Cotter keys on shrouds

[Bowdrie]

Originally Posted by caffel

Add a stop nut to the top threaded rod (often the RH thread).

Stop nuts/Jam nuts are primarily seen on closed body turnbuckles, which themselves are poor practice, (the closed body traps water in its lower section).
As the rigging force tries to pull the ends out of the body adding jam nuts only increases that force and totally relies on friction.
It's not sound engineering for rigging which is constantly changing its loading at various frequency.

[Icarus]

Never heard of a turnbuckle rotating itself loose..but hey
Some have lock nuts..
You can always lock the body to one of the stems with a split ring... Or ad a lock nut

[barryglewis]

I've had wired rigging screws on Shrouds loosen 9n Risky Business in 2018.. they were fitted with lockouts and wired as well. They spun until the wire was twisted very tightly, 6 to 8 turns or so. The rigging is dyform.
Risky is 13.5m, by 3.1 by 3 draft, and displaces about 9 tonnes.
The problem arose after a 140 degree knockdown.