Stainless eye bolt failure

[pugwash60]

Inconveniently I lost my mast mid Atlantic, it was an eye bolt failure on the Port Lower. I’d noticed, post failure, a skim of rust on the surface of the nut below deck and had expected to see crevice corrosion on the fitting which failed mid way through the deck. The fittings are probably all original and are about 16mm diameter and from 1982.
Looking at it now it looks like it just failed with no corrosion.
What does the jury think; am I missing something on cause of failure? Should these things be Replaced every few years or was it just unlucky. I don’t see any manufacturing fault.
Hopefully picture attached.

 

[anoccasionalyachtsman]

It does look it didn't take long. What we need here is a @vyv_cox if there's one passing.

 

[tico]

Looks like a fatigue fracture starting from a crack at about 4:30 looking at it.
Shows the striations as the crack has grown under cyclic load until fast fracture has occurred

 

[vyv_cox]

If ever there was a 'classic' fatigue failure, that's it. Compare it with others on my website under Metallurgy.

 

[Lee Shaw]

Interesting. It looks like the fatigue crack was caused by single direction bending cycles as might be expected for a shroud fixing. Interesting to that fatigue cracks grow fastest in the last part of a component's life so that eye bolt has likely been cracked for a long time, IMO.

 

[penfold]

What everyone else said; classic fatigue failure. Definitely not crevice corrosion cracking or other typical stainless steel misbehaviour.

 

[gus]

I would be disinclined to trust a bolt. Better with s/s flat bar.

 

[Charlie Boy]

Inconveniently I lost my mast mid Atlantic, it was an eye bolt failure on the Port Lower. I’d noticed, post failure, a skim of rust on the surface of the nut below deck and had expected to see crevice corrosion on the fitting which failed mid way through the deck. The fittings are probably all original and are about 16mm diameter and from 1982.
Looking at it now it looks like it just failed with no corrosion.
What does the jury think; am I missing something on cause of failure? Should these things be Replaced every few years or was it just unlucky. I don’t see any manufacturing fault.
Hopefully picture attached.

You can’t leave it at that! We need more details, urgently!

 

[pyrojames]

Best to use forged parts for rigging....

 

[JumbleDuck]

What everyone else said; classic fatigue failure. Definitely not crevice corrosion cracking or other typical stainless steel misbehaviour.

Couldn't be fatigue-ier. all right. Which I suppose leave the question of what initiated the crack. Could that have been corrosion cracking?

 

[penfold]

There's no obvious source, although without close examination it's often not visible with the naked eye; it appears to have initiated at the root of the thread.

 

[Charlie Boy]

I still want to know the whole story of the casually lost mast in mid atlantic.

 

[DownWest]

Cut thread or rolled?

 

[vyv_cox]

Looks like there is a small stress raising section change at the fracture face.

 

[penberth3]

Best to use forged parts for rigging....

Aren't eyebolts forged?

 

[[185615]]

A salutory lesson to us all, a failure following some 40 years of use, a failure hidden away from our eyes, something we are all guilty of i expect.
We have been told over the years that an inspection 5 yearly/replacement 10 yearly routine is something we should all adopt where possible.

 

[pugwash60]

Apologies for being slow to get back, I was sailing with a friend for a week.
Thanks for the replies: so fatigue failure. Pretty much my belief, I was kicking myself for not removing them prior to setting off, but suspect nothing would have shown prior to my setting off. I had; not terrible weather heading West but almost nothing good and nearly all close hauled with lots of relatively uncomfortable seas.
New mast in the process of being ordered. I set up a jury rig and sailed home there’s a blog on beaglecruises.com under ‘Nostar’ for anyone who is interested in the longer story.

 

[pyrojames]

Aren't eyebolts forged?

Some forged, lots cast, many welded. Most of the cheaper ss ones are cast. Buy Wichard if you want good ones .

 

[gordmac]

Probably not a rolled thread. Some metals are more prone than others for fatigue and crack propagation, from memory stainless can be bad. Long time since I did any fracture mechanics.