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Re: [guangzhou] Daisy Chains are the Devil! (Tempting, but bad for you):
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Colinhoglund
Oct 7, 2010, 4:57 PM
Views: 4259
Registered: May 5, 2008
Posts: 338
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guangzhou wrote: Fine, I'll bite. I have used and will continue to use my daisy to safety off when clearing a belay. The key is to clip completely into the sling and not just the bar tacks. In many cases, I use a QD to safety these days, but I understand why a daisy is useful. A daisy is a long sling that has had loops sewn into it to shorten it's usable length. Yes, each loop can fail, but I don't clip the bar tacks, I clip the sling. If you're clipped into the sling and not the bar-tack, every loop can fail and you're still fine. To me, using a daisy chain is just like using a sling. Don't climb above the anchor, clip the whole daisy not just the bar-tack, and you'll be fine. Watch the end of the video, Black Diamond Suggest you use the two binner approach to reduce the risk of a a bar tack being clipped on accident. . You can make a daisy buy using along sling and trying it off into a series of shorter loops if you want.
I'll write this with all the civility I can muster. Daisy chains are a poor use for a tether for several reasons. This may be wordy but here goes.
1) First off lets clear the deck by understanding that the maximum threshold for human survival is said to be 12kn. Beyond that it doesn't matter if your system held - your dead or close to it. Therefore whatever systems we use must have as their primary function, the ability to keep the peak load in a worst case scenario (FF2) well below 12kn.
2) A daisy chain may have the strength to survive a FF2, but I doubt you would on the nearly static sling it is made of. However, a FF2 is highly avoidable. What is more plausible is a smaller loading.
3) In a small loading scenario, (ie slack in tether to move at anchor) the smaller bar tacks on a daisy *could* fail because of the lack of energy absorbing properties. This would lead to a zipper of all pockets to the end of the sling. When this happens the force will be near or above the human survival threshold. (DMM FF1, 13kn nylon, 21kn spectra) You will not survive that kind of impact.
4) Therefore we need to find a tether system that will either A) absorb the impact and keep a small shock from hurting the climber, or B) not allow smaller impacts to multiply into bigger ones.
5) I see two options.
For solution A) a Purcell prussic or a Beal Dynaconnection. Neither of these will ever approach a 12Kn load in any situation (less sure about the prussic, but the Dynaconnection has been lab tested and did quite well)
And B) a knotted nylon sling. At around 15kn total strength it is well above the human threshold. Most importantly, each link will not fail and cascade into a higher load. Secondly; while limited, the energy absorbing properties of nylon and the knot will help limit the total shock load on the climber. And because the knots keep the pockets smaller, the user is more likely to have less slack in the system to cause a longer fall/higher FF. DO NOT USE KNOTTED SPECTRA! According to the data I'm using (DMM Sling test) spectra knotted (low break strength 10kn) or unknotted (high shock load 20kn) does poorly.
6) A few notes to leave with. Even a FF1 on any tether would suck, so try to minimize the slack in your system at all times. I try to keep my'ne taught whenever possible. Just like when leading with a rope, the energy absorbing characteristics of the system are more important than max strength.
Thanks for reading, my intent is to inform. If I have been confusing in any way let me know so I can edit.
Edit for clarity
(This post was edited by Colinhoglund on Oct 7, 2010, 5:59 PM)
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Post edited by Colinhoglund
() on Oct 7, 2010, 5:59 PM
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