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Improved sliding x: Is it really safer?
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vivalargo


Feb 18, 2006, 2:59 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, 3:28 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, 4:19 PM
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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, 4:24 PM
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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, 4:45 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, 4:46 PM
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Aack---double post. Sorry.


curt


Feb 18, 2006, 5:11 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 18, 2006, 9:06 PM
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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 18, 2006, 10:38 PM
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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, 6:54 AM
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http://www.tinypic.com/


bighigaz


Feb 19, 2006, 7:28 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, 7:44 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, 8:11 AM
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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, 8:20 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, 8:32 AM
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Good post :!:


dingus


Feb 19, 2006, 8:47 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, 8:48 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, 10:13 AM
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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, 10:17 AM
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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, 10:31 AM
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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, 11:02 AM
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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, 1:46 PM
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edit - incomplete post.


jeremy11


Feb 19, 2006, 1:48 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, 2:48 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, 3:35 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

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