Fixing crack in aluminum hull?

[reelfishin]

I have to fix a small crack in a lapstrake aluminum hull, it's a small split about 3/8" long right at the corner or upper end of a rib. There is no deformation of the metal, just a small crack. I am debating on whether to just drill and epoxy this or to weld it. I am concerned that welding on the open sheet metal sides may warp the side panel?
Someone had tried to repair it with some sort of sealer but it looked like body filler or some sort of resin or epoxy. They didn't clean it so it didn't stick, and they made no attempt to access the inside area either.
I'll have the floor completely out and will be either epoxy coating or using Gluvit on the entire inside below the water line.
The dark areas in the pic around the damage is still some of what ever sealer they had on it, the rest of the area is rough from someone either trying to use heat, or from someone hammering the area to close up the crack.
Here's a pic:

 

[tashasdaddy]

Re: Fixing crack in aluminum hull?

i filled this one with marine JB weld.

 

[reelfishin]

Re: Fixing crack in aluminum hull?

I'm sort of leaning towards just using epoxy, aluminum this thin will most likely warp when heated. The boat's sides are straight now, I don't want to ruin that.
I looked for two years to find one that wasn't dented or pitted, I don't want to make anything worse. I welded a section on my jon boat with good results, but that was along an existing weld. This is mid panel.
I do want to make the exterior look untouched though, so I may indent the area slightly and use the epoxy as filler and feather it out? Right now it looks like there's a slight bulge there from what ever the last owner was trying to do. Theres some charred paint around the edge, but I think someone was trying to either solder the crack or maybe dry some sort of sealer?

The rest of this hull is mint, they have a few rivets covered with silicone, but after removing the silicone, I can't make those rivets leak and none are loose. I have an air powered riveter for aluminum, it's made for airframe repair that does a really nice job on tightening loose rivets too.

I am pretty impressed how this is built, you can tell that these were built to last. I especially like how easy the transom is to replace, other than four pop rivets on the top corner caps, the rest is all screws and bolts, the wood slides right out the top. It took longer to go get the wood than it looks like it will take to install it.

The floor looks almost as easy, plus, no pumped in foam, just cut to fit pieces of what looks like the same foam as those float noodles from Walmart.

 

[b.gagnon]

Re: Fixing crack in aluminum hull?

That looks more like rotting do to corrosion and a crack.. Locktite makes an Aluminum repair epoxy that the machine shop where I work uses to fix mistakes(big and small) When hardened it holds up with no problem to machining.

 

[iwombat]

Re: Fixing crack in aluminum hull?

I would see what a weld shop would want to fix that. With proper equipment you can weld pop cans.

 

[Zero Balance]

Re: Fixing crack in aluminum hull?

It can be welded (if done properly) without warping. I would think since both sides are accessable it would only be a minimal charge if welded. Maybe 3 hours tops, sanded and buffed out. Then again if having a two tone repair doesnt bother you then fix it yourself with epoxy or JB weld or something.

 

[reelfishin]

Re: Fixing crack in aluminum hull?

I can weld it myself if I so choose that route, I have a good water cooled tig machine here. the problem is that even the slightest amount of heat may cause it to belly or warp. If it weren't in such a location, if it were up against a rib or close between two rivets welding it would be simple. The area is no corroded, the dark spot are somesort of sealer that someone used. I found a tube of something called Liquid Steel in the boat, so I assume it's that. What ever it is its tough, but it only adhered where the surface was really roughed up.
The area is ruff because it looks like someone hammered it out or tried to stretch the metal to close up the crack. The only breach is that vertical crack, about 3/8" long and it runs against the strakes, not with them. The whole area in the pic covers about 6".

If I use epoxy, or weld, there will be no two tone repair, it's a painted hull and it's white and far below the water line. This crack it about 3 strakes from the keel on the left side about midway back. It looks like a stress crack to me, or else maybe someone hit something, and the crack developed after the area was straightened? There looks to be some sort of solder around that area too, not melted aluminum, but some sort of solder or added silver metal. Solder will not stick to aluminum, so I was wondering if it was either some sort of sealer or maybe Alumaweld or something similar?

I have used that stuff before with good results, but it's near imposible to use upside down without some real practice. That stuff does adhere very well, I used it to repair a tear in a hull a while back but the heat of the propane torch warped the hull a bit. On that boat I didn't care, it didn't have a straight section on it anyhow. This one needs to be perfect.

 

[6228SH]

Re: Fixing crack in aluminum hull?

I'd weld it,but you've already said you'd rather not-so if it were me,the stuff the machinist mentioned sounds like something I'd look into...

 

[Bob_VT]

Re: Fixing crack in aluminum hull?

http://www.alumiweld.com/h2uaw.html which only uses a propane torch which is actually a solder type joint OR get some aluminum epoxy and have at it.

I would find out what caused the crack first. A regular aluminum welder will work and the heat distribution is really not as far or severe as you may think. When you use the gluvit inside you only need to apply it on the rivets and seams..... the entire surface will just waste it.