Discussion Topic |
|
This thread has been locked |
Karl Baba
Trad climber
Yosemite, Ca
|
|
|
Dec 11, 2008 - 03:06am PT
|
George R posted this on another thread and I'm taking it upon myself to repost it on two related threads and this is one of them. The forces in question are particularly magnified if the fall goes directly on the belayer and a piece pulls
Peace
Karl
"On Nov 23rd, rgold wrote:
" John, one thing that worries me, and I have to apologize profusely for not catching it early on, is that Jim's tests on the effect of elongation in the anchor, the ones that lead to the conclusion that elongation doesn't matter, do not seem to me to be properly configured to test the real situation. There was too much energy-absorbing rope in the system, relative to the amount of elongation, leading to insignifcant changes in fall-factor and so a conclusion that might not be appropriate for real anchoring situations. In a real situation, it is the belayer's anchor strand that will have to absorb the belayer's fall (plus whatever load the belayer is holding at that instant). Minimally, the anchor strand will have to absorb a fall by the combined weights of leader and belayer. If that anchor strand is short, say a foot and a half, and if the elongation in the anchor is, say, six inches, then you still have a fall factor of 1/3 with something like 350 pounds, and there is no way this isn't going to load the anchor significantly. This means that the intelligent use of sliding systems ought to involve tying into them as long as possible, given the nature of the stance. "
Right. A general conclusion that anchor rigging elongation (aka extension) is harmless is not supported by any test data.
The Long/Sterling tests simulate a situation in which a climber is rope soloing without a haul bag or belayer or any other significant weight on the anchor. This tells us almost nothing about what happens when the belayer (and/or 3rd climber, haul bag, etc.) falls due to extension. Depending on the circumstances, such a fall could have a very high fall factor (possibly greater than FF 2) on a tied-off rope (no belay to slip and limit force). Or worse yet, onto a static tether such as a sling or daisy chain.
Rock & Ice magazine also did some tests to examine the anchor extension question. (See Rock & Ice #135, July 2004). Their conclusion was extension is dangerous. They also made the error of generalizing from one situation to all situations, however their tests are more relevant to the situation we're concerned with. The R&I test was perhaps extreme (no dynamic rope at all) but they more accurately modeled the situation of the belayer falling on to the belay anchor due to extension.
The key to reconciling the differing test results and to understanding the extension problem is the Fall Factor. In the Long/Sterling tests, extension resulted in insignificant additional force placed on the remaining anchor point. Exactly what we should expect in that situation, because the fall factor was not increased much by the extension. In the R&I tests, the fall factor was high and no dynamic rope was involved, so extension caused a large force on the remaining anchor point. Again, just what should be expected.
It should be emphasized that it is the belayer (and/or other large masses attached to the anchor) that matters. A falling climber may have enough dynamic rope out to keep the fall factor low and minimize additional force from anchor extension. The belayer, third climber, haul bag or whatever may not. They will often be tied (not belayed) to the anchor with relatively little dynamic rope or perhaps none at all. Fall factors and forces may therefore be very high. The issue is how much dynamic rope compared to how much extension with respect to each falling mass in the system.
The Long/Sterling tests and the Rock & Ice tests each tell us something, but not everything, about the potential dangers of anchor rigging extension. If we apply the fall factor concept, and consider ALL the significant masses that are involved in a given situation, we can draw the correct conclusion for that situation.
Again, the issue is how much dynamic rope compared to how much extension with respect to each falling mass.
G "
|
|
dirtineye
Trad climber
the south
|
|
|
Dec 12, 2008 - 12:41am PT
|
Just a "make em eat their vegetables" kind of bump.
|
|
Radish
Trad climber
Seki, California
|
|
|
Dec 12, 2008 - 12:25pm PT
|
I think there was an accident on the East Buttress of Middle Cathedral where a two person team got peeled from the belay. There was alot of speculation on what happened and how could the anchor be riped like that. We did the climb soon after and before we knew about what happened. The belay in question had really hard placements all mostly small. We put in as many pieces as we could spare. Then the climb goes straight up above the belayer who is standing on a very skinny ledge. We could see how just a slip the wrong way for the leader could bring the full leader weight right on the belayer. Though its pretty easy just to climb up to where you can get a piece in. I may be wrong on this total description but I like to know about these accidents to gleen anything that will help.How many actual total anchor failures have there been lately, since the newer gear??
|
|
madbolter1
Big Wall climber
Walla Walla, WA
|
|
|
Dec 12, 2008 - 02:18pm PT
|
Uhhh... YEAH, Steve, that IS the point, and the point is that NOBODY can reliably translate the finest theoretical points into any useful (or even quasi-reliable) real world application.
Show me ONE person that looks at an anchor and thinks thus:
"Ok, strongest placement is a #2 head, good for ~xLbs, translates into potentially (best case) ykNs. Leader potentially out 10 feet before first fall-holding placement, so potential 20 foot fall. He weighs 160Lbs, so potential impact force of zkNs, duration of .01 seconds. Clipping lead rope to placement means 1.72 to 1 fall factor, uhhh... means... uhh... placement must absorb 1.83zkNs (blah, blah, blah... insert ridiculous odds calculations here). Odds of the placement holding: ~1013.8752 to 1. Conversely, the whole anchor (blah, blah, blah... insert ridiculous string of similarly ridiculous and unreliable calculations here), meaning that the odds of the whole anchor holding are 647.8845 to 1. Ahhh... in this case, clearly it's better to not lead-clip that strongest placement. It's our lives, so I'll take those better (although still basically sure death) odds any day!"
Oh, sure, almost all of us do a vague assessment of our anchors. My point is that the FINE theoretical points really don't do much to inform such a decision with ANY reliability. In the real world we simply rate anchors from bomber to sh|t, most far closer to the bomber end of the scale; and my assertion is that any anchor that is so sh|t that you can't find any placement (or two) worth clipping the lead line into is an anchor for which you had better find an alternative. The idea that you're going to belay at such an anchor and DEPEND upon the fine advantage of catching the leader fall onto your harness is, in my mind, absurd. There are ALWAYS so many better alternatives than that.
One might respond that there are situations in which there ARE no alternatives, so we had BETTER get these fine calculations RIGHT.
And I will respond: If you find yourself in such a situation, I hope you live through it because I really want to hear how there was NOTHING you could do but choose whether or not to clip the lead line in anywhere at the anchor. And I'm going to present some alternatives and then note that the fine calculations did nothing to actually inform your decision and that the BEST fine calculation you could perform in that case (akin in reliability, btw) would be to calculate the odds of the existence of the Judeo/Christian God and the odds that He would take you to His bosom if you were to bite the big one. Those sorts of calculations would be a more productive use of your energies, as would bending forward to kiss....
Otherwise, just lead-clip the best anchor placement(s) and enjoy the benefits.
|
|
rgold
Trad climber
Poughkeepsie, NY
|
|
|
Topic Author's Reply - Dec 12, 2008 - 03:29pm PT
|
MB wrote, "NOBODY can reliably translate the finest theoretical points into any useful (or even quasi-reliable) real world application."
I guess then that the entire history of science and engineering is a phantasmagorical illusion and the technology that now entirely shapes our lives has sprung fully-realized from seat-of-the-pants intuitions of visionary inventors.
"Show me ONE person that looks at an anchor and thinks thus...
Nobody does that. Does any driver do analogous calculations when they step on the brake? No. Did SOMEBODY do those calculations? Absolutely. Or closer to home, does anyone placing a cam pause to consider the calculations that lead to the ideal cam shape? Do most of the people placing cams even know what the shape of their cams is and why? Did the fine theoretical points involved in those calculations have any useful real-world application?
"In the real world we simply rate anchors from bomber to sh|t, most far closer to the bomber end of the scale; and my assertion is that any anchor that is so sh|t that you can't find any placement (or two) worth clipping the lead line into is an anchor for which you had better find an alternative."
Given that the overwhelming majority of climbers have never tested an anchor to failure after rating it on the bomber-sh|t scale (or b.s. scale for short), how likely is it that their b.s. rating is 100% reliable? OK then, how about their b.s. rating being accurate half the time---how likely is that? Does it then make any sense, then, to think about procedures that could minimize the consequences of inevitable human fallibility?
"The idea that you're going to belay at such an anchor and DEPEND upon the fine advantage of catching the leader fall onto your harness is, in my mind, absurd. There are ALWAYS so many better alternatives than that."
Three points:
(1) One point of the calculations, is to try to decide whether not clipping the anchor is a "fine advantage" in what I take to be your sense, which is "negligible advantage," or whether it might be a substantial advantage, in terms of the load to the anchor. I don't think we have yet arrived at a definitive answer. Conversations such as the one partially carried out here are an essential ingredient in either achieving that answer or concluding, but not prematurely, that clarity will not be attainable. What purpose is served by attempting to curtail such discussions?
(2) The leader fall, as explained in Chris Harmston's rec.climbing post years ago, should not be caught on the harness. It is essentially caught on the anchor, ideally with a some mitigating resistance from the belayer, but without the force-multiplying pulley effect at the anchor one gets by clipping it.
(3) Since you said there is always a better alternative, one can without hesitation respond that such a claim is false. But semantics aside, what if the belayer misjudges the anchor and so does not opt for the better alternative? Or do we have to assume belayer infallibility in order for any of your points to be valid?
|
|
madbolter1
Big Wall climber
Walla Walla, WA
|
|
|
Dec 12, 2008 - 03:59pm PT
|
rgold, you missed the most important word of the first passage from me you quoted: "reliably." Am I claiming that this discussion is completely useless? Of course not? Am I claiming that there are not engineers that do perform all sorts of calculations? Of course not. Don't straw-man my position. My emphasis is on the vast number of unknowns and variables that go into a real-world assessment of a climbing anchor. Is that head REALLY good for 800Lbs? What are the odds of it? And so on. It IS ridiculous to think that the reliability could be achieved that would make the "negligible advantage" tangible in such admittedly sketchy situations. The more pressing the need to decide one way or the other on this question, the more pressing is the measure of unreliability. Engineering doesn't even touch, much less solve, that problem. My only point.
Do I find such discussions themselves useless? No, because a "seat of the pants" understanding derives from SOME measure of thinking about such things. Our intuitions are informed by background knowledge, which is how we can come to an intuitive notion that a placement will or won't hold a fall. So, such discussions are useful in educating all of our intuitions. However, that usefulness does not (imho) translate into providing a useful answer to the topic question of this thread.
The way to minimize human fallibility is to "back it up," but that is the very thing that is denied by the theoretical scenarios suggested as reasons to not lead-clip a placement. At the end of the anchor spectrum this thread is discussing the questions of human fallibility and lack of data are most pressing. Again, the theoretical discussion does not really address the actual topic question of this thread. Does that make it useless? Again, no. As I have said, no. But the usefulness is (imho) not applicable to the topic question.
Now to your three points:
(1) And we will forever lack a definitive answer.
(2) That model seems WORSE to me, not better, for addressing the force-transference issue. By catching the leader on the harness, at least you've got the belayer thrashing around (which actually helps a lot), his body compressing in the harness (which also helps), and so on. On the direct-to-anchor model, the forces go straight to the anchor without benefiting from all of the above "dynamic" aspects of a belayer. But, again, this just makes my point about the "fine" details here that just don't really translate into making an actual difference. No accident report is going to say, "The team died because, unfortunately, the belayer was too ignorant to catch the falling leader onto his harness. His decision to catch the leader with the anchor instead cost the team their lives. If only climbers would read and understand the engineering!"
(3) Is your problem with the word "always" in this context? If so, then I would respond that just because you can use the word "semantics" does not indicate that you understand the underlying logic. If you like, I will produce a mathematical induction (a form of deduction) for you demonstrating that my claim is in fact logically sustainable and correct. Furthermore, I'm baffled by your last sentence. It seems to me that you are making MY point: the whole situation as described is a mess, and the idea that the topic question is really the one that matters in such a situation is a red-herring question. In such a situation, you have much more important and practically-useful things to consider than whether or not to lead-clip an anchor placement.
|
|
dirtineye
Trad climber
the south
|
|
|
Dec 12, 2008 - 05:07pm PT
|
Madbolter1, just so you know, yes, mathematicians and scientists DO have a problem with words like "always", and "every", and other absolute terminology, when it is used improperly.
Just one more tip-- before you really get into a donnybrook with Rgold about this stuff, you'd better have your act together.
The modeling these guys have done is important. If you can find something wrong with it, fine, point out the error! Otherwise...
Oh and back in the says before I had all this trouble, I used to look at mist distribution along the interstate and ponder modeling it with a system of partial DE, so, yeah people do that sort of thing, and there are a lot more of em than you might realize.
|
|
Jaybro
Social climber
wuz real!
|
|
|
Dec 12, 2008 - 05:20pm PT
|
Would you Ever, climb with someone who doesn't do a sort of Clif notes version of that analysis on every single belay? -assuming swapping leads or at least belaying in possibly dicey situations.ie that the other partner is in a position to make decisions, not a n00b client or something.
I wouldn't, either.
|
|
rgold
Trad climber
Poughkeepsie, NY
|
|
|
Topic Author's Reply - Dec 12, 2008 - 06:45pm PT
|
MB wrote, "Am I claiming that this discussion is completely useless? Of course not? Am I claiming that there are not engineers that do perform all sorts of calculations? Of course not. Don't straw-man my position."
You coulda fooled me. As for straw-manning, what is that entire paragraph of dumb pseudo-calculation? Who ever said climbers were making calculations at their belay stations? Let he who is without straw-man sin cast the first stone!
MB wrote, "My emphasis is on the vast number of unknowns and variables that go into a real-world assessment of a climbing anchor...It IS ridiculous to think that the reliability could be achieved that would make the "negligible advantage" tangible in such admittedly sketchy situations. The more pressing the need to decide one way or the other on this question, the more pressing is the measure of unreliability. Engineering doesn't even touch, much less solve, that problem. My only point"
To my perhaps insensitive ears, you have changed your tune. You now seem to be saying that there are so many variables and unknowns that it is impossible for the belayer to reliably judge an anchor, and that the degree of unreliability in belayer judgement increases as the anchor itself becomes increasingly suspect. But if the belayer cannot make reliable judgements, then an engineered solution that protects the anchor, independent of the belayer's potentially faulty analysis, seems to me to be even more desirable, not less. (P.S. I am not an engineer!) Secondly, it is you who have said not clipping provides a negligible advantage, not me.
MB wrote, "Do I find such discussions themselves useless? No, because a "seat of the pants" understanding derives from SOME measure of thinking about such things. Our intuitions are informed by background knowledge, which is how we can come to an intuitive notion that a placement will or won't hold a fall. So, such discussions are useful in educating all of our intuitions. However, that usefulness does not (imho) translate into providing a useful answer to the topic question of this thread."
I agree with you about all of this except that I haven't myself arrived at final judgement on the utility of the answer, and most humbly suggest that you may be premature in your dismissal.
MB wrote, "The way to minimize human fallibility is to "back it up," but that is the very thing that is denied by the theoretical scenarios suggested as reasons to not lead-clip a placement.
If by backing it up you mean placing an independent good piece for the leader, I think everyone agrees with that. In the absence of such a piece, or in the presence of the failure of such a piece, backing up isn't available in the anchor discussion. Clipping the anchor with the lead rope certainly doesn't back it up. So, in the absence of back-ups, isn't it reasonable to ask, "what options will stress the anchor the least?"
MB wrote, "That model seems WORSE to me, not better, for addressing the force-transference issue. By catching the leader on the harness, at least you've got the belayer thrashing around (which actually helps a lot), his body compressing in the harness (which also helps), and so on. On the direct-to-anchor model, the forces go straight to the anchor without benefiting from all of the above "dynamic" aspects of a belayer."
Under equivalent belayer behavior, the anchor gets a higher load from redirection then it does from the direct (belayer mediated) connection, once the break-even point has been passed by the leader. This makes it an interesting and useful theoretical question to ascertain just how far up that break-even point is. Such questions were the focus of the theoretical discussion you have heaped so much scorn upon.
The reason the direct connection might be better than inserting the harness as a critical link in the belay chain is that, as John pointed out, the latter approach might turn the belayer into a second falling object whose fall energy has to be absorbed by the tie-in, and this will raise the load on the anchor.
In any case, as far as the clip/no clip question goes, objecting to the direct vs. indirect belayer connection is irrelevant. Whatever method you use only has to be better than a redirected belay to be significant. So if the direct connection proves significant, your argument simply indicates that the indirect connection would give even better results, rather than somehow constituting a worse model as you suggest.
MB wrote, "Is your problem with the word "always" in this context? If so, then I would respond that just because you can use the word "semantics" does not indicate that you understand the underlying logic."
The word "semantics" belongs to the study of linguistics, so using it does not bear in one way or the other on my logical competence. My sin, for which I apologize, is in being too logical, rather than in failing to understand anything about some unspecified underlying logic. "Always" means without exception. You seriously suggest that there is absolutely never in any case in the past, present, or possibly infinite future that would constitute an exception to your claim? Really?
MB wrote, If you like, I will produce a mathematical induction (a form of deduction) for you demonstrating that my claim is in fact logically sustainable and correct."
I am most interested in seeing a proof of your claim by mathematical induction, and await its appearance.
MB wrote, "Furthermore, I'm baffled by your last sentence. It seems to me that you are making MY point: the whole situation as described is a mess, and the idea that the topic question is really the one that matters in such a situation is a red-herring question."
I thought your point was that if the anchor is good, why not clip a piece and if the anchor is bad, then you should (and ALWAYS would be able to) find an alternative. My point was if the belayer misjudges, then they fail to seek the alternative when they need to. How does this make your point?
As for the topic question (as opposed to the method of answering it) being a red-herring in such situations, this is certainly a position one might take. The term does have the connotation that the poser of the question intentionally means to mislead the audience by shifting attention from the real point, and I doubt you meant that. (Ho, ho, more semantics, eh?) If you had simply said earlier that the question posed as the topic of the thread was irrelevant to what "matters," then perhaps we wouldn't have ended up typing all this crap!
|
|
madbolter1
Big Wall climber
Walla Walla, WA
|
|
|
Dec 12, 2008 - 06:49pm PT
|
Having a Ph.D. in philosophy myself, with a significant emphasis in logic, including mathematical logic, I too dislike uses of a word like "never" and "always," when, as dirtineye pointed out, "it is used improperly." However, I did not use a word "improperly." This is a stupid point to argue about however. The real issue is my supposed need to "have my act together."
Wow, are these engineer types really THAT defensive? All I have stated so far is that all the engineering talk really doesn't address the real-world implications of the TOPIC QUESTION of this thread. You guys can set up and knock down all the straw men of that point you like, if that makes you feel any better.
Jaybro, put these two sentences of mine together, and let's see what you get: "Almost all of us do a vague assessment of our anchors. My point is that the FINE theoretical points really don't do much to inform such a decision with ANY reliability. In the real world we simply rate anchors from bomber to sh|t, most far closer to the bomber end of the scale." And: "Do I find such discussions themselves useless? No, because a 'seat of the pants' understanding derives from SOME measure of thinking about such things."
Now, tell me how you get from those sentences to the (straw man) idea that I am claiming ANYTHING like that I'm advocating climbing with a partner "who doesn't do a sort of Clif [sic] notes version of that analysis on every single belay."
I'm gonna say it really... really...
really
slowly
now:
In the sort of scenario...
you need to imagine...
for the TOPIC QUESTION to even be interesting...
all this engineering talk...
simply does not...
reliably...
inform the answer to the TOPIC QUESTION.
Believe whatever you want, set up anchors however you want, I'll always find a way to set up a strong enough anchor that I can lead-clip at least one placement. Have as much fun with the theory as you want, and I'm NOT dissing that, but them's the real-world facts.
|
|
Karl Baba
Trad climber
Yosemite, Ca
|
|
|
Dec 12, 2008 - 07:06pm PT
|
Rgold wrote
"(2) The leader fall, as explained in Chris Harmston's rec.climbing post years ago, should not be caught on the harness. It is essentially caught on the anchor, ideally with a some mitigating resistance from the belayer, but without the force-multiplying pulley effect at the anchor one gets by clipping it. "
I have to remind the thread that any benefit from avoiding the pulley effect at the anchor is only maintained if the belayer manages to keep his own weight off the anchor while catching the factor 2 fall through the vehicle of his harness setup. That's a tall order and Jroe's calculations show that if the belayer gets swept off his feet, the forces could actually be worse as the belayer becomes a faller as well.
Not be mention the "escape the belay" difficulties, which should only be discounted with evidence.
peace
Karl
|
|
Largo
Sport climber
Venice, Ca
|
|
|
Dec 12, 2008 - 07:43pm PT
|
Madbolter wrote: " I'll always find a way to set up a strong enough anchor that I can lead-clip at least one placement."
The "always" tells volumes about Madbolter's experience, or his penchant to overestimate the robustness of his anchors. I don't know a single experienced trad climber who doesn't have multiple stories about that sketchy anchor on (fill in the blank).
That much said, the "variables" Madbolter and others mention pertain to the security of the primary placements in an anchor array. Indeed, these vary so much, placement to placement, that it's ludicrous to generalize much about how little or how much this or that cam or pin might hold. Not so with rigging systems and protocols, which is what we are discussing here. You can set up a three or four piece anchor in the lab and reliably test which rigging system and what protocol will place the least load on the anchor, no matter if the placemets are A4 or A1.
JL
|
|
dirtineye
Trad climber
the south
|
|
|
Dec 12, 2008 - 08:12pm PT
|
Degree in philosophy eh?
We can stop right there, LOL.
|
|
madbolter1
Big Wall climber
Walla Walla, WA
|
|
|
Dec 12, 2008 - 08:13pm PT
|
rgold, you're starting to type lengthy tomes like I do. Bravo.
Now I'm not sure exactly WHAT you are advocating. At first I thought you were advocating that the engineering talk in this thread is directly and immediately applicable to real-world anchor situations. If that is what you were claiming (my impression), then my little anchor-calculation scenario was most certainly not a straw-man. Just as I pointed out with it, it is ridiculous to think that anybody is going to perform such feats of engineering analysis AT the anchor.
But, from your last post, it seems that we are closer in our view than might initially appear. Now you seem to be saying that the theoretical talk is only intended to inform general thinking or intuitions about anchors, with very limited applicability to real-world situations. If so, then I agree.
But you also seem to say that there is very direct applicability insofar as "protecting the anchor" (and thereby increasing survival odds, which is what this thread is about) is something that can offset epistemic shortcomings in all situations: "If the belayer cannot make reliable judgements, [sic] then an engineered solution that protects the anchor, independent of the belayer's potentially faulty analysis, seems to me to be even more desirable, not less." If I take your meaning correctly, then we continue to disagree. That is a topic that, it seems to me, is worth discussing.
I also think you are confused about the relations between linguistics and logic, but I really don't want to head down that tangent, since most people won't give a rip about it, and those sorts of issues are good only for verbal sparring in this context (a big waste of time). So, I say this only to indicate that I don't agree but don't intend to argue at that level.
You say, "So if the direct connection proves significant, your argument simply indicates that the indirect connection would give even better results, rather than somehow constituting a worse model as you suggest." I respond, "worse" relative to what? I'm confused now (story of my life). It seems that now we have at least three different connection possibilities on the table, and my "even worse" claim concerned only two of them: belayer catches the falling leader on the anchor with no redirection, and belayer catches the falling leader on his harness with no redirection. Properly set up, I think that the first is worse than the second (there have been empirical tests to indicate this). But that is beside the (main) point.
I have not asserted that catching the leader on the harness IS an advantage. If you reread my statement, you will see that it is hypothetical. I'm saying the even if you grant that there is some advantage (of which I remain unconvinced), that it is an insurmountable problem to know when it is best to employ that slight advantage (if there be one). I certainly would not choose to catch all leaders falling past the anchor onto my harness just to "protect the anchor" because there is (might be) some small advantage to that. As this thread has repeatedly asserted, that advantage (if there be one) is really only significant in a tiny subset of really-sketchy-anchor cases. And my response to THAT idea has been to say that in THOSE cases you should put your energies elsewhere to create an anchor that does not any longer remain one of the really-sketchy-anchor cases. AND I have said that it is ALWAYS possible to find a better alternative than to lead above an anchor that is so sketchy that this discussion could find any real-world application.
Regarding "always," this is a silly point to pick on, but perhaps cashing this out will help to make my overarching point. If I need to formalize this, then I'll find some time to do that next week. For now, here is an informal version. I think this should be sufficient.
1) I define a "better alternative" to mean an alternative that increases the cumulative survival odds for the members of the climbing party that are huddled grimly at a severely sketchy anchor.
2) I note that by the very definition of this topic, not sending someone up on lead above the sketchy anchor is prima facie a "better alternative" than sending someone up on lead. "Protecting the anchor" is prima facie best accomplished by not leading above it. In the absence of objective dangers, the prima facie case is made; it is a better alternative to not lead above the anchor: Q.E.D.
3) I note that in cases where there are objective dangers, either the odds for the party are better if they sit tight, or the odds are better if they move.
4) In the case where the odds are better if the party sits tight, it is a better alternative for them to sit tight. Q.E.D.
5) In the case where the odds are better if the party moves, then either the odds are better if someone leads up, or the odds are better if the party moves in some other direction.
6) In the case where the odds are better for the party to rappel down, it is a better alternative that the party rappels down. Q.E.D.
7) In the case where the odds are better for the party to move to the side, it is a better alternative for the party to move to the side. Q.E.D.
8) In the case where the odds are better for someone to lead up, either the party possesses additional useful protection gear, or it does not possess such gear.
9) In the case where the party possesses additional useful protection gear, that gear can be used to improve the anchor. Improving the anchor is a better alternative. Q.E.D.
10) In the case where the party does not possess additional useful protection gear, either the party could/should have possessed such gear or it could not have.
11) In the case where the party does not possess additional protection gear, but could/should have possessed such gear, it is a better alternative for the party to possess such gear. Q.E.D.
12) In the case where the party does not possess additional protection gear and could not have possessed additional protection gear, it is a better alternative for one person to risk life than for all persons to risk life. The leader should lead above the anchor with no belay. An unbelayed leader is a better alternative. Q.E.D.
You should be getting the point. The number of dichotomies is not infinite, and you can run them down. (Since we're not dealing with infinities, this is not a true 'mathematical induction,' although it borrows much from that form of argumentation.) Pick a scenario, and it is possible to construct a "better alternative" to a belayed leader risking impact onto the sketchy anchor and taking everybody out with him. If the risks to the party are so high as to provide real-world motivation for this discussion, then there are ALWAYS "better alternatives" than to risk the leader impacting that anchor.
Of course, we can debate if my definition of "better" is the right one, but survival of the party seems to be the whole point to this discussion thread; so I think I can't be far off on that point. Besides, such further discussion doesn't threaten my use of the word "always."
One could talk about how there are other interests besides survival, such as the commitment to climb. In that case I will respond that it is a better alternative to add a bolt to the anchor and keep climbing.
If one says that we're only interested in situations that don't violate "ethical considerations," then I say that in this case "ethical considerations" have trumped survival considerations, which is not how this thread's question was cast.
Now, it might be an interesting discussion to talk about the topic question in the context of a sort of hyper-constrained thought-experiment where survival is not the primary consideration, so that bolts, rappelling, and other alternatives are ruled out in advance. But then I will note that THAT discussion will be purely theoretical and have nothing to do with real-world considerations.
Which was my point from the beginning.
This is NOT to "heap scorn" upon this discussion. My point is and has always been that the theory discussed here has little real-world application (and what application it has serves the limited, but useful, purpose of informing our intuitions), and none of it affects my decision to lead-clip every real-world anchor.
I'm gone for the weekend at this point.
|
|
madbolter1
Big Wall climber
Walla Walla, WA
|
|
|
Dec 12, 2008 - 08:21pm PT
|
So, John, why the personal attack?
Perhaps you don't remember that it was said of one of the Lowes (I don't remember which one) that he could construct a bombproof anchor in a pile of sand, or some such thing. I would have to look up the quote, but I read it and was impressed by it as a young man. Consequently, I spent many years learning how to construct reliable anchors in all sorts of sketchy situations. We all can put in that time and practice, and exercise the good judgment, to avoid sketchy anchors.
Or perhaps you are suggesting that it SHOULD be a part of every "good" climber's resume that they lacked the skill and judgment to construct good anchors in some situations. If so, then I simply disagree. As you know (or should if you are going to make such statements), I did the fifth ascent of the Sea when it was still hard and still had a legitimate RURP anchor. So, I'm not sure what is the basis of your jibe. There's no call for personal attacks.
It is nice to see that you agree with my main point, btw.
Have a good weekend.
|
|
JohnRoe
Trad climber
State College, PA
|
|
|
Dec 12, 2008 - 08:37pm PT
|
Karl: "That's a tall order and Jroe's calculations show that if the belayer gets swept off his feet, the forces could actually be worse as the belayer becomes a faller as well."
Well, that was a result of calculations based on some simple theory (linear and undamped response, climbers as point masses). IMHO, the shorter and stiffer the tie-in, the less useful this simplified theory is likely to be. Karl pointed out elsewhere that the % extensions it produces are quite extreme.
So right now I'd prefer to say that the calculations "suggest" rather than "show" the possibility that the moving belayer scenario significantly adds to the anchor load.
Peace
JohnR
|
|
Karl Baba
Trad climber
Yosemite, Ca
|
|
|
Dec 12, 2008 - 08:54pm PT
|
Jroe wrote
"So right now I'd prefer to say that the calculations "suggest" rather than "show" the possibility that the moving belayer scenario significantly adds to the anchor load. "
Definitely fair enough. In fact, I think the word "Suggest" should apply to much of what is written by everyone in the this thread until real world test unveil the factors (or at least quantify the difference between theory and reality) that the math hasn't accounted for.
What would really be fun would be to go to a swag crag and have a "logger's jamboree" where climbers choose their belay (with some bomber backup) and take a bunch of gnarly factor two falls on some retired ropes)
Peace
Karl
|
|
rgold
Trad climber
Poughkeepsie, NY
|
|
|
Topic Author's Reply - Dec 12, 2008 - 09:19pm PT
|
MB wrote, "rgold, you're starting to type lengthy tomes like I do. Bravo."
MB, I yield to no one in sheer verbosity. And I must say that anyone with a Ph.D. in Philosophy is my kind of man.
As for my view of theoretical calculations, your second characterization is close to what I think, although your insistence on "very limited" gives me some pause. I guess the degree of applicability may be in the mind of the beholder, so I won't quibble.
Unfortunately, we still disagree about what I would call optimal behavior in the face of uncertainty. I think the gist of the issue is in this statement of yours,
"I'm saying the even if you grant that there is some advantage (of which I remain unconvinced), that it is an insurmountable problem to know when it is best to employ that slight advantage (if there be one). I certainly would not choose to catch all leaders falling past the anchor onto my harness just to "protect the anchor" because there is (might be) some small advantage to that."
And I am saying, in the face of uncertainty, that my choice would be to embrace the small advantage.
As for the logico-linguistics, it best hammered out over endless cups of coffee or pints of beer, depending on your academic proclivities, rather than jointly creating a new 21st century sleep aid (from which, however, we might profit handsomely).
Have a wonderful weekend, come back safe and sound, and may you never encounter anything that could possibly be a subject for this thread.
|
|
Largo
Sport climber
Venice, Ca
|
|
|
Dec 12, 2008 - 10:12pm PT
|
Madbolter wrote: "So, John, why the personal attack?"
No personal attack intended, and my bad if you took it that way. It's just that I don't believe for a second that an El Cap vet like you - or many others on this list - has always belayed from bomber anchors. Man, I remember doing an early ascent of the Shield and belaying and hauling from one buttonhead bolt with a "sleeve" hanger hand-placed over the mo fo. How could you have possibly escaped ALL such situations all these years?
Perhaps it's true - I never rule out the possibility that I'm totally full of sh#t - but it is strictly fantastic if so.
JL
|
|
rgold
Trad climber
Poughkeepsie, NY
|
|
|
Topic Author's Reply - Dec 13, 2008 - 02:32am PT
|
Karl wrote, "I have to remind the thread that any benefit from avoiding the pulley effect at the anchor is only maintained if the belayer manages to keep his own weight off the anchor while catching the factor 2 fall through the vehicle of his harness setup. That's a tall order and Jroe's calculations show that if the belayer gets swept off his feet, the forces could actually be worse as the belayer becomes a faller as well.
In the system I described, it isn't necessarily a tall order at all for the belayer to keep from becoming a free-falling object. If the connection to the power point is two feet long, the belayer's anchor point will displace downward perhaps eight inches, a mere deep knee bend. This is exactly what happened when I caught a factor two fall---I ended up kneeling on the ledge.
And this deep knee bend is a lot better than what is in store for the belayer with a redirect who isn't also tied down. The belayer is going to be violently flung upward, according to JohnR's calculations: "After 372ms, the belay device gets sucked at high speed into the biner on the power point. I didn't attempt to write any equations for what happens after that :-)"
Add to this Mad Bolter's story about being flung six feet up from his hammock until his belay plate smacked into the anchor bolt. A belayer whose waist is three feet from the redirect is going to hit harder and will have less time to get their feeling hand out of the way of a serious mangling. It seems possible to me that the results could be worse for the belayer than the deep knee bend he gets to do in the factor two catch with the anchoring I described.
Morevover, we don't yet have any calculation for what happens in term of anchor load after the belayer hits the redirect. Is there a second peak? Can it be larger than the first peak?
Finally, if the belayer is not anchored down to avoid being slammed into the redirect biner, the anchor itself had better have a solid upward directional component, at least if it is a trad anchor with vertical placements, because otherwise the upward belayer impact could extract the anchor.
I've had a lot of experience BITD catching factor 1.5+ falls for practice using a weight, and I can guarantee that the belayer is going to be flung upward hard---I've experienced this first-hand over and over, and I would not want to be stopped by running into the anchor, nor would I have a lot of confidence in the belay surviving the experience. I'd think that loss of control is highly probable. Kudos to MB for hanging on!
So, if you are going to redirect, then the belayer really had better be tied down, and then we're back with the pulley effect loading of the anchor again...
|
|
|
SuperTopo on the Web
|
Let us know!