Rivets: spreader rivets: look bronze?

[agprice22]

My spreader bases are riveted to the mast. A few rivets are broken! The rivets are dark in color, like bronze or copper. I do not see bronze for sale.
Here is a picture.
Should I use copper, or bronze if I can find them? Or Stainless?
I think the shank looks like 6/32". I think it is a dome head. Any idea what the grip length would be?



Thanks,
Andrew

 

[Crazy Dave Condon]

You have to be careful about using stainless steel on Aluminum as it will corrode due to being dissimilar metals. Often the mfgs. would use the large aluminum pop rivets. Not sure about what is on your spreader base

 

[weinie]

I've read somewhere that "monel" rivets are less susceptible to galvanic corrosion.

 

[Bill Roosa]

Take a fine file to the existing rivet head to determine the actual metal. SS on aluminum is NOT the first solution in a marine environment. however if you let the aluminum rust (wait a day for it to oxidize) AND the rivet is up the mast a ways you may a pretty ling service life. however however aluminum is the recommended solution as the spreaders "work" and SS will eventually rub through the aluminum oxide and rust. Also SS requires a special rivet installer tool to handle the stiffer SS. A regular rivet installer will break after the 2nd or 3rd rivet.

 

[agprice22]

How will the file help me determine the metal? By color? Do you suspect the rivet is aluminum under the patina? Would Aluminum rivets be strong enough? Would copper rivets be strong enough? I would guess it would depend on the nickel content.
I forgot about the corrosion of SS against aluminum. I won't use the SS.
Thanks!

 

[Brian S]

I dunno what kind of rivets those are, but a couple things. First, call Rudy at D&R Marine and ask if he knows. Second, when installing dissimilar metals, for example SS rivets into AL, use Ultra Tef-gel or Forespar's Lanocote to insulate the two metals and inhibit galvanic corrosion. I'd probably opt for Tef-gel, because that Teflon isn't ever going anywhere, but then again the "pure lanolin" I found once (couldn't find anhydrous lanolin locally, didn't want to order Lanocote at the time) sure hasn't gone anywhere on my turnbuckle threads after 3 seasons.

 

[agprice22]

I dunno what kind of rivets those are, but a couple things. First, call Rudy at D&R Marine and ask if he knows. Second, when installing dissimilar metals, for example SS rivets into AL, use Ultra Tef-gel or Forespar's Lanocote to insulate the two metals and inhibit galvanic corrosion. I'd probably opt for Tef-gel, because that Teflon isn't ever going anywhere, but then again the "pure lanolin" I found once (couldn't find anhydrous lanolin locally, didn't want to order Lanocote at the time) sure hasn't gone anywhere on my turnbuckle threads after 3 seasons.

Ok, but would Aluminum rivets be strong enough? I guess I could check the ratings on the rivets from manufacturers.

 

[sesmith]

Another vote for monel. If concerned about galvanic corrosion, treat the hole with Duralac first.

 

[agprice22]

I don't see Monel rivets. I will keep looking!

 

[sesmith]

I don't see Monel rivets. I will keep looking!

I got mine here, but there are other sources. Yours may be larger than the 3/16" diameter than I used. The trick is finding a supplier that sells in quantities smaller than 100. You might try a rigger in your area. The description mentions stainless steel for some reason, but they are monel. The center pin may be stainless.:

http://sailsportmarine.com/fasteners-c-135_24_72/

Duralac, if interested, can be had at Fisheries Supply. It's not cheap, though.

 

[woodster]

Ok, but would Aluminum rivets be strong enough? I guess I could check the ratings on the rivets from manufacturers.

in this application they should be be just fine ...the sole purpose of that fitting is to support the spreader to the mast and all the strain is compression load only

 

[Ron20324]

[QUOTE="... I guess I could check the ratings on the rivets from manufacturers.[/QUOTE]

And what strength numbers would you use as sufficient or not? . They would probably say it depends on how well the hole is made, and how well the rivets are placed.Not any benefit, I'd say.

 

[agprice22]

Got it. I used 3/16" aluminum with 1/4" grip. They worked fine.

 

[agprice22]

[QUOTE="... I guess I could check the ratings on the rivets from manufacturers.

And what strength numbers would you use as sufficient or not? . They would probably say it depends on how well the hole is made, and how well the rivets are placed.Not any benefit, I'd say.[/QUOTE]
I think I would have compared them and used the strongest!!! Then the mast would fail first ...

 

[Ron20324]

I just placed an order with SailsSport. Almost as soon as I got the email confimation, I got a "FedEx" email with a4-digit number and something about personal information having been recently sent- and it had. I should have know better than to click on it. I pulled the plug before the FedEx finished downloading. I'll see if anything happens.

By the way, the 25 rivets were $14.00, the shipping was 7.25.

 

[agprice22]

I just placed an order with SailsSport. Almost as soon as I got the email confimation, I got a "FedEx" email with a4-digit number and something about personal information having been recently sent- and it had. I should have know better than to click on it. I pulled the plug before the FedEx finished downloading. I'll see if anything happens.

By the way, the 25 rivets were $14.00, the shipping was 7.25.

Yikes, dude! I hope you didn't download a virus. What kind of rivets did you buy? Show me a pic when they arrive.
Thanks!

 

[Crazy Dave Condon]

Andrew;
Woodster hit it on the nail head. When running the shrounds thru the spreader tips, it is important that there are no up or down pressures on the spreader, just in a sense compression which the aluminum pop rivets will hold your spreader base in fine.

 

[Ron20324]

[QUOTE.... What kind of rivets did you buy? Show me a pic when they arrive...[/QUOTE]

They're like any other rivet, but monel. /// I saw some rivets at the Harware city that are special purpose, for longer lengths. They have 2 groves on the shank that compresses. Guarantees a perfect squeeze, I guess?

 

[Dennis Kitchen]

My 2 cents,
I would wager that most of the rivets on masts, especially older ones are stainless steel. True, they are galvanic with aluminum but as others have stated they can be coated for some protection. I just replaced SS rivets on my '83 H25 project. There was some pitting under the heads as expected. It was cleaned up, treated with a conversion coat, painted and re-assembled wit SS rivets. Good for another 30 years.
Monel is a more recent solution. It's more costly, and less galvanic with aluminum than SS but still should be coated.
As for aluminum rivets, many have carbon steel pull shanks which break off and leave a tail in the formed bulb. Now you've really invited corrosion.
So what about it; have you all removed all the SS nuts, bolts and screws from your mast and replaced with Monel? Didn't think so.
The OP's original rivets look to me like corroding zinc coated steel. The look reminds me of old worn grommets on a pair of vintage boots.

 

[agprice22]

You can look at the rivet Spec to determine the shaft and mandrel metals. AD6-4A indicates an aluminum, domed head, 6/32 width, 1/4 inch grip, aluminum mandrel rivet.
Monel is steel that is less reactive. Other forums indicate that many people use SS and coat it with 3m adhesives or silicon