By saxfiend
Administrator
From Atlanta, GA
Nov 1, 2007
| Jed Pointer wrote: Knot used on Guide's wall -> person died. Any other questions?
Yes: 1) what makes you conclude from that accident report that the EDK is inherently dangerous? The logical conclusion based on the statements of the people involved is that it was a poorly-tied knot. 2) where in that story does it say the person died?
JL |  |
By Avery Nelson
From Boulder, CO
Nov 1, 2007
| Jed Pointer wrote: The link is in brenta's post. Knot used on Guide's wall -> person died. Any other questions? J
Jed, we've all seen that one before -- noone appears to have died.
I still haven't seen a single article indicating a death as a result of the knot, but that would be interesting to read if one can be scrounged up.
I the words of Ranger Mark:
"It's an interesting point to note that literally millions of rappels have been done involving this knot, without incident. Information on the name "Euro Death Knot" indicates that it was named so because one's first impression of its use is generally "no way."" | |
By Jed Pointer
From Boulder, CO
Nov 1, 2007
| "Knot used on Guide's wall -> person died."
I stand corrected.
Knot used on Guide's wall -> failed.
That's the difference between the lab and the field. You can get all scientific about it, but it still failed. I'd rather use a knot is less likely to come untied by itself, for whatever reason I can't possibly foresee, especially on paper, or in some lab, or from someone's talk on the internet.
J | |
By Zed
From Gotham City
Nov 2, 2007
| Jed Pointer wrote: "Knot used on Guide's wall -> person died." I stand corrected. Knot used on Guide's wall -> failed. That's the difference between the lab and the field. You can get all scientific about it, but it still failed. I'd rather use a knot is less likely to come untied by itself, for whatever reason I can't possibly foresee, especially on paper, or in some lab, or from someone's talk on the internet. J
Jed,
Several things about that story lead me to believe that human error probably had more than not to do with the failure. The first, and most obvious, are the references to 6" tails. Two words: "TOO SHORT".
Secondly, the girls repositioned the knot after the one fastened her rappel device, at which point one mentioned that it seemed loose. Instead of carefully examining the knot and physically checking it, one of the girls admonished the other to leave it alone because nether of them were familiar with his knot. Does anyone else here see the fundamental problem with that statement?
Why were two climbers, who were inexperienced to the extent that they could not safely evaluate a rappel knot, left alone above the guide to set up their own rappels? | |
By Jed Pointer
From Boulder, CO
Nov 2, 2007
| They were unable to repeat the failure. Therefore, we don't know what happened, except that it failed.
I can think of dozens of possible reasons. One rope was new (smooth) and the overhand offers less friction than knots that don't fail. Perhaps it was the cycled loading, like what doesn't get tested in the lab. Yada yada. Feel free to grab a slide rule and pretend you're omnipotent. No repeat = no clue.
The best analogy of this kind of flawed thinking is the Columbia disaster - no way foam could puncture a wing. Tons of testing done by tons of propeller heads for weeks on end. But it was the foam.
My observation has been that a small minority use the EDK knot, so the whole security in [inflated] numbers reasoning seems flawed to me as well.
To each their own, though. Just presenting another view. I design for high volume. 0.1% plus on yield justifies my salary for a year.
J | |
By Kevin Stricker
From Evergreen, CO
Nov 2, 2007
| Mal, The info I have is second hand from Craig Leubben regarding the increased strength of the overhand with a single strand backup...sorry I do not have the actual test results but I am sure you could get them from him.
Jed...I think it is interesting that you feel that a knot used almost exclusivly by professional mountain guides is "not safe enough" for you. Considering their job is tied directly to the safety of their clients, why would they use an inferior knot to join ropes?
As for the "small minority" using EDK's, maybe in your world but I am confident that if you polled climbers worldwide you would see that it actually is used in a large majority by climbers in many different countries. | |
By Ian Wolfe
From Boulder, CO
Nov 2, 2007
| I prefer to have clients pre-rig on rappel. My take on the story is that we don't know what happened.
The most important point to my mind is that the failure, as described, could not be repeated. Cold fusion was all the rage, but was disproven because it was not repeatable. This is how the scientific method works.
I think it is far more likely that human error was involved, either on the part of the guide, or on the parts of the climbers above (which unfortunately, is in most cases reflects an error on the guide's part). For example, I consider it possible that the two climbers messed with the knot, for some unknown gumby reason, then fixed it (or tried to). We already know this is partially the case because they moved the rope. However, if they had been pre-rigged, there would be no opportunity to move the rope, because their rap devices would be attached to it. Who knows what happened up there?
There have been literally millions of safe rappels on this knot. We are not talking about a margin of error of .1%. We are talking about a margin of 10^(-4)% or less. While notably this is speculation, I am sure the order of magnitude is at least comparable. Now compare this to your 1 in 79,746 chance of being killed by a lightning blast in your lifetime (for some fun procrastination, read http://www.nsc.org/lrs/statinfo/odds.htm). | |
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