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desertwanderer81
Apr 22, 2009, 8:49 PM
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Hey, does anyone have any information on what the force which is required for a Jumar to cut through a rope? I realize that this is different for different makes of ropes and diameters, but I'm still interested.
Thanks!
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majid_sabet
Apr 22, 2009, 9:19 PM
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desertwanderer81 wrote: Hey, does anyone have any information on what the force which is required for a Jumar to cut through a rope? I realize that this is different for different makes of ropes and diameters, but I'm still interested. Thanks!
I have some documents but need to find it for you. See fatality accident report on Oct 2008 in Zion national park where a climber falls on jumar and cut the rope. The link should be in Supertopo.com and RC.
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desertwanderer81
Apr 22, 2009, 9:25 PM
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I know of the accident. That was mostly my inspiration for asking if anyone had any testing.
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majid_sabet
Apr 22, 2009, 9:31 PM
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desertwanderer81 wrote: I know of the accident. That was mostly my inspiration for asking if anyone had any testing.
I have some testing document on Gibbs which is not far from Jumar. I will try to find them for you.
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desertwanderer81
Apr 22, 2009, 9:37 PM
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wicked score man! Thanks!
I know a general rule of thumb of "don't fall on it" is good, but it would still be nice to know what kind of ranges we're working with, ya know?
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ryanb
Apr 22, 2009, 10:25 PM
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This doc has some stuff:
http://www.hse.gov.uk/...df/2001/crr01364.pdf
I don't have time to go through it right now and figure out which bits are relevant but it convinced me that toothed (min traxion) was the way to go for solo tr. Wild country has some information on the ropeman mk II vs mk I is also informative.
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clintcummins
Apr 23, 2009, 1:23 AM
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The October 2008 fatality in Zion (James Welton) was unusual for several reasons. He was using Petzl ascenders to ascend a 9.5mm static rope which was weighted below with haul bag(s). The rope was partly secured at the anchor above with a Petzl ProTraxion hauling pulley. Apparently the hauling pulley was not fully closed and the load caused it to open further and 20' or so of rope slipped through suddenly. This caused the haul bag(s) and Welton to drop 20', at which point the ascender(s) reloaded the rope, damaging the sheath to the point of failure. The core then failed as well and the rope broke.
I doubt that changing the type of ascenders or diameter of the rope would change the outcome of this accident (but I could be wrong). Having no haulbag weighting the rope, or a dynamic haul rope might make a difference. But most important is to have the fixed rope you are ascending be properly anchored.
You could test ascenders and ropes to see if they would sever the rope in a more likely situation, such as if a person is cleaning an aid pitch (ascending a dynamic lead rope), and some protection above them fails where the rope makes a turn (such as on a traverse). Say they fall 20' on 80' of rope and they weigh 180 pounds - does the rope get severed?
A second situation where ascenders could be loaded heavily is if you have taken an aid climbing leader fall, and are using ascenders to regain your high point. In the process, if your highest piece of protection fails, you take a leader fall, and it might be long if more protection fails sequentially. In this situation, Pete Zabrok recommends using a GriGri to ascend the rope, because it loads the rope over a larger surface. (In general, ascending with a GriGri is slow, but it may be advised in this situation where a second leader fall is somewhat likely).
In some posts to this thread, they mention Jumars very casually, which might be taken to mean that Jumar brand ascenders were used in the 10/2008 fatality. They were not. You should be careful to use "ascender" instead, unless you have a particular brand in mind. In Majid's second post, he recognizes that Gibbs ascenders impact the rope differently than Jumars (and by implication, other ascenders differ as well).
Links for the 10/2008 Zion accident:
http://www.supertopo.com/...html?topic_id=808440
http://www.supertopo.com/..._id=701629&tn=40
(This post was edited by clintcummins on Apr 23, 2009, 1:33 AM)
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angry
Apr 23, 2009, 1:43 AM
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There are a bunch of things that added up to the fatality. It's quite possible that if you took any away, he'd be fine.
Would it have happened it he
-jugged with prussicks - maybe
-used 11mm rope - maybe
-didn't have the haulbag attached - maybe
-tied to rope off to the anchor, not the protrax - the entire incident would have been avoided.
It is the classic case of the perfect storm. It all just added up.
I've always felt connected to this one, I was across the valley on another route. James and I enjoyed the same sunshine and watched the same birds all day. We even looked down at the same buses running their tours. I was home before I knew what happened, it turns out that I left 1/2 hour before he fell.
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desertwanderer81
Apr 23, 2009, 1:58 AM
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It's always upsetting when one of us passes on due to an accident. It's even worse when you were climbing nearby the same day and especially worse when that person was a partner of yours.
I've experienced both, but luckily never at the same time.
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angry
Apr 23, 2009, 2:27 AM
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I didn't know him.
Sometimes it's just as bad to lose a kindred spirit.
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desertwanderer81
Apr 23, 2009, 1:04 PM
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From personal experience, it's always worse when it's a close personal friend who has passed on doing the thing that you've both love and have done together.
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clintcummins
Apr 23, 2009, 8:11 PM
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angry wrote: There are a bunch of things that added up to the fatality. It's quite possible that if you took any away, he'd be fine. Would it have happened it he -jugged with prussicks - maybe -used 11mm rope - maybe -didn't have the haulbag attached - maybe -tied to rope off to the anchor, not the protrax - the entire incident would have been avoided. It is the classic case of the perfect storm. It all just added up. ...
Good points.
One comment: substituting prusiks for ascenders is still pretty risky. While the prusik will not sever the climbing rope, in a fall it is likely to slip down the rope and will melt itself and fail if it slips far enough.
http://en.wikipedia.org/wiki/Prusik (for spelling)
Sorry that you knew him and were there that day.
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Terry2124
Apr 24, 2009, 2:42 AM
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desertwanderer81 wrote: Hey, does anyone have any information on what the force which is required for a Jumar to cut through a rope? I realize that this is different for different makes of ropes and diameters, but I'm still interested. Thanks!
Not sure on the stats but I know on the instructions it says its not made to take a fall.
I din't know they cut through rope on a fall, that sucks. Must have been a big fall.
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