100% true 2 boats in our club this year had cotter pins break on their boom and had it fall off while sailing .. These are new pins as we take our masts off and step every year
Do they take a load? Side load against a clevis pin? Why do they need to be so strong! Cotter pin—pull it out, throw it away, put in a new one.
On a turn buckle obviously no ,however on a boom you do get some side loading and I can direct you to some youtube channels where they have had the same failure of boom cotter pin and boom pin falls out . I 've spent my life repairing making things stronger and more reliable and I'll stick to stainless split rings
Makes me want to inspect my boom pins this weekend!!
I bought quite a few different sizes 316 ss split rings off ebay in packs of 100 .I believe 30mm for turnbuckles .
On my US spars mast I have to use cotter pins on the speaders and then tape over , rings don't fit
Work hardening usually occurs with repeated bending, not a single bend. Short story, don't reuse cotter pins in critical situations.
Interesting. Do you have photos?
Typically forestay tension is set at about 12-15% of breaking strength. The swage has to be able to withstand considerably more tension than that. The terminal ends, whether swaged or mechanical are typically almost as strong as the wire itself. if the loss of a backstay caused the swage to fail, then I think the swage was either poorly made or about to fail anyway.
The important story is how the standing rigging is a robust and fragile system that keeps the mast up. Failure in any part of the system can lead to failure of the whole system. For those who leave their masts up, out of sight, out of mind is not a good strategy.
What's the story about how the kingdom was lost for the want of a nail?
Hope your insurance company steps up to the plate and helps you out.
Thanks. The second photo shows some rust staining inside the swage. That may have weakened the wire. One weakness of swaged fittings is work hardening. Because there is a sharp transition between the swage and the wire there can be a sharp bend. When the wire is flexed at the transition it becomes brittle and can break. Couple that with some crevice corrosion inside the swage fitting and the wire is not as strong as it needs to be. Throw in some extra movement from a missing backstay and the wire breaks.
I'd be interested in hearing what an competent and experienced rigger has to say.
I'd be interested in hearing what an competent and experienced rigger has to say.
Since the wires are visible inside the swage I guess I wouldn't call it a swage failure - implying the wires pulled out of the swage. It looks like the wires broke and cleanly at that. Maybe that's a distinction without a difference but it's important to understand how the failure occurred. Dave's scenario about work hardening makes sense. It's a wonder there aren't more failures.
Is that a furler drum in the first photo? The wire strands look pretty mangled above it, not just severed. I’m not a metallurgist, but I wonder if the halyard may have wrapped the stay at some point, weakening the wires.
Did that on Wednesday. Broke a finger nail putting in the split ring. Those holes in the clevis pins can be so ornery.
