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David Trippett

Interesting Cordellette Study

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Of course figure eights do not fail. Neither do cordelettes. I will happily stand corrected if someone has some good counterexamples.

 

 

Take a look in ANAM at the Tahquitz double fatality where a cordelette caused sequential failure of a three point anchor because it did not equalize the three pieces. Sliding X's or an equalette would not have failed, as simulated replications of the accident using the same gear that failed in the same placements and test weights showed

 

It seems this was an error in setting up (equalizing) the anchor, not a problem with cordelette. The reason I do not use the Sliding X is because if one anchor point fails, the resulting extension will likely cause the others to fail...as in this case of a poorly equalized anchor. And, of course, the reason we use multiple anchor points is b/c we do not assume any single point will hold a fall.

 

Am I mistaken? Should I be reconsidering using the sliding x over an equalized and tied cordellette? In what situations?

 

Just read the Supertopo post for details if you are interested, but in essence, even if a cordelette LOOKS equalized, it transmits the majority of the force to the shortest arm, resulting in asymmetric loading of the pieces. Also, it is non-directional - if you move even a little bit, it unloads one arm and maxi-loads another.

 

In contrast, it turns out that when tested in actual failures, even if one arm of the Sliding X unclips, the friction of the X sliding, together with stretch from the nylon, results in no shockload on the anchor.

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There were some mondo-discussions elsewhere about this topic, and I started a thread here about the potential shortcomings of the cordalette but it went down in flames at the time.

 

Seems like there was some rough agreement that a doodad called the equalette that combined some of the best qualities of the cordalette and the sliding X in one rig. I think this may have been discussed in Long's latest book on anchor's but I haven't seen the book so I'm not sure.

 

equalette_4.JPG

 

image001.jpg

 

Lower graph and quote poached from gravsports:

 

"The whole concept of equalizing belay anchors has been discussed heavily lately, both over on rockclimbing.com and also on supertopo.com. I've also had some correspondance with Jim Ewing over at Sterling, who did much of the actual lab work referenced. The basic concept is that it's very difficult to effectively equalize multiple pieces in a belay, and that shock loading when one piece pulls is surprisingly minimal. We all want to do the "right" thing when building anchors, but as I've written previously, the "right" thing often isn't. This picture is lifted from supertopo.com, where a user lifted it from John Long's new book (I still need to buy a copy of that, hopefully he won't mind posting it here as it's promo for his book--I've known Long for years, he's not the sort of individual you really want pissed at you, not because of his iron addiction but because he flips words with style). I thought people might enjoy seeing the data, when I got it from Jim it wasn't in a viewer-friendly format. I find the whole discussion sort of humorous because we all used the "sliding X" years ago, then were told that the cordellette was plus bon, now it's pretty clear that the old sliding X is pretty darn good in comparison. I've played with the "equallette," overall it seems like it's more prone to mis-rigging and requires more biners than I'm likely to carry for its performance advantage over a simple sliding X. Might use it on nice sunny days when I have unlimited time to set up an anchor, but for winter climbing it's a right pain. One of the main problems with cordellettes is that the central knot often becomes set for the day after only one use, I see the equalette as being worse. At least with a sliding X frozen knots aren't a problem. I'll likely go with a sliding X with the biner clipped directly into the rope, and the rope then clipped into a third piece as a "All hell breaks loose" backup to the two primary pieces. Or something else depending on what the situation callls for, the bottom line is that no one system for building belays will be the best for all possible circumstances. I'll continue to carry a cordellette as they are very useful for slinging pillars or other features, chopping up for V-threads, rigging rap anchors, etc., but less useful than I always thought for building equalized anchors.

 

All of this discussion has also changed my viewpoint that tying together some "OK" pieces will make a "really good" belay. I'm now more interested in having at least one "bomber" piece in the belay, and then backing that up with with at least one and hopefully two "OK" or better pieces. I've always built my rap anchors around one "bomber" piece (Abalakov or super solid pin/nut/bush/whatever) with a backup, I'm starting to look at belays more like this given how relatively poorly even the best equalized anchor works in the lab. In combat situations systems are likely to work even less well in my experience. Lots of good gear is a good thing, this whole climbing thing is pretty unpredictable when it comes right down to it. I'm very fond of 3.5 inch stainless bolts that I've placed, grin."

http://gravsports.blogspot.com/2007_01_21_archive.html

 

 

 

To tie....

Take your coradalette, tie a couple of overhand knots a couple of feet apart to create a closed loops in the middle, secure each "arm" of each loop to the biner attached to the pro with a clove hitch instead of clipping the end of the loops through the biner, then clip a biner over each strand in the center loop to create the sliding-X effect.

 

Wouldn't be my default anchor, but worth having in the tool kit for some situations.

 

 

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although i rarely take a cord into the mountains (double ropes are AWESOME for quick alpine anchors)....

 

few weeks ago my faith in rock gear and cordallette (strength, at least) skyrocketted. space hauling a 200+ lb pig w/ a 200+ lb person hanging on the system. we did this on everything from a 2 bolt anchor and a cord doubled over and tied in an overhand...to multi gear anchor brought together w/ a cord (again, tied in an overhand).

 

as said before, you can't get 'perfect' equalization - but you get something that is STRONG ENOUGH.

 

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It was exactly the situation in which most climbers would have used a cordelette... because they believed it was a tool to equalize a three point anchor.

 

It is directly because of this accident that professionals and guides have reevaluated the cordelette and found it wanting.

 

So no one here makes a double sliding X for a 3-piece anchor using a cordelette?

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It was exactly the situation in which most climbers would have used a cordelette... because they believed it was a tool to equalize a three point anchor.

 

It is directly because of this accident that professionals and guides have reevaluated the cordelette and found it wanting.

 

So no one here makes a double sliding X for a 3-piece anchor using a cordelette?

I don't. It has too much potential for extension. The other issue with it is that it doesn't really equalize as well as you'd expect. There is so much friction between strands that it doesn't test out much better than a tied off cordellette.

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Yeah, probably even more true with the small locking carabiners we're using these days, crowding the strands all together...

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the double sliding x is basically the equalette with no knots

 

Exactly the point, but less knot tying and other jiggery pokery. The equalette looks like it also might have less effective length for a given length of line.

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The idea of the equallette and the duoglide was that the sliding-x suffered from too much friction because of the twist. The knots serve several functions.

 

1) They act as limiters to reduce extension.

2) They prevent failure of the system just as the twist does in a sliding-x.

3) They isolate the cord or sling into independent segments. By putting two carabiners instead of one, there is redundancy. A single strand can be cut in any place without total failure of the anchor.

 

By the way, the equallette has more effective length because you are no longer sending two strands to each piece, but rather one, since you are using a clove hitch. How much cord is used will depend on how far apart the pieces are.

Edited by catbirdseat

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Bill- I agree eveything has there ups and downs, with your system is good, I sometines use it when swapping leads and especially when I use double ropes, though I don't use an 8 on a bight, but instead I use girth hitches.

 

Marko- the only time I use a double sliding X is if I don't have enough cordage to tie at least an overhand, though I don't like doing that for the reason that CBS mentioned.

 

Jay- thanks for the post and link especially since Dru is too lazy to put something up for the sake of this discussion. I will have to check it out.

 

 

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Alright I think this old dawg needs to learn some new tricks, meaning me. So with all of this discussion I decided to blow off work this afternoon and look at the info out there, well then saw so much drivel out there, I decided to ask a frined of mine in the rope manufacturing industry that I respect and I know is always busy testing shit out. Here is what he had to say:

 

 

"Yeah, lots of hate and turmoil was created by that whole cordelette BS. Basically the deal is that the traditional cordelette method that everyone knows and loves doesn't equalize worth a damn. The majority of the load will always land on one piece, always. Even when tied so as to orient in the anticipated direction of the load it will not equalize as the shortest arm will always reach its peak extension first as it has the least potential elongation. It doesn't matter what the material is, the ratios of load will always be distributed the same on any given set up. It is not a dangerous matter unless you are concerned with the integrity of the pieces that make up the anchor. There used to be, and probably still is, concerns of 'shock loading' with sliding X but in reality shock loading is a myth. As long as you are tied in with the rope shock loading does not occur. The problem is extension and the

possibility of the belayer crapping their pants and losing control of the brake.

 

So there's been about a hundred proposed systems, 99% of which are worthless. Here's my take: use the traditional cordelette method if you are totally confident the pieces are bomber. Use sliding X's when they're suspect. There are some decent rigs that people came up with but I haven't tested any of them. The simplest system is called the 'quad' and is perfect with 2 bomber pieces. The next one is what was named the 'equalette'. The 'equalette' is difficult to explain but you can find all kinds of diagrams in RC.com."

 

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mooselette.jpg

 

Interesting setup. I can see the benefits. I'm assuming that the center loop is the one connected to the bomber piece?

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So is that last photo "The Quad?" If not, can someone post a link/diagram?

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A lot of those proposed set-ups were just intellectual exercises thrown out there for discussion. People love being creative, if not always practical. Anchors will always be a compromise between equalization, extension and complexity.

 

I think the Equallette isn't too bad when it comes to set-up time, provided that the cord is carried with the limiter knots already tied on it. The problem with that is that is if you wanted to go back to the conventional tie-off method, it would take time to remove those knots.

 

I've worked with teaching the Equallette to novices and to my surprise, they don't have any more trouble learning it than the tie-off method. They seem to be able to tie it about as fast too.

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these are slow and complex (relatively speaking)...and thus used for complex situations. that is, marginal anchors or high load stuff, whatever. what are novices doing with this. if a novice, on a novice type climb needs something like this, they probably (mistakingly) climbed past an obviouser bomber'er place for an anchor.

 

granted, it is fun to come up w/ creative solutions to these idealized problems - but what situations are you guys using this stuff on? ie - what made you say 'i need to make this frankenanchor'??

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In contrast, it turns out that when tested in actual failures, even if one arm of the Sliding X unclips, the friction of the X sliding, together with stretch from the nylon, results in no shockload on the anchor.

 

I find this hard to believe...source?

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Just briefly, I climb sometimes with rg@ofmc of that whole thread.

 

He can set up his wacky anchor that Mal Daly made for him in about as much time as it takes me to put my shoes while keeping him on belay. While sometimes I'm willing to suspect that's because of his 40 years of climbing in the gunks or the thousands of times he's done any particular route, I do vaguely remember that it took him longer to do the set up with his old cordalette method or his old clove hitch method.

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So anyone know where there is step by step diagram for rigging an equalette, I like to mess around with rigging one this weekend.

 

 

This rig seems pretty cool ACR (alpine cock ring)

 

Hey Ken, lay out your cordalette, start at the center, tie a couple of overhand knots a couple of feet apart, and then tie off your pieces with clove hitches. Seems to take about the same amount of time to rig as a cordalette if you've already got the knots in the middle.

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