ACR Anchor Method?

clevernamehere wrote: One last question, totally seperate from the above - has anyone tried this ACR with a rap ring like this: SMC Rap Ring

I have one of those rigging rings on one of my two ACRs that I have been using since this thread started. It works just fine and yes it is stronger, however, it has a slightly smaller aperture and therefor is harder to get 3 biners clipped in to. I prefer the Omega rap ring.

Regarding the 8, what do you gain out of it other than a second loop? If you need a directional, just clip another carabiner into the rap ring or clip the same path that the cord wraps the ring if you don't have the room. But in my experience so far, you never have more than 3 lockers clipped to the ring at any one time. The 8 seems too heavy and bulky to be any improvement in my eyes.

So if you substituted a locker for the cockring wouldn't
You just have a cordalette with a locker? What's the big deal?

Tom Grummon wrote:I don't like the idea of putting the upward directional in the rig because of the equalization: Say I have some nuts in that will pop with upward force. As an upward force is applied to the ACR it will automatically equalize and put some of that force on the nuts, thus popping them and extending/ shock loading the anchor. Not tested, just hypothetical.

Barring a ton of slack, another free body diagram like goatboywonder posted should assuage your fears.

mudbuzz wrote:So if you substituted a locker for the cockring wouldn't You just have a cordalette with a locker? What's the big deal?

You might want to take another look. Its not a cordalette, since it is self-equalizing. The power point can move and doesn't have to be statically pre-equalized for the direction of fall like a cordalette does. Its like a mix between a cordalette and a sliding x that has three or four points of pro, and can be setup and adjusted really fast.

mudbuzz wrote:So if you substituted a locker for the cockring wouldn't You just have a cordalette with a locker? What's the big deal?

You could set something up that's functionally equivalent with an cordalette and a locker, but there are some significant drawbacks:

1) unlike a rap ring, a biner has a weak axis; it can easily be loaded in unsafe ways. A three point anchor almost guarantees triaxial loading.

2) a locker also has edges that can snag and possibly abrade cord running through it. with this kind of rigging, you really can't control the loaded axis of the biner.

3) a locker can come unlocked from cord running over the locking mechanism.

4) you have to remember to put the correct twist in the cord every time you build an anchor. if you forget, or if you do it wrong, the anchor will be subject to huge extension. it's very difficult to evaluate if this has been done correctly after you've set up the anchor. best to have it pre-tied so you never have to worry about it.

mudbuzz wrote:So if you substituted a locker for the cockring wouldn't You just have a cordalette with a locker? What's the big deal?

Its not a big deal, and you are right, they are the same thing. The "improvements" I've found over the cordalette w/ locker is primarily speed and the reduction of human error. Also, this remains prerigged, but doesn't lose the functionality of an open cordalette. But its not a big deal, its just another way to skin the cat.

Suggestion:
On the PDF it mentioned that tying an extension limiting knot on two or more strands will stop the anchor from equalizing.

I don't find this to be necessarily the case. If limiting knots are tied to the two outside strands and not the middle strand with the ring, I find that there is still equalization. Plus you get the benefits of limiting extension, and if the cord is cut above the limiting knots, you also get redundancy.

Just wanted to throw this up here. I've been using the ACR since I found this thread and I'm very happy with it. Got caught off route and out of rope today and threw this together pretty quickly with a lot of bad quality rock. It's a 6 piece anchor using the ACR.

Great googly moogly.

Restie wrote:Suggestion: On the PDF it mentioned that tying an extension limiting knot on two or more strands will stop the anchor from equalizing. I don't find this to be necessarily the case. If limiting knots are tied to the two outside strands and not the middle strand with the ring, I find that there is still equalization. Plus you get the benefits of limiting extension, and if the cord is cut above the limiting knots, you also get redundancy.

You're right, this does work. It seems to me create a lot more friction than with a single limiting knot. I'm not sure how often the advantages of having two limiting knots would outweigh this.

Loving the A.C.R. Fast is important in a lot of places, spring in North Carolina is no exception. These set up faster than anything. Clipping in other stuff, like tag line or your second, is fast and idiot proof. Can be made redundant by picking the strongest placement, in this case a bomber #13 BD Stopper slotted behind a wire-width crack. Limited extension via an 8 on a bite on the right arm, which was the longest.



That's what it would look like if a piece had blown. Measurable extension, yes, but easily limited more so than I did, and by using somewhat dynamic Mammut Procord, and anchoring in with the dynamic rope, I think you are still ahead at the end of the day. Speed equals success, and you're covered enough on the other SERENE goals that this method is worth consideration.

Is it just me or does that top piece look like the spine of the biner is loaded over an edge? I like Mark's earlier statement of good pro and good angles. I will definitely give this crazy rig a try if for nothing else prurient interest in climbing anchors.

Is this a larger than life "O" ring. I am not sure my OP ring would work so well.

Rick Blair wrote:Is it just me or does that top piece look like the spine of the biner is loaded over an edge? I like Mark's earlier statement of good pro and good angles. I will definitely give this crazy rig a try if for nothing else prurient interest in climbing anchors.

just the angle of the photo, and pulling the anchor for the photo, this anchor was actually built on a pretty large ledge so i was leashed out towards the edge, creating a more horizontal pull. anyway...not the point of the photo, this isn't a stopper placement thread.

vincent penoso wrote:Is this a larger than life "O" ring. I am not sure my OP ring would work so well.

its just a standard rap ring my local gear shop sells. can't tell you much about it unfortunately.

vincent penoso wrote:Is this a larger than life "O" ring. I am not sure my OP ring would work so well.

I use a standard OP ring and it works fine. I would rather something a little larger, but it'll do.

whatever the ring, make sure it's rated adequately as it's probably the most important component in this rigging. Some of those rap rings were made for just small loads and very little, if any, friction.

Seems to me the weak part of Kranz's anchor is the biner on that nut. I wouldn't even be concerned about the cam as much as that middle placement. I realize it's probably just a demo rig, but the point being, planning for failure by using placements that aren't solid isn't a good way to build a trad anchor.

If a placement is bad, don't use it. Granted, if that's all you have, then that's all you have. But realize, you still have anchor you can't fall on and making an ACR isn't really going to be a benefit here. Rather, maybe it's better to say you still don't have an anchor no matter what rigging you chose.

One weakness to this system that I haven't seen pointed out yet:

Tying an overhand not to limit extension is not ideal. By using an overhand, of fig. 8, you are setting the knot to be able to "capsize" if it is pulled from either end as opposed to the bight... the very forces that this knot is being tied for should a piece pull.

Seems to me that this would be begging for a knot to capsize out if that piece blows in a real situation.

Solution: tie an alpine butterfly instead, that actually is designed to sustain a pull from either side of rope, or the bight.

I did make a point to not even consider extension limiters and focus on placements and angles for load distribution. So to me any limiter knots, overhand, 8, butterfly, cloves, I really wouldn't emphasize using limiters for multi-point load distribution over a range of travel, which is the purpose of this type of rigging.

If you have bad placements, then why use them? It seems to me whatever weakness is pointed out in comparing limiter knots is far outweighed by weakness in using crappy placements.

Peter Springs wrote:One weakness to this system that I haven't seen pointed out yet: Tying an overhand not to limit extension is not ideal. By using an overhand, of fig. 8, you are setting the knot to be able to "capsize" if it is pulled from either end as opposed to the bight... the very forces that this knot is being tied for should a piece pull. Seems to me that this would be begging for a knot to capsize out if that piece blows in a real situation. Solution: tie an alpine butterfly instead, that actually is designed to sustain a pull from either side of rope, or the bight.

The pull tests done on the extension limiting knots didn't show this to be an issue, either with 7mm nylon or 6mm technora. Jim Ewing at Sterling said that the weakest of the knots, tied sloppily, held 12KN without trouble. In other words, in a worst case scenario the knotted arm could hold a factor 2 fall all by itself.

The knot would be very low on your list of things to worry about.

paulraphael wrote: The pull tests done on the extension limiting knots didn't show this to be an issue, either with 7mm nylon or 6mm technora. Jim Ewing at Sterling said that the weakest of the knots, tied sloppily, held 12KN without trouble. In other words, in a worst case scenario the knotted arm could hold a factor 2 fall all by itself. The knot would be very low on your list of things to worry about.

Is there a reason that it wouldnt be better to tie an Alpine Butterfly? If there isnt, why not tie a knot that doesnt have that possibility? It's not like the Butterfly is hard to tie...