ACR Anchor Method?

Lots of good points all around. I'm the guy who originally came up with the ACR, and am happy to see that some people have used it even more than I have.

My assumption is that there's still room for refinement, and also probably some undiscovered tricks and applications. I think the ACR would benefit from becoming open-source ... something hosted on a wiki page instead of just a static PDF on my personal site.

If anyone would be interested in contributing to an effort like this, please let me know.

It might also help put some weight behind it, so we could more easily convince the engineers at Black Diamond or Sterling to do the kind of drop tests we all want to see (in order to learn the real world effects of friction, etc).

Cheers,
Paul

goatboywonder wrote: Not trying to start anything here but I am not sure how you get this. Can you explain a bit more...

rgold, is this diagram for the ACR setup?

And the nerd-fest continues...

OK, I see where the confusion is. The free body diagram you posted is composed of two cords, each with fixed ends, but the ACR is not arranged that way. It is a single loop of cord with no fixed ends (the knot does add some constraint, though). Consider this (poor quality) FBD:

i agree. rgold's diagram shows a 2nd pulley, which i don't see in the ACR setup (the ring and the biner that has the strand from piece A to piece C move in tandem).

Rgold's diagram shows a different anchor (setups like the equalette will distribute loads asymmetrically like that, when rigged for three pieces of pro).

The ACR distributes loads symmetrically in most of its iterations. There are ways to use it (like with four pieces) that are asymmetrical.

What happened here is that someone, I think the name was Just Another MP Douche (yeah, that's it I think) posted a picture of something that works exactly like the schematic diagram I posted, claiming it had "perfect equalization." After some corrections, Mr. Douche deleted all his posts, leaving my response without any antecedent.

The original subject having now vanished, I guess people interpreted my post as being about the ACR. But I was never talking about the ACR.

rgold - that makes more sense. so, my big question is how is the ACR really that different from a simple cordalette setup with no limiting knots? i don't really see a big difference, other than the addition of the rap ring.(?)

Regular cordalette trades poor equalization for no extension.

ACR trades extension for better equalization.

i guess i can see maybe a slight improvement in equalization (due to fewer strands running over each other in one place), but it would be interesting to see how much better. i guess for me it is somewhat of a moot point, as i fall into the "anchor with rope" which offers better equalization AND no extension.

Larry wrote:Regular cordalette trades poor equalization for no extension. ACR trades extension for better equalization.

Subjectively, you feel much less friction with the ACR. You also don't have to remember to put a twist in the cord (the twist greatly limits extension if a piece blows). And you don't have strands pulling at the carabiner from wide angles, running over the gate, the locking mechanism, etc.. And you have a more easliy identifiable powerpoint to clip.

As far as anchoring with the rope, I think everyone should be comfortable doing that. If you're swinging leads, and especially if you're on a route with vertical cracks, it's the simplest option. But I don't think it's always the best option. The ACR isn't always the best option either, but it's one of the more versatile ones, because it's just a cord with a ring attached to it. You can use it as described, or as a cordelette, or as a sling, or you can cut into pieces and run home with your tail between your legs.

Slim, nothing else says manly-anchor at a belay ledge like the ACR.

"What's that, sweetie?"

"Just my ACR, baby"

see, cordalette just sounds friggin gay

Mark Nelson wrote:I say forget those unwarranted fears of shockloading and redundancy, make your anchors distribute loads with solid pro, good angles, and move fast.

I agree with Mark.

What I'm thinking about with this is a functional x but that can distribute between 3 or 4 placements and use the resilience of nylon cord; fantastic idea.

I'd get rid of all those extension limiters.

2-3 placements are fine; but if you need to think about 4 to work into that 16kN, you can actually make the rig do it self-contained by double wrapping the ring, then pulling those two strands up to the middle pro points; instead of that contrived outside leg double-clove depicted in the paper.

I'd probably go with 4 placements max at an anchor looking to take about 16kN in total, worst case. My hypothesis is you won't get this drastic as a climbing team using a dynamic rope; my observation is from rescue mass drops on static systems.

Rich, I think the friction in this rig might actually be a good thing to help draw away some energy. It's not so pronounced as that sling-ed x rig which clutches on itself during a directional shift so that it possibly can't distribute. All the nylon cord moves here, similar thinking as to the Super Munter as all the nylon moves, none of the nylon is seeing excessive heat generated, and is able to adjust to the load. We're not looking for perfect equalization; we want a good load distribution using solid placements over a range of motion. I think the ACR is fine.

Another observation, the connecting knot is a friggin pain in the ass for planning range of motion. It seems to me the outer legs see more movement so the knot either hits the pro-biner or the cock-ring. I'd like to put the connecting knot in one of the middle placements, meaning I'd stack the knot right on the ring to start, use that to make my interior clip, then adjust for range of motion.

Thinking further into this for rescue loading, you can incorporate a Rescue-8/similar as the ring, increase the size of the cord. Should be workable as quick & effective load distributing anchor (LDA) using a 4 placement at 5kN regardless quasi-rule-of-thumb.

Mark Nelson wrote:Another observation, the connecting knot is a friggin pain in the ass for planning range of motion. It seems to me the outer legs see more movement so the knot either hits the pro-biner or the cock-ring. I'd like to put the connecting knot in one of the middle placements, meaning I'd stack the knot right on the ring to start, use that to make my interior clip, then adjust for range of motion.

Have you tried it? I'm curiuos to know if this makes life easier.

I like the idea of the ACR, and can't really think of a reason not to have a rap ring on your cordelette; other than the wraps around the ring potentially weakening the chord, but that seems negligible (maybe? Spectra may weaken, nylon may not). With the ring you can still do the equalette and cordelette methods as well as the ACR.

Mark Nelson wrote:Another observation, the connecting knot is a friggin pain in the ass for planning range of motion. It seems to me the outer legs see more movement so the knot either hits the pro-biner or the cock-ring. I'd like to put the connecting knot in one of the middle placements, meaning I'd stack the knot right on the ring to start, use that to make my interior clip, then adjust for range of motion.

I'm thinking about perma-cloving one of the outside legs to a biner with the connector knot just below this to avoid the knot jamming the system. Seems reasonable, anybody else?

Wehling wrote: I'm thinking about perma-cloving one of the outside legs to a biner with the connector knot just below this to avoid the knot jamming the system. Seems reasonable, anybody else?

Make sure that it doesn't stop the whole thing from equalizing. If you cloved one leg to a biner, you'd have to use that leg for any extension / length limiting knots. Not sure if it would be a help or a hindrance.

In general, ideas for getting the knot out of the way are welcome.

The best way to get the knot out of the way i can think of is always putting it on the leg with the extension limiting knot.

The PDF shows a not recommended way of connecting upward directionals. Are there any updates on how to connect them?

-Glenn