The information I received from my rope distributor is that the initial
breaking strength is reduced by 25% with use. We incorporated this in
the operating procedures at our club (LISA). We use 250' (230' when
doubled at the ends) of 5/16" hollow braided polypropeleyne rope (HBPR) with a
nominal breaking strength of 1500 lb.


This is interesting information and coincides with some of my
experience.

A few years ago I did a bunch of winch launches with an operation that
was using a length of 5/16" HBPR as a weak link. We would pretty
consistly break the weak link after about 15 to 20 launches. I had
pretty much assumed the rope was loosing its strength as it was used. I
just had never heard a number as to how much.

Brian
CFIIG/ASEL