by Kahuna » Fri Aug 31, 2012 5:57 pm
by TimB » Fri Aug 31, 2012 6:08 pm
mattyj wrote:A5RP wrote:A standard 24-36" runner that is already on ones rack, of any type, girth hitched to your belay loop for the entire multi-pitch rap evolution, will do. This is a static and not a dynamic situ. Thus the dyneema vs. nylon issue is a moot one.
This is what I do too, but I think you and Wastral are missing the point. There are two separate issues: convenience and safety. I don't find a PAS convenient enough to justify the weight/bulk, so I don't own one. For someone that does lots of climbing on single-pitch bolted routes, I understand how it could be convenient, especially if you're frequently untying to clean a TR and thread the rope for rappel. You wouldn't bring ascenders on a free climb for self rescue and you wouldn't jug el cap on prusiks - different styles of climbing call for different tradeoffs w/ respect to gear.
From a safety perspective it's irrelevant whether you tie in with a PAS or a dyneema sling; the issue is how dyneema handles accidental shock loading relative to nylon. So-called "static" situations are exactly where the risk is highest - eventually you'll do something that turns it into a dynamic one, like the incident TimB references. You notice a knot in the end of the rope and scramble to grab it before your partner pulls it out of reach, or more commonly, how many people sit on the edge of a cliff and clip a bolt at their feet when setting TRs? People who are new to climbing look at that and go "it's a short fall, it's safe" rather than "that's a factor 1 onto static gear".
Drop tests show that this can be a serious issue. Yet so far, it's not a major cause of accidents. Maybe the drop tests are unrealistically harsh, maybe climbers just don't tend to fall on their static tie-ins. I see nothing wrong with clipping in using dyneema - sling or PAS - so long as you're mindful of the slack, and I do it myself. But telling someone to use a dyneema runner instead of a PAS does nothing to address the original safety question.
Tim, if I build a trad anchor and clove myself in with the rope, I generally don't bother with a backup tie-in method. If I do want one, I go just downstream of my clove, tie and overhand on a bight, and clip that to my anchor somewhere. I don't personally feel the need to back my rope up.
by mattyj » Fri Aug 31, 2012 6:35 pm
A5RP wrote:The shock load test by DMM is a leader fall situ.
by Kahuna » Fri Aug 31, 2012 6:40 pm
mattyj wrote:A5RP wrote:The shock load test by DMM is a leader fall situ.
Huh? The DMM test simulates someone clipping into a bolt with a dyneema runner and then accidentally falling on it.
At DMM’s test-tower we took a look to see what implications this difference has for a dynamic loading on to a Dyneema® sling
"If you do use slings then ensuring there is no slack in the system is paramount."
by mattyj » Fri Aug 31, 2012 8:28 pm
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