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Old 08-09-2021, 12:42   #1
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T bolt is suspect

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One of my critical few (3) stays on this boat.

I had a rigging inspection just a few months ago and this little crevice corrosion spot was not noted. Iím not sure he saw it.
Should I sand/grind this out to see how deep it goes?
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Old 08-09-2021, 12:50   #2
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Re: T bolt is suspect

For me, this falls squarely in the "if in doubt replace" category. Standing rigging is not a place to save money.
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Old 08-09-2021, 13:37   #3
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Re: T bolt is suspect

It's my understanding surface rust on stainless can indicate crevice corrosion that weakens the piece.

I've taken rusty stainless bolts, and squished them with a pair of plyers like playdough, they crumbled into little cubes.

Definitely get it tested, or replaced.
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Old 08-09-2021, 13:43   #4
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Re: T bolt is suspect

Those bolts are known to ge a point of failure. Grinding it out certainly isn’t going to strengthen it. Welding it closed will just make the problem worse. And all that work for a maybe $50 piece that is critical? I wouldn’t.
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Old 08-09-2021, 14:07   #5
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Re: T bolt is suspect

It is cracked. Replace it. Now. As mentioned above, grinding it out will weaken it.

It is that you can't--nobody can--tell when it will fail, and it would only be good luck if it failed unloaded in light airs.

Is it time to replace the standing rigging anyway? I'd be somewhat concerned about other bits, too, especially if you have T-balls at the top. They tend to fail from stress hardening in the center of the right angle bend up there. The outside of the curve is fine, the crack has begun where it is hardest to see....However, can sometimes been seen using binoculars from on deck.

Ann
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Old 08-09-2021, 14:17   #6
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Re: T bolt is suspect

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Old 08-09-2021, 14:20   #7
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Re: T bolt is suspect

Replace it. It's quite likely its much worse on the inside then it is on the outside and any cracking in an application subject to cyclic loading is bad news.
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Old 08-09-2021, 14:39   #8
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Re: T bolt is suspect

Here is an x-ray of a single pit in stainless steel and the prop shaft it was taken from. It clearly shows that the sub-surface corrosion is hundreds of times larger than what you see on the surface.
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Old 08-09-2021, 14:47   #9
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Re: T bolt is suspect

Quote:
Originally Posted by boatpoker View Post
Here is an x-ray of a single pit in stainless steel and the prop shaft it was taken from. It clearly shows that the sub-surface corrosion is hundreds of times larger than what you see on the surface.
I had the base of staunchion that had some crows foot cracks in the surface. I ground them out to repair with the TIG and as soon as the arc hit it, it fizzled like there was no gas. Long story short, all that remained of the internals of the base was rust. Hitting it with a hammer turned it literally to powder
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Old 08-09-2021, 17:29   #10
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Re: T bolt is suspect

Replacing it is the way to go but if you wanted to check for a crack dye checking is the way to go, it doesn't harm the metal being tested.
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Old 08-09-2021, 21:29   #11
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Re: T bolt is suspect

replace it...no question

on my boat i would also replace all similar / same age parts (if one is gone / on the way out, what's to say the others aren't about to follow ?)

however i value a quiet life whereas you may prefer the drama of having your rig fall down on top of family and friends. up to you...

cheers,

ps : if the rigging inspector did not see this, you definitely need to get another guy to go right over the rig. what else did he miss ?

how old is the rig anyway ?
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Old 09-09-2021, 09:39   #12
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Re: T bolt is suspect

Replace them all.
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Old 09-09-2021, 12:39   #13
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Re: T bolt is suspect

Quote:
Originally Posted by RaymondR View Post
Replacing it is the way to go but if you wanted to check for a crack dye checking is the way to go, it doesn't harm the metal being tested.
I agree with Raymond- go get it dye tested and that will answer a good deal of questions.
Not sure where you are located, but I would suspect $50 is not going to touch it. Meanwhile, look at the other fittings as well- If the previous rigging inspection was by eye and not removed and dye tested- then its really not much more than the inspection that you just did to discovered this.
Also don't forget to check the upper connections as well- they are often neglected and so better to fail.
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Old 09-09-2021, 12:56   #14
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Re: T bolt is suspect

Quote:
Originally Posted by boat driver View Post
I agree with Raymond- go get it dye tested and that will answer a good deal of questions.
Not sure where you are located, but I would suspect $50 is not going to touch it. Meanwhile, look at the other fittings as well- If the previous rigging inspection was by eye and not removed and dye tested- then its really not much more than the inspection that you just did to discovered this.
Also don't forget to check the upper connections as well- they are often neglected and so better to fail.
I've inspected hundreds of rigs. I've never found anything with dye testing that I could not find with my magnifying glass. The Marine Corrosion Certification certainly helped.
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Old 09-09-2021, 13:16   #15
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Re: T bolt is suspect

An abrasive stone on my Dremel tool took the "crack" away before .01" depth was reached. Age of the rigging is unknown. Keep those comments coming, especially the gloom and doom ones.
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