Cracks in aluminum hull repair options

[Shane C]

I apologize if this topic has been beaten to death on this forum but I mainly want some direction due to reading many different approaches/opinions on it. The first image shows where each crack is from the topside, at the end of each rib. I'm in between getting it TIG welded or riveting a patch on sandwiched with 5200, as I'm sure they would recrack in time if they were only welded up with no reinforcement. Any feedback is appreciated.

 

[jbcurt00]

@classiccat did extensive repairs using patch plates on his riveted Starcraft

Plates were factory installed in 18ftrs and above between the rib ends and the hull because of rib end cracking.

What year, length model boat? Is it a Starcraft?

 

[Scott Danforth]

2 methods: tig welding and patch plates.

since the rib and transom lips come together, I would lean toward using a patch plate

 

[Shane C]

@classiccat did extensive repairs using patch plates on his riveted Starcraft

Plates were factory installed in 18ftrs and above between the rib ends and the hull because of rib end cracking.

What year, length model boat? Is it a Starcraft?

Yes, I've read his reply on a similar post and I think the patch is the best option. It's a 14 ft 1984 Lowe Sport V.

 

[Shane C]

2 methods: tig welding and patch plates.

since the rib and transom lips come together, I would lean toward using a patch plate

Roger that I think that's what I'll do. No experience working with rivets but it seems pretty straightforward.

 

[Scott Danforth]

Roger that I think that's what I'll do. No experience working with rivets but it seems pretty straightforward.

hammer, rivet tool, and a helper with a big hammer to back up the head

 

[Shane C]

hammer, rivet tool, and a helper with a big hammer to back up the head

Cool, I do have access to both sides of the cracks, so I've read that solid rivets are the best to use? Can you use a rivet tool on those or do you have to use an air hammer with the rivet attachment like I've seen others use? Thanks a lot

 

[Scott Danforth]

Cool, I do have access to both sides of the cracks, so I've read that solid rivets are the best to use? Can you use a rivet tool on those or do you have to use an air hammer with the rivet attachment like I've seen others use? Thanks a lot

one path is an arm swinging a hammer to hit a tool (converting impact into force). the other is a pneumatic piston and spring to smack a tool (also converting impact to force)

the result is a bucked rivet in both cases

 

[classiccat]

View attachment 360868View attachment 360869View attachment 360870

I apologize if this topic has been beaten to death on this forum but I mainly want some direction due to reading many different approaches/opinions on it. The first image shows where each crack is from the topside, at the end of each rib. I'm in between getting it TIG welded or riveting a patch on sandwiched with 5200, as I'm sure they would recrack in time if they were only welded up with no reinforcement. Any feedback is appreciated.

There are a few reasons to avoid welding...an obvious one would be the proximity to the double-seam which has an adhesive sandwich in there. It melts at a very low temperature. So I strongly recommend that you use an external patch (riveted and buttered with 3M5200). You'll also want to drill small holes at the end of the cracks so they stop progressing/advancing. Lastly, take a good look at the failed area and determine root cause. They occur on old starcrafts when the wood no longer reinforces the outerchine...then are transported on poorly setup trailers, slammed through chop, etc. By chance was the boat secured to the trailer with a winch strap thrown over the gunnels?

 

[Shane C]

There are a few reasons to avoid welding...an obvious one would be the proximity to the double-seam which has an adhesive sandwich in there. It melts at a very low temperature. So I strongly recommend that you use an external patch (riveted and buttered with 3M5200). You'll also want to drill small holes at the end of the cracks so they stop progressing/advancing. Lastly, take a good look at the failed area and determine root cause. They occur on old starcrafts when the wood no longer reinforces the outerchine...then are transported on poorly setup trailers, slammed through chop, etc. By chance was the boat secured to the trailer with a winch strap thrown over the gunnels?

Thanks for the response, I've ordered all the materials to apply some patches. It's only been towed properly strapped down at the transom and winched up at the bow eye. Looking at the cracks, the one sitting on the bunks is old as a previous owner patched it with some kind of epoxy, and the newer one is only a few inches in front of it.

I'd say they're from operating in rough water because it didn't leak for the entirety of last summer with heavy use on mostly calm lakes, this year I've been running it in rougher water. I don't know anything about boat construction but the middle of the hull is pretty thin aluminum with no wood framing or foam, really only reinforced by the ribs and the ridges (strakes?) running down the bottom. I use a carpeted piece of plywood as a floor that just sits in there screwed to some brackets, I'm thinking of adding some framing in there with 2x3s for reinforcement.

 

[Sprig]

Most don’t realize this but cracks in heavy gauge aluminum boats are not that uncommon. I had a leaking 2 inch long crack in the bottom of my 19’ Alumaweld. The hull was guaranteed for life. I talked to the factory engineers and was told they tig weld the cracks and that it’s important to weld both sides of the hull not just one side. Even when they use a plate on the outside they weld the inside also.

 

[classiccat]

Thanks for the response, I've ordered all the materials to apply some patches. It's only been towed properly strapped down at the transom and winched up at the bow eye. Looking at the cracks, the one sitting on the bunks is old as a previous owner patched it with some kind of epoxy, and the newer one is only a few inches in front of it.

I'd say they're from operating in rough water because it didn't leak for the entirety of last summer with heavy use on mostly calm lakes, this year I've been running it in rougher water. I don't know anything about boat construction but the middle of the hull is pretty thin aluminum with no wood framing or foam, really only reinforced by the ribs and the ridges (strakes?) running down the bottom. I use a carpeted piece of plywood as a floor that just sits in there screwed to some brackets, I'm thinking of adding some framing in there with 2x3s for reinforcement.

I wonder if outer chine supports of some form (heavy stock, a bench seat, etc.) were there and removed by a PO. I spy some fresh bucktails:



If it were mine and the interior design allowed, I'd consider boxing-in the entire outer chine. You can even add compartments into the boxed area.

 

[Shane C]

I wonder if outer chine supports of some form (heavy stock, a bench seat, etc.) were there and removed by a PO. I spy some fresh bucktails:

View attachment 361059

If it were mine and the interior design allowed, I'd consider boxing-in the entire outer chine. You can even add compartments into the boxed area.

View attachment 361060

Nice boat! Yeah, I looked it up and there was indeed a middle bench seat taken out. Boxing in that area is a good idea, it definitely needs some support. I'll try to come up with something. Thanks again.

 

[classiccat]

Nice boat! Yeah, I looked it up and there was indeed a middle bench seat taken out. Boxing in that area is a good idea, it definitely needs some support. I'll try to come up with something. Thanks again.

that was a random internet pic of an entry level Lund (still probably more $$ than our last car cost new ).

Here's a vid of my patched-up tinnie:

 

[Shane C]

Just wanna say a huge thanks to @classiccat as I used your method to a T to apply patches to the cracks, not as pretty as yours but they're on. I also sealed entire bottom with Gluv-It and overcoated with some paint for UV protection. Not the best paint job as you can probably tell but at least it's on the bottom.

The boat takes on probably 80% less water than before, so I'd consider it a success. Now, water is slowly seeping in from one or more of the seams of the ribs crossing the hull horizontally. I'm not yanking the boat off the trailer again, so I'm considering sealing the seams from the inside with 3M 5200 or something similar as a final shot to get it bone dry. Regardless, I feel safe to operate it again with a bilge pump onboard if needed.