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#31455 - 07/23/07 09:49 PM Re: cordelette-attention RG [Re: chip]
paulraphael Offline
enthusiast

Registered: 01/22/02
Posts: 321
Loc: New York, NY
That's certainly true, but I don't know of any faster way to tie four pieces together (at least in a way that does a halfway decent way of distributing the loads).

In general, when I've had to use four or more pieces in an anchor, it's been when there's a really small or sketchy feature that I've had to frig the grear into. So I'll have a couple of marginal nuts or small cams right next to each other. those are often good candidates for clove hitching onto one arm of the anchor, so they each take about half the load that the other pieces take.

You could also throw a sliding x onto them, but I haven't yet been inclined to do that. In places like the gunks good gear is usually available; in the mountains i rarely have time for that kind of thing.

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#31469 - 07/24/07 03:45 PM Re: cordelette-attention RG [Re: paulraphael]
dalguard Offline
veteran

Registered: 03/22/00
Posts: 1515
Loc: CT
What's the advantage of it over a plain old sliding X?

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#31474 - 07/24/07 07:11 PM Re: cordelette-attention RG [Re: dalguard]
rickcee Offline
enthusiast

Registered: 06/08/01
Posts: 248
Loc: central Jersey
Hi - just noticed - P.R. - there may be a similar item , hard to tell from photo :
trango ' alpine equalizer' ( bentgear.com )
your proposal does look interesting.

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#31475 - 07/24/07 07:59 PM Re: cordelette-attention RG [Re: rickcee]
quanto_the_mad Offline
Carpal Tunnel

Registered: 05/14/02
Posts: 2628
Loc: brooklyn
Looks similar, may work similar to some extent, but the Trango AE has more parts. It has two rings and two fixed, sewn loops, thus you actually have to buy the AE. The benefit ACR is that it's just your cordalette with a steel ring. It can still be used the old way as needed, or you can untie and remove the ring. I don't think the Trango AE is as flexible.
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#31477 - 07/24/07 08:58 PM Re: cordelette-attention RG [Re: chip]
D75 Offline
enthusiast

Registered: 03/18/05
Posts: 293
Loc: Holiday Inn Express
RG, an FF2 fall requires a free fall. So it would not occur only before placing first piece, but rather only before placing first piece and not hitting anything on the way to the same distance below where you started.

ACR looks interesting!

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#31478 - 07/24/07 09:19 PM Re: cordelette-attention RG [Re: dalguard]
Chas Offline
Pooh-Bah

Registered: 03/22/01
Posts: 1754
Loc: Flagstaff
 Originally Posted By: dalguard
He said he moved the belayer, which implies a reidirect to me. But redirection is a different argument.
 Quote:
The folks who climb with me will testify that I haven't commented even once about their anchors, whether constructed with the rope, stretchy cordalettes, stiff cordalettes, or a combination of some or all of these.
From what I hear, this is true, and kudos to you for it. As our common friend once said to someone we were about to share a rap with: I don't care what knot we use as long as we don't have to talk about it.
 Quote:
I just explained why a person might choose to use a stretchy cordalette.
Which is actually the first useful piece of advice I've managed to glean from all of this. As you know, I object to one method being debunked without a better one being provided and I've yet to hear why any non-lette option is better than any-lette option (or even convincingly why one lette option is better than another). If a stretchy lette can really make a difference, well, that's an easy substitution. Are you saying that simply nylon vs. tech cord is really going to make a measurable difference in stretch for the distances involved? I don't like the bulkiness of nylon (why all of us who choose tech do, I'm sure) but I need a new a cordelette and I could perhaps be convinced.



Naw, my belayer was facing me looking up, and the next minute she was shoved around as the rope and I went flying past her (good thing for REALLY steep climbs.

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#31480 - 07/24/07 11:16 PM Re: cordelette-attention RG [Re: quanto_the_mad]
paulraphael Offline
enthusiast

Registered: 01/22/02
Posts: 321
Loc: New York, NY
 Originally Posted By: quanto_the_mad
Looks similar, may work similar to some extent, but the Trango AE has more parts. It has two rings and two fixed, sewn loops, thus you actually have to buy the AE. The benefit ACR is that it's just your cordalette with a steel ring. It can still be used the old way as needed, or you can untie and remove the ring. I don't think the Trango AE is as flexible.


Right. And another thing with the AE is that the powerpoint is sewn in place. Because of this, any extension limiting knot that you tie will stop the whole thing from self-equalizing. It just becomes a cordelette. The ACR's powerpoint floats free, so you can tie a couple of different types of shortening / limiting knots in one of the strands without interfereing with the way it works.

This might not make much sense from my description, but if you play with it for a minute you'll see what I mean.

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#31481 - 07/24/07 11:30 PM Re: cordelette-attention RG [Re: dalguard]
paulraphael Offline
enthusiast

Registered: 01/22/02
Posts: 321
Loc: New York, NY
 Originally Posted By: dalguard
What's the advantage of it over a plain old sliding X?


The whole project started by examing the sliding W (basically cordelette that's left untied). I liked the simplicity of the W (and have met people who use this setup). But there are a few limitations that I wanted to address:

-the outer strand of cord binds over the inner strands, because they're all piled into the same carabiner. this can cause a lot of friction. It's likely that the friction is proportional to the load that's on powerpoint, so it could easily interfere with the anchor's ability to equalize.

-there's a possibility of the carabiner being loaded across the gate or far off axis. There's even a slight possibility of the cord running over sharp edges at the base of the gate and getting damaged.

-you have to remember to put a twist in the cord when you clip the carabiner, or you get massive extension if one of the outer pieces blows. This is just like what you have to do with a sliding X, but with the W, there are so many strands going through the biner that it's almost impossible to tell if it's been set up right from visual inspection.

That little ring in the ACR addresses all these things. It's basically a refined, more idiot-proof sliding W.

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#31486 - 07/25/07 05:00 AM Re: cordelette-attention RG [Re: paulraphael]
rg@ofmc Offline
Pooh-Bah

Registered: 12/25/99
Posts: 2454
Loc: Poughkeepsie, NY
Dawn, the reasons for using a 7mm cordelette as opposed to tech cord or webbing mostly have to do with achieving better equalization. (If you are tying together pieces, any one of which would be plenty good enough, then equalization is not much of an issue.)

Stretchiness helps to mitigate the effects of legs not tied the exact correct length (they never are), leg length made incorrect by the (unpredictable) results of knot tightening, and large arm angles---up to 120 degrees between outer arms is ok with a 7mm cordelette.

In combination with spectra webbing, a stretchy cordelette allows one to reduce otherwise unavoidable load inequalities resulting from very unequal leg lengths. The low-stretch webbing is used on the pieces furthest from the power point in order to make the stretchy arms of more nearly equal length.

(Those who have read my earlier posts in this thread will note that this appears to represent a change of opinion for me. To some extent, it is a change in opinion, but my original comments about the relative unimportance of stretchiness were really aimed at self-equalizing systems, not fixed-arm cordelettes. Unfortunately, my writing did not reflect that.)

As far as tensile strength, the tech cords have no advantage over 7mm nylon in loop strength, the reason being that knot efficiencies in tech cord are much lower. Even in the single strand strength department, it takes about 200 bending cycles for the tech cord strength to fall at or below that of 7mm nylon, which doesn't deteriorate at all after 1000 cycles.

On balance, the only advantage tech cords have over 7mm nylon is their lower weight and bulk, otherwise they are inferior. But lower weight and bulk matter, and it is ultimately up to the climber to decide whether the trade-offs in equalizing ability and resistance to wear favor nylon or dyneema.

Paul, until your contraption can be drop tested with load cells on each of the equalizing arms, I think you ought to mention in your .pdf and in any other place you post that theoretical considerations suggest that the friction of the turns of rope around the ring and biners may nullify the hypothetical ability of the rig to equalize loads.

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#31488 - 07/25/07 12:43 PM Re: cordelette-attention RG [Re: rg@ofmc]
paulraphael Offline
enthusiast

Registered: 01/22/02
Posts: 321
Loc: New York, NY
 Originally Posted By: rg@ofmc
Paul, until your contraption can be drop tested with load cells on each of the equalizing arms, I think you ought to mention in your .pdf and in any other place you post that theoretical considerations suggest that the friction of the turns of rope around the ring and biners may nullify the hypothetical ability of the rig to equalize loads.


We do mention this, and we're waiting to get some drop tests done, but it's no minor feat. Jim Ewing plans to include it in his next batch of tests, which might not happen for a while.

My assumption watching the thing in use under combat conditions is that most of the time it will distribute loads reasonably well (somewhat better than a sliding x) and that some of the time it will distribute them poorly (cord getting twisted and gnarled up, the incoming storm looking more threatening than a factor 2 fall, etc). And it's my strong assumption that it will distribute loads better than a tied cordelette, in any circumstance.

I definitely look forward to seeing a test with load cells, though I believe the results will only be meaningful when compared to other riggings tested in the exact same way. I think this whole anchor building endeavor is more about seeking artful compromise than perfection.

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