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ACR Anchor Method?
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By rgold
From Poughkeepsie, NY
Feb 15, 2012
The traverse out to the Yellow Ridge on the Dogstick Ridge link-up.  Photo by Myriam Bouchard

After hearing what Jim has to say, I'll add some thoughts that are somewhat new for me:

(1) Sliding systems are similar to fixed systems in performance if none of the anchor pieces blows, and do not confer equalization advantages.

(2) An emerging rule of thumb for any anchor rigging is that one of the pieces is likely to get half the load.

(3) If one of the anchor pieces does blow, then sliding systems seem to be worse than fixed systems in terms of the increased load to the remaining pieces.

Ultimate conclusion: don't use sliding systems for three-point anchors.


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By paulraphael
Feb 15, 2012

I'd like to see the test results, including all the details of the test circumstances that lead to these conclusions.


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By MegaGaper2000
From Indianola, Wa
Feb 15, 2012
the dragon's tail, or dragon's tooth, or whatever. And me.

+1

Anybody know a link for where we can find them?


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By Jim Titt
From Germany
Feb 15, 2012

paulraphael wrote:
I'd like to see the test results, including all the details of the test circumstances that lead to these conclusions.


IŽm afraid youŽll have to wait until IŽve finished writing it all up, the whole subject of the dynamics in belays is complicated and the amount of testing to get reliable and realistic results is enormous.
Or would you like a short paper specifically on the ACR which fundamentally no worse than other similar systems but has no specific advantages either.


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By paulraphael
Feb 15, 2012

I'm sure we can all wait for the whole whole report. I'm glad you're planning a thorough writeup.


Jim Titt wrote:
IŽm afraid youŽll have to wait until IŽve finished writing it all up, the whole subject of the dynamics in belays is complicated and the amount of testing to get reliable and realistic results is enormous. Or would you like a short paper specifically on the ACR which fundamentally no worse than other similar systems but has no specific advantages either.


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By BHMBen
From The Deeper South
Feb 16, 2012
Post climb snack... <br /> <br />Photo is of Strappo Hughes, taken in the Yosemite Lodge parking lot in 1982 by Russ Walling.

I would be interested, in the face of all this postulating, how many users on this site have ever actually had a partial belay anchor failure...one, two pieces blowing....

My bet: < 1%.


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By Dan Dalton
From Boulder, CO
Feb 16, 2012
Working the sick hand-jams on Stemwide aka Big Dihedral (5.8) at North Table. Photo courtesy of Scott Borger.

Mike wrote:
People probably hate to see posts like this in threads like these, but... Why not just anchor with the rope instead of bringing all the extra thingamajigs along? You are already tied in to a super-strong, super-dynamic cord. Just use it.


+1 here, the simplest system is the best! Also, although I understand the twist in the cordelette around the rap ring, anytime you twist a cord/rope you also weaken it! Great to know how to do, but I see minimal useful applications. Cool post!


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By paulraphael
Feb 16, 2012

BirminghamBen wrote:
I would be interested, in the face of all this postulating, how many users on this site have ever actually had a partial belay anchor failure...one, two pieces blowing.... My bet: < 1%.


That's because most climbers are careful enough to avoid falls onto the anchor altogether. Anchors aren't important because you're likely to fall onto them, but because of the catastrophic consequences in the rare case that you do and the anchor fails.

The low number of factor-2 falls is why threads like this go on for so long, fueled mostly by speculation. We lack the real world experience to know for sure what works and what doesn't.


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By Jim Titt
From Germany
Feb 16, 2012

paulraphael wrote:
That's because most climbers are careful enough to avoid falls onto the anchor altogether. Anchors aren't important because you're likely to fall onto them, but because of the catastrophic consequences in the rare case that you do and the anchor fails. The low number of factor-2 falls is why threads like this go on for so long, fueled mostly by speculation. We lack the real world experience to know for sure what works and what doesn't.


Quite so. In fact the amount of armchair theorising and speculation on the subject compared with experience or even testing is amazing, probably the most discussed to no effect and misunderstood subject ever to crop up in climbing.

One reason for the difficulty is the moment you start to look at one part another slight difficulty pops its head up and the complications and variables become exponentially harder to keep in view, at least if a few more belays failed we would have something to work on.

To obtain a definitive answer (if there is one) and with help from others in the industry I decided to review all the available information and then do the testing required to give an accurate overview of the potential and pitfalls of every belay system. Currently I have performed over 400 hours of testing and have 700 drop and pull test tables (which normally are between 1500 and 2000 data sets each), 300 force diagrams, 80 graphics and 120 pages of notes, all of which have to be written up in a way the general public could understand. In my normal capacity as a climbing equipment designer and manufacturer IŽve done a number of similar projects but this is by far the worst and most complex.

The good news is that as far as I can tell it doesnŽt really matter what you do, the number of different ideas related to the minimal incidence of belay failure is proof of this.

The bad news is that anyone who claims their system is `betterŽis wrong since in some circumstances this will be so and in others not.

Richard GoldŽs advice and comments on this thread are well worth reading and remembering, he has a good grasp of the complexities and his opinions are almost 100% correct, a rarity in discussions on equalisation and belays in general.
John Long (who is probably most responsible for the entire equalisation controversy) is also on record stating that in his normal climbing he just uses the rope, like every experienced climbers always has done and probably will continue to do.
Having tried and tested every possible (and some pretty impossible) systems I too will continue to join up a load of pieces of gear in a generally haphazard way and clip the rope into them, confident it wonŽt get any better unless I use a couple of bolts.

Jim Titt
Bolt Products
Germany


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By Yarp
Feb 16, 2012

Thanks for the research Jim. Looking forward to reading that report.

Interesting how the actual research is starting to verify what the old farts have been saying about all these different anchor methods since this nonsense first started getting espoused.

When it comes to actually understand the physics involved in this a little bit of knowledge is a dangerous thing. I agree that most of the discussions around anchors and anchor building are full of emotions and rhetoric. Some people seem to be very emotionally attached to the subject. Glad to see honest and applicable research happening. This could go a long way towards dispelling many of the myths that are commonly held by climbers regarding their preferred belay anchor.


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By vincent penoso
Mar 22, 2012
ACR-VV  (vince variation)

John Braun wrote:
Bumping this thread to ask two questions: 1. Anyone have any new thoughts or ideas? It's been a few months since anyone has weighed in. 2. Any new thoughts on integrating an upward pull piece into this anchor? The last suggestions (IIRC) were just an upward piece rigged to a sling clipped to either the power point or the belayer's harness. Thoughts?


ACR-VV  (vince variation)
ACR-VV (vince variation)

In my first post to this thread a year or 2 ago, I referred to a variation of ACR that I have used which incorporates a 4th leg for the upward pull, affectionately "the vince variation". I have always tied the ACR this way since it came out. 3 pieces were great but I always used one for the upward pull in any anchor I built and 2 for the top just didnt do it for me. Now 3 for the downward and one for the up makes me happy. I always wanted to post a picture of my alleged ACR-VV but never got around to it until today @ Carderock, MD.

I have always carried 2 ACRs on lead and at least one was the "VV". I use the regular flavor sometimes on ICE for building that bomber anchor with 3 screws.

I am not endorsing this setup for anyone else to use and I don't mind if you do or not, it's just what I have used for years and feel confident I could hang a truck off this anchor.


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