, and has thermal expansion properties similar to aluminum and a bond strength of about 7000 psi. The ceramic coatings they put on exhaust systems only have a bond strength of 1000 psi or so, and they last for years.

After I coated my intake, I noticed I had gotten some epoxy on one of the mating surfaces. Unfortunately the epoxy had already cured. I tried a brass wire brush in a power drill and couldn't get it off. I had to switch to a steel brush before the epoxy would come off, and I had to be real careful not to erode the aluminum.

Here's where I got the epoxy I used.

http://www.epoxies.com/

[alan white]

Another twist: Cut around at the waterline, seperating the top from the bottom half, and stretch the metal enough to create a lap of maybe an inch and a half. Seal with suggested epoxy and rivet with aluminum.
Similar to a Grumman canoe. The result will be cheap and look like it was born that way. You're out one sawzall blade, a few hundred rivets, and a quart of glop. The result makes a double thickness joint just where you'd like it to be.
If the hulls look good elsewhere, they will probably be as good as new, so why cover them with anything so long as they continue to stand inspection? And at the first sign of deterioration, if ever experienced, paint something on. All large aluminum hulls, at least those I've seen, are faired with epoxy/filler. It's standard practice, I'm pretty sure.

A.