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 Post subject: Aluminum Rivet
PostPosted: Wed Feb 09, 2005 9:18 pm 
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Joined: Mon Aug 30, 2004 12:31 pm
Posts: 88
Location: Redlands, Ca
I upgraded my mast tang when I installed my comptip on my old 74, I tested one of the 12 stainless steel rivets on my new gun, I assumed there was an extra rivet. I was wrong, I now have 11 rivets installed on my mast tang, but need 12, can an aluminum rivet fill the hole? Stainless Steel Rivets are hard to find


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 Post subject:
PostPosted: Wed Feb 09, 2005 9:46 pm 
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Joined: Thu Mar 25, 2004 5:39 pm
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Location: West Texas
You would probably be able to get away with it, especially if there are already *11* SS rivets there. On the other hand another rivet is only like, 50¢. I'd get some sail repair tape and a rivet from West Marine or something (just so you don't pay $1.50 shipping on a 50¢ item) and wait the 5 more days for it to show up. Just for your peace of mind, however, here's some simple math:

According to one rivet web page, a 3/16" stainless rivet has 950lbs. shear strength. The same 3/16" rivet in aluminum is 260lbs. shear strength. Granted, the rivets will be under a combination of shear and (tensile?) loadings; but the tensile strength value is higher, so I'm being conservative here. :)

Total shear strength (this is admittedly simplistic) for 12 stainless rivets would be 11,400 lbs.
Total shear strength for 11xSS + 1xAL rivets would be 10,710 lbs., which is 94% as strong as all stainless. Looking at shackles in the Hobie Cat parts catalog, the strongest one I could find had a load limit of 6600lbs. In the West Marine catalog, the highest strength one I could find was 3/4" steel and it had a load limit of 9000lbs., so I think the shackle up there would probably break before you reached the shear strength of either the above-calculated values.

For that matter I'd bet if you put 9000lbs. of lateral pressure on the mast it'd buckle like a soda can. :oops:

Just my 2¢. :)

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Jim

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 Post subject:
PostPosted: Thu Feb 10, 2005 6:45 am 
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Location: Virginia
Yeah! What he said! 8)


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 Post subject:
PostPosted: Thu Feb 10, 2005 12:20 pm 
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Joined: Mon Aug 30, 2004 12:31 pm
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Location: Redlands, Ca
Thats crazy! I would have never expected an answer like he said.
Im not going to use the alluminum rivet, I was just wondering


Also I posted a forum about the sleves that go around the rivets in the mast tang, the sleves broke my other riveter, so I didnt use them in the other 10 rivets, Does that present a problem? I also epoxied my tang to my mast for extra strenght...

What do you think?


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 Post subject:
PostPosted: Thu Feb 10, 2005 2:51 pm 
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Joined: Thu Mar 25, 2004 5:39 pm
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Location: West Texas
Those are there to keep water from going in through the holes in the rivets. If you didn't use the sheaths then I'd squirt some epoxy into all the little holes in the rivets and also around the edges just to make sure it's sealed really well. Good luck with that!

Jim


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