Pinholes in my transom

[gsh341]

I bought a 1985 Sea Nymph FM161 Fishing Machine. I have the whole thing disassembled and I'm working on rebuilding the transom.

My problem is the previous owner did a horrible job of taking care of it and the transom wood was completely rotted.

Now that it's disassembled and I've taken a good look at it I've discovered that the aluminum on the outside of the boat where the rotted wood was has corroded and there are pinholes in the metal. Everywhere the metal is shiny is where there is a hole.

Anyone have any ideas on the best way to deal with the problem?

 

[JediFish]

Tbh yours looks better than mine lol I’m dealing with the same issue but I have full on 1-2” holes in my outer skin. I think mine will require a full on new transom welded in but yours looks salvageable. I’ve read everything from alloy brazing rods, jb weld, welding, and other epoxies used for those pinholes and everyone says each works well or won’t work at all so maybe someone with experience in one of those can persuade you one way or another. Good luck getting it up and running! Interested in seeing what others think and how you solve this issue.


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[nccatfisher]

Do yourself a favor, replace that transom. If it was cleaned fully you would find more. That isn't to mention the areas that it has decomposed down to half thickness. I do aluminum repairs and see this pretty often.

 

[gsh341]

Do yourself a favor, replace that transom. If it was cleaned fully you would find more. That isn't to mention the areas that it has decomposed down to half thickness. I do aluminum repairs and see this pretty often.

Replace by removing the 80 or so rivets and having a piece custom made or weld a new piece on to cover all the holes?

This is the inside.

 

[nccatfisher]

If it were me I would just take a plasma cutter and remove it and weld in a new one. But that is what I do. Putting one over it is a PITA and unsightly and you still have the additional weight of the old one there and it really will serve no purpose.

 

[Charlie B]

Hey I know this post is like 7 years old but maybe one of you guys still checks in or obviously anyone else can chime in. I have a similar problem with one single small pin hole just about at the water line. There is a ton of pitting farther up. Im planning on replacing the rotted pressure treated wood with 1.5" Thick HDPE. I've sanded down to shiny aluminum everywhere. Im wondering what anyone recommends to do prior to putting in the HDPE. I was thinking about JB aluminum weld the single pin hole. I was also thinking about a rivet with silicone. Id really like to avoid a transom replacement as advised to gsh341.

This is a 1979 Duranautic 13 in otherwise excellent shape.

 

[The John]

I wouldn't use silicone, I would repair it with Marine 5200.... not sure about JB weld (sounds like a good idea, but thats when you have to be paranoid...) :wink:

 

[Jim]

rivet with silicone will work for sure.

 

[DaleH]

rivet with silicone will work for sure.

... and cause the tin to corrode. Silicone has curing agents that attack tin. Even tin must be primed before using something like 5200 or ANY epoxy or 'goop' product.

For the Duranautic hole ... I'd clean well with vinegar and copper brushes, then rinse well. Prime with zinc chromate, then I'd apply 2-part West System G-Flex flexible epoxy ($21) and once kicked (i.e., tacky) I'd rivet the patch piece in place. Done once ... done right!

For the Duranautic transom ... I would not use HDPE, too heavy and too flexible. See my signature post for the '16 foot V-tin hull refurb' for an easy, last-a-lifetime, transom replacement.

For the other boat ... I'd replace the entire transom skin :shock: , see my posts on how I did it to a Starcraft 16-footer, not that I'd ever want to do it again!

 

[Jim]

I thought I read that certain silicone can cause that but others don't. :-k

 

[Jim]

I thought I read that certain silicone can cause that but others don't. :-k

 

[Charlie B]

Thanks folks. All good info. I appreciate the replies. The internet and forums like this have made home projects way more successful. I ended up sanding down all the old paint using a copper brush then nylon brush then sand paper to clean off all the old paint. I primed with an aluminum primer and finished with the Duranautic spray paint from Marathon Boat. I then did use HDPE because I had already ordered it before you had made the suggestion about not using it. But its really jammed in there and not such a large piece. Its also 1.25" thick so not so flexible. Its also a 9.9 hp motor so not so much power. I haven't actually put the boat in the water but im confident it will be solid. The pin hole I filled with 5200. I did not use a rivet which I hope I won't regret. It is pretty easy to access it I want to do it later. Here is a few photos.
I used 5200 for all the bolt holes, I just left the 5200 white glue that seeped out on the bolts below the water line for additional piece of mind.

 

[TMO8413]

Thanks folks. All good info. I appreciate the replies. The internet and forums like this have made home projects way more successful. I ended up sanding down all the old paint using a copper brush then nylon brush then sand paper to clean off all the old paint. I primed with an aluminum primer and finished with the Duranautic spray paint from Marathon Boat. I then did use HDPE because I had already ordered it before you had made the suggestion about not using it. But its really jammed in there and not such a large piece. Its also 1.25" thick so not so flexible. Its also a 9.9 hp motor so not so much power. I haven't actually put the boat in the water but im confident it will be solid. The pin hole I filled with 5200. I did not use a rivet which I hope I won't regret. It is pretty easy to access it I want to do it later. Here is a few photos.
I used 5200 for all the bolt holes, I just left the 5200 white glue that seeped out on the bolts below the water line for additional piece of mind.

What’s the thickness of this? Also, SS screws no?