Fasteners in Aluminum

[GregE]

I plan to use 1/8 gauge (possibly 3/16) inch aluminum angle in my jon boat and in some places would be securing it to existing aluminum structure, most (if not all) of which is .1000 gauge 5052 aluminum. In some places, I will not be able to use a nut/bolt combo as I won't have access to the threads on the other side opposite the bolt head. The angle will be used to create structure on which to build casting decks with storage compartments.

I will be using stainless fasteners and I need to use a self-tapping screw or rivet for this type of fastening. What are some of your experiences with this and will a self-tapping screw be strong? I hate the thought of not being able to use a nut/bolt combo to ensure strength, but I'm not going to have that option in all places.

Thanks!

 

[Bondo]

Re: Fasteners in Aluminum

Pop-Rivets.......

 

[gcboat]

Re: Fasteners in Aluminum

blind pop rivets. ( only needed if going through the hull )

 

[Chris1956]

Re: Fasteners in Aluminum

Greg, I recommend aluminum pop rivets. You can get waterproof pop rivets if needed. Make sure the holes you drill are not oversize, and use backing plates wherever you can.

 

[GregE]

Re: Fasteners in Aluminum

Thanks all. I was hoping rivets weren't the consensus, but it appears to be. Nothing will be going thru the hull. This will all be all internal structure. As for backing plates, I'm not sure I'm following you. If I have access to use a backing plate, then I'll also have access to get a nut on the end of a bolt and will take that route in those situations. At least I think so. This is just all in my head right now, nothing actually happening yet.

 

[tmcalavy]

Re: Fasteners in Aluminum

The problem I had with run-of-the mill stainless screws when installing the floor to the aluminum stringers on my 15-foot aluminum runabout was the screw head twisting off when the screw ran out of threads. Very annoying. So, go slowly and drill pilot holes (this helped greatly) the right size. If you can unit-ize the design, you could fit it in the boat, mark alignments, remove and assemble out of the boat...then install in the boat as units. That would maybe give you room enough to use nuts/bolts or rivets rather than screws.

 

[External Combustion]

Re: Fasteners in Aluminum

Stainless steel screws plus aluminum structure equals galvanic corrosion. It won't bite now, it won't bite in months, but it will bite. The stainless alloy will make a difference, but if you know enough to specify it and get it, then you know enough that aluminum rivets will be as strong and not have the problems.

If and when you choose the aluminum rivets, and I assume they will be pop rivets. Make sure that the stem is also aluminum. Some aluminum rivets use steel stems.

Harbor Freight is but one of the many companies that offer acceptable rivet guns for just a few bucks. I think once you use a pop rivet gun you may wonder why you even asked this question and I am a die hard drill and tap kind of guy!

 

[GregE]

Re: Fasteners in Aluminum

Thanks External_Combustion. I didn't know that, and I know many like to use stainless fasteners since they don't rust, not taking into account what the reaction can be in contact with other metals. I just looked up galvanic corrosion and there's very interesting info of which I had no clue. Thanks for the tips, and I'll be sure to see that my rivets are all aluminum.

 

[GregE]

Re: Fasteners in Aluminum

Just thought about something else that will be important along the lines of fastening. When I build the structure on which to place the deck, I may build the deck higher than the bench seats (the thickness of the wood higher, something like 5/8 inch if I go with that in the wood) so I can fasten plywood flat on the bench seats as well and it be flush against the wood on the deck I'll build.

What would be the best method of that? The bench seats are full of foam so I would not be able to use a bolt/nut combo. Would self-tapping screws be best here or maybe an adhesive and no screws?

 

[Bondo]

Re: Fasteners in Aluminum

Why not just more Rivets,......

They're available in lengths up to over an inch.....
Especially if you go with 3/16", instead of 1/8".......

blind pop rivets. ( only needed if going through the hull )

Actually,..... All Pop Rivets are Blind Rivets,....
I think you're refering to "Closed-end" pop rivets, which are used for Below the waterline app.s......