I was recently given some well worn 11.2mm climbing rope that I thought was static (no tag on it). I became suspicious yesterday when looking at the rope stretch on my rig under load. I tested it by measuring and marking 100mm on an unloaded rope segment then taking the rope to ~200kg tension. The marks were now 120mm apart. ~20% stretch has to be dynamic rope, right?
What sort of stretch percentages do we expect to see between static and dynamic rope? If you get given an unknown piece of climbing rope is there a way of knowing straightaway what type it is?
Your evidenced stretch surely reveals the rope as dynamic.
Also, low-elongation rope typically has a coarser braid in its
sheath. (Google should bring up many images.)
Thank you Dan, your comment confirmed things for me. I have been trialling in 11.2mm dynamic and not even known it : :o
This explains to me why some knots I was previously ‘happy’ with just did not live up to expectations when I trialled them in this rope (eg. I discarded some of my early bowline proposals, they just did not load well). Some of the trials I have done recently and stated them as being in static rope are falsely advertised, time to fix things up.
:o