Aluminum fasteners

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DMack

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Hey all,
Starting to do some repairs to a 12' Sears Gamefisher. I need to replace or beef up the aluminum L channel where the seats mount to the hull. Is anyone using aluminum bolts, washers and nuts to replace rivets? I want to avoid stainless steel but I need a source for aluminum fasteners if folks are using them.
Thanks, Dan
 
Huh, I was curious so googled Alum Fasteners. Several suppliers are listed. One called Pro Bolt has dome headed aluminum bolts, washers, and nylocs that I would envision for your project. Not done it myself though.
 
Here's some pics:
 

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Those L channel brackets are pretty thin so I'd like to leave them in place and beef them up or replace with something more substantial. If I replace them I'd have to grind off the rivets and re-secure the new ones. Can I use pop rivets or do they have to be the other style (brazier, I think?) It would be easier for me to use bolts, washers and nylock nuts but I think stainless would react with the aluminum. Thanks in advance for any tips, this will definitely be a learning curve for me.
Dan
 
You can insulate the SS from the tin by using adhesive-lined heatshrink on the body of the bolt where it passes through the tin and then nylon washers against the hull/tin and under the SS nylok nut and bolt head. On one of my first tins I wrapped the bolt body with duct tape and did same on one side of the SS washers. Never had an issue ...

Or, I have some 1/4" diameter high-strength aluminum pop rivets and could send you 10, but you'd need an A-frame rivet gun to set them.
 
When ever a part looks like it is starting to fail, like rails holding up your seats, beef it up and fix the problem once.
Welding aluminum is not so easy but would be the best way to start.

You can do a lot with bolts. Is there galvanic action with steel bolts? My boat is all welded so I have not thought much about hardware on aluminum boats.
 
Thanks for the tips. I guess I would love to leave the bracket there but try to beef it up somehow. Where it is riveted to the hull is sound so I'd hate to replace those with something that will potentially loosen up and leak over time. I guess I should first ask, what would you guys do to repair, replace or beef up those brackets? Regarding welding, I would love to keep it a DIY project and welding a new set of brackets is out of my league.

If it comes down to replacing with bolts, washers and nuts I guess I can just go with stainless and isolate with nylon washers. I don't need it to last another 40 years.
Thanks, Dan
 
I have a 1976 Lund that has stainless screws that are on the seats and transom. They are there from the factory and no problems. Boat is no where near satlwater so maybe that has something to do with it .
 
Stainless steel and aluminum are pretty close together on the galvanic scale. They don't corrode each other very much. I have stainless steel fasteners all over my aluminum boat and have no problems. My boat is a salt water boat but spends most of its time on a trailer. A boat that lives in salt water all day every day might be more of a concern but I would still not worry much about stainless and aluminum. Especially in an area where you can see the fasteners - if you have any corrosion in 10 years, you'll see it and can do something about it.

A boat that's in fresh water - no worries at all.

I've never used aluminum fasteners and know nothing about them. But, I would be concerned that the threads would tend to strip easily - especially in smaller sizes. Aluminum is pretty soft compared to steel.
 
maintenanceguy said:
Stainless steel and aluminum are pretty close together on the galvanic scale. They don't corrode each other very much. I have stainless steel fasteners all over my aluminum boat and have no problems. My boat is a salt water boat but spends most of its time on a trailer. A boat that lives in salt water all day every day might be more of a concern but I would still not worry much about stainless and aluminum. Especially in an area where you can see the fasteners - if you have any corrosion in 10 years, you'll see it and can do something about it.

A boat that's in fresh water - no worries at all.

I've never used aluminum fasteners and know nothing about them. But, I would be concerned that the threads would tend to strip easily - especially in smaller sizes. Aluminum is pretty soft compared to steel.

I had the same thought as your last paragraph and also have never used them. If I did use them, I think I would be careful about ratcheting them down and would also use some thread lock or nyloc type nut. Some of the ones I see on line look like they are anodized. I wonder if that changes the property at all with respect to galvanic action.

I also have SS fasteners in various places around my boat. Mine never sees saltwater, so I'm in the "what, me worry" category. haha
 
I would tig weld the cracks in the existing brackets. Grind the welds smooth. Tig weld flat bar to the existing brackets. Drill the holes and reinstall the seats.
I do not find tig welding aluminum hard to do.
 
Thanks Bill. I think I'm going to just sandwich the whole works between a couple of pieces of flat stock and screw it all together with stainless.
 
DMack said:
Thanks Bill. I think I'm going to just sandwich the whole works between a couple of pieces of flat stock and screw it all together with stainless.
Just my opinion. I think it will still continue to crack. It will slow the cracking process down but it isn't a fix.
 
I would not be the least concerned about replacing the brackets with new stock, which I would recommend. Don't need to grind rivets. Center punch the heads and drill them out. Use stainless pan head bolts and washers and nuts. Could add some marine sealant to assure leak tight. Should be able to find heavy enough 2-6 foot piece of stock most anywhere. Farm supply, hardware store, big box, etc.
 
The aluminum fasteners that I’ve used (not on a boat) were miserably weak. I had to be very careful with them to avoid stripping out the heads or threads.
 
WV1951 said:
I would not be the least concerned about replacing the brackets with new stock, which I would recommend. Don't need to grind rivets. Center punch the heads and drill them out. Use stainless pan head bolts and washers and nuts. Could add some marine sealant to assure leak tight. Should be able to find heavy enough 2-6 foot piece of stock most anywhere. Farm supply, hardware store, big box, etc.

Not having any tools or experience doing rivets, this is exactly what I would do too.
 
Ok so I bought some 1 1/2" L channel and 1 1/2" flat stock, 1/8" thick from Home Depot. Much thicker than what's there now. I didn't really want to replace the rivets that go through the side of the hull but I decided to just bite the bullet and go for it, replacing with stainless steel fasteners and a dab of 5200 to prevent leakage. The 1/8" stock will be much stronger. I plan on putting the flat stock on top of the seat when I bolt it all back together just to strengthen the seat a little where the bolts go through because that aluminum is starting to split here and there. The seats, especially the middle one, end up under a lot of pressure from torque and twisting. I think they provide quite a bit of structure to the boat.
 
DMack said:
Hey all,
Starting to do some repairs to a 12' Sears Gamefisher. I need to replace or beef up the aluminum L channel where the seats mount to the hull. Is anyone using aluminum bolts, washers and nuts to replace rivets? I want to avoid stainless steel but I need a source for aluminum fasteners if folks are using them.
Thanks, Dan


I have a 20+ y.o. Crestliner that I put an aluminum floor in at the time of purchase. Used all stainless fasteners (screws). No problems to date. Aluminum bolts/nuts are too soft for the long term; the threads will stretch over time and the fastener will become loose. I've seen it happen. Coat your stainless hardware with a marine protector such as Lanocote by CRC which is specifically designed for this application. Or stick with tried and true aluminum rivets. Heck, they may just outlast you.
 

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