Got my first boat! Could use advice on corrosion repairs.

[sunnyg]

Hello Friends,

I just got my first boat and feeling some concearn. After a few days with it I'm finding corrosion. I would love to hear your advice on coming up with a plan for repairs.

The boat is a 2003 Duranautic 16' DN-16SST, 2003 Johnson 25hp, and 2022 trailer. It's a welded hull. I got it for 4000$. I bought it from a local shade tree shop that also sells boats on commission.

Issues I found before buying the boat:

• Wiring was corroded and brittle. Only the motors electric start worked as is.
• Stern wood decking had soft edges.
• Saw a filler patch on the transom, lower starboard side. I was naive and figured it was just an ugly job to fill in unused holes or something.
• Found blisters in the bottom paint, almost all in the rear, but didn't peel anything away
• The transom wood near the live well pump was soft and like dirt. What I can see at the top is still solid.
• The transom had reinforcing plates bolted over. So I suspected plates were added as an easier fix than replacing the wood.

After I got the boat and started digging deeper I found some concerning things.

• Under the blistered bottom paint I found layers of silicone, flakes of jb weld or similar, layers or hard yellow stuff, hard light grey stuff, white salty powder, and finally corroded aluminum. The worst area is under the starboard rear bench. Its corroded the entire way through and I can see flotation foam. The exposed hole is about the size of my fingertip.
• I peeled away silicone around the transom wood and plates and found deep pitting right along the edge of the wood. I can see at least one pin hole through the skin.
  • I recently found forum posts saying Duranautics of this year used treated ply in the transom that corroded the hull
  • the patch on the transom I saw is covering an entire bolt.
  • The transom ply has some old seafoam green paint on it. So I think this still has the original and possibly treated plywood.
• I can see some corrosion in the keel weld seam shown in the pictures.

Some good news:

• Thankfully under the rear deck the hull appears good.
• Transom is still stiff. I can't flex it standing on the outboard.
• I fixed a tiny bit of wiring and have a working auto bilge.
• I took it out on the water for an hour and it stayed dry ( this was before I peeled away the blistered bottom paint ).

So here is where I could use some advice.

My current plan is to do a simple patch over the holes I exposed and enjoy it the remainder of the season. I'll be surprised if I get out 10 more times. I'll be using it in freshwater and parking it under a car port. At the end of the season, I'll take apart the boat and really inspect every inch to evaluate the state of this corrosion. Until then, I want to start doing research and preparing myself for repairs.

For the temporary patches, I've peeled away the loose blisters and junk and cleaned the areas with 50/50 water and cleaning vinegar and brass brush and rinsed well. The pictures I attached are after this cleaning. Next I think I'm going to de-grease the area and apply Flexpaste. I'm considering Flexpaste so I have an slightly easier time removing it to do a better repair later. I have Oshpo, should I use some of that too?

I've been doing as much reading on transom repairs and re-skins as I can. Seems like most people recommend to find a good welder to do the work. Has anyone gone through something similar with a boat repair shop and can share some advice or approximately what this could cost? Any recommendations for a shop near Havre De Grace / Baltimore MD area?

As far as DIY repairs, I'd be willing to try doing what was shown in the video below. He removes all corrosion and sandwiches the skin between two new aluminum sheets with g-flex epoxy and rivets. I'm curious if this would eventually start wicking water between the sheets and start corroding again. Any thoughts?



I'll probably get a quote for welding the hull as well. If I go the DIY route what is considered the best repair apart from welding? I've brazed steel before, but it seems like the general opinion is this isn't a good repair on aluminum boats. Is a sandwich of new aluminum gflex epoxied and riveted a good option?

Or is this all a waste of good money and I should just enjoy it while it lasts and watch classifieds for the next boat lol.

Thank you if you've read all this and have some advice to share. I appreciate your time.

 

[sunnyg]

Some more pictures.

Removed one of the bench covers and lifted the floor as much as I could to get to another hole I found. I'll have to remove benches to get the floor out totally. All the corrosion I am finding is along the edges of the plywood. I put an aluminum patch with flexpaste over that hole.... doesn't feel good...

 

[airshot]

Diesn't appear to have had the best of care. Good luck with all your repairs!

 

[Wayne Roberts]

Scrub er down and remove all the corrosion and then start packing in the epoxy filler like JB Weld or similar then top coat the bare spots with a zinc chromate primer (stops corrosion) and then go catch some fish!

 

[sunnyg]

Zinc chromate. I'm going to add that to my shopping list. Thank you.

 

[Wayne Roberts]

Zinc chromate. I'm going to add that to my shopping list. Thank you.

Yes sir it's perfect corrosion protection for aluminum BUT do heed the warning to wear protective gear especially a quality painters mask...........it is very dangerous to breath the fumes or paint particles. Take that part seriously and you will be fine.

 

[thill]

I've cleaned the pits and used JB weld with great success. Rustoleum makes a zinc rich primer for aluminum that works well, but the straight zinc chromate stuff is hard to beat, if you can easily find it.

Lately, I've been using my MIG welder with 100% argon gas to weld aluminum, and it works well, obviously. Lots of YouTube videos on this. That's how I learned.

But the former method works, just make sure to clean, prime and then paint the areas carefully, so water doesn't continue the corrosion process

 

[sunnyg]

I would love to learn to weld, but I don't think I want to make a huge investment in tools, and I don't know if a thin boat hull is the place I want to start.

Did you get your MIG just to work your boat?

 

[thill]

Pretty much, yes.

I've have stick welders, and use them for fixing trailers and fabricating stuff. We were helping a neighbor move, and I saw his Eastwood MIG and said I wanted one someday. He said I could have it for $100. DEAL!

I'd seen videos of how to set up a MIG to weld aluminum, so I immediately rented an Argon bottle of gas and started testing, and it worked much easier than I had been led to believe. You just have to move FAST to prevent burn-through, or just stop and go a lot.

If you want to try welding, find a MIG on Marketplace for cheap and play around with it. MIG is great especially for lighter gauge steel welding. A nice tool to have in your arsenal.

Once you start welding, it gets kind of addictive. You find yourself fixing and making stuff you never would have before.

 

[michaelaskew]

Lately, I've been using my MIG welder with 100% argon gas to weld aluminum, and it works well, obviously. Lots of YouTube videos on this. That's how I learned. coin flipper