"Charlie Morgan" wrote in message
...

Although it would probably be good for natural fiber lines, I
think it might
actually contribute to failure of nylon lines in bad conditions.
Nylon lines
depend on water for lubrication as they stretch and contract. If
you cover them
with something that keeps water out, the individual nylon fibers
work against
each other and the friction gets them hot enough to melt and
break. That's why
lengths of old garden hose are also a bad idea. Nylon requires
water.

For everyday chafe protection in mild conditions this wouldn't
be as much of a
problem. When things get rough, however, it's a very different
story.

OK, friction creates heat, lubrication reduces friction. I've
noted that wetting the line where it passes through the fairlead
stops it squeaking.

However, internal friction within a line is trivial compared to
the external friction created by chafe, which is highly localised.
A hardened area where a nylon line passes through a fairlead is
common. A low friction sleeve, or a thick sleeve which has
elasticity, will prevent this occurring.

My favourites are irrigation hose (PTFE, low friction, good for
faileads) or thick soft plastic hose (high friction, but loads of
elasticity, good for eyes around bollards). Both these have to be
threaded onto the line before use. The advertised product can be
added later - seems to be a good idea.

My testing ground is Kalamata marina, which suffers a couple of
times each winter from heavy surge for a day or three. One session
of about 20 hours, heavy rain, took one of the pair of bow lines
(nylon) beyond its stretch recovery point (all the long term berth
yachts had a further pair of back up lines . . .). Neither line
melted or broke. Mine didn't chafe through - though some (without
protection) did.

My damage points (apart from the lengthened rope!) were the
bowline knot nips (which made the loops which went around the
bollards). They were hardened. I now use eye splices.

I think a lengthened rope (20mm diameter for a 12m yacht) is a
good indicator that stresses were high, and 20 hours is a long
time to withstand a 5 second cycle of stresses. I'd define that as
rough. So from this experience I find it difficult to believe that
anti chafe sleeves may contribute to line damage.
--
JimB
http://www.jimbaerselman.f2s.com/
Describing some Greek and Spanish cruising areas