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rgold
Jul 23, 2007, 10:51 PM
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Scrambled, here is a quote from: Measurement of Dynamic Rope System Stiffness in a Sequential Failure for Lead Climbing Falls. J. Mark Beverly and Stephen W. Attaway.
In reply to: Except for knot tightening, we did not observe rope hardening in the two impact drop. The rapid unloading after an anchor fails apears to reset the rope to its initial state. Testing on two-impact drops showed that a failing piece of climbing protection absorbs energy and reduces the total fall factor. In the example studied, about half of the energy was absorbed on the first impact. The "snap back" effect that seems to alleviate or eliminate rope hardening when the top piece of pro fails in a leader fall occurs in the slack rope that is created at the moment the top protection fails. If an arm on a tied cordalette fails, the belay experiences at most a pendulum-type fall, perhaps producing no slack in the belayer's tie-in. In this case, the failure of an anchor may simply harden the tie-in rope and so contribute nothing to lowering the peak force on other anchors. In the case of an extending anchor, paradoxically, the snap-back effect on the belayer's tie-in might, if the proportions are right, allow for the effects of energy absorbtion to reduce the load on the other anchors. If this is true, so called shock-loading might have a beneficial effect, as I rashly suggested in a SuperTopo thread entitled Equalizing Anchors, before Beverly and Attaway's tests became known. However, the belay anchor failure configuration is different from the climbing protection failure situation, for one thing the dynamics are much more complicated---even in the ideal case we have a two spring-mass system rather than a single spring-mass system. So all this is totally speculative and awaits some drop tests that simulate a falling leader and a tied-in belayer.
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sittingduck
Jul 23, 2007, 11:23 PM
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The myth: The fact: Correct?
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curt
Jul 24, 2007, 1:13 AM
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weiman wrote: Well, balanced or equalized means the same thing in my mind. You can easily build an anchor that is equalized, in one direction, and at the same time doesn't extend... Who (who had no idea what they were talking about) told you that? It is actually almost impossible to construct a real-world anchor that is both equalized and non-extending. At best you will get some very unequal type of load sharing between the various anchor elements. Curt
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majid_sabet
Jul 24, 2007, 1:48 AM
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curt wrote: weiman wrote: Well, balanced or equalized means the same thing in my mind. You can easily build an anchor that is equalized, in one direction, and at the same time doesn't extend... Who (who had no idea what they were talking about) told you that? It is actually almost impossible to construct a real-world anchor that is both equalized and non-extending. At best you will get some very unequal type of load sharing between the various anchor elements. Curt That would be nice if we could have an anchor checker to see which anchor is well balanced or equalized . Belay Anchor #1 Belay Anchor #2 Directional anchor #1 backup #1,2 and 3 Personal anchor 1 ,2,3 main anchor 1 [URL=http://imageshack.us]
(This post was edited by majid_sabet on Jul 24, 2007, 1:49 AM)
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weiman
Jul 24, 2007, 3:46 AM
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It is true that you cannot equalize multiple anchors perfectly and at the same time have absolutely no extension in case of a failure. However, it is possible to reasonably equalize multiple anchors in one major direction and at the same time have very little extension. Since I personally always want each of the anchors to be strong enough to support any potential force, I think it is more important to minimize the potential extension in case of a failure than to have perfect equalization. You can find many examples on how to equalize multiple anchors with minimal extension in any basic climbing book. Page 106 in How To Rock Climb (3rd edition) by John Long just to give you one example.
(This post was edited by weiman on Jul 24, 2007, 3:55 AM)
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tradklime
Jul 24, 2007, 4:36 AM
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weiman wrote: It is true that you cannot equalize multiple anchors perfectly and at the same time have absolutely no extension in case of a failure. However, it is possible to reasonably equalize multiple anchors in one major direction and at the same time have very little extension. Since I personally always want each of the anchors to be strong enough to support any potential force, I think it is more important to minimize the potential extension in case of a failure than to have perfect equalization. You can find many examples on how to equalize multiple anchors with minimal extension in any basic climbing book. Page 106 in How To Rock Climb (3rd edition) by John Long just to give you one example. I find it interesting how often peoples expressed comprehension of a subject is inversely proportional with their experience with said subject.
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jt512
Jul 24, 2007, 4:53 AM
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tradklime wrote: weiman wrote: It is true that you cannot equalize multiple anchors perfectly and at the same time have absolutely no extension in case of a failure. However, it is possible to reasonably equalize multiple anchors in one major direction and at the same time have very little extension. Since I personally always want each of the anchors to be strong enough to support any potential force, I think it is more important to minimize the potential extension in case of a failure than to have perfect equalization. You can find many examples on how to equalize multiple anchors with minimal extension in any basic climbing book. Page 106 in How To Rock Climb (3rd edition) by John Long just to give you one example. I find it interesting how often peoples expressed comprehension of a subject is inversely proportional with their experience with said subject. That's unfair. OK, I mean, maybe you'd have a point if the guy only lead like 5.1 or 5.2. But he leads 5.3. You must be one them elitists I keep hearin' about. Jay
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weiman
Jul 24, 2007, 4:58 AM
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That is a very good observation. Someone once told me the following that explains this in an interesting way: Knowledge is like being inside an inflated baloon. The more knowledge and experience you gain the more the ballon inflates. The inner surface of the baloon is shielding you from everything you don't know - everything that's outside of th baloon. When the baloon is small it looks like the area of the surface is small but the more you inflate it the more the area of the surface increases. This basically tells you that the more you learn about any given subject, the more you realize how much more there is that you don't know.
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jt512
Jul 24, 2007, 5:06 AM
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weiman wrote: That is a very good observation. Someone once told me the following that explains this in an interesting way: Knowledge is like being inside an inflated baloon. The more knowledge and experience you gain the more the ballon inflates. The inner surface of the baloon is shielding you from everything you don't know - everything that's outside of th baloon. When the baloon is small it looks like the area of the surface is small but the more you inflate it the more the area of the surface increases. This basically tells you that the more you learn about any given subject, the more you realize how much more there is that you don't know. Maybe I can help you get of your balloon: You're a beginner who climbed for less than a year 5 years ago, and has climbed for a few months this year. Your knowledge of anchors is essentially limited by what you've read in a single book that was written primarily for beginners. You have less experience (essentially none) than everyone else in this thread, and practically everyone else on this website. In other words, you don't know much at all. So, please, opine less, and listen more. Jay
(This post was edited by jt512 on Jul 24, 2007, 5:09 AM)
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majid_sabet
Jul 24, 2007, 5:42 AM
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jt512 wrote: weiman wrote: That is a very good observation. Someone once told me the following that explains this in an interesting way: Knowledge is like being inside an inflated baloon. The more knowledge and experience you gain the more the ballon inflates. The inner surface of the baloon is shielding you from everything you don't know - everything that's outside of th baloon. When the baloon is small it looks like the area of the surface is small but the more you inflate it the more the area of the surface increases. This basically tells you that the more you learn about any given subject, the more you realize how much more there is that you don't know. Maybe I can help you get of your balloon: You're a beginner who climbed for less than a year 5 years ago, and has climbed for a few months this year. Your knowledge of anchors is essentially limited by what you've read in a single book that was written primarily for beginners. You have less experience (essentially none) than everyone else in this thread, and practically everyone else on this website. In other words, you don't know much at all. So, please, opine less, and listen more. Jay I love it when Jay gets mad and then in a nice way is calling the guy a n00b.
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weiman
Jul 24, 2007, 5:52 AM
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Well, a lot of reading and less writing than you get from almost anyone else who writes on this forum is exactly what you have gotten from me over the last couple of years. If there is a rule that you have to be able to climb 5.12 to be allowed to participate in the discussions here then I'm afraid I have to shut up for the foreseeable future. Unfortunately I have failed to find any information of such a rule anywhere on the site. I love climbing and as I am a beginner I am very eager to learn everything I can from all the more experienced climbers. One way I am going to continue to learn is by reading a lot from this forum and other sources, and participating in the discussions when I find a reason to do so. If you don't like that - sorry, you have to deal with it. To conclude this discussion I want to tell you that one of the reasons I like climbing more and more is because almost everyone I have come across at the crags are really nice and helpful people willing to share their knowledge and help in any way they can. Maybe I should spend more time at the crags and less time at the computer? P.S. If you think it is possible for anyone to get outside of the knowledge balloon then you have missed the whole point of that part of the discussion.
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majid_sabet
Jul 24, 2007, 6:01 AM
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ohh boy The war of n00b against the mighty Jay on a very serious topic. Let me get some popcorn ready
(This post was edited by majid_sabet on Jul 24, 2007, 6:02 AM)
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curt
Jul 24, 2007, 6:05 AM
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weiman wrote: ...I love climbing and as I am a beginner I am very eager to learn everything I can from all the more experienced climbers. One way I am going to continue to learn is by reading a lot from this forum and other sources, and participating in the discussions when I find a reason to do so. If you don't like that - sorry, you have to deal with it... Oh, all of that is perfectly fine. Just stop posting stupid stuff. Curt
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mojede
Jul 24, 2007, 6:18 AM
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Up the ante folks--put it into a rescue/raising scenario that has the victim, the litter-tender, and usually a medical person on the static line. With a 500+ lb. load on the non-dynamic system, a piece ripping could essentially create a catastrophe to the people involved. If you are not convinced that "shock loading" is a real danger, go do some tests using yourself as the "live load"--you will not pose the question again.
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jt512
Jul 24, 2007, 6:21 AM
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weiman wrote: I love climbing and as I am a beginner I am very eager to learn everything I can from all the more experienced climbers. One way I am going to continue to learn is by reading a lot from this forum and other sources, and participating in the discussions when I find a reason to do so. If you don't like that - sorry, you have to deal with it. Fair enough. You keep posting uninformed opinions, I'll keep pointing out that you don't know what you're talking about, and we'll both just "deal with it."
In reply to: To conclude this discussion... Is that a promise? Jay
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majid_sabet
Jul 24, 2007, 7:00 AM
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mojede wrote: Up the ante folks--put it into a rescue/raising scenario that has the victim, the litter-tender, and usually a medical person on the static line. With a 500+ lb. load on the non-dynamic system, a piece ripping could essentially create a catastrophe to the people involved. If you are not convinced that "shock loading" is a real danger, go do some tests using yourself as the "live load"--you will not pose the question again. These guys already have problem understanding the basic climbing anchor. Please do not confuse them with heavier topics.
(This post was edited by majid_sabet on Jul 24, 2007, 7:03 AM)
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microbarn
Jul 27, 2007, 10:51 AM
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John Long has amended his stance. Have you read the new anchor book? Some people that can't climb 5.12 discussed shock loads in anchors with real test results here: http://www.rockclimbing.com/...post=1306133#1306133 There are some summary threads around too if you wanted to search for them.
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weiman
Jul 27, 2007, 12:47 PM
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Thanks a lot for the pointer. Those discussions are really useful and interesting. I have heard about JL's new book. Haven't bought it yet but I will definitely do so.
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sterlingjim
Jul 27, 2007, 2:58 PM
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microbarn wrote: John Long has amended his stance. Have you read the new anchor book? Some people that can't climb 5.12 discussed shock loads in anchors with real test results here: http://www.rockclimbing.com/...post=1306133#1306133 There are some summary threads around too if you wanted to search for them. I was wondering when someone would bring up that thread.
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sittingduck
Jul 30, 2007, 12:47 PM
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microbarn wrote: John Long has amended his stance. Have you read the new anchor book? Some people that can't climb 5.12 discussed shock loads in anchors with real test results here: http://www.rockclimbing.com/...post=1306133#1306133 There are some summary threads around too if you wanted to search for them. I have not seen the book, anyone know what it says about this matter? Is it more accurate than what JL say here in the sliding x thread?
(from the huge sliding x thread) vivalargo wrote: In other words, the phobia about extension in the Sliding X (with limiter knots) producing "shock loading," or for that matter, ANY significant increase in loading, is looking almost certainly like another anchoring myth. Did he amend this, and if so, in what direction?
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verticon
Jul 31, 2007, 6:59 AM
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Let's get back to the definition of shock loading. Are we speaking about impact loading (where the load is applied at a speed close to the propagation speed of the mechanical waves in a solid - certainly a mith in climbing if you don't use a funkness device instead of a rope) or just high speed loading ?
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blueeyedclimber
Jul 31, 2007, 1:02 PM
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whether shock-loading exists or not, it is not necessarily a consideration in every anchor. I agree with John Long that the basis for EVERY anchor should be solid individual pieces. Josh
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