Her is my experience with a swivel on a mooring in Australia. (I realize
you're talking on an anchor)
I had a boat "head off" after the nut came off a 7/8" ground tackle swivel.
I must admit it wasn't brand new but what happened was that in the
manufacturing process, after assembly (screwing on the nut), it had been hit
with an arc welder to prevent it from coming unsrewed. There wasn't a lot of
weld on it.
Over some time the corrosion or electrolisis etc "ate" off the weld.
In Australia or anywhere else in the Southern Hemisphere, the weather cycles
almost without fail, always go in a anti-clockwise direction. You folk in
the Northern Hemisphere will notice that your weather will always go in a
clockwise direction??
I'll explain a little...........
After a North wind you will get a Westerly, then a Southerly. Before you get
your next Northerly you will get an Easterly. This is in the South.
The opposite is applicable in the North??

Now as you know.... most threads are clockwise? Guess what happens in the
Southern Hemisphere??
I honestly feel that this problen should be addressed with the utmost
urgency. There have been many examples of valuable fishing boats on a
mooring taking off with only half of the swivel hanging on the end of the
mooring rope.
If anyone doubts what I'm saying, I still have in my possession the two
halves of the swivell, as well as the almost complete net which I dived for
& recovered. I suspected sabotage as I had a check of the tackle only a few
weeks prior to this happening. If this is an insurance claim & it was on
ground tackle & it was in the Southern Hemisphere, Then I suggest the claim
be paid!!!

In summary, I bekieve that the manufacturer of these swivell's needs to
produce a run of "left hand threads" for the South.
Regards.... BruceM


"John" wrote in message
om...
"Leanne" wrote in message
...
"Glenn Ashmore" wrote in message
news:2P5Bc.1470$Pa4.98@lakeread04...
Has anyone ever had any experience with or heard of a Nyloc nylon
lined
nut backing off a bolt?

Now the problem. A New Zealand sailor is claiming that his anchor
(which thankfully I did not sell) failed because the nut backed
completely off the bolt which allowed the bolt to fall out. There is
very little vibration and no torque on the bolt. The nut was in good
condition, new when installed and had never been removed. Is there any
way that a Nyloc nut in good condition could possibly make more than
20
turns on a loose bolt on its own?


Aren't the Nyloc nuts for a one time use. I know the similar type in
aircraft are that way. One solution would be to double nut it with a
standard nut and then a nyloc on top of it. Myself, I would drill the
bolt
and use a cottor pin so the nut could not run off the end of the bolt.

Leanne
s/v Fundy

Your correct, they are supposed to be used one time, the nylon looses
it's grip with repeated removals. You will note this when installing
an old used one, it starts to go on with little effort at all, a new
one requires w wrench.