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Old 13-10-2012, 00:38   #1
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Thumbs down check out this bolt

Was one of four (and the worst looking one) that was holding the chainplate on for an upper cap shroud. If I get bored and curious I might take a hacksaw to it tomorrow just to see how hollowed out that thing got. The chainplate itself looks fine (replacing regardless), but the bolts all had varying degrees of corrosion.

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Old 13-10-2012, 00:48   #2
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Re: check out this bolt

OOOhhh, I bet PooBeetle is having an orgasm right now!

That's nasty looking, but somehow it still was holding the mast up. I bet that you are glad that you drew those bolts and had a look!

Good one!

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Old 13-10-2012, 00:57   #3
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Re: check out this bolt



Good catch.

This chainplate broke on the way from Africa. I'd been carefully inspecting these above and below deck, but never went to the trouble of removing them. The break is in the place I couldn't see, the part that went through the deck and was covered by caulk. There were not even rusty drip lines on the part below deck, it still looked shiney and perfect.
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Old 13-10-2012, 01:14   #4
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Re: check out this bolt

Sadly these are pretty normal examples of crevice and pitting corrosion. And this is the danger of stainless, everything looks good, right up until the time it breaks in half and you realize there was just a sliver of material left.
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Old 13-10-2012, 01:15   #5
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Re: check out this bolt

Quote:
Originally Posted by msponer View Post


Good catch.

This chainplate broke on the way from Africa. I'd been carefully inspecting these above and below deck, but never went to the trouble of removing them. The break is in the place I couldn't see, the part that went through the deck and was covered by caulk. There were not even rusty drip lines on the part below deck, it still looked shiney and perfect.
Curiously, what's that insert in the clevis pin hole? All of mine are just a simple hole punched through the stainless. Yours looks like it has some kind of insert.
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Old 13-10-2012, 01:24   #6
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Re: check out this bolt

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Originally Posted by Stumble View Post
Sadly these are pretty normal examples of crevice and pitting corrosion. And this is the danger of stainless, everything looks good, right up until the time it breaks in half and you realize there was just a sliver of material left.
Well to be fair the stuff does last a pretty long amount of time. And a lot of the material is sufficiently overbuilt to the point that it will even handle some thinning out and badness. One thing I've realized about oversized chainplates and bolts is that it's done to calculate in (I think) some pitting and metal failure.
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Old 13-10-2012, 01:30   #7
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Re: check out this bolt

Quote:
Originally Posted by Stumble View Post
Sadly these are pretty normal examples of crevice and pitting corrosion. And this is the danger of stainless, everything looks good, right up until the time it breaks in half and you realize there was just a sliver of material left.
I agree unfortunately the recient thread on SS got rather derailed, but it was sad to see experienced members dismissing crevice corrosion in 304 and 316SS.

It is a real and common problem that boat owners need to aware of.
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Old 13-10-2012, 05:04   #8
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Re: check out this bolt

Quote:
Originally Posted by noelex 77 View Post
I agree unfortunately the recient thread on SS got rather derailed, but it was sad to see experienced members dismissing crevice corrosion in 304 and 316SS.

It is a real and common problem that boat owners need to aware of.
I would never again use S/S for chain plates....

The ones in my current boat are circa 87' mild steel, and other than slight surface rust are as good as the day they where fitted.

The ones on my previous boat where 304 S/S of 98' vintage and where all suffering from crevis corrosion (the back stay popped in 2004), i replaced them all with mild steel and that boat has never had a similar problem since.

I should also point out on my previous boat all the S/S chain plates where glassed over, a mistake i did not make when replacing them with mild steel, and thankfully a mistake not repeated on my current vessel........
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Old 13-10-2012, 05:43   #9
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Re: check out this bolt

Thank you for these beautiful pictures. I will pull out two of our 6 (new 2006) chainplates and inspect them this year!

barnie
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Old 13-10-2012, 07:08   #10
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Re: check out this bolt

Crevice corrosion !!! Here's my rudder pintle and the bronze one I got made to replace it.
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Old 13-10-2012, 07:15   #11
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Re: check out this bolt

The pin on the original pintle looks just like rotten wood.
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Old 13-10-2012, 07:50   #12
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Re: check out this bolt

I was lifting a 300 pound diesel with a comealong from the ground to the cockpit just 4 days ago.
A ss fitting went " ping" and the engine fell back to earth. I should have known better, being a rallier against the use of ss.
Nothing broke, it was only a foot up and the pan landed on soft dirt.
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Old 13-10-2012, 23:17   #13
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Re: check out this bolt

Quote:
Originally Posted by rebel heart View Post
Curiously, what's that insert in the clevis pin hole? All of mine are just a simple hole punched through the stainless. Yours looks like it has some kind of insert.
That fixes a riggers mistake: 5/16ths wire is odd because there are two sizes of clevis pins for it's associated swages and turnbuckles. When I replaced the standing rigging the rigger ordered the wrong size.

If it adds context, this chainplate was 22 years old when it broke, and had gone pretty far.
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Old 14-10-2012, 00:12   #14
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Re: check out this bolt

Quote:
Originally Posted by IslandHopper View Post
I would never again use S/S for chain plates....

The ones in my current boat are circa 87' mild steel, and other than slight surface rust are as good as the day they where fitted.

The ones on my previous boat where 304 S/S of 98' vintage and where all suffering from crevis corrosion (the back stay popped in 2004), i replaced them all with mild steel and that boat has never had a similar problem since.

I should also point out on my previous boat all the S/S chain plates where glassed over, a mistake i did not make when replacing them with mild steel, and thankfully a mistake not repeated on my current vessel........
Mild steel? In a marine environment?

I may be missing something, but please explain how mild steel properties are superior to 316 stainless? And yes, we all know (I think) that 316 does have a shelf life, especially if it is not exposed to air.

How would you know if your chain plates are as good as the day they were fitted with out dying them or x raying them? I'm not trying to be argumentative, I really just can't see how you could be so sure.
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Old 14-10-2012, 06:24   #15
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Re: check out this bolt

Proably spent more on Band Aid's for busted Knuckles removing and replaceing chainplates than new chainplates.Why take them off for inspection and not renew them.Not that expensive in the overall scope of things.Don't forget the Tang's and clevis pin's they flex more and are subject to the same load's if not more.I,am also curious about Mild Steel seem's rust would be a problem.
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