Originally Posted by MacEntyre
That's the "walking" I was referring to... after stretching a small amount, polypropylene walks, in that it no longer rebounds or recovers 100%. The result of walking is narrowing; it's kind of a permanent stretch. If the load is enough to cause it to walk, it can eventually lead to failure, as each time you hang it walks a little further.
Of course, we probably have lots of hangers here who will say that they have hung for years with light, braided polypropylene, without any problems!
I think that the stretch under tension of all ropes leads to failure and is why over the years I have brought up my concerns of people tying too low on the trees and repeatedly retightening with some of the suspension adjustments that allow them to pull the suspension very taut. (I have wondered if a certain load caused a certain amount of stretch and it was the specific stretch that caused the failure rather than a specific load causing a failure. If a load was hanging straight down that argument would be mute; but with our horizontal loading that is reduced by stretching under some initially tremendous loading and can be retightened and stretched again before it has recovered, that may not be a mute point.)
I used the 3/8 hollow braid polypropylene for a few years without any problems, but without a structural ridgeline and have know of quite a few others that have as well. I don't know what Clark Hammocks is using these days but at one time they used 3 twisted stands of polypropylene rope, 1/4 on some and maybe 3/8 on others? I didn't like the 3 strands on my home made hammock because I had the strands separate enough where I had tied and released a slippery bowline that it looked like only 2 strands might take the load, and I didn't like that.