Which epoxy for attaching sheet aluminum

[cwinfrey]

Hey ya'll,

I have a 1442 alumacraft with corroded rivets and I was able to alumalloy some of the ones that werent eaten all the way through, just to give it a little more strength and smooth it out...it worked great by the way! I beat on it with a screwdriver and hammer and couldnt get it to come off. But I have a few that corroded all the way through and I have a hole in the hull where the rivet is supposed to be that is about the size of a dime, maybe a little larger in some spots. I dont want to use the alumalloy on those spots, so I was thinking I wanted to keep it easy and just cut some 5052 .063" aluminum "patches" and patch over these larger holes. I have read up on epoxies and resins, but it was all geared towards patching and filling holes, not adhearing a patch of aluminum. I want to patch with aluminum so I can come back in and put another rivet in the rib to mainain the structural integrity. I believe if I used a resin patch kit, I wouldn't be able to replace the rivet.
I think some type of adhesive epoxy that also cures slightly flexible, that way it wont crack and start to leak again. I waterfowl hunt so I will be in cold water, possibly ice, and I think the chance of a crack may go up in cold water if I use a rigid epoxy, so something slightly flexible but strong would be nice.

Thanks!

 

[Woodonglass]

Re: Which epoxy for attaching sheet aluminum

Welcome to iBoats!

Gluvit is the product you are looking for.
Gluvit Epoxy Water Sealer brushes away leaks, seeks out and fills and seals leaks throughout boats and homes. Gluvit is a paintable waterproof epoxy sealer that seeks, fills, and seals cracks in wood, fiberglass, and metal.
Application results in a hard, impact and abrasion resistant protective barrier coat that minimizes fiberglass blistering and corrosion. In addition, the hard protective coating flexes with hull movements to bridge and seal hairline cracks. Application to aluminum fishing boats seals leaky aluminum seams and rivets. The cure rate gives a long working time that allows penetration into cracks to seal and strengthen. Gluvit fills minor chips and pinholes and is easily painted with most bottom or topside coatings and paints. Can be pigmented with Fiberglass Evercoat coloring agents for color matching. One coat 10 mils thick withstands 4000 Lbs. per square foot of water pressure. Neutral color can be pigmented or painted. Pot life is 1 to 2 hours. Qt.= 2 Lb. unit Gal. = 8 Lb. unit.

Can be used on boats, surfboards, snow boards, etc.

I'm just sayin...

 

[erikgreen]

Re: Which epoxy for attaching sheet aluminum

The problem with aluminum of any kind is that the same oxide coating that protects against corrosion also keeps glues, including epoxies, from adhering well.

The right way to fix those holes is to rivet on patches that are sealed with Gluvit. For a neater look, work from the inside.

If you want a temporary fix you could glue the patches from the inside with 3m 5200 or gluvit, but I personally would want something more durable than glue to fasten aluminum with.

There are some low temperature (like blowtorch temp) "aluminum repair" rods you can get here and there.. they work ok with practice on smaller projects, and are much stronger than glue.

Whatever you do, make sure the aluminum is clean, then brush it with a stainless steel brush just before you glue/fasten it to remove as much of the coating as you can. Don't use a steel brush, it can leave little bits of steel in the surface to rust.

Erik

 

[sschefer]

Re: Which epoxy for attaching sheet aluminum

Erik's got the right idea except the patch needs to be on the outside so the pressure holds it tight against the hull and is not pushing it away as would be the case of a patch from the inside.

Ideally if you patch it, the patch will be on both the inside and the outside with a rubber membrane between the patch and the hull on both sides and then riveted on.

I think the best solution and probably the most cost effective will be to have a small external patch TIG welded into place. Take the boat to the welder upside down so he doesn't have to weld out of position and you'll get a better job.

Most importantly, let them know that it's likely 6000 series tempered aluminim. Probably 6063 or 6061 and usually T6 temper.

If you're ever near the San Francisco Bay Area, bring it on by and I'll TIG it up for you. Better hurry though, the weather is turning and that stuff doesn't like being welded when it gets below 50 degrees.

 

[erikgreen]

Re: Which epoxy for attaching sheet aluminum

Don't you preheat when TIG welding aluminum? Makes things work better.

Inside or outside doesn't matter as much as the toughness of the bond... if it's weak enough that water pressure on the outside holds it in place, then a solid kick from the inside will make it leak.

I'd guess it's probably one of the marine grade aluminums like 5xxx series alloys, FYI.

 

[Faztbullet]

Re: Which epoxy for attaching sheet aluminum

I waterfowl hunt so I will be in cold water, possibly ice, and I think the chance of a crack may go up in cold water if I use a rigid epoxy, so something slightly flexible but strong would be nice.

The duckhunters in my area are having the insides of their boats sprayed with Rhino lining as it can be any color you want and it will not leak,flexible and gives a non skid floor!!! It works great on the old rivet hulls of the 50-70's, scroll thru the pictures at below link.

http://www.rhinolinings.com/applications/marine/boat

 

[cwinfrey]

Re: Which epoxy for attaching sheet aluminum

Thanks for all the info guys! The holes I am talkin about are on the rivets of the ribs, so a patch on the inside may not be the easiest, unless I slide a patch under the ribs.
I was going to clean up the underside of the hull where I was going to put the patches, paste it with a good bit of Gluvit, and put on a patch. The boat is apparently made of 5052 aluminum .063" thick....thats what it says on the alumacraft website. When the gluvit is dry, I was going to re-drill the holes for the rivets and re-revit.
I do feel that TIG welding the patches on would be the best idea, but the way Gluvit is praised so much on here, I think it should work just as well, right?
The rhino lining of the inside is a good idea too. I may get the DIY Herculiner kit and use my compressor and spray gun and spray it in rather than roll it on. But I'm not sure if I want the inside of myu boat to be black. That will get super hot in the summer when I'm fishing... so I may pass on that and just do a good job with my patches.
I really wish the alumalloy was easier to use. It tends to gather up at the low end of the angle my boat is sitting at and looks like crap. And its pretty sturdy stuff, so grinding it isnt the easiest unless I go buy a grinding wheel for my angle grinder. My pneumatic air tool and grinding stones aren't course enough to get the job done in a timely manner. And its hard to get the boat to sit at the right angle to use the alumalloy and keep it from puddling up.....Anyway.
I believe a friend of mine has a TIG welder, I'll ask him today. Not sure if he has aluminum wire... I may go that route if its faster than going to get the Gluvit and all that.

ACTUALLY, I was just thinking about this just now....as I have mentioned, the alumalloy is pretty sturdy stuf if you do it right, so I was thinking about using that to attach my patches, then cover the patch with gluvit, and putting more gluvit on the inside of the boat as well....what do ya'll think of that?

 

[sschefer]

Re: Which epoxy for attaching sheet aluminum

Don't you preheat when TIG welding aluminum? Makes things work better.

Inside or outside doesn't matter as much as the toughness of the bond... if it's weak enough that water pressure on the outside holds it in place, then a solid kick from the inside will make it leak.

I'd guess it's probably one of the marine grade aluminums like 5xxx series alloys, FYI.

You do have to pre-heat on the 6000 series. It's really hard to guess what they used it could be 6061 T6 or whatever else they got at a good price. 5056 is the bomb for boats but 5052 is more common because of the price. You won't find either of those on a production boat.

Pre heating, using a pulser, lots of pedal work, short welds, working from side to side, pre welding at the edges to prevent cracks, etc. You pretty much have to pull all the tricks out of the bag when you work with some of this stuff. 4043 rod also flows better rather than 5056 rod. I also use a 1/16th 2% lanthanated tungsten cut at 30 degrees with a flat end.

 

[erikgreen]

Re: Which epoxy for attaching sheet aluminum

I have an inverter machine so I use a 1/8 lanthanated with a pointed end, but ditto on the preheat and 4043 filler. I use a 1/16 filler rod. I clean first with zircon paper and then acid etch, and of course the tungsten, cup, collet etc I use on aluminum only.

For thinner aluminum (boat hull work), if I had samples to adjust and practice on I'd go to a thinner tungsten. Given the heat control issues with aluminum I might actually just braze the patch on to avoid accidental melting of a significant part of the boat

Erik

 

[sschefer]

Re: Which epoxy for attaching sheet aluminum

I have an inverter machine so I use a 1/8 lanthanated with a pointed end, but ditto on the preheat and 4043 filler. I use a 1/16 filler rod. I clean first with zircon paper and then acid etch, and of course the tungsten, cup, collet etc I use on aluminum only.

For thinner aluminum (boat hull work), if I had samples to adjust and practice on I'd go to a thinner tungsten. Given the heat control issues with aluminum I might actually just braze the patch on to avoid accidental melting of a significant part of the boat

Erik

For those of you who are following this thread and the OP of the thread, you may think we've gone astray but the reality is that we are making some good points about the difficulties in repairing production aluminum boats correctly.

As I think you can see, it's not at all easy to do it correctly and often the best decision is to have a qualified shop do it for you.

If that's what you decide to do be careful. Go in armed with the info you're reading here and beware of the shops that just say "No Problem, we can fix it". A good shop will not tell you they can weld without doing some basic tests.

On the other hand if you just want to epoxy it up and be done with it. Why not give it a try and see what happens. Just make sure your bilge pump is in good working order in case it fails and stay out of deep water until you're sure it's going to hold.