Need help, strange holes in transom

I did a water test on my boat today and I was pleased. Only a few leaks that can be fixed easily with some tig welding. But I discovered some issues with the transom that has me concerned. There are places where the aluminum seems to be thin and dissolving. Almost seems like its from the inside out. I can see a 1/8 inch hole and stick a 1/4 inch wide flat head screw driver in it and then rotate it to ream it out and what appears to be white powdered falls out. The wood behind it is solid. Hoping the chemically treated transom wood is not eating it away. Has anyone seen this?

Looks like salt water corrosion. At least it is corrosion of some sort.

Definitely corrosion. How extensive is it?

Littlejohn, BTW I am not far from you. As you can see I have removed the paint (airplane stripper) The obvious solution is to cut a piece of aluminum and weld over the entire transom, piggy back if you would. I am concerned that the metal is to fatigue to try and weld. So, I am thinking of filling holes ( JB Weld, 5200 or something) and going over with steelflex or Rino liner-- what you think? This is the only place I find the corrosion so it must be from the plywood.

If your transom is just a flat sheet of aluminum and nothing special like mine, and if you're going to go through the trouble to piggyback a new piece in there, I'd just have a shop cut the whole thing out and replace it with a new piece.

Whereabouts are you located?

littlejohn said:

If your transom is just a flat sheet of aluminum and nothing special like mine, and if you're going to go through the trouble to piggyback a new piece in there, I'd just have a shop cut the whole thing out and replace it with a new piece.

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I concur.

Looks to me like the wood on the inside has done a number on the transom. I don't know if it was pressure treated wood or not, but even if it is not, salt water easily could have gotten trapped between the aluminum and the wood, the water evaporated, and the salt left eating your transom away. The outside is bad enough, but I would be willing to bet that on the inside, you'll find the corrosion to be much worse, with more pinholes that haven't quite made it all the way through yet.

littlejohn- I am in Dacula and Bassboy I am sure it is worse on the inside. I just tried some JB Water Weld and it went on and sanded down really good. Not sure I want to go through the expensive of replacing it, I do know that is the best fix. Might be worth looking into, could not hurt I guess.

I did as best of a inspection as I could to the transom. I wanted to see how much damage is surface damage and see how many weak spots I had. Best I can tell its less then 10% of the transom and probably less then that below the water line. I decided to spend $15 on JB Water Weld and give it a shot. Pics show much excess because I worked it out and away from any of the damaged areas. I will feather it back with a sander. If it feels like it holds then I will etch prime and then apply a coat of regular primer. Worst scenario I will need to come back and revisit, replace transom or piggy back over.

My transom looked just like that when I got my boat...but much worse. I took my transom wood out and sanded the entire inside. I layed several layers of fiberglass down and covered all of the holes. I then drilled a few holes and pop riveted the glass to the hull so that it would not pop off. Then I sanded the outside and used a 2 part epoxy stick and mashed the epoxy into the holes and against the fiberglass. Mine has lasted several years. I have a 40hp Yamaha on it and I still do not have any issues.

I am using a 2 part epoxy stick and my wood transon is solid. I seem to be doing the same without pulling the wood out. If it holds I will cover with steelflex. Thanks for the info and thought your repairs was really smart.

They are right about never, never use treated wood against aluminum, bad from the get go.

Most people don6t know that pressure treated wood is corosive to alu, they probably fixed the transom a few Years back ( like 10).

There are no signs that this transom was taken out. Still has factory rivets through the outside back into angle supports on inside. The boat originally came from a town about 30 miles off the coast of SC so it probably seen some saltwater action at some point. Rest of boat if fine. Just got done sanding all areas, now if I can only find some spray etching primer. HD and Wally world did not have it.

Did you check the automotive section at Walmart?

I did but to be honest not well enough because I did not find the body repair section. Is this where it can be found?

The self etching primer is in the automotive section.

Some Wal-marts don't have it. If not try the auto parts store.

Thanks gents, will try both..........

Howard, Do you think there might still be salt between the transom wood and the transom aluminum doing damage while you sleep? Is there any way to rinse between the two? I got to mulling it over last night and had to post today so I could get some sleep tonight.

tccanoe- I don't because I know this boat came out of Walterboro SC near the coast 20 years ago. I bought it inland near Atlanta where it was used locally- how long I don't know. I am stripping the paint know and see zero signs of corrosion anywhere but the transom so I think it was used little in saltwater but that is a place it could of been trapped at one time. HOWEVER- I also am very concerned of this and was thinking of a way to flush it out with fresh water. I would need to create some ports at the top and then cover them. I can post a pic if you have any ideas.Thank you so much for the question!!