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s. o.
Trad climber
academia
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Jan 14, 2007 - 07:35am PT
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A Few thoughts:
I have heard of the figure 8 knot refered to as static equalization.
ditto to rgold and Tom
If a piece fails in the "sliding W" the powerpoint on the achor will drop causing a dynamic load to the rest of the anchor.
The angle between pieces is far more important than the anchoring system used. It is possible and easily done that the individual points have more force exerted on them than if they were the only point in the system. This happens with useing a runner, short cordelette, or having the anchor spread over a large area.
The figure 8 knot increases these forces by increasing the angle.
In the rare case that your cordelette breaks or your knot sucks, or you make a mistake clipping the "w" correctly; your anchor may fail.
Most important: use bomber gear for your anchor - if your anchor fails it is most likely because the RURP, micro nut, and bush you built into an anchor failed.
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Largo
Sport climber
Venice, Ca
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Jan 14, 2007 - 10:32am PT
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"Some people seem fixated on the idea of equalizing, thinking it's always required. Nonsense. Equalization is actually a relatively new idea (last 30 years or so). The fact is the gear is strong enough (usually) without equalization."
I would argue this point--at least a little. The rigging challenges are much greater today than they were when I first started climbing, over 30 years ago. Back then, we slugged titanically strong (and easy to use) chromolly pegs into the rock. It mattered little how we tied them off as even one or two was often good for the whole anchor. Trying to achieve the same brute strength with passive camming devices presents another magnitude of difficulty hence the modern day need trend toward equalizing.
JL
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rgold
Trad climber
Poughkeepsie, NY
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Jan 14, 2007 - 10:45am PT
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Mr. Goldstone has mentioned some of the difficulties in actually achieving "equalization". In the real world, it aint gone to happen.
I do not believe this. The equalette already works for two anchor points, and I think it is just a matter of time before there are acceptable solutions in general. But the solutions cannot be achieved by fixed-length arms.
Equalization is actually a relatively new idea (last 30 years or so). The fact is the gear is strong enough (usually) without equalization. In most cases, you want more than one piece to provide backup for the unexpected, not because one isn't strong enough.
I agree with Largo that equalization has become more important as individual pieces of gear have become both less strong and harder to evaluate. As for the gear being strong enough without equalization, I would submit that we really don't know, because so few belay anchors have ever been subjected to a severe test. I wouldn't be shocked to learn that, say, 10% of all gear belay anchors will not survive a factor-2 fall onto the belay.
Of course, there are exceptions, in which case, load sharing (a far more accurate term) strategies are called for.
One of the reasons to pursue equalization as a general strategy is that a party, yes even an experienced one, may be unaware that it is in one of these exceptional cases.
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dirtineye
Trad climber
the south
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Jan 14, 2007 - 11:56am PT
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I'll just add very slightly to what Rgold said in his last sentence:
Most people who got into a serious jam, and got injured or even maybe died, were probably not thinking, "Gee, I'm really in trouble here. This looks bad, I'd better be careful.", right before the shyte hit the fan.
But I guess if you are going to climb over anchors that seriously need equalization to be good, you have to ask youself, "How much lipstick does it take to make a pig kissable?".
I'm not against equalization or even agaist doing dumb things while climbing, I just like to know when I'm doing it, although, as Rgold pointed out, sometimes you really don't know.
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WoodySt
Trad climber
Riverside
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Jan 14, 2007 - 12:04pm PT
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Just pick up a good sized rock; drop it on the flat; sit behind it; wrap your legs around it and enjoy your partner's screaming and sputtering when he or she arrives.
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andanother
climber
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Jan 14, 2007 - 05:43pm PT
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did rockclimbing.com go offline again?
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Nick
climber
portland, Oregon
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Jan 14, 2007 - 07:22pm PT
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I hate to throw even one cent into the ring on such a discussion, but at the risk of pointing out something obvious. My daughter came home from college a month or so ago with a copy of Largo's new book and one of these equalette things. It looks like a good solution except the arms are too long and you have to tie them up all the time. So, I tied a bowline on a bight into each end and viola. Easy to rack. Two bolts, just clip and go. Four pieces, separate the loops and adjust their length, instant equalization. It worked well for us. If your anchor was all in one vertical crack clove hitches might be better.
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s. o.
Trad climber
academia
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Jan 14, 2007 - 10:13pm PT
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"How much lipstick does it take to make a pig kissable?"
poetry
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healyje
Trad climber
Portland, Oregon
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Jan 15, 2007 - 04:33am PT
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As Ed said, this whole business got flogged to death on rc.com and the horse buried, dug up, and buried several more times just before Largo put out his latest anchor book. The discussion is still there, but due to choices rc.com made that included eliminating in-line photos, the thread isn't quite what it was. That could be good or bad depending on your perspective. Recreating it all here seems ill-advised at best. Largo, haven't had a chance to look at your book but the rc.com discussion was interesting most of the time...
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climbrunride
Trad climber
Durango, CO
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Jan 15, 2007 - 04:35am PT
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Well, this might not be rcN00B.com, but I'm a gear weenine with a science background, so I like a gear discussion every once in a while...
All of the above could be the correct anchor. It just depends on where you use it. For toproping on nice, bomber anchors, where we are climbing left, right, center, etc. on the same rope, a self-adjusting setup like the sliding-W, or linked, equalized slings seems appropriate. You can always get highly gear intensive and clip a loose backup sling to a couple pieces, to minimize extension in case of gear failure.
I can't remember how many times I've found nothing but crap from which to build an anchor. In those cases, I try to get 3 pieces carefully equalized and tied-off with an overhand (not 8) knot on my cordalette. Then, if I can, I still get another one or three pieces to buff it out. Then I very carefully stand, or painfully hang, so I load the anchor just right. If I'm really lucky, I can belay off my wiast and hold most of the load on my legs, should my second take a slip. (Kind of an "improved Spencer Tracy belay" - painful on the kidneys when he falls, but less chance I take flight.) Once I'm all set up and ready to go, I yell those words any second just loves to hear from his belayer, "DON'T FALL!"
EDIT: Thanks for letting me got that gear discussion out of my blood. I don't use that other site, so I had lots of pent-up energy waiting to jump on a tech-weenie topic. Even though I really did't say much, I think I'm now satisfied. Thank you.
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Ed Hartouni
Trad climber
Livermore, CA
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Jan 15, 2007 - 10:19am PT
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Back in the day it was not uncommon to belay off a single, well placed pin. While that was not redundant, it often was overkill safe, especially for the types of climbs that were being done by the majority of climbers. It helped that taking a lead fall was not a part of the the climbing mentality back then.
The introduction of passive climbing protection forced a major rethinking of the whole anchor system. Building a safe anchor became an exercise in finding multiple placements which were usually "serial," that is, you tied off one piece to another to another to you. You were counting on one of the pieces holding if the loaded piece blew out.
When cams came out they were incorporated into these redundant systems. While equalizing was known, it wasn't practiced widely (I believe) until John's book made the case. I remember looking at some of his "bad example" photos with much recognition... and I personally worked hard at an "equalized" anchor system which was very clean. The cordolette idea made the whole system neat and easy to critique vs. the tied of slings, etc, of old systems.
As rgold points out, however, there are not a lot of well understood tests of anchor systems, either failed or successful. The tests recently done for the latest edition of John's book point out a major problem for cordolette equalization, but also studied other anchor tie off systems.
In the end, it is important to remember many of the hard learned lessons:
1) the anchor system should be redundant and each point as secure as possible, ideally each point able to sustain a factor 2 fall
2) it is important that the whole anchor system be considered, especially to avoid a factor 2 fall right off the belay by placing anchors to "protect the belay"
3) rock has finite strength and anchor protection should be placed, as much as possible, in a way that does not depend on a single rock feature... e.g., don't put all you pieces behind the same flake... a "redundant system" includes the material you are anchoring in also...
The analysis of the cordolette forces shows that if each of the arms of the cordolette are the same length, then it works to equalize... if they are not the same length then there are higher forces on the anchors attached with the shortest cordolette arm. This might be entirely acceptable if you consider it when you arrange your anchor attachment, but you have to be aware of the fact that the anchor is not equalized in such a configuration.
Other ways of anchor attachments are valid, as they always have been. The point is to do the "what if" analysis whenever you set up the anchor.
And most importantly, you should keep foremost in your mind that the anchor must be good enough to secure you and your partner in the event of a fall. You life depends on it, always.
Constructing a safe anchor is not impossible, and cordolette or not, constructing a safe anchor always required careful attention.
Once you can do this, you can go out and have fun.
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dirtineye
Trad climber
the south
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Jan 15, 2007 - 10:48am PT
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I do believe that,"Kissable Pig", would make an excellent route name, and I have just such a line in mind.
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bwancy1
Trad climber
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Jan 15, 2007 - 11:53am PT
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I have been using a webolette for a few years now. I equalize as best I can, and tie a figure 8. By leaving the figure 8 a little "loose", there is enough give in the knot to compensate for slightly imperfect lengths on the three legs. I think that an anchor like this would auto-equalize fairly well when loaded.
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rgold
Trad climber
Poughkeepsie, NY
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Jan 15, 2007 - 01:28pm PT
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The analysis of the cordolette forces shows that if each of the arms of the cordolette are the same length, then it works to equalize
...if the cordelette has been tied exactly right. Any errors would have to be partially compensated by give in the knot (completely unpredictable) or stretch in the material (which is one reason why nylon is preferable to spectra).
The so-called "equal arm" situation is essentially three pieces in a horizontal crack. If either the left or right piece fails, the entire load is transferred to the middle piece with no load at all distributed to the other piece. This sets up the "cascade failure" scenario in which each piece in succession is required to bear the entire load.
The other problem with fixed-arm rigging is that it only distributes when the load is applied directly downward (or in whatever direction the rigging has been tied for). If the leader falls on one side or the other of the belayer, then when the rope comes taut the downward fall will be turned into a pendulum. This change of direction comes with a very high acceleration and so it is very reasonable to expect that such a fall will impose a high load on the belay that is not straight down, the direction the anchor was tied for. This load will have to be born by one of the outer single pieces of the anchor, and so will also set up the cascade failure scenario.
The usual response to these observations is that if things are really this bad, why aren't parties regularly plunging to their death? The answer, in my view, is that it is very rare that an anchor is tested.
Here is another way to look at the situation. Suppose there was a way to achieve practical equalization with directional tolerance, a way that was as easy to deploy as a cordelette. Wouldn't it be sensible to adopt such a method and thereby eliminate or at least significantly reduce potential scenarios such as the ones above?
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wootles
climber
Gamma Quadrant
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Jan 15, 2007 - 02:20pm PT
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The analysis of the cordolette forces shows that if each of the arms of the cordolette are the same length, then it works to equalize
Actually... no.
I did the drop tests for Largo's book and it may be pointed out in there that even when the legs of the cordelette were tied as near to perfectly equal as I could get them there was still significant differences in the force to each anchor. It should also be noted that it was easy to judge the direction of pull for each drop because I was using a guided mass where the pull, obviously, was in the same spot every time.
It's all in the book and as much as you all love to bust on rc.com everything is pretty well covered over there, that is if you can wade through the 1000 or so impertinent posts.
Constructing a safe anchor is not impossible, and cordolette or not, constructing a safe anchor always required careful attention.
I think this is a point that may have been missing in the discussion on rc.com. There seemed to be too much black and white thinking and that will only limit your 'bag of tricks' to building a safe anchor.
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Thom
Trad climber
South Orange County, CA
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Jan 15, 2007 - 06:17pm PT
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Man, this topic HAS been beaten to death 10x over...
I do believe the argument AGAINST the "sliding W" or any self-equalizing anchor set-up goes something like this:
If any single piece fails, the remaining pieces are shock-loaded as the anchor re-equalizes itself, thus requiring the remaining pieces to be "bomb-proof" to prevent their failure also. Since one does not know which of the pieces will fail, when using any self-equalizing system, we must be certain that EVERY piece is "bomb-proof" thus negating the need to use a self-equalizing system to begin with.
Someone needs to do some testing:
Rig up a tied-off, 3-piece cordelette anchor with the appropriate angles to promote equalization throughout the system; then, release one of the pieces and record how the weight transfers to the remaining pieces via the cordelette. I doubt there is much difference between the two.
Maybe hang 3 scales from a beam, rig the cordelette, hang a weight on the power-point, and record the weight on each scale; then, cut one of the cords and watch how the weight transfers.
I'd do it myself but don't have the equipment.
Cheers,
T.
Edit: haven't read the book, just saw the above posts and apparently somone has done some testing (finally) with the cordelette system. Guess I'll have to obtain said book to see the results. t.
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healyje
Trad climber
Portland, Oregon
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Jan 15, 2007 - 06:44pm PT
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It's a testament to the new RC forum software that you can do a "show all" on that thread. The pictures have been replaced with links to them and I'd recommend you right-click on those links and do "Open in a new window" so you keep your place in the thread easier. I'd also recommend you consider all the ideas more from a component perspective versus accepting or rejecting whole anchor designs. There are a lot of interesting ideas presented and many good ones are not necessarily in the best anchor proposals (imho). On the whole it was a pretty worthy exploration of the space even if later in the thread the conversation suffers a bit here and there...
RockClimbing.com: [url="http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=1306133;page=1;sb=post_latest_reply;so=ASC;mh=25;guest=3555152" target="new"]Improved sliding x: Is it really safer?[/url]
P.S. Please do not rouse the sleeping beast that is that thread. Let that poor damn horse rest in peace - it went through hell for the cause...
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rhyang
Ice climber
SJC
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Jan 15, 2007 - 07:05pm PT
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I read JL's new book over the holiday, and was quite amazed. I'd like to experiment with the equalette more, since it seems like a useful technique.
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WBraun
climber
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Jan 15, 2007 - 08:26pm PT
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So Cjones
Still sliding on that W?
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rgold
Trad climber
Poughkeepsie, NY
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Jan 15, 2007 - 08:55pm PT
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Man, this topic HAS been beaten to death 10x over...Someone needs to do some testing
The trick now is to keep up with the beatings...which is why, Joe's urgent pleas not withstanding, there still appears to be some use in these discussions. And although the rc.com thread is gargantuan, there are a number of fundamental questions still unanswered and perhaps even unposed, primarily because that thread was, perhaps prematurely, about solutions.
So I'm gonna take up my club and administer another some more whacks for time number 11. In partial justification, the points made here have not been made in the rc.com thread. [Edit: This claim is overblown. In particular, GoClimb repeatedly raised the question about the effect of the belayer falling during anchor extension in the rc.com thread.] Nonetheless, they're probably of interest to only a few folks out there; to the rest I apologize for blabbering on so, but suggest that there may be something worth considering in the final two points.
In the case at hand, testing has been performed for a two-anchor equalized system (the equalette) with a drop of a bit under 5". The results, reported in the rc.com thread---which almost no one can bear to read---and reiterated in JL's anchor book, pp 190--191, are that the extension makes little difference in the peak loads.
I'm not exactly sure what question one should be asking for this situation, but I think it is this: If a fixed-arm system (e.g. cordelette) has one arm fail and all the load is transferred to the other anchor(s), how does the peak load in that situation compare to what happens if a sliding system fails and transfers the load to the same anchor(s)? I don't think this question has been answered yet. JL? Wootles?
Moreover, I think result reported by JL has to be understood properly. Those tests were conducted by dropping a weight directly onto the anchor. In such a test, the length of rope involved becomes important for understanding the results.
As is now well-known, the load on the anchor depends on the fall factor. When the anchor blows, the length of rope remains the same (I'm assuming an equalette made up of extremely low-stretch material that doesn't contribute to energy absorbtion) but the length of the fall increases by the amount of anchor extension. If this extension is very small compared to the amount of rope, then the fall factor barely changes and we wouldn't expect to see much difference in the loads on the anchor. I suspect this is what happened in the tests JL reported; perhaps Wootles could clarify this point.
If, however, the extension in the anchor is significant compared to the length of rope involved, then there could be a big increase in fall factor leading to a much higher anchor load.
In a climbing situation, the load on the anchor is delivered by the tension in the belayer's tie-in, which is usually relatively short. The dynamics of the situation are those of coupled harmonic oscillators (two sections of rope, one section between falling leader and belayer, the other section the belayer's tie-in), and I haven't worked out what would, in theory, happen to the tension in the belayer's tie-in. But it is possible to make some rough estimates by treating the leader's fall and the belayer's fall as if they were not coupled events.
The leader's fall energy is absorbed by the full length of rope involved, and a small extension from the anchor would have a negligible effect on the fall factor and so on the anchor load. But, assuming the fall pulls the belayer off and the anchor extends, the belayer's fall energy has to be absorbed by the short tie-in.
If an 80 kg belayer tied in with two feet of rope with 9 kN impact rating falls 4 inches because of anchor extension, then there is a fall factor of 1/6 with consequent load of about 3.2 kN, a bit less than 720 lbf. So given the showdown I proposed above between the cordelette and the sliding anchor, I'd expect the remaining anchor to have to withstand a somewhat higher load---it is hard to know how good an estimate 720 lbf is.
This effect might be mitigated by the fact extension might allow the extraction of the piece to absorb some fall energy. This point has been argued a lot too; it depends on whether the falling leader's rope can recover during the brief interval when it is unweighted. There are some theoretical reasons to believe this, and I think the data from the drop tests with arm failure suggest it too.
So there is reason to believe that an extension that is small compared to the tie-in length, although it will increase the load on the remaining anchors, has benefits that outweigh the deficits. [Edited.] But there are some caveats worth observing too:
(1) All bets are off if you tie in with slings or daisies. You will then have thrown out the belayer's energy absorber and a small extension might provoke a big load increase. Anyone using an extendible system must tie in with the climbing rope (and indeed this is true for all tie-ins in my opinion.)
(2) If there's a choice of belay positions, The longer your tie-in the better, since you want to minimize the ratio (extension) / (tie-in length).
Sorry Joe, I know you begged me not to do this.
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