sliding X
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rgold wrote: how about I get rid of the algebra? .Clearly, you don't know my background. But, since you are commenting on a public forum where readers have various mathematical backgrounds, you may want to provide better clarity for all to understand. But, again, you have complicated the question at hand. And, since you like to ask this question: Could you please cite multiple accounts where a sliding x led to anchor failure. Now, I'm really tired. |
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Greg D wrote: Clearly, you don't know my background. No I don't, but the fact that a basic argument involving just high-school algebra and physics "exhausted" you, combined with your suggestion that I'm wrong, a suggestion unaccompanied by any of the reasoning a mathematician or physicist or engineer would normally supply for such an assertion, made me think you aren't well-versed in at least one of those areas. Greg D wrote: But, since you are commenting on a public forum where readers have various mathematical backgrounds, you may want to provide better clarity for all to understand.I tried that with my second post, apparently without success. Greg D wrote:But, again, you have complicated the question at hand. First it didn't add up, now I complicated it, but you haven't explained anything, and I gave some very explicit arguments, twice now in response to your request. If the explanations I've offered are wrong, I'm more interested in finding out why then anyone. So it is now past time to actually explain your objections, in the technical terms appropriate to your background. Greg D wrote: Could you please cite multiple accounts where a sliding x led to anchor failure.Now you're just trying to avoid to explaining what's wrong with what I've said! But to answer your question, I'm not aware of even a single such anchor failure, much less multiple accounts. I've given what I believe to be a plausible explanation of how it could happen. Do we need to wait until that hypothetical situation comes true? Because if and when it does, you won't be able to tell what happened anyway once the anchor has totally failed. The situation is this: I've given what seems to me to be a plausible explanation of how an anchor extension could create very high loads. I also explained that Long and Gaines did a test which predictably would not find such increases. I mentioned, somewhat vaguely, that the DAV did some tests in 2009 that confirmed that such anchor load increases can occur. Unless you can offer some actual explanations of what the problems are with all this, there really isn't anything left to discuss is there? |
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rgold wrote: No I don't, but the fact that a very basic argument "exhausted" you, combined with your suggestion that I'm wrong, unaccompanied by any of the reasoning a mathematician or physicist or engineer would normally supply, made me think you aren't well-versed in at least one of those areas. I tried that with my second post, apparently without success. First it didn't add up, now I complicated it, but you haven't explained anything, and I gave some very explicit arguments, twice now in response to your request. If the explanations I've offered are wrong, I'm more interested in finding out why then anyone. So it is now past time to actually explain your objections, in the technical terms appropriate to your background. Now you're just trying to avoid to explaining what's wrong with what I've said! But to answer your question, I'm not aware of even a single such anchor failure, much less multiple accounts. I've given what I believe to be a plausible explanation of how it could happen. Do we need to wait until that hypothetical situation comes true? Because if and when it does, you won't be able to tell what happened anyway once the anchor has totally failed. The situation is this: I've given what seems to me to be a plausible explanation of how an anchor extension could create very high loads. Long and Gaines did a test which predictably would not find such increases. The DAV did some tests in 2009 that confirmed that such anchor load increases can occur. Unless you can offer some actual explanations of what the problems are with all this, there really isn't anything left to discuss is there?Go to bed. it's 3am your time! |
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I'm always up at this time! |
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I suppose you could tie an overhand on a bight in the middle of the sling instead of using the X...? |
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eli poss wrote: because there is a possibility that i may fall in a place that would cause it to load from one side or the other rather than directly below the anchor. the line i'm looking at traverses left for a little bit about 10 ft from the top and then goes up about 5 ft and then traverses back right. are there any other anchor set-ups that are multi-directional because the sliding X is the only one that i know ofare you thinking that somehow the masterpoint will explode in a pendulum toprope fall? I don't think you understand the term "multi-directional" in this case. |
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Greg D wrote: NoWhat this a "No" to shock loading being a myth? I don't have a formal education in physics, but it appears to me that shock loading is a real thing. If it isn't, could you explain why? |
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Greg DeMatteo wrote:I suppose you could tie an overhand on a bight in the middle of the sling instead of using the X...? Congratulations. You just became comfortable making a masterpoint. I never count a sliding x as being more than 1 anchor "point." I'll use it on occasion to load share between a couple stoppers, but I only count that as one piece.i know how to tie a master point, just not how to do it in a way that is equalized in an off-axis fall |
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redlude97 wrote: are you thinking that somehow the masterpoint will explode in a pendulum toprope fall? I don't think you understand the term "multi-directional" in this case.not really sure exactly what as pendulum top rope fall. and no i don't think it will explode, but there is no way to tell for sure whether a tree will hold until you fall on it which is why i want to use two equalized trees. i don't expect to take an off-axis fall but because of the nature of the route, there is a possibility of it happening and if i just tied a fig 8 in a bight and took an off-axis fall, most if not all of the force would be on one of the trees. i think what i'll do is extend the girth hitch over the edge and then use an equalette. |
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Folks, here's the article in DAV Panorama 2/2009 I mentioned that contains test results on the sliding X. You have to read German, of course. |
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Rgold, |
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eli poss wrote:there is no way to tell for sure whether a tree will hold until you fall on it which is why i want to use two equalized trees.If you don't trust either tree, are they really suitable as an anchor? I don't mind sketchy pieces on lead too much because there are many pieces below it, but I have higher standards for anchors. |
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eli poss wrote: i know how to tie a master point, just not how to do it in a way that is equalized in an off-axis fallThere isn't a way. Masterpoints are built to take a fall in one direction of force and "self-equalizing" anchors don't self-equalize. In both scenarios you need to build your anchor to take a fall in the most likely direction of force and then use directionals/common sense to ensure that it happens that way. |
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Patrick Shyvers wrote: If you don't trust either tree, are they really suitable as an anchor? I don't mind sketchy pieces on lead too much because there are many pieces below it, but I have higher standards for anchors.i do trust them but considering my life is in their hands, i'd like to have a back-up. its the same kind of thought process that causes us to make everything in our anchor set-up redundant. |
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Guy Keesee wrote:Why do you need to equalize Bolts or Trees?Exactly. Not directly related to the OP's question but still relevant -- It amazes me that so many climbers are obsessive about equalizing (modern) bolt anchors with webbing (sliding X) that is likely much weaker than either of the bolts themselves. Or they equalize it with a cordlette only to negate the redundancy they just created by using a single locking 'biner. Just use 2 quickdraws with gates opposed -- provided the bolts are evenly spaced. No need to build a science project at the anchor. |
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i would never equalize bolts unless they were placed oddly and couldn't just do it with different sized sling/draws. and the reason i equalize trees is because their strength is less predictable than bolts and if my life is on the line, then IMHO it is worth the few extra mins for the added safety and peace of mind. |
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eli poss wrote:also, how does a cordalette negate the redundancy of a single locking biner?It doesn't. |
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Greg DeMatteo wrote: It doesn't.i know but i wanted to see the guy's reasoning |
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I think he meant that using only one locker was negating the redundancy. His sentence structure was confusing and negated his logic. |
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eli poss wrote: i do trust them but considering my life is in their hands, i'd like to have a back-up. its the same kind of thought process that causes us to make everything in our anchor set-up redundant.Right, I'm not necessarily telling you to use just one tree as an anchor. But you can never really make an anchor that is maximally SERENE in all respects. There is no anchor that meets all 5 criteria perfectly, especially if you want dynamic equalization. So, you compromise. An anchor that is very Strong (trees, boulders) can sacrifice some Equalization or Non-Extending in the name of Efficiency. An anchor that is not very Strong (RURP pitons?) can make up for it with Redundancy and good Equalization. Basically what people are telling you here is, if you believe the trees are very Strong, don't worry about Equalization so much and think about making an anchor that is good for the other three, RENE |