closed end blind rivets?

[wiesmanr]

which ones should I use on my aluminum boat to patch holes? Aluminum/aluminum mandrel or aluminum/steel mandrel. The aluminum/steel mandrel would be stronger, but my concern is how they can combine the two materials in the rivet and not cause a reaction between the two? any suggestions which I should use?

 

[Bondo]

Re: closed end blind rivets?

Ayuh,.... 99.99% of the steel is what Pops....

I've never had 1 rust,....

 

[jigngrub]

Re: closed end blind rivets?

Another vote for aluminum/steel mandrel here. Very strong rivets, just dab a bit of epoxy or 5200 over the mandrel hole if you're concerned about rust or corrosion.

You may want to eat a can of spinach or some Cheerios if you're going to set 3/16" dia. with the "light duty" (one hand) tool, they show you just how strong they are... but a stronger rivet means a tighter seal.

 

[Grandad]

Re: closed end blind rivets?

I agree with your concern about combining steel with aluminum. And it's not that I'd be worried the steel will rust, though that wouldn't be pleasant. Steel is a more noble metal than aluminum, which means that given the right conditions for electrolysis, aluminum will self sacrifice to the steel. The sacrifice will be made not only by the aluminum rivet, but by the surrounding aluminum hull as well. Is this patch below the waterline? If not, corrosion may not be much of a problem. There's not much salt water in Wisconsin, either. Also, a patch typically doesn't have to be structurally strong, so any concern about a steel mandrel being stronger than an all aluminum rivet are moot. - Grandad

 

[BillP]

Re: closed end blind rivets?

I agree with your concern about combining steel with aluminum. And it's not that I'd be worried the steel will rust, though that wouldn't be pleasant. Steel is a more noble metal than aluminum, which means that given the right conditions for electrolysis, aluminum will self sacrifice to the steel. The sacrifice will be made not only by the aluminum rivet, but by the surrounding aluminum hull as well. Is this patch below the waterline? If not, corrosion may not be much of a problem. There's not much salt water in Wisconsin, either. Also, a patch typically doesn't have to be structurally strong, so any concern about a steel mandrel being stronger than an all aluminum rivet are moot. - Grandad

That's very true and accurate info. The "right conditions" to make electrolysis are disimilar metals and water for the electrical path. However, you can put a sacrificial anode on the boat to eliminate most of the electrolysis. If your electrical system has stray currents it makes the problem worse. After owning several aluminum boats and seeing how easy they are eaten by electrolysis, I'd personally use all aluminum rivets and have an anode attached anyway.
bp

bp

 

[jigngrub]

Re: closed end blind rivets?

I agree with your concern about combining steel with aluminum. And it's not that I'd be worried the steel will rust, though that wouldn't be pleasant. Steel is a more noble metal than aluminum, which means that given the right conditions for electrolysis, aluminum will self sacrifice to the steel. The sacrifice will be made not only by the aluminum rivet, but by the surrounding aluminum hull as well. Is this patch below the waterline? If not, corrosion may not be much of a problem. There's not much salt water in Wisconsin, either. Also, a patch typically doesn't have to be structurally strong, so any concern about a steel mandrel being stronger than an all aluminum rivet are moot. - Grandad

That's very true and accurate info. The "right conditions" to make electrolysis are disimilar metals and water for the electrical path. However, you can put a sacrificial anode on the boat to eliminate most of the electrolysis. If your electrical system has stray currents it makes the problem worse. After owning several aluminum boats and seeing how easy they are eaten by electrolysis, I'd personally use all aluminum rivets and have an anode attached anyway.
bp

bp

Did you hear that Bond-o?... our boats are going to self sacrifice themselves!

Well I for one will not tolerate this kind of behavior from my boat, I'll be keeping a close eye on my boat and be ready for a boat self sacrificing intervention at the drop of a hat... better than that, at the slightest twitch of a hat! If I have to sacrifice an anode or two in front of my boat to show it what kind of pain and suffering self sacrificing brings on, the so be it. I'm not a violent or sadistic person by nature... but I can be driven!


btw... y'all forgot to mention how much weaker blind rivets are than solid rivets, and how much more superior solid rivets are than blind rivets.

I'm sure if closed end blind rivets were an inferior product people wouldn't buy them and rivet companies wouldn't make and sell them because no one would buy them... and they sure as heck wouldn't use them in the construction of aircraft!

 

[wiesmanr]

Re: closed end blind rivets?

yes, the rivet would be below the waterline and it would be replacing a couple of original rivets that have failed and are not able to be rebucked. my concern is with the electrolosis of the aluminum, not rusting of the steel in the rivet. would the all aluminum closed end blind rivet be strong enough in this case?

 

[jigngrub]

Re: closed end blind rivets?

would the all aluminum closed end blind rivet be strong enough in this case?

The all aluminum rivet will probably be strong enough, but I'd do an epoxy dip like in this vid for extra insurance.

http://www.youtube.com/watch?v=L0MA1-5NXjs&feature=related

I believe the epoxy dip will insulate/isolate any electrolysis to the rivet itself on the alum./steel rivet... if there was enough electrolysis to worry about, which I believe there isn't.

 

[BillP]

Re: closed end blind rivets?

That's a funny comment but go check the nobility scale for electrolysis. Industry wide, alum aircraft and alum boats use all alum rivets. There are many shapes, sizes and grades. Even homebuilt aircraft use them. Boats use the same type and strength isn't an issue. If you do steel on aluminum it will eventually show deterioration from electrolysis...depending on use. Trailer boats kept indoors and dry will last longer that ones sitting outside. It took 10 yrs for my alum pontoon boat to show major electrolysis where the stainless cleats were installed with ss bolts...they weren't isolated. The boat hung in a boatlift over saltwater. If you want to see what types of alum rivets are available go to aircraft spruce dot com. I bought many lbs of alum rivets from them to build an experimental plane. The ones you buck are the hardest and strongest but the solid shank pop rivets are super strong and way easier to use.
bp

 

[jigngrub]

Re: closed end blind rivets?

That's a funny comment but go check the nobility scale for electrolysis. Industry wide, alum aircraft and alum boats use all alum rivets. There are many shapes, sizes and grades. Even homebuilt aircraft use them. Boats use the same type and strength isn't an issue. If you do steel on aluminum it will eventually show deterioration from electrolysis...depending on use. Trailer boats kept indoors and dry will last longer that ones sitting outside. It took 10 yrs for my alum pontoon boat to show major electrolysis where the stainless cleats were installed with ss bolts...they weren't isolated. The boat hung in a boatlift over saltwater. If you want to see what types of alum rivets are available go to aircraft spruce dot com. I bought many lbs of alum rivets from them to build an experimental plane. The ones you buck are the hardest and strongest but the solid shank pop rivets are super strong and way easier to use.
bp

Yeah, I'd never use a stainless steel bodied rivet on an aluminum boat... but an aluminum bodied rivet with a tiny piece of steel mandrel in it... yeah, I'm using that.

After being dipped in the epoxy and installed, the electrolysis might show up on the rivet in 30 or 40 years eh?!... then I'll just drill 'er out and put a new rivet dipped in epoxy in, if I'm still alive and able not to poop on myself when installing the rivet with the setting tool.

 

[wiesmanr]

Re: closed end blind rivets?



Here are some pics of what I am trying to fix. The first pic is from inside the boat and the second pic is under the boat. This is where the supports go across for the front seats and are riveted through the hull. You can see that the support is cracked. There is a angle that is riveted on the back side if the seat supports. The rivets on the right side of the crack that attach the angle to the seat support have failed, causing the flex to crack the seat support. On the underside, you can see where to PO tried to seal it with some sort of epoxy. I am thinking of replacing the failed rivets with the aluminum closed end blind rivets with the steel mandrels coated with 5200. Then epoxy the inside around the rivets with MarineTex. Finally I would coat all the seams on the inside with Gluvit. Anyone have some good ideas of how I should go about fixing this up? Thanks

 

[wiesmanr]

Re: closed end blind rivets?

anybody have any comments or suggestions?

 

[Grandad]

Re: closed end blind rivets?

anybody have any comments or suggestions?

I'm struggling with the inside picture a little bit. Perhaps others are too. I don't know your boat model well enough to understand what I'm looking at. At first blush, I'd say that the square cross-section member must either be replaced or substantially stiffened with perhaps an aluminum angle. I'd need a wider view before commenting further. - Grandad

 

[wiesmanr]

Re: closed end blind rivets?

Here are some more pics from farther back. In the first two pics, you can see that there actually is a factory piece of angle that runs across for stiffening and support of the floorboards. The rivets on the passenger side to the angle gave way, thus the flex and crack. The cross pieces are for the box wells for the back to back seating. This is on a 1965 Alumacraft Bel Mara.

 

[Grandad]

Re: closed end blind rivets?

I think that I would install a stiffener of aluminum flat stock sandwiched between the cracked cross-member and the existing aluminum angle. I'd make the stiffener at least 1/8" thick about 30" long and as wide as the maximum depth at the centerline. I'd curve cut the lower edge to just clear the curvature of the hull skin to keep a maximum width for strength. I'd "glue" the stiffener to the existing structure with 3M 5200 and then install lots of rivets to ensure the stiffener is solidly laminated to the structure.

I'd investigate the epoxy patch on the bottom by removing as much of the material as possible. Perhaps this was an attempt to cure leaking rivets in the local area. Unless the hull itself has fatigue cracks, I'd rebuck the existing rivets or replace them with your choice as per earlier discussions above. If the hull is cracked, you may need to remove some rivets between the cross-member and the skin and apply a sheet aluminum patch over the crack using 5200 and more rivets. - Grandad

 

[wiesmanr]

Re: closed end blind rivets?

sounds good. thanks