Anyone ever stick welded aluminum? (Boat repair/patchwork)

I’m not a welder but you’ve just gotten to the point that everyone fooling with an old aluminum boat gets to eventually. The short answer is yes, you can stick weld aluminum, but it’s probably not going to work out like you’re envisioning it. The correct way to weld aluminum is to TIG weld it. YouTube will point you towards some ways it can potentially be done, but all will start with a disclaimer that it isn’t supposed to be done this way.

Brazing and rivets will work out much better in the long run. There’s plenty on YouTube about that too. I’ve brazed several things on my boat and have been very impressed with the results.

How strong is brazing? Will it hold up against vibrations from a trailer? Or choppy waters?

Dont do it. I run a machine shop. We use a portable mig gun or tig weld on site. If you want to get it done, go with the SS rivets and permatex

Couple things:

For that kind of patch you're gonna want to use marine 5200 as a sealant.

Two, I wouldn't feel comfortable with screws there that could vibrate loose. Use stainless nuts, bolts, and lock washers just long enough to get a good grip. With regular steel hardware you are gonna have corrosion issues in aluminum.

eta: it's probably a good thing you didn't try to weld that. You would have either burned through and been really pissed or it wouldn't have made a good bond and popped right off first time out. I wouldn't braze it either with an area that will flex, that's the one downfall of brazing is it can be brittle if not done just right. Sealant and fasteners are gonna be the best bet there.

I would use aluminum rivets because stainless steel ones will corrode the aluminum over time.
The other option is to use stainless through bolts and use tef gel & plastic washers to prevent the corrosion.

Kinda damned if you do, damned if you don't.

Aluminum rivets are soft and may give out pretty quickly depending on stress.

Stainless won't corrode aluminum as bad as other materials, in general it's ok to use stainless fasteners as long as they're going into a plate or other large area. Even if the aluminum around the fastener corrodes a bit the fastener will still hold because it's compressing against itself and a sealant. The bigger risk would be using an aluminum fastener in stainless, where the fastener could corrode and lose grip.

Yes, and on that thickness I wouldn't even bother trying. Those rods are smoky as hell and you damn near can not see the puddle because of that. On top of all that the rods melt down with a quickickness.

Without access to a spool gun or tig, the patch job is what I would go for with 5200 and large head aluminum pop rivets.

Brazing is going to require the areas to be really clean and fluxed to last. Also Aluminum has that funny way of not telling you how hot it is until it just melts at about 1221 F.

I've never heard of good experiences using those rods, especially not on thin aluminum. I'd use Alumiweld brand rods before I used those. The alumiweld rods are actually very effective if used exactly to spec.

No way I'd trust that setup as it is right now with those screws, but with 3 items you can make it good enough for gov'ment work: 1) Marine 5200 2) Marine silicone 3) Rivnuts from harbor freight (item # 1210) and maybe some rubber washers with stainless hardware to be safe.

I'd clean that aluminum up again, match your drill bit size to the EXACT spec of the rivnut hole diameter, drill em out, and then apply the marine 5200 and tighten everything down with the rivnuts while caulking the bolts and rivnuts to be thorough. Caulking with silicone would give you the option to remove them later- unlike if you used marine 5200 to caulk with.

Those rivnuts are legit. I've used hundreds of them and in many applications the rivet has a bolt screwed in and out of it daily. The rivnut tool kinda sucks regarding longevity, but it's harbor freight. The rivets themselves are much more secure than those screws, as well as using standard aluminum pop rivets.

If not tig welded, that's what I'd do; that, or use Alumiweld rods and even then I'd still back the weld up with rivnuts or some type of fastener. (The Alumiweld BRAND rods can also be bought at harbor freight, although they are not a HF product. Per usual with welding aluminum, you have to use a clean, STAINLESS steel brush and acetone and clean your joints up really well and, at a minimum, use a MAP gas torch to heat the joints.)

I just think of yall got out in some tooth rattling chop that those screws are gonna shear. That's my .02 cents on it anyway.