Tam/WB2TT wrote:

If you live anywhere near water, a boat shop might be a good source for rope
that will withstand weather and UV. Think of all the rope on a sail boat. I
haven't checked prices.

Ironically, polypropylene rope, the very worst kind for UV, is often
sold as water ski tow rope and for other marine applications, because it
floats. So check the label carefully.

A friend of mine once built an 80 meter vertical from PVC pipe, with a
wire inside or outside of it. Being an analytical sort of person, he
carefully calculated the wind loading, allowing for the 100+ MPH winds
not uncommon in his area of Colorado. Then he selected guy rope of the
required strength, with a hefty safety margin. It worked fine for about
6 months, then the antenna fell over on a day when there was only a
slight breeze. Mystified, he inspected the antenna and found that he
could pull the rope apart with his bare hands. That was when he, and I,
learned about polypropylene rope and sunlight. Of course, his location
at about a mile elevation and where the sky is clear 300 or so days per
year was a particularly harsh environment for plastic as well as for
fair-skinned people. I got away with using the stuff for a couple of
years here in western Oregon. But there are a lot better choices.

Roy Lewallen, W7EL