Stainless vs. Aluminum Pop Rivets Question

Alan S. Glos

Well-Known Member
I am rigging a stock Sunfish for racing and need to attach Clam Cleats (for the outhaul and cunningham) to the boom and a halyard cleat on the mast. Would stainless pop rivets be better than aluminum? If so, (a) where can I get some and (b) will a standard pop rivet gun be powerful enough to attach them?

Alan Glos
Clueless in Cazenovia, NY
 
All aluminum rivets are preferable (no steel mandrel). Galvanic corrosion will eventually be an issue with an dissimilar metal, the timeframe for when it becomes an issue is open for debate. I've lost a boom from galvanic corrosion at the boom block from stainless fasteners. It took years and I store the boat on a seaside facility, but it can happen.

McMaster is a great resource for getting exactly what you want.

I use 3/16 rivets on my spars. The rated shear strength for these is 260 pounds, and tensile strength is 320 pounds, for a single rivet. More than adequate for a sunfish with plenty of safety factor to spare.
 
No. Please use aluminum. Stainless rivets are a pain to pull and even more of a pain to drill out. We can't be your friend anymore if you use them. Plus there is the galvanic corrosion issue.

Lowes has an assortment pack of Arrow brand aluminum rivets, with sizes you'd need to do the job. Other hardware stores may have similar.
 
I just recently broke a handle on my nice Arrow pop-rivet gun. :(

Fortunately, I kept a rusted-tight--but identical--Arrow gun. I'll swap the handles when I'm back in Florida. :cool:

The pop-rivet I was securing was some kind of steel alloy--but not stainless. (Monel, maybe?) Stainless is a tough steel alloy, so why risk a cheaper gun? :confused:
 
I am rigging a stock Sunfish for racing and need to attach Clam Cleats (for the outhaul and cunningham) to the boom and a halyard cleat on the mast. Would stainless pop rivets be better than aluminum? If so, (a) where can I get some and (b) will a standard pop rivet gun be powerful enough to attach them?

Alan Glos
Clueless in Cazenovia, NY
Alan, I’ve had this same concern also. Certainly galvanic corrosion is something to be concerned with but after owning & racing over a dozen sunfish over 45 years I really believe the factory spars use SS rivets on the eye straps when mounting mainsheet blocks to boom. When replacing a block on a recent sunfish I used an aluminum pop rivet because of corrosion concerns. While going over my boat in preparation for a upcoming regatta I noticed the head of the aluminum rivet was opening up & deformed & also the aluminum rivet has a distinct white color as opposed to the slight grey hue of the original rivets, eye strap & SS hardware in general.
Please see pic& please offer any feedback anyone might have.
Thanks & Sail Fast!
 

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Anytime you put dissimilar metals together ther will be galvanic corrosion. Rivets are cheaper than booms, and much easier to ship. What you're seeing there is galvanic corrosion between the rivet and stainless strap. A piece of tape, plastic or any number of commercial corrosion barrier products will help the rivets last longer.

If that is a 1/8 inch rivet, if bump it up to 3/16 (assuming the strap had enough meat), the extra material will be greatly increase service life. Make sure your rivets have an aluminum mandrel and not steel. Put a piece of tape on both sides of the stainless eye where it meets the boom and the rivet for good measure if you like.

I recommend a piece of high strength small diameter lashing line be passed thru the sheet block, around the mast, and be securely knotted to itself. If the block pulls off the boom it will now be held by this line. Belt and suspenders.
 
My guess is stainless.

Lets face it we have a mix of metals no matter what. The 40+ year old aluminum booms and masts fail due to corrosion. I have fixed a few.

BUT

An aluminum rivet is not really strong enough to handle the forces. If there is slight corrosion on the rivet then it will break. This is likely to happen faster then the failure of the boom or mast aluminum. I think stainless would be the better choice.

I could be completely wrong.
 
Aluminum rivets are plenty strong, you can pick an entire boat from one properly prepared rivet

If you really want over kill spend the extra money of monel rivets.
 

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