Mooring Shackle mousing

[lw395]

Technically you shouldn't be using "Screw Pin Shackles" for this kind of mooring application. The correct shackle is an "Anchor Shackle" which uses a "bolt type" pin and there is split pin to hold the nut in place. The shackle body is not threaded. The advantage is that the pin can gently rotate in the shackle without danger of coming loose. Screw Pin Shackles are designed for use when the shackle pin needs to be frequently removed, such as on a halyard. Anchor Shackles (Bolt Type) should always be used when inspection is difficult or less frequent.

I found that this could be 'approximated' by replacing the shackle pin with a bolt and then putting an extra nut on the end. The bolt won't rotate in the shackle, so all the wear will be between the bolt and the chain where you can see it. As others have said, Loctite helps.
If you must mouse with wire, the heaviest green plastic coated garden wire seems to work quite well, the plastic means there is no galvanic corrosion with other metal bits.
Another trick I have used is to drill through the lock nut and bolt, tap the hole M5 and screw a zinc plated machine screw in with plenty of Loctite. I've used that OK on the bottom swivel of a rod buoy.

One thing with mousing wire is that cretins from sailing schools will rip it off when they lasso your mooring.

If corrosion is severe in your area, try putting last year's anode on the swivel.