Forums: Climbing Information: The Lab: Re: [kaizen] Stupid Simple Elette: Edit Log

Partner rgold

Aug 18, 2011, 8:02 AM

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Registered: Dec 3, 2002
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Re: [kaizen] Stupid Simple Elette
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There are no further tests that I know of. (*) Patto's comment is based on the description of the original tests, which makes it absolutely clear that (1) they do not model what can happen with a factor-2 leader fall onto the anchor in the real world, because, as he says, the tests contained no mass corresponding to the belayer, and (2) the dismissive results of the tests as performed were easily predictable from the set-up.

The tests modeled a rope soloing fall of the climber onto an anchor that extends. The extension in the anchor was very small compared to the amount of rope in the system for absorbing fall energy, so it is no surprise that the conclusion was that the anchor extension mattered little.

Having a mass corresponding to the belayer is critical, because if the belayer is dragged off the stance, the only part of the system absorbing that fall energy is the belayer's tie-in, and the length of that relative to anchor extension could be small enough to result in much increased anchor loads.

(*) Edit: From Jim Titt in Germany:

Well, as usual the DAV have done this one (Panorama 2/2009, also interesting for the dynamic and static tests on various sling materials tied with a clove hitch).

5m drop, 80kg, dynamic rope belayed with HMS on sliding X with 60cm legs. Hanging belayer weight 65kg.

Single leg failure gave 40% higher force than the same test with no extension.

Of course, results like this were predictable and were predicted.

As for this anchor, it is a variation in the highly non-equalizing genre of 50/25/25 configurations, using a figure-8 variation instead of clove hitches to possibly getting better distribution to the two low-load pieces. If you need equalization, the ACR is a better bet. The rest of the time, I'd go with the rope by itself or (say on a wall) the classical cordelette.

(This post was edited by rgold on Aug 18, 2011, 8:41 AM)

Edit Log:
Post edited by rgold () on Aug 18, 2011, 8:11 AM
Post edited by rgold () on Aug 18, 2011, 8:41 AM

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