How do I repair a pitted and corroded transom? Large holes?

[Windman7]

This is what the patch looked like. I'm not loving it, but I guess it's functional. I took the boat outside and discovered several pin holes from corrosion. I will probably epoxy both sides to seal before installing the transom boards. If I can figure out how to braze as mentioned earlier, I would like to tidy up some of the holes.

 

[bigwave]

Hey its not bad, just run some 5200 around all the seams. Your going to cover that patch with the new transom anyways. Out of sight, out of mind....at least it won't leak.

 

[Windman7]

Yeah, I'm beginning to learn that 5200 and Gluvit covers a multitude of sins.....

 

[Windman7]

Question: What is the best way to treat the aluminum? I can only sand to a point, then how do I treat the corrosion? Is there a chemical treatment for it?

 

[JMichael]

If you have a compressor you can rig up a home made sand blaster for small areas. I found this several years ago when refurbishing my antique motorcycle and needed to clean up the aluminum.

P.S. Soda is much finer than sand so it's safer and won't remove too much material too fast.

https://www.aircooledtech.com/tools-on-the-cheap/soda_blaster/

 

[Windman7]

Thanks JMichael. That's a creative way to make a sand blaster. I've actually have a cheepie I bought from Harbor Freight that I've been looking for an excuse to use it on. I like the baking soda idea too.

Researching last night a blog mentioned using a 10% solution of Chromic acid and sulfuric acid to clean and neutralize the aluminum. I'm not sure where one would find Chromic acid. It did mention to coat the aluminum in less than 24hrs before corrosion begins again. I'm thinking epoxy should protect and strengthen the aluminum.

 

[Windman7]

I just got in West System epoxy for the transom. I need to fill some holes and chunks of the face plywood that popped off during cutting and drilling. What amount of filler should I use? Will it run if it is on the edges?