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bloodyhands


Feb 6, 2006, 12:08 AM
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Improved sliding x: Is it really safer?
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Ok, there’ve been a lot of threads discussing the safety of a “sliding x” anchor equalizing system. Everybody knows the big problem with the “sliding x”; if one anchor fails, the remaining anchor will be severely shock loaded.

The most common way to reduce the possible shock load (other than using a different equalizing system) is to tie an overhand knot in both legs. If one anchor blows, the rope bearing biner will drop only a short distance onto the overhand knot.

My question: Has anyone given thought to how much relative strength the sling has with the biner loaded onto the overhand knot in this configuration? It seems to me like it might be significantly weaker, but I hesitate to abandon my favorite equalizing system.

Your thoughts, please.


landgolier


Feb 6, 2006, 1:05 AM
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it's pretty generally agreed that you can't do much to a standard sling with knots that can reduce its strength by more than 50%, which still leaves you well north of 10kN


pico23


Feb 10, 2006, 1:36 AM
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Ok, there’ve been a lot of threads discussing the safety of a “sliding x” anchor equalizing system. Everybody knows the big problem with the “sliding x”; if one anchor fails, the remaining anchor will be severely shock loaded.

The most common way to reduce the possible shock load (other than using a different equalizing system) is to tie an overhand knot in both legs. If one anchor blows, the rope bearing biner will drop only a short distance onto the overhand knot.

My question: Has anyone given thought to how much relative strength the sling has with the biner loaded onto the overhand knot in this configuration? It seems to me like it might be significantly weaker, but I hesitate to abandon my favorite equalizing system.

Your thoughts, please.

IMO, if I was building an anchor and I thought that one of the two pieces was bound to fail I would not use the sliding X.

I use the sliding X when attached to bomber pieces because it is simple and fast.

Any tied knot reduces rope and sling strenght but the shock load on your gear from an already extended sling even with the overhand would concern me more.


vivalargo


Feb 10, 2006, 11:32 AM
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Funny this should come along just now. I'm just finishing redoing the anchor books into one big anchor building omnibus. We're basically done --all that's left is a bit of editing, and incorporating a slew of drop tests we did with Sterling Ropes (conducted by America's leading drop/test dude, Jim Ewing, with statistical analysis by trad master Dr. Larry Hamilton and climber/fitness model/criminology professor, the esteemd "Crimpgirl," Dr. Callie Rennisson).

The tests were to determine, once and for all, which system was better at load sharing when sustaining a dynamic fall (Factor 1 for our testing)--the Cordelette, or the Sliding X. Both rigging systems were tested when rigged to vertical and horizontally oriented anchor points. In the vertical configuration--as you find in a crack--the rigging systems have unequal sized legs; in the horizontal configured anchor (as found, for instance, with bolts placed side to side on top of a sport climb), the legs are as close to equal as they could be tied.

Moreover, each set up was tested with several diameters of high tensile strength cord and webbing (Dyneema, Technora, Spectra, et al), as well as with old style nylon cord and webbing.

It is still too early to release the results, but I can say right now that there is a significant difference in load sharing performance between the two systems, and much that has been written about the cordelette's equalizing capacities is strictly untrue.

More later. I'm just eyeballing the graphs I got from Jim, Larry and Crimpy. At least now we finally know what's up with these systems, and that's a real good thing.

JL


trenchdigger


Feb 10, 2006, 11:53 AM
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Ok, there’ve been a lot of threads discussing the safety of a “sliding x” anchor equalizing system. Everybody knows the big problem with the “sliding x”; if one anchor fails, the remaining anchor will be severely shock loaded.

Shockloading the big problem? I was always bothered more by the lack of redundancy in the sling.


elvislegs


Feb 10, 2006, 11:54 AM
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Funny this should come along just now. I'm just finishing redoing the anchor books into one big anchor building omnibus. We're basically done --all that's left is a bit of editing, and incorporating a slew of drop tests we did with Sterling Ropes (conducted by America's leading drop/test dude, Jim Ewing, with statistical analysis by trad master Dr. Larry Hamilton and climber/fitness model/criminology professor, the esteemd "Crimpgirl," Dr. Callie Rennisson).

The tests were to determine, once and for all, which system was better at load sharing when sustaining a dynamic fall (Factor 1 for our testing)--the Cordelette, or the Sliding X. Both rigging systems were tested when rigged to vertical and horizontally oriented anchor points. In the vertical configuration--as you find in a crack--the rigging systems have unequal sized legs; in the horizontal configured anchor (as found, for instance, with bolts placed side to side on top of a sport climb), the legs are as close to equal as they could be tied.

Moreover, each set up was tested with several diameters of high tensile strength cord and webbing (Dyneema, Technora, Spectra, et al), as well as with old style nylon cord and webbing.

It is still too early to release the results, but I can say right now that there is a significant difference in load sharing performance between the two systems, and much that has been written about the cordelette's equalizing capacities is strictly untrue.

More later. I'm just eyeballing the graphs I got from Jim, Larry and Crimpy. At least now we finally know what's up with these systems, and that's a real good thing.

JL

well... THAT was one of the most useful things i've ever seen posted on the web. straight from the horses mouth. looking forward to the new publication.



shit. did i just call largo a horse?


bloodyhands


Feb 10, 2006, 12:11 PM
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Ok, there’ve been a lot of threads discussing the safety of a “sliding x” anchor equalizing system. Everybody knows the big problem with the “sliding x”; if one anchor fails, the remaining anchor will be severely shock loaded.

Shockloading the big problem? I was always bothered more by the lack of redundancy in the sling.

The improved sliding x does offer a bit of redundancy; even if part of the sling fails ( provided that it fails above the knot) the rope will still be caught. If the the sling fails below the knot, you are indeed, thoroughly f**ked. But this never bothered me; my anchor sling's in excellent condition.


trenchdigger


Feb 10, 2006, 12:22 PM
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Ok, there’ve been a lot of threads discussing the safety of a “sliding x” anchor equalizing system. Everybody knows the big problem with the “sliding x”; if one anchor fails, the remaining anchor will be severely shock loaded.

Shockloading the big problem? I was always bothered more by the lack of redundancy in the sling.

The improved sliding x does offer a bit of redundancy; even if part of the sling fails ( provided that it fails above the knot) the rope will still be caught. If the the sling fails below the knot, you are indeed, thoroughly f**ked. But this never bothered me; my anchor sling's in excellent condition.

True, and it depends a lot on the anchor and if abrasion/cut resistance is a factor.


healyje


Feb 10, 2006, 12:29 PM
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In our anchor replacement project all the anchors are the heavy Metolius Rap anchors with 3/8"x3 3/4" SS bolts and dressed out with tandem X slings threaded through two Fixe 50kn SS rap rings. We opted for both quality and redundancy to insure long term safety in spite of the costs given the amount of traffic this [trad] crag receives.


wings


Feb 10, 2006, 12:31 PM
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Ok, there’ve been a lot of threads discussing the safety of a “sliding x” anchor equalizing system. Everybody knows the big problem with the “sliding x”; if one anchor fails, the remaining anchor will be severely shock loaded.

Shockloading the big problem? I was always bothered more by the lack of redundancy in the sling.

Then use two slings.

- Seyil


greenketch


Feb 10, 2006, 12:40 PM
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Largo, thanks for a great post. I'm looking forward to the new book.

Just a bit of thinking out loud here. Did you do any testing where part of the anchor failed? The OP brings up a good point regarding the shockload potential vs the limited equalization. I'm trying to imagine a test rig that would have one bomber anchor point and one that could be rigged to fail at less than the applied force. Thus a test could be done that simulated a partial failure each trial. Have you done anything like that?


maldaly


Feb 10, 2006, 12:52 PM
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Most of the time I set up and EQ anchor I use a sliding x. I have ants in my pants and can't seem to stay in one place long enough to keep anthing with at "master" knot even remotely equalized. I do worry about lack of redundancy with a sliding x so I always tie directly into one of the anchors with my lead rope as well.
Mal


vivalargo


Feb 10, 2006, 1:05 PM
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Largo, thanks for a great post. I'm looking forward to the new book.

Just a bit of thinking out loud here. Did you do any testing where part of the anchor failed? The OP brings up a good point regarding the shockload potential vs the limited equalization. I'm trying to imagine a test rig that would have one bomber anchor point and one that could be rigged to fail at less than the applied force. Thus a test could be done that simulated a partial failure each trial. Have you done anything like that?

That sounds like an easy question to answer, but it's not. Yes, Jim started doing some tests like this just to see what figures came up. It's easy to rig: you just tie off one anchor with a piece of sling that gives out at, say, 1,000 pounds, and you do a drop that generates 1,200 pounds.

What makes this tricky is that so long as you are climbing with a dynamic rope that is belayed, true "shock loading" never really occurs owing to the stretch in the rope and, most importantly, rope slip through the belay device. In other words, when a Sliding X is configured with limiter knots, the few inches of extension will never produce a true shock load, or anything even approaching that kind of stress.

A genuine shock load will only occur in those instances reflected in Duane Raleigh's recent tests for Rock and Ice, say, when someone is tied off to an anchor with a short shank of high tensile cord. He climbs a few feet above the anchor and falls. Here, you have true shock loading, where biners blow apart and anchors rip out because there's no rope slip at the belay device, no stretch in the rope, no human body to absorb loading, et al.

This doesn't happen when a placement blows out on a Sliding X or a Cordelette, owing to flex and give in other parts of the system during loading.

JL


pastprime


Feb 10, 2006, 1:39 PM
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I have long suspected, but kept it to myself for lack of proof, that the concerns over shock loading when one leg of an equalized anchor failed, were not to be ignored, but were probably overblown.

My hunch has been that the realistic way to see this situation is that the extra force on the remaining good piece, when the piece it is paired with fails, is probably not hugely more than the extra force generated by whatever amount the fall distance is increased, which usually isn't much.

In other words, say you have 2 pieces sliding x'ed together with a 24" sling. A 10 foot fall occurs, loading the pieces, and one pulls, the other holds. Rather than this now becoming some huge catastrophe, this just means the leader has now taken an 11 foot fall, and the remaining good piece now feels that appropriate load.

There has been a lot of conjecture about how much the impact absorption abilities of the rope would have been used up in pulling out the first piece, and this is of course affected by whether the first piece pulled very easily, or almost held until pulling at the final few pounds of impact.
The remaining impact absorption of the rope is also going to be very dependent on how much rope of the ropes ultimate shock absorption ability was used up in the first hit. If the first hit almost stopped the climber, but that was still a low fall factor fall, the rope would, I expect, still have a lot more absorption left. If the first hit was a high fall factor, and the piece almost, but not quite, held, the rope's give is much more likely to have been used up.

In the case where the ropes ability to absorb was almost used up, that would also usually mean it had already come about as close to stopping the fall as it could in any case; then the faller continues 1 more foot than they would have had the X not failed.

I'm wide open here. Is this close to what the data shows, or is this wacked?


greenketch


Feb 10, 2006, 1:54 PM
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Largo, thanks for a great post. I'm looking forward to the new book.

Just a bit of thinking out loud here. Did you do any testing where part of the anchor failed? The OP brings up a good point regarding the shockload potential vs the limited equalization. I'm trying to imagine a test rig that would have one bomber anchor point and one that could be rigged to fail at less than the applied force. Thus a test could be done that simulated a partial failure each trial. Have you done anything like that?

That sounds like an easy question to answer, but it's not. Yes, Jim started doing some tests like this just to see what figures came up. It's easy to rig: you just tie off one anchor with a piece of sling that gives out at, say, 1,000 pounds, and you do a drop that generates 1,200 pounds.

What makes this tricky is that so long as you are climbing with a dynamic rope that is belayed, true "shock loading" never really occurs owing to the stretch in the rope and, most importantly, rope slip through the belay device. In other words, when a Sliding X is configured with limiter knots, the few inches of extension will never produce a true shock load, or anything even approaching that kind of stress.

A genuine shock load will only occur in those instances reflected in Duane Raleigh's recent tests for Rock and Ice, say, when someone is tied off to an anchor with a short shank of high tensile cord. He climbs a few feet above the anchor and falls. Here, you have true shock loading, where biners blow apart and anchors rip out because there's no rope slip at the belay device, no stretch in the rope, no human body to absorb loading, et al.

This doesn't happen when a placement blows out on a Sliding X or a Cordelette, owing to flex and give in other parts of the system during loading.

JL

Thanks again, You stated exactly what I would suspect and basically the test that I would propose as well. I was more interested to see if there was data to suport what the diagnostics would suggest. My belief is that there is a significant reduction in force prior to the piece pulling (unless it is really bad) and the that in the minor extension that occurs only minimal energy is regained.


Partner cracklover


Feb 10, 2006, 2:12 PM
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Largo, thanks for a great post. I'm looking forward to the new book.

Just a bit of thinking out loud here. Did you do any testing where part of the anchor failed? The OP brings up a good point regarding the shockload potential vs the limited equalization. I'm trying to imagine a test rig that would have one bomber anchor point and one that could be rigged to fail at less than the applied force. Thus a test could be done that simulated a partial failure each trial. Have you done anything like that?

I'm extremely interested in this question, too. Basically, there are two sides to this argument. Those who say:

1 - When a piece rips from a two-point anchor, and a sliding-x extends, the remaining piece will feel a huge force due to having to catch that foot-long fall on a rope that's already stretched out.

versus those who say:

2 - This "shock load" is nothing more than a one foot fall on however much rope is out. It is more or less equivalent to increasing the fall distance by a foot. Do your fall-factor calculation with one more foot of fall distance - that's all that's happening. Although it may feel less than this due to the fact that one foot's worth of tension in the rope is released first.

GO


vivalargo


Feb 10, 2006, 2:21 PM
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In reply to:
In reply to:
Largo, thanks for a great post. I'm looking forward to the new book.

Just a bit of thinking out loud here. Did you do any testing where part of the anchor failed? The OP brings up a good point regarding the shockload potential vs the limited equalization. I'm trying to imagine a test rig that would have one bomber anchor point and one that could be rigged to fail at less than the applied force. Thus a test could be done that simulated a partial failure each trial. Have you done anything like that?

That sounds like an easy question to answer, but it's not. Yes, Jim started doing some tests like this just to see what figures came up. It's easy to rig: you just tie off one anchor with a piece of sling that gives out at, say, 1,000 pounds, and you do a drop that generates 1,200 pounds.

What makes this tricky is that so long as you are climbing with a dynamic rope that is belayed, true "shock loading" never really occurs owing to the stretch in the rope and, most importantly, rope slip through the belay device. In other words, when a Sliding X is configured with limiter knots, the few inches of extension will never produce a true shock load, or anything even approaching that kind of stress.

A genuine shock load will only occur in those instances reflected in Duane Raleigh's recent tests for Rock and Ice, say, when someone is tied off to an anchor with a short shank of high tensile cord. He climbs a few feet above the anchor and falls. Here, you have true shock loading, where biners blow apart and anchors rip out because there's no rope slip at the belay device, no stretch in the rope, no human body to absorb loading, et al.

This doesn't happen when a placement blows out on a Sliding X or a Cordelette, owing to flex and give in other parts of the system during loading.

JL

Thanks again, You stated exactly what I would suspect and basically the test that I would propose as well. I was more interested to see if there was data to suport what the diagnostics would suggest. My belief is that there is a significant reduction in force prior to the piece pulling (unless it is really bad) and the that in the minor extension that occurs only minimal energy is regained.

I'm still putting all of this together--with a lot of help from the statistical experts--but understand that it's rope slippage through the belay device, and the absorbtion qualities of the human body, that provide the crucial flex and give in the system. That much said, the testing suggests that the difference in loading between a six and a seven foot fall are no significant because of several factors. One, mass doesn't accellerate that fast, and two, there is some initial (and very variable) load reduction with one piece rips out and the load is then caught on by the rest of the system--sort of like a Yates screamer. Of course the amount of reduction will vary according to the placemet, but again, when limiter knots are used on the Sliding X, the extension is mere inches, and the load increase here is almost nill.

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.

I promise more on this later.

JL


pastprime


Feb 10, 2006, 3:05 PM
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So I haven't really been alone in all the world in thinking the terrors of shockloading were exageratted in these situations?

Gee, I feel all warm and fuzzy.


Can we hug?


pastprime


Feb 10, 2006, 3:15 PM
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Vivalargo: Any idea when the book may be on the shelves? Is it a updated version of one of your existing books, or something new entirely?


healyje


Feb 10, 2006, 3:36 PM
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John,

I assume when you're talking about shockloading "myths" you are talking about run-of-the-mill multi-pitch climbs as opposed to the demands and accidental loads that can be placed on big wall anchors by blowing ledges, hauling, and flying pigs?


vivalargo


Feb 10, 2006, 4:47 PM
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What I'm saying here is that it was thought by some that the Sliding X (with limiter knots) was a poor choice because if one piece in the system failed the extension in the system would produce a "shock load" on the remaining piece(s). So far, testing says otherwise.

The business of what a true shock load is, and why, is a very long discussion.

JL


roy_hinkley_jr


Feb 10, 2006, 4:55 PM
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What I'm saying here is that it was thought by some that the Sliding X (with limiter knots) was a poor choice

Did you test without the limiter knots too? That's how the Sliding-X is most commonly used. How about when the load comes from a different angle than anticipated when using the 'lette?


bloodyhands


Feb 10, 2006, 4:57 PM
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but how strong are those limiter knots?


healyje


Feb 10, 2006, 4:57 PM
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So I can take from that you make no distinction about the use of the anchor relative to any reality of shock loading?


jklap


Feb 10, 2006, 5:02 PM
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Ok, it seems like there an assumption that the shockload of an anchor failing (sliding x, no extension limitiation) is identical to a fall of an additional foot? I don't think they are the same at all-- when the anchor fails the rope is already stretched out from the initial fall-- so instead of 30%ish of elongation it's more like 5%ish-- which means if the anchors were equalized in the first place the remaining anchor is going to take a shock larger then it did the first time (if not equalized, and assuming the failed anchor had taken the majority of the previous load, then the remaining anchor is taking a load much higher then previously). In addition, the directional load on the anchor is going to change (it's might have been fine with the previous direction of pull, but now you just wiggled it around). If you were using a longish sling (say 120cm) to get the best equalization angle, it also means the extension is two feet, not one.

Given that the directional change is going to happen no matter what, I think I would try to limit the amount of new load the single anchor is about to take--- especially since it's now the last piece protecting my butt.

Ok-- what am I missing or screwed up?


tradklime


Feb 10, 2006, 6:18 PM
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Ok-- what am I missing or screwed up?

Other dynamic properties of the system. Rope slipping through the belay device, belayers body absorbing some energy, etc. I'll add friction in the sliding-x itself as it equalizes, lots of variables.

Just using your numbers, if a 6 foot fall creates 30% elongation of the rope, what is the difference if an andditional 1 ft. fall only creates an additional 5% elongation? Its proportionally the same.

I think the real point is that a static (semi) fall of a few inches, as the sliding -x slides to the limiting knot, generates negligible force.

Couple that with the fact that cordelettes are rarely, if ever, equalized...

Thanks to John for initiating some testing to help dispell some of the myths.


jklap


Feb 10, 2006, 6:33 PM
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I'm guessing the initial fall would have taken up most of the slack (ie though the belay device) so that wouldn't reduce the shock much.

Sorry--- what I meant by the elongation of the rope is the initial fall causes a larger elongation than a soon after second fall-- ie the rope becomes stretched, doesn't have time to recover and won't stretch as much the second time--- hence a higher shockload on the remaining anchor.


In reply to:
I think the real point is that a static (semi) fall of a few inches, as the sliding -x slides to the limiting knot, generates negligible force.

Ah, this is my point--- what I was questioning was the statement that the shockload of an anchor failing without a limiting knot is no different then that of a fall + a foot (ie the length of the sling slipping)


roy_hinkley_jr


Feb 10, 2006, 6:37 PM
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belayers body absorbing some energy

The Italian Alpine Club disspelled that one a while ago at their drop tower. Same with tightening of the tie-in knot absorbing energy. Both are so minimal they're inconsequential.

In reply to:
Thanks to John for initiating some testing to help dispell some of the myths.

Yep, good effort! Though it's a shame our own alpine club is pretty worthless for things like this.


vivalargo


Feb 10, 2006, 6:40 PM
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So I can take from that you make no distinction about the use of the anchor relative to any reality of shock loading?

I'm not sure what you're asking, and my sense of it is that you already have an answer in your head--and you should simply state that answer and we can work from there.

To briefly answer the question of off angle loading on a cordelett, what happens (according to the testing) is that almost the entire load is taken by the shortest arm of the cordelette.

Also, the notion that an initial load, if it blows out one arm or a sliding x, will then quickly multiply to a higher weight when it drops onto the next arm--be it 4 inches or 1 foot--is something not happening in the actual drop tests. And these tests have load capturing devices accurate to one kilo.

That much said, the million dollar question was, and still is--what rigging strategy, the Cordelette, or the Sliding X, works best at achieving equalization between anchor points rigged in vertical, horizontal, and other axis'. And so far one of these rigs is losing by an overwhelming statistical margin. It's not even close.

JL

PS: Hi Ron. The I-talian tests were a little confusing if you look at them closely. For instance, when a load is straight down on a belayer lashed snug to a belay anchor, body flex/abosrbsion is minimal. But when a leader falls above, and the belayer is pulled UPWARDS, the body acts as a counter weight to the sudden loading and then it plays a role in load absorbtion, though not remotely as much as the rope slippage at the belay device.


jklap


Feb 10, 2006, 7:00 PM
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Also, the notion that an initial load, if it blows out one arm or a sliding x, will then quickly multiply to a higher weight when it drops onto the next arm--be it 4 inches or 1 foot--is something not happening in the actual drop tests. And these tests have load capturing devices accurate to one kilo.

Ok, I'm confused--- if you have two anchors, each joined together with a sling and say a 40 degree angle between them, then they each share a part of the initial load. Correct? How is it then that if one of those fails that the other anchor doesn't take the full load plus some for the initial shockloading part? I'm not questioning the results of the tests, just questioning if I'm understanding it correctly..

-J


healyje


Feb 10, 2006, 7:05 PM
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John,

Actually I don't at all!

I'm just curious if you consider shock loading a "myth" in general. That, along with normal multi-pitch, you don't need to worry about the X shocking in a hauling accident or in a case of a heavy bag slipping off a ledge, or maybe a portaledge getting slammed up and down in a storm. I can't tell whether, from your description of the role of belaying in all this, you mean just climbing as opposed to also including the forces involved with all the other various big wall activities.

I'm asking because you're the one that's spent endless hours on all those wall anchors of varying quality over the years - I haven't but would still like to and am trying to figure out if it's worth it to do all the Chongo/PTPP major construction projects with cordalette powerpoints, etc. or should you just throw in a couple of X's and call it good...


antiqued


Feb 10, 2006, 7:15 PM
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In reply to:

Ok, I'm confused--- if you have two anchors, each joined together with a sling and say a 40 degree angle between them, then they each share a part of the initial load. Correct? How is it then that if one of those fails that the other anchor doesn't take the full load plus some for the initial shockloading part? I'm not questioning the results of the tests, just questioning if I'm understanding it correctly..

-J

I think he means that the load on the remaining single anchor is approximately equal to the sum of the loads on the original two anchors, and is not significantly raised by the further extension or by the 'hardening' of the rope.

It follows from the equations of stiffness - if any leg of a structure connected in series is soft, then the whole series is soft - so as long as a significant length of the rope is included in the only linked structure between the falling object (leader) and the anchor, then the catch is soft. Alternatively, if there is a parallel connection (tied in with rope and a parallel steel cable of the same length), then the system is 'hard'.

So for aid falls on daisies, or belayer falls direcly on the anchor, the system is hard and 'shock loading' is possible, but for lead falls it is not, unless the nut tool catches on the slings as he flies by.


fracture


Feb 10, 2006, 7:17 PM
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Hey John; I recall a passage in Freedom of the Hills 7th ed. (I don't feel like looking up the quote, sorry) which claims that there is test data out there saying that the X doesn't really adjust instantly to sudden changes in the direction of the load, supposedly making the "dynamic equalization" aspect of it significantly less effective. They don't say where they got that information, though....

Does your data contradict this?


Partner cracklover


Feb 10, 2006, 7:23 PM
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In reply to:
Ok-- what am I missing or screwed up?

Question: What creates force on the anchor?
Answer: The tension in the rope.

A piece rips out of a two piece sliding-x anchor. The sling extends and all the force comes onto the other remaining piece.

Question: What is the maximum amount of force that can come onto that piece?
Answer: Exactly as much force as the tension in the rope is creating. No more. That's the only place where force is.

In fact, the immediate force will be slightly less, because a foot (or whatever) of tension will be taken *off* of the rope.

Does that help?

GO


Partner cracklover


Feb 10, 2006, 7:28 PM
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In reply to:
Sorry--- what I meant by the elongation of the rope is the initial fall causes a larger elongation than a soon after second fall-- ie the rope becomes stretched, doesn't have time to recover and won't stretch as much the second time--- hence a higher shockload on the remaining anchor.

Um, what do you think it means to add a foot to a fall. That extra foot *is* on a rope that's already stretched as much as it's stretched. Take a five foot fall on a given rope length, or a six foot fall on a given rope length - the six foot fall is like adding an extra foot of fall on an already stretched rope.

Sorry, it's late on a Friday and it's been a long week - my writing skills are not at their best. Am I helping?

GO


roy_hinkley_jr


Feb 10, 2006, 8:23 PM
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the six foot fall is like adding an extra foot of fall on an already stretched rope.

Except a dynamic rope doesn't stop stretching...till it breaks.


Partner cracklover


Feb 10, 2006, 8:47 PM
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In reply to:
In reply to:
the six foot fall is like adding an extra foot of fall on an already stretched rope.

Except a dynamic rope doesn't stop stretching...till it breaks.

That's my point.

GO


papounet


Feb 14, 2006, 7:20 PM
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Dear

I am eagerly waiting for the results to be published.

And yet I have a question:
did you have the opportunity to test a "ropalette" ( a cordalette/ anchor system made with rope or equally strechable material) ?

My poor attempts at physics have made suspect that the stiffer the material, the worst a manually-tied anchorpoint is.
Any deviation from the predicted angle would load only one protection.

(for example sake, one may try to build an anchor with 3 nuts with rigid steel cable; there may be a configuration for which a biner distribute the pull between the 3 nuts, but any deviation in the force direction would load only one nut)


roy_hinkley_jr


Feb 14, 2006, 8:18 PM
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In reply to:
In reply to:
In reply to:
the six foot fall is like adding an extra foot of fall on an already stretched rope.

Except a dynamic rope doesn't stop stretching...till it breaks.

That's my point.

Mine too...all those broken climbing ropes, tragic.

It really should be no surprise that death-o-lettes were over-sold and under-tested for trad climbs. Even with nylon instead of spectra, they've always been sketchy.


crotch


Feb 14, 2006, 8:51 PM
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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.

Does this hold up in the special situation where one is hauling loads off a sliding X setup with a static rope?


lofstromc


Feb 14, 2006, 9:28 PM
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Hey all,

Dumb question coming up...What is the limiter knot in the sliding X that was mentioned?
The more I know the better.

Thanks


Partner cracklover


Feb 14, 2006, 10:49 PM
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In reply to:
Hey all,

Dumb question coming up...What is the limiter knot in the sliding X that was mentioned?
The more I know the better.

Thanks

http://i26.photobucket.com/...triker/sliding_x.jpg

http://i26.photobucket.com/...liding_x_knotted.jpg

GO


vivalargo


Feb 14, 2006, 11:06 PM
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In reply to:
In reply to:
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.

Does this hold up in the special situation where one is hauling loads off a sliding X setup with a static rope?

All of our tests are with a shank of dynamic climbing rope featuring a dynamic fall. You'd have to do some tests to get that data. This is a question worth answering, but not one we went after in our tests, which were geared to show the performance differences (measured equalization under a dynamic load) between a cordelette, a sliding x, and a third rigging option known as the "Duo Glide" or simply, the Slider.

JL


curt


Feb 14, 2006, 11:40 PM
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In reply to:
In reply to:
So I can take from that you make no distinction about the use of the anchor relative to any reality of shock loading?

I'm not sure what you're asking, and my sense of it is that you already have an answer in your head--and you should simply state that answer and we can work from there.

To briefly answer the question of off angle loading on a cordelett, what happens (according to the testing) is that almost the entire load is taken by the shortest arm of the cordelette...

Actually, that should be obvious. This point has been made numerous times here on RC.com by rgold, myself and others. Still, it is good that your new book (that will, no doubt, be widely read and regarded in the climbing community) will make this point clear.

Curt


patto


Feb 15, 2006, 1:24 AM
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I was scepical at first about the dismissal of the dangers of shock loading in this thread. However being an avid fan of physics I gave it a bit of thought, and found that there is some basis claiming that the danger of shock loading is overstated.

To summerise: If there is little mass attached to the belay point then there is little danger of shock loading.

However if a piece blows and causes extension when the belay is off a harness then there is a severe risk of a large shock loading (we are talking a few multiples of the original force). This is because the falling climber has accelerated a mass (the belaying climbing), which is connected to an anchor via a static, non energy absorbing link. Luckily relative to the smallish extension distances a climber's mass deformation is not negligable, and so would likely prevent the forces multiplying to order 10x the total.

EDIT:
Of course if the extension was mere inches due to a knotted sliding-x as vivalargo suggested then shock loading would be negligable in both case. If the extension was a foot or greater with a climber attached then you would be getting into a danger zone.


healyje


Feb 15, 2006, 2:15 AM
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In reply to:
I'm just curious if you consider shock loading a "myth" in general. That, along with normal multi-pitch, you don't need to worry about the X shocking in a hauling accident or in a case of a heavy bag slipping off a ledge, or maybe a portaledge getting slammed up and down in a storm. I can't tell whether, from your description of the role of belaying in all this, you mean just climbing as opposed to also including the forces involved with all the other various big wall activities.

I'm asking because you're the one that's spent endless hours on all those wall anchors of varying quality over the years - I haven't but would still like to and am trying to figure out if it's worth it to do all the Chongo/PTPP major construction projects with cordalette powerpoints, etc. or should you just throw in a couple of X's and call it good...

John and Curt,

I guess I'm feeling incredibly stupid and dense on this because I'm not getting it at all. I think I've just been programming for way too many week/days/hours in a row now and am starting to lose it. Couldn't you guys show a little pity, put me out of my misery, and just answer this question for me because I really do want to know the answer?


patto


Feb 15, 2006, 2:32 AM
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In reply to:
In reply to:
I'm just curious if you consider shock loading a "myth" in general. That, along with normal multi-pitch, you don't need to worry about the X shocking in a hauling accident or in a case of a heavy bag slipping off a ledge, or maybe a portaledge getting slammed up and down in a storm. I can't tell whether, from your description of the role of belaying in all this, you mean just climbing as opposed to also including the forces involved with all the other various big wall activities.

I'm asking because you're the one that's spent endless hours on all those wall anchors of varying quality over the years - I haven't but would still like to and am trying to figure out if it's worth it to do all the Chongo/PTPP major construction projects with cordalette powerpoints, etc. or should you just throw in a couple of X's and call it good...

John and Curt,

I guess I'm feeling incredibly stupid and dense on this because I'm not getting it at all. I think I've just been programming for way too many week/days/hours in a row now and am starting to lose it. Couldn't you guys show a little pity, put me out of my misery, and just answer this question for me because I really do want to know the answer?

If anything of considerable mass is attached via static line only then any free movement will allow shock loading to occur. This shock loading will be present even before any possible protection piece failure so it is not restricted to the sliding-x setup.

Any mass falling on a static line at an achor can create a dangerous scenario. Thus a heavy bag falling off a ledge IS dangerous.


For example if I can drop a ridgid 50kg weight 4 feet on static sling, which extends on 1in then the force on the anchor and a the sling is 2400kg which is the rated strength of most biners and slings!


verticon


Feb 15, 2006, 4:20 AM
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So we have a bomber pro and a failing one equalized with a sliding X.

The good piece will take two yanks: the first one will be at the same force as the failure force of the poor piece. At this point, the fall is nearly consumed, and the rope still have (?) some stretching reserve.

The bad pro fails and the sliding X extends. Here occurs the second yank. Some of the energy of the fall is already dissipated by the rope stretch and the failure of the bad piece. The remaining energy will produce a load only on the good piece.

So, the total energy of the fall, which is a constant for a given fall, will be shared between the two yanks, instead of producing a single (shock ?)load on the system.

IMO, "how strong is the failing piece?" is an important aspect to think about. If it blows when you sneeze on it, the whole energy of the fall will load only the good anchor, which could produce it's failure as well. If the poor placement holds a fair amount of the force, it could work like a screamer by absorbing part of the energy of the fall before failing.

Could this be used as an emergency protection for a weak anchor or for belaying a leader on a little protection pitch ?
I mean that in extremis, one could intentionally place an additional weak piece of pro (say a 5 kN nut) which will lower the impact force on the system by braking if a shock occurs.
What do you think ?


patto


Feb 15, 2006, 7:11 AM
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In reply to:
So we have a bomber pro and a failing one equalized with a sliding X.

The good piece will take two yanks: the first one will be at the same force as the failure force of the poor piece. At this point, the fall is nearly consumed, and the rope still have (?) some stretching reserve.

The bad pro fails and the sliding X extends. Here occurs the second yank. Some of the energy of the fall is already dissipated by the rope stretch and the failure of the bad piece. The remaining energy will produce a load only on the good piece.

So, the total energy of the fall, which is a constant for a given fall, will be shared between the two yanks, instead of producing a single (shock ?)load on the system.

IMO, "how strong is the failing piece?" is an important aspect to think about. If it blows when you sneeze on it, the whole energy of the fall will load only the good anchor, which could produce it's failure as well. If the poor placement holds a fair amount of the force, it could work like a screamer by absorbing part of the energy of the fall before failing.

Could this be used as an emergency protection for a weak anchor or for belaying a leader on a little protection pitch ?
I mean that in extremis, one could intentionally place an additional weak piece of pro (say a 5 kN nut) which will lower the impact force on the system by braking if a shock occurs.
What do you think ?

There is little evidence in this post of any understanding of physics. Energy and force is being completely confused in this post, it makes hardly any sense at all.

To answer the final question, not it is unlikely to absorb much energy and would do more harm than good. Screamers work because they exert a force over a distance. Most of the time when a piece blows it blows suddenly and at a single point, thus very little energy is absorbed.

EDIT: Sorry I don't mean to be rude, I was just posting how I see it. I noticed your location is Bucharest, nice one! You english is good! :)


healyje


Feb 15, 2006, 7:43 AM
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Actually, a screamer equalized to a weak anchor is way better than no screamer at all, and one that has been pre-sliced at a steep angle to provide a kinder, gentler loading profile can be especially helpful. I have built several "spider webs" of 6-8 micro nuts in a circle all equalized to the center with a pre-sliced screamer and fallen on them to the tune of four different screamers worth of falls.


verticon


Feb 15, 2006, 9:53 AM
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In reply to:
There is little evidence in this post of any understanding of physics. Energy and force is being completely confused in this post, it makes hardly any sense at all.

To answer the final question, not it is unlikely to absorb much energy and would do more harm than good. Screamers work because they exert a force over a distance. Most of the time when a piece blows it blows suddenly and at a single point, thus very little energy is absorbed.

EDIT: Sorry I don't mean to be rude, I was just posting how I see it. I noticed your location is Bucharest, nice one! You english is good! :)

I must admit that I didn't care to explain all the steps and the result is a little mixed-up. I'll try to help you reconsider your oppinion.
Here we are again: you have to agree that during a fall the potential energy (m*g*h) is converted into cinetic energy (m*v2/2). In order to stop this movement (at speed V) this energy is absorbed by the system (rope, friction device, friction with biners and rock, etc)
Decelerating the fall will produce a force (m*a) which will load the system.
Of course, the longer the time to absorb this energy, the lower the force will be (the priciple applied for a dynamic belay...). What I was speaking of, was that any piece of pro that breaks will absorb some amount of energy. The deceleration produced in the process will apply on the system (it's true, for a very short time) a force equal to the breaking strenght of the piece.

I was thinking of this because I've seen a whipper when the falling guy un-zipped 15 m of crack ripping 3 pitons and breaking a #2 wired nut, and the piece which finally holded the fall was a # 1 nut rated at 4 kN. How else could you explain this ?


landgolier


Feb 15, 2006, 10:21 AM
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I want to get out in front of this one before any more foolishness goes down, so excuse me if this is a bit terse, but...

The equations to calculate this crap in a meaningful way aren't in a high school physics text, and they probably aren't in a first or second semester college text either.

If you knew a hell of a lot about the materials in question and had a crib sheet drawn from a book that said something like "Mechanics of Deformable Solids" on the cover, you might get there. But there's a reason why the world's expert on this topic is doing lab testing to determine the forces involved, not dicking around with f=ma and integrating over the distance of extension and crap like that. Unless you're a qualified mechanical engineer (not me, but I know there are some in this discussion, and I hope they agree with me), everybody needs to put away the TI-86 and the Addison Wesley physics book, and just chill out and wait for Largo to publish his findings and explain to this new extendomatic system he thinks we should start using.

Flame away, and my apologies to the people in this discussion that do know their stuff.


tradklime


Feb 15, 2006, 10:42 AM
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I'm asking because you're the one that's spent endless hours on all those wall anchors of varying quality over the years - I haven't but would still like to and am trying to figure out if it's worth it to do all the Chongo/PTPP major construction projects with cordalette powerpoints, etc. or should you just throw in a couple of X's and call it good...

I don't have the experience level to draw from that you are looking for but I'll take a swing anyway...

Because John's tests include a section for climbing rope, the results likely won't directly transfer to the situation you are asking about, however, I'd say that a sliding-x (s) with limiting knots would be better than a cordalette. The amount of force generated in a fall of a few inches is very small. If you want the load to be shared by multiple pieces, you have to include some dynamic equalization.

The next best choice would be a Trango Alpine equalizer. I've been playing with the 3 ft. version and it has some neat properties. Even if you make it static by tying a knot in the middle leg, I think the equalization between the three pieces is better than trying to tie a perfect knot in a cordalette. That said, It does offer efficient equalization without any knots in the system, but intuitively (to me) the extension is a tad more than I'd like of a piece were to fail.

My unsolicited 2 cents


tradklime


Feb 15, 2006, 10:50 AM
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....
Flame away, and my apologies to the people in this discussion that do know their stuff.

Very good point.

I still think discussion of the issue is valuable, even if it is based on conjecture, but we should all be very clear that it is mostly conjecture.

At least I'm willing to admit that on my part.


dingus


Feb 15, 2006, 11:07 AM
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I will be very interested in the final results as I reckon most of us would. I scraped cordelettes and such after a brief trial period and went back to X's with direct backups. I never bought this whole shock load bullshit, nor did I buy the cordelettes equalization properties.

I went back to my old ways out of convenience coupled with a sense of 'good enough.' Now it turns out that good enough may in fact be better anyway.

Cordelettes have their places. Love em for big walls belays and such. But for free climbing I find them to be a huge inconvenience and totally unnecessary. Just one more piece of bullshit to carry up a climb.

Cheerio
DMT


vivalargo


Feb 15, 2006, 1:14 PM
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Hey, it's all good--and these questions are really worth answering. Thankfully I have access to questionably the best dude in the US to do all this testing, as well as all the UIAA test tower gadgets, computer analysis and so forth, without which dynamic load testing -- as seen in real world climbing -- would be impossible to conduct. FYI, most testing is slow loading or static loading and that has little to do with real world dynamic falls.

Another thing--don't forget that no matter if you're on a hard (tech cord/webing) or soft (nylon cord/webbing) system, so long as the line is belayed, rope slip at the belay device greatly limits the possiblity of a true "shock load," a term that has never been properly defined. If you have dynamic loading on tech cord/webbing sans belay--watch out folks. Picture a few haul bags connected to an anchor via a spectra sling(s), and have them bouncing around in a huge storm (hard to imagine but it happens)--that could actually bust the biners.

Lastly, we did a few tests to try and determine the degree of loading on a sliding x where one arm blows out and the other arm captures the entire load. The X had limiter knots and only extended, like, six inches. Also the piece that blew out held a good part of the load before blowing out--and this is a VERY important variable. But so far we have found no "load muiltiplication" or anything remotely like a shock load during the resultant "catch" by the remaining piece(s).

This is actually another series of tests that need to be thoroughly conducted--our testing is really to find out the performance differences (how well each system actually equalizes loading over the anchor points) between s cordelette, sliding x, and the "Duo Glide" or "Slider" rigging systems.

I've just about got the thing licked, thanks to the efforts of many experts (testers, statistical professors/climbers, et al, who I will name later) but it will still be a short while before everything is worked out.

An interesting note is that while the sliding x is the clear winner so far as equalization goes, it still had a tendency to be erratic, owing to the x clutching or binding on itself. The solution was simple--use a wide mouthed, anodized biner at the master point, and the loading on 2 points was just about equal (less than 10% difference).

More later . . .

JL


maldaly


Feb 15, 2006, 2:04 PM
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I'm w/ dingus all the way on this one. Loose the formulas and textbooks and lets figure out what actually happens in a loading situation. Mucho thanx for all the testingf largo. If there were a Mother Theresa award in the climbing industry, you'd deserve it; even if you stretch the morals a bit...
Mal


dr_monkey


Feb 15, 2006, 3:33 PM
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This thread has been interesting and I am re-evaluating my preferred equalizing method (cordelette.) I used to think that the Alpine equalizer was to specialized a piece of equipment and due to shock loading. Now it is looking much better.

All of this discussion got me thinking though, this may be a little too far off topic, but... What would be the disadvantages of using a very dynamic material for either a cordelette or sliding-x? There must be some glaring problem I am overlooking, otherwise we would all use a length of a super stretchy twin to build anchors, right? Or better yet manufacturers would be making a specific cord or sling with optimal properties for the application. Maybe it would not make a big enough difference within the greater system?

Anyone out there have actual data or knowledge about this?

Cheers,
DRS


landgolier


Feb 15, 2006, 3:49 PM
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In reply to:
This thread has been interesting and I am re-evaluating my preferred equalizing method (cordelette.) I used to think that the Alpine equalizer was to specialized a piece of equipment and due to shock loading. Now it is looking much better.

All of this discussion got me thinking though, this may be a little too far off topic, but... What would be the disadvantages of using a very dynamic material for either a cordelette or sliding-x? There must be some glaring problem I am overlooking, otherwise we would all use a length of a super stretchy twin to build anchors, right? Or better yet manufacturers would be making a specific cord or sling with optimal properties for the application. Maybe it would not make a big enough difference within the greater system?

Anyone out there have actual data or knowledge about this?

Cheers,
DRS

Bluewater makes something they call "dynamic prusik" in 6.5, 7, and 8 mils. It's not tested as a single, though, so can't say much is actually known about its properties. Can't hurt I guess.


johngo


Feb 15, 2006, 5:20 PM
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Largo and friends,

This has been a great thread! I echo the thanks of many here for the work you are doing on your new book, and for sharing some of the results with us. You'll sell a heap of books as soon as they're available. I'm teaching a few anchor classes this spring, and I want to be sure the students are getting the latest. This post has helped a lot. (And yes, the cordelettes on my rack are now catching some suspicious glances . . .)

Be Well,
johnGo


slcliffdiver


Feb 15, 2006, 5:38 PM
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A genuine shock load will only occur in those instances reflected in Duane Raleigh's recent tests for Rock and Ice, say, when someone is tied off to an anchor with a short shank of high tensile cord. He climbs a few feet above the anchor and falls. Here, you have true shock loading, where biners blow apart and anchors rip out because there's no rope slip at the belay device, no stretch in the rope, no human body to absorb loading, et al.

JL

A few senerio's with the sliding X (belayer hooked in with sling or such):
Factor two fall a piece fails if it is a hanging belay the belayer falls directly onto the extended no stretch material and is probably accelerated by the tension in climbers rope and energy of falling climber and or possibly the spring force in the rope to climber.

Factor two fall a piece fails if it is a non hanging belay the belayer is probably accelerated by the tension in climbers rope and energy of falling climber and or possibly the spring force in the climbers rope to climber.

Hanging belayer is lifted by climber from a high factor fall and either losses control of the belay (hits something? on the way up) or the top piece fails and drops the belayer onto the anchor.

It's always been my understanding that the belayer is the source of potential shock loading and not the climber.

I skimmed through the posts fast so forgive me if this has been cover and I missed it. I just prefer there not to be "a generalized myth of shock loading" out there until I'm satisfied that these issuses have been adressed. I think I've posted here more than once and agree that a climber will not cause true shock loading it's the belayer. So maybe something worded a little more narrowly. Sorry if I'm missing or miss reading something but I'm short on time for the moment and just am uncomfortable with how I percieve things are being discussed and don't know how many people read then leave without comming back.


tradklime


Feb 15, 2006, 5:46 PM
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In reply to:
A few senerio's with the sliding X (belayer hooked in with sling or such):

Attach yourself with a section of climbing rope, just as most do with a cordalette.


healyje


Feb 15, 2006, 7:42 PM
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Yet another day of being stupifyingly dense I guess...

So based on all this, if I arrive at some random anchor on WFLT, am I building a cordalette powerpoint ala Chongo/PPTP or should I simply be multi-X'ing it? I'm sure I'm missing volumes here at this point but it still seems like a pretty simple question to me.


vivalargo


Feb 15, 2006, 8:49 PM
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Yet another day of being stupifyingly dense I guess...

So based on all this, if I arrive at some random anchor on WFLT, am I building a cordalette powerpoint ala Chongo/PPTP or should I simply be multi-X'ing it? I'm sure I'm missing volumes here at this point but it still seems like a pretty simple question to me.


Okay, say you've just finished the first bolt ladder on the Leaning Tower and come to a two bolt (bomber 3/8 inch SS bolts) anchor. Here are your options: You can certainly go with a cordelette because when the arms of the cordelette are virtually equal (so far as you can get them equal), you get adequate but not great equalization between the two bolts--so if the bolts are good, you should be golden. If you wanted a better ratio of equalization between the bolts, you'd go with the sliding x, and if you wanted better equalization still, you'd clip the materpoint off with a wide mouthed, anodized biner which keeps the x from binding, which it sometimes does.

But say you are on some other wall and get to belay where you have to hand build with nuts and cams placed in two vertical cracks that are close to each other, in which you have two primary placements in both cracks, totaling four placements in all. In this scenario, a cordelette would involve four arms that are all different lengths, a scenario that testing has shown to be a total bust so far as equalization goes. Here, a cordelette isn't even a redundant system, since most all the load will fall on the shortest arm--meaning the cordelette is a backed up, rather than a redundant, system.

The drawback with using the sliding x here is that it can only combine two placements, so you'd have to double up the system with two x's--no big deal, but extra hassle.


There is yet a third system called the Duo Glide that is looking probable as the best of them all--by far, but we still are working out the bugs in this thing since we only stumbled on the idea a few days ago.

If there is any interest in people doing some contrilled field testing of the Duo Glide, I'll post how it works and you guys can help figure out how to dial in the fine points. It so far looks amazing in the figures it's spitting out.

JL


healyje


Feb 15, 2006, 9:18 PM
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John,

Sorry to be such a nuisance, but that was just what I was looking for! Thanks much and do keep up the good work as it is much appreciated.

Whatever the Duo Glide business is, count me in, I'd love to take a look at whatever you've come up with - particularly anything you appear to be as excited about as this...


dood


Feb 15, 2006, 9:27 PM
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Very interesting indeed, and I'm looking forward to the final results. While raised on cordolettes, I've used the sliding X in situations where rockfall was a possibility, in an effort to give myself a little more mobility for dodging missiles. Now it is no longer a trade-off of mobility for a stronger anchor.


slcliffdiver


Feb 15, 2006, 10:33 PM
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In reply to:
In reply to:
A few senerio's with the sliding X (belayer hooked in with sling or such):

Attach yourself with a section of climbing rope, just as most do with a cordalette.

Exactly it's the "most do" part that's troubling.

There are currently some climbers that at least part of the time who hook into the the anchore directly or with static material (which in general I don't like). They are going to be in potentially more trouble if they go from a non extending system to an extending system with out realizing how things work or changing their habits.

Problems when the belayer is hooked to extending system.
Belayer shock loading the system ; tie in with enough rope to absorb most of the shock (more rope than the potential extension).
Belayer loosing control of rope because they lost balance and fell and or hit their tailbone or whatever because of the extension; limit extension watch where you are belaying from etc.

Many things in trad are situation specific. I'm concerned if their is a shift away from the no extension part of sere"ne" their will be potentially new problems for people who don't understand the new factors involved with a potentially extending systems when they've been operating under the principle of no extention for a long time. Specifically the potential for the belayers body to shock load the system. I'm not proposing a specific solutions or changes. I just think it would be wise include information on the potential downsides and precautions that need to be taken with potentially extending systems and I'm hoping that'll be included with a new anchor book if it includes or emphasizes systems that can potentially extend.

But it also disturbs me a bit that many trad climbers don't seem to reallize in general that the belayer can actually shock load the system. Trad climbers tend to be creative out of neccesity sometimes. If you don't understand the principles what you build can potentally be less than ideal. I just wish the trad climbing public at large would be better educated at how shock loading really works. And if the community ends up shifting a bit away from the "no extention" principle it seems like it will become a more important for more people to understand.


curt


Feb 15, 2006, 10:40 PM
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In reply to:
I'm just curious if you consider shock loading a "myth" in general. That, along with normal multi-pitch, you don't need to worry about the X shocking in a hauling accident or in a case of a heavy bag slipping off a ledge, or maybe a portaledge getting slammed up and down in a storm. I can't tell whether, from your description of the role of belaying in all this, you mean just climbing as opposed to also including the forces involved with all the other various big wall activities.

I'm asking because you're the one that's spent endless hours on all those wall anchors of varying quality over the years - I haven't but would still like to and am trying to figure out if it's worth it to do all the Chongo/PTPP major construction projects with cordalette powerpoints, etc. or should you just throw in a couple of X's and call it good...

John and Curt,

I guess I'm feeling incredibly stupid and dense on this because I'm not getting it at all. I think I've just been programming for way too many week/days/hours in a row now and am starting to lose it. Couldn't you guys show a little pity, put me out of my misery, and just answer this question for me because I really do want to know the answer?

What has been pointed out in the past is that a cordalette does a fairly poor job of equalizing forces on the various anchor elements. Even in the best case scenario with only two placements (or bolts) a cordalette will not truly equalize force on the two anchor points if the falling force is not exactly in-line with the masterpoint--as it was designed. The only exception to this rule is if the two anchor points are in a vertical line--i.e. one anchor element is directly above the other.

With three or more anchor elements things get much worse and a fall will transfer virtually all of the force of a fall to a single anchor piece--i.e. one anchor piece "sees" nearly 100% of the force on the anchor. Only after that piece fails does the next piece become significantly loaded--again with 100% of the force. So, clearly this is not optimal.

What I believe John is bringing to the party here is some actual data that suggest the failure of a "sliding x" anchor does not result in a huge shock load on the remaining anchor piece--if the other one should happen to fail. Perhaps this is because the two anchor elements in a "sliding x" anchor are at least truly sharing the force of a fall in a meaningful way, when initially loaded.

Curt


healyje


Feb 15, 2006, 10:54 PM
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Curt,

Thanks for that. I basically got most of that part out of the thread, but couldn't tell in the end what John would suggest I do on arriving at an anchor on a big wall in light of this new data.


vivalargo


Feb 15, 2006, 11:06 PM
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Okay, here is what we have so far found about so-called shock loading. Because our testing was basically to determine the equalization ratios of the cordelette and the sliding x, the main concern was to determine what happens to the dynamic load if one arm of a sliding x (with limiter knots) should blow out and the system should "extend" a few inches before the other arm holds. We are still doing more tests, but this kind of very minor extension so far looks to be insignificant SO LONG AS THE FALLING CLIMBER IS ON A DYNAMIC NYLON ROPE (THROUGH WHICH THE FORCE IS TRANSMITTED) AND THE ROPE IS BELAYED. If you have a piece of static cord and no belay, any extension/fall is very disruptive on the anchors. That's why a person should never tie into the anchor with a tech cord/web daisy. A daisy made out of anything but nylon is a serious liability because it can cause shock loading (as seen in the recent Rock and Ice expose). You ALWAYS tie into the anchor master point with the climbing rope. NO exceptions.

I can get even more technical if need be, but ain't that clear enough? Bear in mind that the above is basically only possible if the belay anchor is forced to take the entire loading--normal with bringing up a second, but here the forces are low, and if an arm of your tigging system blows from belaying a sceond, your anchor is not nearly "good enough."

JL


desertclimber


Feb 16, 2006, 12:31 AM
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VivaLargo, have you tested the "sliding x" with a three-point setup?

We've always used sliding x's, but on occasion when the anchor is three points: Instead of using two separate x's (One for two pieces, then another between that x and the third piece) a sliding x with three pieces was built. Same principle, just a slightly different setup.

Curious, as I had not seen that mentioned anywhere in the thread...


roy_hinkley_jr


Feb 16, 2006, 12:46 AM
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If you wanted a better ratio of equalization between the bolts, you'd go with the sliding x, and if you wanted better equalization still, you'd clip the materpoint off with a wide mouthed, anodized biner which keeps the x from binding, which it sometimes does.

How much does the choice of sling material or biner affect this equalization? For example, does using a sling of plain ol' nylon supertape, one with a low ratio of spectra/nylon (12mm, though even weave and amount of fuzz could be factors), or one that's nearly all spectra (6-8 mm) matter in terms of friction? Is biner diameter (10mm vs 12 mm) as important as shape and anodizing? Have you tried the Trango Equalizer rig? Definitely post info on the Duo Glide!


patto


Feb 16, 2006, 4:42 AM
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this energy is absorbed by the system (rope, friction device, friction with biners and rock, etc)

Rock effectively absorbs no energy as the rock generally does not deform.

In reply to:
What I was speaking of, was that any piece of pro that breaks will absorb some amount of energy.

Breaking pro absorbs only a very small amount of energy, as the distance of deformation is small. Certainly setting up a deliberately un-bomber piece to act 'like a screamer' is foolhardy.


patto


Feb 16, 2006, 4:50 AM
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I want to get out in front of this one before any more foolishness goes down, so excuse me if this is a bit terse, but...

The equations to calculate this crap in a meaningful way aren't in a high school physics text, and they probably aren't in a first or second semester college text either.

If you knew a hell of a lot about the materials in question and had a crib sheet drawn from a book that said something like "Mechanics of Deformable Solids" on the cover, you might get there. But there's a reason why the world's expert on this topic is doing lab testing to determine the forces involved, not dicking around with f=ma and integrating over the distance of extension and crap like that. Unless you're a qualified mechanical engineer (not me, but I know there are some in this discussion, and I hope they agree with me), everybody needs to put away the TI-86 and the Addison Wesley physics book, and just chill out and wait for Largo to publish his findings and explain to this new extendomatic system he thinks we should start using.

Flame away, and my apologies to the people in this discussion that do know their stuff.
Flame started.

It is certainly possible to accomplish alot with basic F=MA physics. F=MA physics is indisputable as long as the correct assumptions are used. Certainly there is alot we cannot answer without real world testing. For example I cannot begin to tell you using basic physics the real world load sharing of 'equalised' anchors compared to the sliding-x. For that I think Largo's testing is fantasic.

However I can tell you that the so called 'shock loading' is negligable during extension of a sliding-x when there is no mass at the belay. (The weight of a biner and a belay device is negligable) I can tell you this because there is nothing to carrying that energy to produce the 'shock load'. That is undeniable physics.


norushnomore


Feb 16, 2006, 5:18 AM
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Looks like Alpine Eq dude is getting vindicated here.

He pointed out few years ago these two issues:
1. Cordelette is very likely to put all the load on the shortest arm
2. Sliding x binds easily

Thus his invention with the ring to address both of the above.
So much for bashing him here

JL, please post the details of the Duo Glide, there is definitely an interest.


papounet


Feb 16, 2006, 8:02 AM
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Dear vivalargo,

Did you ever come across Multi Point Force Distribution Anchor (MPFDA) ?
as described in http://www.prolearn.org/stealth/r-mpfda.html and other rigging texts ?

It provides load distribution and decreases impact of protection failure. as the anchor adjusts itself, some energy of the fall is also dissipated.


roy_hinkley_jr


Feb 16, 2006, 12:57 PM
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Papounet, FYI, the Trango Equalizer is a commercial version of that.


tradklime


Feb 16, 2006, 1:51 PM
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I'm concerned if their is a shift away from the no extension part of sere"ne" their will be potentially new problems for people who don't understand the new factors involved with a potentially extending systems when they've been operating under the principle of no extention for a long time.

Well all this time apparently most people didn't understand the inherent lack of "equalization" (another principal of serene) with a cordalette and the associated problems.

I guess it's just part of the evolution of knowledge. Thanks to John for providing some hard data to support what an apparent minority has understood for awhile.


vivalargo


Feb 16, 2006, 4:26 PM
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In reply to:
VivaLargo, have you tested the "sliding x" with a three-point setup?

We've always used sliding x's, but on occasion when the anchor is three points: Instead of using two separate x's (One for two pieces, then another between that x and the third piece) a sliding x with three pieces was built. Same principle, just a slightly different setup.

Curious, as I had not seen that mentioned anywhere in the thread...

I PMed you on this 3 piece sliding X configuration, but I'm sure the climbing community would appreciate knowing how you're rigging this. Our way is to use the two strands (on one side) above the limiter knots at the bottom, attaching each strand indidvidually to two placements via clove hitches.

Incidentally, the "Duo Glide" system (aka, "Equalette") I mentioned simply does away with the "X" and clips off both strands (individually, with lockers) at the bottom of the rig, between the pre-tied limiter knots. The ease and equalization of this set up spanks all others--by far.

Pro guides Tom Cecil and Bob Gaines have been field testing this rig along with us cocking around in the lab, and in a few days we should be ready to bust out something that really and truly works like charm--and believe me, it's been months of work to figure all of this out, a regular love of labor by a stack of really talented folks.

JL


slcliffdiver


Feb 16, 2006, 8:30 PM
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In reply to:
Well all this time apparently most people didn't understand the inherent lack of "equalization" (another principal of serene) with a cordalette and the associated problems.

I guess it's just part of the evolution of knowledge. Thanks to John for providing some hard data to support what an apparent minority has understood for awhile.

Agreed, I think it's really good of John to put forth the limitations of equalization with cordelletts and I'm looking forward to the details of the results. I'm guessing I might be modifying what I do to an extent at least in some circumstances maybe a lot.
If the equalette performs as advertised (when my brain clears up enough to set it up from the discription) we may have a lot more to be greatful for for those that worked on it. Fast, versitile, truely equalizing limited extention is the holy grail for anchors. I'm really excited to have a chance to try it out.


jeremy11


Feb 16, 2006, 9:39 PM
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papounet wrote
In reply to:
Did you ever come across Multi Point Force Distribution Anchor (MPFDA) ?
as described in http://www.prolearn.org/stealth/r-mpfda.html and other rigging texts ?

really interesting article, thanks for filling us in. looks like the trango alpine equalizer http://trango.com/prod.php?id=19 (or the alpine equalizer looks like the MPFDA) but that is another piece of expensive single purpose gear to lug around...
Any testing on this to see how effective it is in light of the new research?


vivalargo


Feb 17, 2006, 12:19 PM
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Designers of the Trango Equalizer recognized the basic problem: any rigging system with a fixed, non-sliding master point can never load up in a way that will ever achieve really solid equalization/load distribution. However, the Equalizer is not that versitile since it's basically built for three placements. It also has a small master point, is expensive, has too many widgets, and is a single-use item (meaning you can't use it for other purposes other than as a rigging tool). It also is made out of slinig, and tech cord or 6/7 mm nylon rope is much better when using clove hitches--which are required for tying off when you want a system for which you can tie off 2, 3, or 4 primary placements.

Testing of the "Equalette" (aka, the "Jimbolon," after Jim Ewing of Sterling Ropes) is going on just now, and this system simply uses a 20 or so foot piece of cord and can be used to tie off 2, 3, or 4 placements and achieves solid equalization--or that's the way it's looking so far.

JL


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Feb 17, 2006, 2:57 PM
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I'm nervous about a couple of things I do now in top belays. John mentions a few times in this thread the relevance of the belayer in the shock absorbtion equation. If you use a Reverso or Gri-Gri attached to the strong point of the anchor, aren't you removing this? Is it significantly safer to attach the belay device to your harness and redirect through the strong point?

Secondly is the importance of the small rope slippage through the belay device. Do auto-locking devices such as the Gri-Gri and Reverso bind so quickly as to remove this from the equation?


landgolier


Feb 17, 2006, 4:12 PM
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These teasers about this new rig are killing me, I think I can mostly picture it but it seems to rely on single strands of cordelette-sized material (like 7 mil perlon), which conventional wisdom says is too weak; there have been a couple threads where people wanted to make a rabbit runner out of 7 or 8 mil, and the answer was always "death-o-lette." I think somebody did actually buy the farm on a rig like this once, but I can't remember enough details to dig it up. I guess maybe if the thing actually equalizes it's not so bad, tho, or maybe I just have the wrong idea.

In reply to:
I'm nervous about a couple of things I do now in top belays. John mentions a few times in this thread the relevance of the belayer in the shock absorbtion equation. If you use a Reverso or Gri-Gri attached to the strong point of the anchor, aren't you removing this? Is it significantly safer to attach the belay device to your harness and redirect through the strong point?

Secondly is the importance of the small rope slippage through the belay device. Do auto-locking devices such as the Gri-Gri and Reverso bind so quickly as to remove this from the equation?

Grigris are one thing since you can belay a lead with them, and even petzl admits they increase force on anchors. I think the concensus is that they are best for sport, or situations where autolocking trumps all other considerations (walls being one), though plenty of people belay 1-3 pitch trad with them and don't die.

However, you bring up top belays pretty specifically. In that situation the fall is generally so short and of such low factor that the forces aren't that big, though shit can always happen. I know my B-52 definitely doesn't let much rope slip in a fall, but I also often don't even know the second has fallen or if I'm just belaying too tight. I'm not sure how much slippage there would be if you dropped 80kg on a 3m factor 1, but I'm also not eager to find out. Also keep in mind that belaying off the harness and redirecting increases the forces on the anchor (theoretically 2x but there is friction and other stuff going on), so doing that may lose you in the straightaways what you gain in the curves, so to speak.

Conventional wisdom is that if you have doubts about the anchor's ability to hold a second's fall, and you can't do better on the anchor (double scary since that means there is no good pro above the current location, and you will presumbably be leading up into that and risking a factor 2 onto your crap anchor), you can belay directly from the harness and try to keep the force off the anchor with your legs, assuming you have a decent stance. I'll defer to the alpine masters and old schoolers who passed the Dartmouth belay test on the subject of stance belays.


clmbnski


Feb 17, 2006, 4:13 PM
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While I realize there are problems with cordelettes I think they are worth defending.

First of all I dont believe that only one peice in the anchor takes 100% of the load when using a cordelette. I know the longest arm stretches more than the shortest reducing the equalization but there is still some distribution of the load between the other peices. Not perfectly equilized but one may be able do deal with it by trying to get the best peice on the shortest arm and puting a little more tension in the longest arms.

That sounds complicated and given a simple anchor with two bolts, the sliding x is probably the way to go, but I think the cordellet really works well when building tricky multi piece trad anchors while keeping things clean and eliminating clusterf*ck. I regularly climb in an area where the anchors vary from all gear to small trees to big trees to boulders and the cord is more versatile than trying to make slings the right length and equilized. I recently topped out on a climb to find a completely flat rock summit without any trees or cracks for an anchor. But there was a very large boulder on top that I was able to wrap the cord around. Without it I would have had to girth hitch 5 or 6 slings together to get something to work.

So my point is while cordellets have some issues they are still useful and versatile.

Chris


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Feb 17, 2006, 4:55 PM
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These teasers about this new rig are killing me, I think I can mostly picture it but it seems to rely on single strands of cordelette-sized material (like 7 mil perlon),.

He said it was one 20' piece though. And the strands are clipped individually. Does he mean this?

http://rugby.net/images/duoglide.jpg


healyje


Feb 17, 2006, 6:04 PM
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Hi, no, I believe he means this (John, correct me if I'm wrong here):

http://www.cascadeclimbers.com/...500/6299DuoGlide.JPG


Partner dominic7


Feb 17, 2006, 6:21 PM
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In reply to:
Hi, no, I believe he means this (John, correct me if I'm wrong here):

http://www.cascadeclimbers.com/...500/6299DuoGlide.JPG

Very interesting. You need the two biners though - you wouldn't want to clip both of the little bottom loops with one biner, because potentially if both pieces on one side of your picture failed the whole rig could slide right through it. Clip just one loop and you are ok though.


vivalargo


Feb 17, 2006, 6:49 PM
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Jeeeeeeeez, you guys don't let a man rest. But then I went and opened up my fat trap and now I have to explain myself.

Healyje has the basic idea in that graphic, but please understand that as we speak Jim at Sterling is still doing testing on this (looks sensational so far) and pro guides Tom Cecil and Bob Gaines are field testing this rig (I think the name is probably going to be the Equalette) just now as well.

As Healyje has it set up, the pieces are so spread out I doubt any system could cover it and remain well equalized--here you'd probably want to connect both pairs with a sliding x and then last it off with the equalette. For use with 3 or 4 pieces more closely spaced--especially when they are placed in a vertical crack, or side by side cracks or features, the equalization is so far looking quite even, with some good leeway for changes in the direction of pull.

There's still bugs to be worked out with this system, and I'm sure it will change shape in the next few weeks as others keep fiddling with it. I think Healyje's graphic feaurtes a unit that is needlessly big.

We were originally wondering about redundancy in each strand, but because they are connected (looped), and because there is no real world evidence of a strand of 5mm tech cord or 7 mm perlon (in good shape) in a rigging system acutually breaking (how often does the tech loop on Cams ever bust??), this was dismissed as being a practical worry (it is still a theoretical worry, however).

The bottom line here is that testing (upwards of 200 drop tests so far) has shown that any rigging system featuring a fixed masterpoint will never even remotely equalize three or more pieces, and will only partially equalize 2 pieces when the arms of the rigging system are virtually the same length. So the fixed masterpoint knot is the workaround thus far, and the Equalette is just the first of many potential and promising systems that might deliver on the promise of equalization. In the tests with the equalette connected to two pieces, the equalization was almost 50/50 to each piece--by far the best so far.

But the work goes on . . .

JL


healyje


Feb 17, 2006, 6:56 PM
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John,

Sorry to jump the gun, was just wanting set the other posted drawings straight. Also, I was in no way intending to show scale or a real world anchor, but rather exaggerated it by spreading it all out to be able to show the basic idea / components and have some room for labelling.

My only comment on it so far is it takes at least a little tuning. Like I just want to get it up and loosely cloved, then clip into it so there is a bit of weight on it, adjust one strand to that length, and then load it a bit more and do up all the remaining cloves so they are all really are snug against a load.


vivalargo


Feb 17, 2006, 7:08 PM
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Healyje--
You didn't jump the gun--I did.

Anyhow, the trick to rigging this is to first clove off the BOTTOM placements on each arm--then you only have to feather the other two cloves. After going thrugh the process a few times you'll find it's nearly as fast as rigging a cordelette-and quicker to break down since the limiter knots stay in the rig, and the cloves untie faster than overhands and figure 8s.

JL


patto


Feb 17, 2006, 10:30 PM
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An easy way to solve the equalisation issue is with a dynamic cordellete.


dwebster


Feb 18, 2006, 12:05 AM
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In reply to:
An easy way to solve the equalisation issue is with a dynamic cordellete.

This might seem to be true and in some cases it probably is but certainly not always. For instance: a vertical crack where you have a short leg, a medium leg, and a long leg. Think of the legs as three different length rubber bands made of the same thickness of, well, rubber. Hang all three on a pencil. Now put your finger through all three as well. Now pull your finger and the pencil in opposite directions. You will feel the short one load first and if it's a lot shorter than the second one it could be almost fully extended and taking the full load before the second or third starts to take any. Of course there are an infinite number of variables on the lengths of the rubber bands (legs of a cordelette) but the principle will always be the same. It doesn't matter if the cord is super stretchy or super not stretchy (low modulus or high modulus for you techies). As long as all the legs of the cordelette are of the same material this principle will apply.


patto


Feb 18, 2006, 2:53 AM
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In reply to:
In reply to:
An easy way to solve the equalisation issue is with a dynamic cordellete.

This might seem to be true and in some cases it probably is but certainly not always. For instance: a vertical crack where you have a short leg, a medium leg, and a long leg. Think of the legs as three different length rubber bands made of the same thickness of, well, rubber. Hang all three on a pencil. Now put your finger through all three as well. Now pull your finger and the pencil in opposite directions. You will feel the short one load first and if it's a lot shorter than the second one it could be almost fully extended and taking the full load before the second or third starts to take any. Of course there are an infinite number of variables on the lengths of the rubber bands (legs of a cordelette) but the principle will always be the same. It doesn't matter if the cord is super stretchy or super not stretchy (low modulus or high modulus for you techies). As long as all the legs of the cordelette are of the same material this principle will apply.

True equalisation wont be perfect in this situation, but it would be far superior to static cord used in the same way. In this situations you would be hard pressed to load more than one strand if static is used.


dwebster


Feb 18, 2006, 10:39 AM
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In reply to:
True equalisation wont be perfect in this situation, but it would be far superior to static cord used in the same way. In this situations you would be hard pressed to load more than one strand if static is used.

It will only be better in the sense that there will be some energy absorption. Static cord, dynamic cord, webbing, or even wire cable, the principle still applies because elongation ratios between the legs will remain the same (assuming the exact same setup with each material).


curt


Feb 18, 2006, 11:07 AM
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In reply to:
In reply to:
True equalisation wont be perfect in this situation, but it would be far superior to static cord used in the same way. In this situations you would be hard pressed to load more than one strand if static is used.

It will only be better in the sense that there will be some energy absorption. Static cord, dynamic cord, webbing, or even wire cable, the principle still applies because elongation ratios between the legs will remain the same (assuming the exact same setup with each material).

Correct. Unless the tension is equal in each leg of the cordalette, you won't have equalization.

Curt


dwebster


Feb 18, 2006, 11:44 AM
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Right, and as long as you have cordelette legs of different lengths you can never achieve perfect equalization in standard cordelette mode. Unless of course you have load/force measuring devices on each leg and can adjust the direction of pull.

Starting with each leg under equal tension (again with different length legs) you will still get different loads on each leg as the load is increased because the longer legs have more potential elongation. In other words they will have to stretch more than the shorter leg to maintain the same load.


vivalargo


Feb 18, 2006, 12:46 PM
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Mr. Webster--

You pretty much have the thing reckoned. The business of stretch of unequal arms is also germane to most any rigging system with unequal arms, though we're fiddling with one system we're (so far) calling the "Quad" which seems to pretty much equalize (nearly 50/50 on each placement) two anchor points even with unequal length arms. Once you move into three and four arm configurations you're tying off strands of an arm, and while the arms themselves might remain pretty well equalized, the strands will not load with the same degree of equalization. To expect to get equal loading across three or four placements is to expect too much from any rigging system. The boon of these new rigging systems is that they offer far better equalization between the two arms--but it's all a work in progress.

Again, as a general rule, any system (at least all the ones we've looked at) featuring a fixed powerpoint knot is not going to equalize even the two arms very well, and the individual strands (or plus 2 arms) are going to be weighted at very different ratios.

The true magic bullet is going to be a system (rigged on a standard length of cord sans widgets) where you can clip off the placements with loops (not knots), and which features a sliding powerpoint. Perhaps the two are mutually exclusive, but I bet this can somehow be rigged if enough people start fiddling around with the idea.

JL


bloodyhands


Feb 18, 2006, 1:59 PM
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In reply to:
The true magic bullet is going to be a system (rigged on a standard length of cord sans widgets) where you can clip off the placements with loops (not knots), and which features a sliding powerpoint. Perhaps the two are mutually exclusive, but I bet this can somehow be rigged if enough people start fiddling around with the idea.

JL

Like Trango's easy alpine equalizer?
http://www.trango.com/.../alpineequalizer.jpg

In reply to:
The original versions were made with 9/16" webbing and rap-rings.

Looks pretty easy to replicate.

Slide two(or more) rap rings onto a piece of webbing. Form a loop (not a bight) containing the rap rings in the line with two side by side out water knots about 5" apart. Take the middle of the loop and tie an over hand knot on the bight containing the two rap rings. Ten tread the two ends of the webbing through the rap rings and tie them together with a double fisherman's knot. Clip the powerpoint between the two water knots.


jakedatc


Feb 18, 2006, 5:07 PM
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John, can't wait until your new book comes out.

i find it funny that when i did a search for alpine equalizers it came back with an thread that had probly 75% passionately defending their cordalettes. Looks like with a knot in one of the legs or cloves on the pro it should be SERENE with actual NE instead of percieved NE of cordalettes. question i have is 6' or 3' for multipitch trad purposes?
http://www.rockclimbing.com/forums/viewtopic.php?t=49735&postdays=0&postorder=asc&topic_view=&start=0


vivalargo


Feb 18, 2006, 5:59 PM
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The whole challenge with introducing a new rigging system (and none of them are really new, they just have new features) is that they can't have doo-dads and widgets like rap rings and what not. It's gotta be something you can tie on a standard length of 5.5 tech or 6/7mm nylon cord.

I'm pretty good at figuring out what something really and truly is and what needs to be done, but I'm not especially skilled at figuring out the fine points of how to rig a new system. But you guys out there probably are so start fiddling around with stuff if you please. It's actually pretty fun--just get a cordelette and tie it off to chair legs or biners in a chain link fence and go to work.

Help me out here folks . . . (remember, no doo-dads, just a regular cordelette).

JL


bloodyhands


Feb 18, 2006, 6:28 PM
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In reply to:
Help me out here folks . . . (remember, no doo-dads, just a regular cordelette).

JL

so no binners?


Partner rgold


Feb 18, 2006, 7:19 PM
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Re: Improved sliding x: Is it really safer? [In reply to]
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In reply to:
To expect to get equal loading across three or four placements is to expect too much from any rigging system.

I think the problem is with the use of limiter knots. In principle, equal loading is possible if the set-up is essentially a pulley, which will even redistribute the otherwise unequal tensions in arms of different lengths. (I don't know whether this theoretical fact has been tested yet, i.e. I don't know whether the friction in the real system will overwhelm the system's equalizing potential.)

The alpine equalizer seems to come close to the pulley ideal for three strands as long as no limiter knots are used. But of course no limiter knots means unacceptable extension if a piece blows. The solution, it seems to me, is to use an "equalizing pulley" with relatively little total rope in it, so that not so much extension is possible. This would be done by extending the placements in some other way so that all the connections to the "equalizer pulley" were already very close together.

Actually, Trango has anticipated this by offering a version of the Alpine Equalizer with---if I understand their copy---a total of three feet of sling in it. Tied off to three pieces (extended so as to make this possible), this would produce three 6 inch arms and nearly full equalization potential (mitigated by the friction of the slings in the rings and over the biners). If one of the arms blows, the one foot of sling material in the blown arm would be distributed to the other two arms, making them approximately 9 inches each and so resulting in an acceptable 3 inch drop in the system.

It is true that the Alpine Equalizer can probably be well approximated by a carabiner, some rap rings, and slings carried by the climber, and in such a case could be adapted with relative ease to either two or more than three anchor points. Fixe rap rings are certainly strong enough, and I think the new solid aluminum rings by OP are too. They probably will introduce more friction then the Alpine Equalizer's rings. Merely carrying four rap rings on a biner isn't enormously gimmicky to me, considering that they could also be used in a pinch as...rap rings. But setting up anchors with this system is probably much too finicky for general use, and I suppose this is John's basic and quite reasonable objection.

And yet...there may be times when finickyness has its place. If you find yourself confronted with relatively poor anchors, full equalization might be worth the extra effort and could indeed be the difference between life and death, especially now that we know how possible a "cascade failure" is with fixed power point rigging. If such a moment arises, few people would, I think, find a few extra rap rings on a biner too high a price to have paid for a lot more security. BUT, you still have to know how to rig up the system in an efficient and timely fashion, and this will take some of the homegrown practice John has already recommended.

It is also true that such a system could be rigged just with biners, but a four-anchor system would consume eight biners, which might strain the rack's ability to deal with the next pitch and belay anchor.


patto


Feb 18, 2006, 7:24 PM
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Re: Improved sliding x: Is it really safer? [In reply to]
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In reply to:
It will only be better in the sense that there will be some energy absorption. Static cord, dynamic cord, webbing, or even wire cable, the principle still applies because elongation ratios between the legs will remain the same (assuming the exact same setup with each material).

In reply to:
Correct. Unless the tension is equal in each leg of the cordalette, you won't have equalization.

No, incorrect.

Dynamic cord DOES perform significantly better that static cord. Forget the energy absorbion, it is better because the elongation ratios between the legs AREN'T equal. The larger the load on a line the larger it's stretch and thus load is transferred to the other lines.

I am not claiming superiority of dynamic over sliding-x but your claim that dynamic line vs static line being roughly the same equalisation is blatently false.


Partner rgold


Feb 18, 2006, 7:45 PM
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In reply to:
Dynamic cord DOES perform significantly better that static cord. Forget the energy absorbion, it is better because the elongation ratios between the legs AREN'T equal. The larger the load on a line the larger it's stretch and thus load is transferred to the other lines.

I am not claiming superiority of dynamic over sliding-x but your claim that dynamic line vs static line being roughly the same equalisation is blatently false.

The tension in any arm is proportional to the elongation of the arm, regardless of the material. This means that, in general, the ratios of tensions between pairs of arms will be equal in the two systems. In turn, this in means that a static cord or webbing system will distribute the load in the same way as a more dynamic one. However, although the distribution ratios will be more or less the same for the two systems, the dynamic system will result in lower absolute tensions in each arm. I don't know how much lower these tensions would be in practice.

The claims above are true without the expressed hedges for pieces in a vertical line. For other configurations, the additional stretch in the dynamic system will result in smaller angles at the power point, and this would translate into an advantage for the dynamic system, although I suspect it would be negligible in practice.

Perhaps the main reason to prefer more dynamic rigging material for a fixed powerpoint anchor is that the additional stretch available might help to counter the inevitable imperfections in tying the arm lengths.


Partner rgold


Feb 18, 2006, 7:46 PM
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Aack---double post. Sorry.


curt


Feb 18, 2006, 8:11 PM
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In reply to:
In reply to:
Correct. Unless the tension is equal in each leg of the cordalette, you won't have equalization.

No, incorrect.

Before you jump right in--and call someone else wrong, you really should have at least some minimal understanding of the topic.

Curt


pipsqueekspire


Feb 19, 2006, 12:06 AM
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THis is just a thought for a rig but it seems to me that the dreaded single stranded Death-o-lette is about to make a HUGE comback.

THis is my idea of a super simple rig using a rabbit runner style cordolette.

ACK I have no idea how to upload an image. Any help?


moose_droppings


Feb 19, 2006, 1:38 AM
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I got a strong feeling the death-o-lette is not going to make a strong comeback.
I too would like to know a place on the www I can upload a drawing to and then post it here.


Partner euroford


Feb 19, 2006, 9:54 AM
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http://www.tinypic.com/


bighigaz


Feb 19, 2006, 10:28 AM
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I didn't read the entire forum, (I apologize), but wanted to share my .02...

How many people out there still use the sliding x at all? Seems to me a good cordellette would be a superior alternative in any situation that could use the sliding x.

I could be mistaken, but I believe the AMGA actually recommend NOT using the sliding x configuration... because of the shockload factor.

Well, next week we're actually doing a class out here in Tucson, so I'll ask them a bit about it. Maybe there is still some use to the method, and a good way to eliminate a shock load?

I just can't see it... my mind is trained for a cordellette, and equalization is fairly easy to achieve, even on oddly spaced pieces if your cordellette is long enough.

I could be completely off... I'll follow up after the class...

Oh, and I promise to read the rest of the forum when I get back this afternoon...


jakedatc


Feb 19, 2006, 10:44 AM
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bighigaz

from largo page 2(bold is mine) :
In reply to:
What makes this tricky is that so long as you are climbing with a dynamic rope that is belayed, true "shock loading" never really occurs owing to the stretch in the rope and, most importantly, rope slip through the belay device. In other words, when a Sliding X is configured with limiter knots, the few inches of extension will never produce a true shock load, or anything even approaching that kind of stress.


gordo


Feb 19, 2006, 11:11 AM
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Re: Improved sliding x: Is it really safer? [In reply to]
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In reply to:
I didn't read the entire forum, (I apologize), but wanted to share my .02...
Well, I'm not carrying the flamethrower today, but it's tempting. By not reading and "sharing" you've totally ignored the whole premise of the whole thread...that evidence is clear that the cordolette does not equalize, that the sliding x does, and that extension is a myth. There isn't one line I can think of that makes me want to flame as much as "I didn't read the thread but..." :roll: :roll: :roll:


OK, on the subject. I've been reading all along, since the OP. I've never stopped using the sliding x for 2 bomber bolts, but for anything else I've been a cordolette guy. I carry 2 on every climb. So..........

After reading Johns stuff and the pictures a few pages back, I started building anchors in the living room. (Wife loved that :D )

I basically took my cordolette and tied 2 limiter knots on the middle, giving me two 8 inch equalizing loops. Then I set up a variety of possible situations on the anchor pieces.

Given 3 to 5 anchors pieces in a horizontal or vertical plane, this idea seems to work (like the pic on page 6 I think) BUT When the pieces of the anchor are not in the same plane, and the "elevation" for lack of a better word changes, the equalization fails. The sliding biners only equalize in the direction that the equalization loops run, and if the master point moves in a different direction, it changes the length of one leg.

That's my hands on so far.


altelis


Feb 19, 2006, 11:20 AM
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bighigaz,

1) i would suggest reading the whole topic....a post like yours is somewhat redundant and helps make a long (yet VITALLY important and well thought out) topic even longer and a little less virtuous

2) as an (ex) amga'er they have absolutely nothing against the sliding x. in fact we made a few 3 piece anchor with 1 piece of webbing sliding x anchors. there are very few accepted practices that a guide guiding school will not recomend. the key is having a deep understanding of the pros and cons of every system, understanding the situation you are about to dive into and choose the appropriate system. there are 10001 ways to set up an anchor and i doubt that the information we gleen here will result in the holy grail of anchor rigging. rather it will add another piece of information (or perhaps better said: it will adjust our understanding of already used rigging systems to align closer with the reality of physics). whatever system john long et al take out of this there will be perfectly legitimate situations for using a cordollette with a fixed master point, for simple 2 point magic x without limitter knots, for anchoring into a two bolt anchor with a double loop figure eight or bowlline directly in the climbing rope, etc, etc.

[soapbox]
i hope that your guide class opens your eyes a little bit more. i have a quotation around here somewhere from NOLS about the different stages of knowledge (of a skill). its pretty good, but in essence the "beginners" take their limitted experience and what they have been taught as an accurate example of ALL experiences possible. eg, "a good cordellette would be a superior alternative in any situation that could use the sliding x." the more experience we get the more we understand how many more possible scenarios are out there and the more we must augment our base of knowledge. this represents john long et al quite well. he has been climbing a long, long, time and written numerous books on the subject of anchor rigging and is still researching the topic and coming up with new information.

one of the most important things i learned in my guide course is that a good guide (hell, a good climber) understands that there are a thousand and one ways to get a task done and only having/using a few is not efficient and possibly not safe. learn the pros and cons of every system you possibly can and learn how to judiciously, thoroughly and quickly evaluate the scenario in front of you and pick the right tool. ya know, you get a new shiny hammer and all of a sudden everything you see in front of you is a nail.....aquire some screw drivers, allen wrenches, socket wrenches, saws, and all of a sudden there are a lot fewer nails in the world....

hope that made sense and didn't seem to far off topic....

[/soapbox]


gordo


Feb 19, 2006, 11:32 AM
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Good post :!:


dingus


Feb 19, 2006, 11:47 AM
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http://img273.imageshack.us/...cktonjohnbelay28.jpg
I never stopped using the sliding X. Cordelettes suck.

DMT


vivalargo


Feb 19, 2006, 11:48 AM
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In reply to:
bighigaz,

whatever system john long et al take out of this there will be perfectly legitimate situations for using a cordollette with a fixed master point
[/soapbox]

Correct. But if you're going to heed the hard data we got from upwards of 200 drop tests, you'd change situations to "situation," as in singular. A cordelette is a viable rigging tool so long as the anchors are pretty sound and the the arms of the cordelette or of equal length--and, the loading direction is constant--up and down.

The sliding x with anodized biner is better, the equalette better still, and a third system called the quad is almost perfect in equalizing 2 pieces. The cordelette equal length arms has the most variation in loading drop to drop (about 1 kN higher than all other systems) but when the anchors are bomber this is not an issue.

But really and truly folks, the data is very clear that a cordelette with unequal length arms is a total bust so far as equalization goes, with the variance in arm loading sometime exceeding 5kN during a factor 1 fall. The reason this system hasn't failed more in the past is almost certainly because so verty few anchors ever are actually tested by a factor 2 fall.

JL


dr_monkey


Feb 19, 2006, 1:13 PM
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I have been following along and got out some gear and started building anchors (my wife helps, sorry gordo.) I tried to build as many different anchors as possible, varying number of pieces and positions, as well as using as many different techniques for connecting it all together that I could think of. I then played with different setups by moving the power-point around and releasing a piece from the anchor and just watching what happens.

It is pretty simple to achieve an equalized and limited anchor consisting of 2 pieces (duh.) It gets harder as you add pieces (duh again, sorry about stating the obvious but the process helps me.) Any knot that limits extension also limits a dimension of equalization, potentially differentially loading the piece that is controlling the limited dimension.

This is when I decided the most entertainment potential would come from playing with complex anchors (3+ pieces in non-linear placements.)

The point is I have two crude ideas that I thought I would put out there in hopes that others might play around with them and come up with solutions, or at least help eliminate some possibilities.

The ideas revolve around various sliding knots, i.e. overhand slip knots and munter hitches amongst other more obscure rope tricks. The advantage being they slip too some extent, but potentially limit extension. So far I haven't come up with a satisfactory arrangement, but maybe somebody else more clever than me can figure it out.

Cheers,
DRS

P.S. This thread has one of the highest ratios of contributions over junk posts I have seen so far on rc.com, lets keep it up.


dingus


Feb 19, 2006, 1:17 PM
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It will be intersting in a couple of years to chart the lifespan of the rockstar Cordelette, from birth, to its naming, to its adoption as the defacto standard, to its penultimate 'conventional wisdom' status, to this, to its ultimate fade to 'just another limited rigging method.'

It makes me ponder two things:

1. How many other 'accepted standards' have been revealed to be far less than their practioneers believed, and faded to obscurity later?

2. The influence of John Long, haha. That isn't a dig John, more a salute. I appreciate your totaly willingness to revisit this issue, a genuine service.

The guide's advice above rings so true however... when we learn of some official way there is a tendency among us all to accept it as concrete and never changing. I reckon that sort of thinking could get us all killed in this sport. That a person who perhaps more than any other individual, brought us the cordelette and power point, now is willing to drive nails in its coffin should help the rest of us to appreciate that we should never stop learning.

Thanks largo, and too, the many others who through time have visited this particular subject. From boring but able physics discussions on rec.climbing a decade or more ago, tracked through to now, I have long appreicated and valued the internet networking ability. Sifting through the piles of crap there are indeed life saving gems.

DMT


kachoong


Feb 19, 2006, 1:31 PM
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Phewwww, now that took a while to read, but it was well worth my time.

Great stuff Largo!! It seems you guys are busy extending the pool of knowledge that climbers draw from.... with this combined wisdom and open-mindedness, community knowledge (along with the tools and strategies we apply at the crag) will embrace further levels of safety.... as it can be seen from some very good posts by Largo, Rgold, Altelis and others, simple concepts can be developed and employed using an open mind.... This will certainly benefit the climbing community by increased awareness.

We as climbers should place the responsibility on ourselves to research and understand as much as we can about the gear we use and how to use it correctly. When new techniques are found, find time to understand it's structure and the processes involved and decide when the appropriate time and place is to utilse it. I like John's dedication in keeping an important factor alive in employing techniques- Efficiency!

In reply to:
learn the pros and cons of every system you possibly can and learn how to judiciously, thoroughly and quickly evaluate the scenario in front of you and pick the right tool.

I'm looking forward to the results, playing around with a new trick and also your new book, Largo. Kudos to your team and keep up the great work!


gordo


Feb 19, 2006, 2:02 PM
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In reply to:
I have been following along and got out some gear and started building anchors (my wife helps, sorry gordo.)

Lucky guy :lol: Mine's very supportive...as in "you're crazy, but have fun"...she just thinks I'm a bit weird when I pull out gear and start rigging in the living room.


jeremy11


Feb 19, 2006, 4:46 PM
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edit - incomplete post.


jeremy11


Feb 19, 2006, 4:48 PM
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http://www.rockclimbing.com/...p.cgi?Detailed=69709

here is an idea for using a cordalette to dynamically equalize 2 or more pieces. it is based on the trango alpine equalizer but without any specialized extra gear. just a cordalette and some locking biners. just tie a butterfly knot to make the clip in point and clip the powerpoint biner to the butterfly knot and the main strand, then clip the other lockers to just the butterfly knot loop. equalize as shown. the shorter the cordalette is the less it will extend. shorten it by tying two butterflys (also for loop redundancy) and/or make the butterfly loop(s) bigger. then if you need the extra length you have it. this system can work on more than 3 pieces as well, just put another biner in and clip the new leg too it. of course, friction is a growing problem the more legs there are.

http://www.rockclimbing.com/...p.cgi?Detailed=69710

a close up of two butterfly's at the main loop

is this the idea of the equalette? it seems simple enough it can't possibly be original. any feedback on this one?


moose_droppings


Feb 19, 2006, 5:48 PM
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Here's a plain old sliding x with 3 legs. A limiter knot on the middle leg prevents excess extension. The biners (d,e) tie from the middle leg over to the outer 2 legs to help reduce extention on them. The upper knot on the middle leg can be adjusted up or down to accommodate different distances between the outer legs. At home on a board, I just clipped biners e&d to biner b directly. I did this with a 4ft by 9/16's runner, you could do it just as well with a cordelette loop of whatever length. Seems to work well on horizontal, but I've yet to work it out completely on vertical simulation.
Wish I had a digital camera to post a pick of this, my drawing sux.

http://i1.tinypic.com/o5ud0k.jpg


vivalargo


Feb 19, 2006, 6:35 PM
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Jeremy--As you wrote that Tom Cecil is field testing a similar rig with butterfly knots but I think your system looks cleaner and simplier. I think you'd want some limiter knots in the arms or the extension problem would be pretty considerable. So long as you have a sliding master point the limiter knots don't compromise equalization if the direction of pull doesn't get real screwy. That's a really clean looking system, Jeremy.

Moose-I can't understand much from that graphic. Can you try again??

Dingus--You got me on that one. I pretty much rammed the cordelette down everyone's throats with that first anchor book and when I was in the process of redoing same I realized I didn't really know what the thing was really and truly doing, so I couldn't honestly say what system to use, when and where--and as author of the book, I was being trusted to know. Rich Goldstone got me thinking and so I really had no choice but to try and inniate testing, and was very fortunate to get Jim Ewing at Sterling to conduct the tests. The guy's got all the UIAA gear and has the whole process totally dialed. We entered the testing not trying to prove or disprove anything, only to find out the performance differences between the various rigging systems in terms of what the drop tests actually told us. When the numbers came back from the unequal arm cordelette I was amazed.

Someone (I think Rich G. again) also mentioned to me that every other national alpine club has a testing branch that is continuously testing everything. In fact this kind of testing should be an ongoing, institutional gig, and perhaps I can con the AAC into getting into this work.

But once you know the numbers the real work is what's going on here--with everyone trying to cook up new and better ways to do the same old things. I find it pretty exciting "discovery" work, and it's work that should never stop. It's a gas to just grab a loop of sling and a few biners and start fiddling around. I think Jeremy's idea is a great start.

JL


healyje


Feb 19, 2006, 7:18 PM
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In reply to:
Perhaps the two are mutually exclusive
John,

I think to some degree this is what makes this such a difficult problem - that equalization and extension are somewhat mutually exclusive goals. And to those I would add redunancy, which the AE-type anchors don't past muster on. As RGold points out, the minute you add a limiting knot to the works equalization goes out the window. While it doesn't necessarily "feel" right to look at, the "DuoGlide" rig you guys suggested does represent a pretty fair compromise of the three - equalization, extension, and redundancy. I like the AE rigs in general, and again as RGold points out, you can manage the extension problem by keeping them compact - but I would get quite nervous about the lack of redundancy in the case of using it for, say, a portaledge anchor. So I did play around with the DuoGlide, a bunch of different AE rigs, and I guess in the end I can live with the DuoGlide a bit more comfortably than the others even if I do get a tad nervous about relying on a single overhand knot if one side blew completely. But all-in-all in the end I just can't see any obvious way around the "mutual exclusion" problem no matter how "clever" I try to be.

Also, with regards to tied AE rigs - I did do one with alpine butterflies, but it seems so much simpler to just fold over a section of the doubled cord and tie a figure 8 giving two loops out the bottom for the anchor and one out the top for equalization.


dr.ed
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A very interesting and thought provoking thread. And kudos to John for an honest and open approach to rethinking his Anchors book recommendation.

Just musing about the topic I am trying to understand what the important issue is, so if I am way behind all of you I'm sorry.

The first issue being addressed is what rig distributes the load of a fall evenly among all of the anchors. In an idealized case, the cord rigging the anchors must be able to run unconstrained. In an impractical setup, each anchor has a pulley through which the rig ran, each strand connecting one anchor to another would also have a pulley, and those pulleys would connect together to the master point. In this case, the master point is free to move as is the rig, this would always distribute the load evenly.

If an anchor fails, then the rig lengthens by some amount shock loading the remaining anchors, evenly. This may still be too much loading for the remaining anchors.

If the rig is constrained from running free through all of the anchors, then there is no way to get an even distribution of a load among all of the anchors. That is a statement which may not be strictly true, and I will have to think about it more carefully, one anchor constraint may be possible, but I am sure that many are not. Richard might be able to give a proof actually, the master point lies on a surface of constraint.

Here is my guess at an optimum solution. For two anchors, a sliding X, for three anchors, three slideing X's. In this case, the load is almost always equalized by one of the X's among two anchors, with care it might be possible to have 2 of the X's equalizing. Now if any of the anchors fails, the X between the two surviving anchors takes over, with minimal shock and equalized load.

Still kind of tricky to set up.

This post is way to long and probably garbled... but maybe it helps illustrate the issues.

Ed Hartouni


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Feb 19, 2006, 8:15 PM
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Jeremy--As you wrote that Tom Cecil is field testing a similar rig with butterfly knots but I think your system looks cleaner and simplier. I think you'd want some limiter knots in the arms or the extension problem would be pretty considerable. So long as you have a sliding master point the limiter knots don't compromise equalization if the direction of pull doesn't get real screwy. That's a really clean looking system, Jeremy.

Very cool system, Jeremy! Only I can't see how it beats a standard *unknotted* cordelette by that much.

JL: Unfortunately, limiter knots keep whatever leg you tie them in from equalizing through the biner that leg is on. However with a reasonably short cordelette, the extension if one leg blows is reasonably small. If I used this system, I'd probably use add a sling to make one leg much longer than the others. That way no one leg will create a major extension if it blows.

GO


vivalargo


Feb 19, 2006, 8:47 PM
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[JL: Unfortunately, limiter knots keep whatever leg you tie them in from equalizing through the biner that leg is on. GO

Not exactly what you mean by "through the biner," if you mean the pulley effect of just that anchoir that the biner is clipped through. But in the actual tests we've found that a 2 point anchor can be rigged with limiter knots and the rig (the Quad) achieves almost perfect equalization with a limited amount of direction of pull change as well. This is achieved, I think, because the master point slips along a section of cord strung between the limiter knots.

But we are getting down to brass tacs here, and that's a good thing. But as good as stuff can sound here on this thread, I've learned it all must be tested to know for sure.

JL


kachoong


Feb 19, 2006, 8:50 PM
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Jeremy--As you wrote that Tom Cecil is field testing a similar rig with butterfly knots but I think your system looks cleaner and simplier. I think you'd want some limiter knots in the arms or the extension problem would be pretty considerable. So long as you have a sliding master point the limiter knots don't compromise equalization if the direction of pull doesn't get real screwy. That's a really clean looking system, Jeremy.

Very cool system, Jeremy!

JL: Unfortunately, limiter knots keep whatever leg you tie them in from equalizing through the biner that leg is on. However with a reasonably short cordelette, the extension if one leg blows is reasonably small. If I used this system, I'd probably use add a sling to make one leg much longer than the others. That way no one leg will create a major extension if it blows.

GO
That's a really good idea Gabe. It also eliminates the problem of increased angle between anchor points associated with using a shorter cordelette (as you shorten the cordelette, you bring the powerpoint closer to the anchor points and increase the angle between each point).

Good job Jeremy. I first looked at your setup and thought ....why isn't there a twist in each V coming down to your sliding lockers? So I set up myself and had a play and found when one piece pulled (despite the excess extention explained by John and Gabe) the locker was still 'captured' in the setup once fully extended on the remaining pieces.


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Feb 19, 2006, 9:10 PM
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[JL: Unfortunately, limiter knots keep whatever leg you tie them in from equalizing through the biner that leg is on. GO

Not exactly what you mean by "through the biner," if you mean the pulley effect of just that anchoir that the biner is clipped through.

Yup, that's what I meant. But it's more complicated than I first thought. Will play around some more, and then perhaps post my findings on a separate thread.

But if anyone has other new ideas, this seems a great place to put 'em out there.

Cheers!

GO


kachoong


Feb 19, 2006, 9:36 PM
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Tried a few different things over the last half hour and came up with something I liked. It's just an idea to help throw in the pool. It's similar to Jeremy's, however I wasn't satisfied with the butterfly setup as it was too bulky and slower to set up than this one.

I also found that putting a limiter knot on the middle leg didn't allow it to slide and equalize. (unless I'm doing something wrong) :? It only worked with limiter knots on the outside legs.

My set up here uses clove hitches tied with the outside strand of the outside leg, tied to the 'bottom' of a locking biner (on each side), where the top of the biner is free to slide through the V's made with the centre piece. When it's loaded by the belayer the locking biners sit correctly and don't rotate at all when you slide from side to side. Again, as mentioned, friction causes problems the more pieces you use. This could be countered by using those pulley-type biners at each anchor point (you know, the ones with the little wheels on one end.) This picture shows no limiter knots on the outside legs. It would be preferable to use them if strength isn't considerably compromised.

http://www.rockclimbing.com/...p.cgi?Detailed=69733


moose_droppings


Feb 19, 2006, 9:59 PM
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Dr Ed,
I've played with tha 3x's idea, have 1 hanging in my doorway right now, and your right, its a handfull to set up.
Like this,
http://i1.tinypic.com/o6bbt3.jpg

John, here's another try at the other one. Basicaly, you start out like a regular 3 legged cordelette anchor, but instead of tying of an overhead knot for the power point, just clip a biner to all the strands. Then tie a limiter knot on the middle leg right above the pp. This reduces extention if the middle leg blows. To reduce the extention on the outer two legs, clip a biner into the middle leg, right above the upper knot, out to the loop on the right outer leg, and another biner in the same spot on the middle leg, out to the loop on the left leg. The middle leg is kept at fixed lenght while the other two are allowed to share a common strand and equalize the whole works. If any one of the 3 legs blow, the extention is about 3". Since my 1st post I've set this up on another doorway downstairs here and swung from side to side on the anchor and the equalization is great throughout the arc.
Hope this mickey mouse drawing is a little clearer for you.
http://i1.tinypic.com/o6bn9y.jpg


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Feb 19, 2006, 10:15 PM
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Will play around some more, and then perhaps post my findings on a separate thread.

Okay, well my findings are simple, so I'll post 'em here. Tie a limiter on an outer leg of Jeremy's anchor and you're fine. Tie off more than one leg, or the inner of the three, and you lose dynamic equalization.

I also built Moose's setup. Brilliant! It's easy to set up, very successful at limiting extension, and allows a wide range of motion. I'd be curious to see how it performs on the machine John's using for testing. The only things I'd be concerned about are 1: Whether you get any larger forces if the pieces are spread out at a large angle, due to the pseudo American Triangle in the sytem and 2: whether all those slings can move freely in the event that one of the pieces blows.

One other note on building the Mooselette: you must make sure to create and clip a "crossed sling" with the outer strands, otherwise the lower limiter knot won't work.

Very cool work, guys!

GO


kachoong


Feb 19, 2006, 10:20 PM
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The only things I'd be concerned about are 1: Whether you get any larger forces if the pieces are spread out at a large angle, due to the pseudo American Triangle in the sytem and
That's what I noticed when building the Mooselette.... the triangles are more obvious when the powerpoint is positioned centrally, rather than off to one side.... cordelette knot positioning (meaning the fishermans knot in the cordelette itself) is also very crutial in these setups.... most people put it off to one side anyhoo.

This is all exciting stuff....


gordo


Feb 19, 2006, 10:59 PM
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Am I the only one right now who's thinking redundancy may be more important than perfect equalization? I've been building and building and changing and re-building...and everything I do along the lines of this thread leaves me wondering.

Jeremy's rig is perfect EQ, but I just couldn't live with it on top of a 300 foot wall. Given bomber pieces I'd feel safer with a good old, poorly EQ'd cordolette than any of these rigs with no redundancy. I just gotta have more than one loop of cord/webbing to put my life on. Given poor placements, I'd rather EQ with sliding x and combine with cordolette.

I know, never heard of one breaking. but it's possable.

I guess we're still looking for that perfect rig, I hope John shows us exacly what he's thinking soon :)


bloodyhands


Feb 19, 2006, 11:15 PM
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Am I the only one right now who's thinking redundancy may be more important than perfect equalization?

I inspect my slings and cordelettes before every climb. I've never been that concerned with redundancy on trusted gear.


Partner cracklover


Feb 19, 2006, 11:29 PM
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Am I the only one right now who's thinking redundancy may be more important than perfect equalization?

I inspect my slings and cordelettes before every climb. I've never been that concerned with redundancy on trusted gear.

Fair enough, but it wouldn't take a very big falling rock to slice through/crush a singl strande of cordelette.

You could clip directly into your best piece with your rope (with some slack in it) as a backup.

GO


bloodyhands


Feb 19, 2006, 11:47 PM
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Am I the only one right now who's thinking redundancy may be more important than perfect equalization?

I inspect my slings and cordelettes before every climb. I've never been that concerned with redundancy on trusted gear.

Fair enough, but it wouldn't take a very big falling rock to slice through/crush a singl strande of cordelette.

You could clip directly into your best piece with your rope (with some slack in it) as a backup.

GO

Good point. Good idea.


gordo


Feb 20, 2006, 12:00 AM
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Ok, so the search goes on. I've got this one working right now. I call it the Gordo-lette ( :roll: Yeah, I know)

Sorry the pics are really bad, my flash quit.

http://members.cox.net/gbisapk/Gordo-lette.jpg

Drawing....very important to note that the inside strands on the outside loops are free to move.

http://members.cox.net/...esrc/Gordo-lette.bmp

This provides very little extension, and full redundancy. Cut any leg and you get the same extension as loosing any piece of the anchor. The cloves will need to be adjusted to get them level for whatever arrangement the pieces are in. Moving the master point around moves the cloved biners but keeps the system equalized. I'll get a better pic tomorrow if I haven't figured out the glaring reason this is dumb.


jakedatc


Feb 20, 2006, 12:30 AM
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few things.. put it on a light background so it doesnt blend in. if you turn the flash off it should eliminate the glare and just use natural light.

are the oval biners at all weighted? if so having them horizontal like that seems like it wouldnt be the strongest orientation.

i like kachoongs the best so far. as long as it's redundant if any of the legs blow out it'll extend and still be ok. Simple and pretty speedy if you just leave the powerpoint and cloves intact on the rack.

conspiracty theory: JL has no anchor and is trying to suck us for information ;)


gordo


Feb 20, 2006, 12:37 AM
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are the oval biners at all weighted? if so having them horizontal like that seems like it wouldn't be the strongest orientation.

i like kachoongs the best so far. as long as it's redundant

The biners (would be locking if real) are only weighted in a failure mode, then it is weighted vertically.

I started with something like kachooongs...but I see it as zero redundency...am I missing something? Looks like if it blows the cord it's gone completely.

I like the conspiracy theory!! :lol:

I'll build this tomorrow with clothes line, start cutting strands and stuff, see what it's really doing. So far, it seems to be the best of all worlds. Pretty quick to rig too.


jakedatc


Feb 20, 2006, 12:57 AM
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Cool.. seems like your knots sacrifice quicker equalizing(having to adjust the knots and slide them etc) for more redundancy.

glad you like it ;) we're keeping an eye on you john *squints* (and reading the Close calls book... though i'm not sure if thats such a good idea combined with an anchor thread... :shock: )


dr.ed
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Moose - not quite what I had in mind... instead of the third X connecting the two X's, the third X connects the two pieces which are not directly connected. Also, no knots...

my guess is to make this work, you have to put three 'biners (one for each X) and perhaps a cordellete to the three 'biners to a master point.

As I said, this gets complicated. But the idea is that you have optimally equalized the pieces, and reduced the effect of shock loading.

The shock loading comes from the change of momentum over the time to change the momentum. If the belay is "dynamic" the time to stop (change the momentum to zero) lengthens and the force decreases considerably.

F_shock = (delta p)/(delta t)

you can't do much about (delta p)...


healyje


Feb 20, 2006, 5:09 AM
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The difference in the central knot structures of the [pure] AE rigs shown so far adds up to "six of one - half dozen of the other" from my perspective. I don't really see any particular advantages to using either butterflies (Jeremy's) or cloves (Kachoong) over a doubled over figure 8 as shown below. And for that matter I'm not all that convinced that two carabiners makes all that much difference compared with one for equalizing when everything is said and done. If you folks think there are advantages to these other knot structures over the figure 8 below I'd be interested what you think they are and why.

But I do agree with Gordo on redundancy. In my previous post I also mentioned not being comfortable with the fact [pure] AE rigs lack redundancy and limiter knots (or two extra limiting carabiners ala Gordo) pretty much defeat the whole point of using them. The more I think about the whole affair the more it makes me want a completely redundant, double-stranded 5mm tech cord AE rig or a backup tech cord X on each half of the AE rig.

And John, are you now using "Quad" and "DuoGlide" interchangeably or is this yet a different one?

http://www.cascadeclimbers.com/...6299DuoGlide_008.jpg

http://www.cascadeclimbers.com/...6299DuoGlide_009.jpg


patto


Feb 20, 2006, 9:03 AM
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Am I the only one right now who's thinking redundancy may be more important than perfect equalization? I've been building and building and changing and re-building...and everything I do along the lines of this thread leaves me wondering.

Jeremy's rig is perfect EQ, but I just couldn't live with it on top of a 300 foot wall. Given bomber pieces I'd feel safer with a good old, poorly EQ'd cordolette than any of these rigs with no redundancy. I just gotta have more than one loop of cord/webbing to put my life on. Given poor placements, I'd rather EQ with sliding x and combine with cordolette.

I know, never heard of one breaking. but it's possable.

I guess we're still looking for that perfect rig, I hope John shows us exacly what he's thinking soon :)

I completely agree.

I have never fooled myself into thinking that the pieces were truly equalised. Although equalising 3 or more pieces is very difficult, you can always achieve rough load spreading across two pieces, this in my eyes is enough.


gordo


Feb 20, 2006, 9:33 AM
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[pure] AE rigs lack redundancy and limiter knots (or two extra limiting carabiners ala Gordo) pretty much defeat the whole point of using them.

Trying not to sound defensive, as I'm not. I doubt this thing will be the answer. BUT.....

The beauty of the biners as I have them is that they don't defeat the equalization like limiter knots do. Build it real quick and move it around. The eq stays perfect because the biners don't tie the legs together, but rather connect the opposite sides strands for redundancy only. It acts like the AE except for limited extension and full redundancy.

After a lot of working it around, I've decided the way to do it is remove the biners after every use. Setting up the AE takes seconds, then adding 4 cloves on 2 biners takes about 2 minutes.

I've built every rig here, and more. I'm having a great time with this, glad to have something to do while the snow/ice keeps me indoors :(


Partner dominic7


Feb 20, 2006, 10:18 AM
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Perhaps the two are mutually exclusive
John,

I think to some degree this is what makes this such a difficult problem - that equalization and extension are somewhat mutually exclusive goals.

An important point. If you take, for arguments sake, that an equalizing system does not limit extension, we could look to other ways of limiting extension. Some general points:
    "some" extension isn't necessarily catastrophic as shockloading isn't as much of a risk as it's made out in some circles
    The extension of a truly equalizing system is a function of the lengths of the legs. In general, a system will extend somewhere less 2x the length of the failing leg, depending on the angle of the leg.
    One might surmise that limiting the lengths of the legs would thus limit the extension potential of the system.
    The minimum safe length of the legs of any given anchor is different, where an anchor with vertically aligned legs could have the shortest and a horizontally aligned anchor the longest.
    An equalizing anchor could be constructed that allowed for adjustment of the leg lengths to bring them to the minimum length, thus minimizing the potential extension of the system.


For instance you could use a munter hitch in an equalizing anchor that you could slide up to the point where you felt the legs were the shortest they could be to give safe angles between the legs. Then you would have an equalizing anchor that had the minimum extension. I couldn't quite get it right but I have to run to work so this is all I could come up with:

http://rugby.net/images/domolette1.jpg

(sorry for the poor image quality - camera phone)

I would also like to point out that I am not a professional climber, or even a very good or experienced one for that matter. If you are reading this, do not assume that the above picture or anything I say represents something that is safe for climbing.


dingus


Feb 20, 2006, 10:26 AM
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Most of these proposals totally blow the KISS principle out of the water. I think the chance of mis-rigging increase very quickly each time you add a knot to the assembly, especially if that knot is not a figure 8... the defacto standard.

I look at some of these riggings and imagine trying to teach that to Billy Bob Noob...

DMT


ambler


Feb 20, 2006, 10:45 AM
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In reply to:
In reply to:
In reply to:
Am I the only one right now who's thinking redundancy may be more important than perfect equalization?
I inspect my slings and cordelettes before every climb. I've never been that concerned with redundancy on trusted gear.
Fair enough, but it wouldn't take a very big falling rock to slice through/crush a singl strande of cordelette.
Nope. I've watched a rock the size of my hand slice halfway through a new 9mm rope that was sitting next to me on a ledge.

On an unrelated note ... for some reason this thread about equalization makes me think of Bridwell's infamous clove-hitched RURP belay (was it Sea of Dreams?). Anyone know an online source for that photo?


Partner dominic7


Feb 20, 2006, 10:55 AM
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The extension of a truly equalizing system is a function of the lengths of the legs. In general, a system will extend somewhere less 2x the length of the failing leg, depending on the angle of the leg.[

Sorry I mispoke here. The extension of an anchor where a leg of length x fails is somewhere around x/n, where n is number of remaining legs.


dingus


Feb 20, 2006, 11:07 AM
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On an unrelated note ... for some reason this thread about equalization makes me think of Bridwell's infamous clove-hitched RURP belay (was it Sea of Dreams?). Anyone know an online source for that photo?

I looked for it recently and couldn't find it.

DMT


kachoong


Feb 20, 2006, 11:11 AM
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Gordo,
In reply to:
http://members.cox.net/gbisapk/Gordo-lette.jpg
This provides very little extension, and full redundancy. Cut any leg and you get the same extension as loosing any piece of the anchor. The cloves will need to be adjusted to get them level for whatever arrangement the pieces are in. Moving the master point around moves the cloved biners but keeps the system equalized. I'll get a better pic tomorrow if I haven't figured out the glaring reason this is dumb.

Do you have the inside strand of the out side legs running through the biners? To me that looks like it could cause problems when a piece blows. When the system then extends to equalize, the speed of these strands running through the biner could infact cut into the clove hitches. Does that make sense?

In reply to:
are the oval biners at all weighted? if so having them horizontal like that seems like it wouldnt be the strongest orientation.

I agree.... I prefer to have the biners 'vertically' aligned. Though all these ideas have their pros and cons, none of them should be used until proper testing is done.

http://www.rockclimbing.com/...p.cgi?Detailed=69733

In reply to:
i like kachoongs the best so far. as long as it's redundant if any of the legs blow out it'll extend and still be ok. Simple and pretty speedy if you just leave the powerpoint and cloves intact on the rack.

Using limiter knots, which I didn't show in my picture, on the outside arm reduces the extention somewhat. It's definately a fast setup and the clove hitches don't have to be in an exact spot. The sliding nature of the setup counteracts this.

I really like the 'bunny ears' part of healyje's pivot point set up.


roy_hinkley_jr


Feb 20, 2006, 11:44 AM
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Gotta agree with Dingus that none of these rigs are practical in the real world. KISS outranks SRENE. I'd clove hitch the rope to sequential pieces (like we've done for decades) before any of these clusterfucks. The short Trango Equalizer is looking better all the time for a fast, compact, cheap rig that you can easily escape the belay.

The AAC has always been pathetic on gear testing and standards; this has been pointed out numerous times and doesn't appear likely to change.


ambler


Feb 20, 2006, 12:57 PM
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Most of these proposals totally blow the KISS principle out of the water. I think the chance of mis-rigging increase very quickly each time you add a knot to the assembly, especially if that knot is not a figure 8... the defacto standard.

I look at some of these riggings and imagine trying to teach that to Billy Bob Noob...
Or to crusty old-timers.

http://im1.shutterfly.com/...000027108AbOWzdszbNh


healyje


Feb 20, 2006, 2:09 PM
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That's a bit too cluster crusty, even for an old guy passing through...


dingus


Feb 20, 2006, 2:29 PM
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I always liked this one:

http://img410.imageshack.us/...seanalyzethis1ew.jpg

DMT


ambler


Feb 20, 2006, 2:33 PM
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That's a bit too cluster crusty, even for an old guy passing through...
Well it looks like a cluster ... but looks are sometimes deceiving. 8^)


gordo


Feb 20, 2006, 3:37 PM
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