Sta-Lok stud corrosion?

[Joe Henderson]

Dear Richard,

Having re-read your post and after Brion's reply, I have thought some more on your rig.

The rust may be tool residue at the end of the thread where it should blend smoothly into the body of the terminal.

I may be mistaken, but I seem to remember that some early Sta-Lok studs had cut threads which were superceded by rolled threads later on. I am talking about the stud portion that fits the turnbuckle body, not the terminal assembling threads.

Sometimes the tool chatters on withdrawal when coming to the end or at the start of a thread, particularly if the section of the workpiece changes as per the thread to body interface of mechanical terminals, leaving some of the carbon steel/tungsten/ceramic/whatever the tool is made of, embedded in the stainless. This can cause staining at an existing stress concentration/notch and in severe cases it can be the start of a more serious problem, cracks etc.

Just such a defect caused a yacht called Amazon to lose the Sydney to Hobart race one year after the turnbuckle on the headstay broke at the end of the thread where it met the lower eye/toggle. Only lightning fast reflexes on the part of helmsman Hugh Treharne ( Him of Australia II fame [and I purposely use a capital H !] ) saved the rig allowing the boat to return to Sydney safely, if not quickly.

Whatever the cause, inspection is warranted.

Regards,

Joe.