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Anyone ever use the equalizing 2-loop Eight in anchors?

Original Post
Rob P · · Duluth, MN · Joined Sep 2008 · Points: 612

I've been using this one for a while now, but everyone who sees me use it dumbfonded. Apparently not many people know it. I drew a crude picture to try and show it.

Basically, it is a 2-loop (dog-ear) figure eight knot with one loop much longer than the other. You clip the long loop through two(can do 3 as well) pieces, and drop down the middle (between the 2 pieces), and clip it to the smaller loop in the knot with an extra carabiner.

It acts like a sliding-x, but you don't need an extra sling...just an extra carabiner.

img132.imageshack.us/img132…

Sorry for the terrible drawing.

Unboundquark · · Unknown Hometown · Joined May 2008 · Points: 195

That looks like what Trango sells as a sewn and packaged item called an Alpine Equalizer (AE).

The major difference I can spot is that you're using a single biner whereas the AE uses an aluminum ring. In fact it uses two rings (in parallel) which permits you to also take up slack between the two rings and then pick up a possible third anchor.

But what you have shown probably inspired the AE.



Am I reading your drawing correctly?

Here is a current thread happenin' in the "Trad" forum about the AE...

mountainproject.com/v/trad_…

Here is a YouTube demo of the AE...

youtube.com/watch?v=ocp1EYmjop

-Glenn
Kevin Stricker · · Evergreen, CO · Joined Oct 2002 · Points: 1,242

That's interesting, I have never tried that before. Have you every tried the Bunny ear knot(see Mark H's picture description below)? Does basically the same thing but is not self equalizing, you have to equalize it before tightening. The best part is that each loop is independent, so you don't have to worry about shock loading. I stay away from any sliding anchor system, and like to use my rope whenever possible to build an anchor. I don't like carrying extra stuff that does not have uses outside of anchor building.

I guess a short answer would be .."No"..

Rob P · · Duluth, MN · Joined Sep 2008 · Points: 612

Thanks for posting that freerangequark. I haven't seen that thing before, but it looks like it works on the same exact principal as the 2-loop eight method I posted.

Buff Johnson · · Unknown Hometown · Joined Dec 2005 · Points: 1,145

Here's more the example using 3 points:



This is a rig based on creation from Bill May's RMRG publication in looking at distributing a load from piton points. This is probably what really formed the basis for the AE, but with nylon accessory cord (course what is pictured is a little beefier than your standard 6mm).

It offers a range of motion, load distribution, resiliency of materials with absorption, & knot absorption. It does offer some load limiting but this relates to the extent of the slack introduced should one anchor point fail. So you still don’t have a rig with both a full range of motion and no-extension redundancy.

In this model, the assumption is that you need all three marginal anchors maintaining or the system fails itself because the other two can’t take the load. However, this assumption can be subjective, what if 2 out of 3 anchors might be adequate; you might be able to re-capture the system by using elastic rig materials should one protection point fail.

Buff Johnson · · Unknown Hometown · Joined Dec 2005 · Points: 1,145
Rob P. wrote: It acts like a sliding-x, but you don't need an extra sling...just an extra carabiner.
some things I like about it is the ability to use cord & knots for absorption, it does distribute, and it does so without clutching should you have quick directional changes -- which is where the x can have trouble.

As with the pic I just posted, the 2-point also relies on load distribution between placements -- both acting together are adequate, but either acting on their own can't handle the load, further meaning that looking into redundancy with this rig is irrelevant.
Greg D · · Here · Joined Apr 2006 · Points: 883
Rob P. wrote:I It acts like a sliding-x, but you don't need an extra sling...just an extra carabiner.
Your rig does nothing more than a sliding x. It equalizes two pieces, it has extension if one piece fails, it has complete failure if the cord breaks. A sliding x doesn't require an extra sling unless you want redundancy, same as your rig. Your rig requires an extra biner and more time to set up/break down. I don't see any benefit to your rig. I hope you don't mind my straight talk.
Kelly Cordes · · Estes Park, CO · Joined Oct 2001 · Points: 95

here's one that you might like. it uses the climbing rope, which i like to do in some situations -- when swinging leads, for example, and you have a couple of good anchor points that are close together. it's quick, and works well. it sort-of (with some friction...) self-equalizes, though i adjust it manually first to get it close. so, there would be extension if one piece failed. on the other hand, ya get true equalization and thus a piece is less likely to fail, which isn't the case when you tie-off the anchor points (not true equalization) -- indeed, the never-ending debate over which method is better...

anyway, pics attached. you'll see that the loop that you pass through the top of your 8 (a big-looped 8-on-a-bight, made a couple of feet away from your tie-in) thus creates 3 loops. if you only need 2, just drop/collapse the middle one. hope this helps.




Marc H · · Longmont, CO · Joined May 2007 · Points: 265

I use a double bowline on a bight for several different purposes. One of which is to equalize two pieces of gear if I'm out of slings. Here's a pic sequence:

Start with an overhand on a bight. It's important that you put your hand through the bight correctly. The way I look at it is I'm coming in through the "bottom" of the loop. My middle finger indicates the top one of the two strands that you'll be manipulating:



Keeping the loop on your wrist for this step, separate the two strands from the overhand to give yourself a little room to work with:


At this point, flip the loop from your wrist over the (loosened overhand) knot that's in your hand:


Now snug up the two strands that you initially separated from the overhand knot, using the loop that was initially on your wrist:


The two loops that you initially separate from the overhand become your clip-in points. You can clip them in together for a great master point knot (I use it this way when I know it's going to be heavily loaded, like someone jugging on it, because it's unbelievably easy to untie after even the heaviest of loads), or separate the two bights to be clipped independently (see pic below). The knot can also be made as large or as small as you want, depending on how much rope you have left when you're making your anchor. Anyway you slice this knot, it's handy.



When you clip the bights independent of one another, you can finagle the knot around so that the points are equally loaded regardless of the position relative to each other. It takes some practice, but when you get it, you realize how useful the knot really is when you find yourself lacking slings, cordalette, etc..

--Marc

jcntrl · · Smoulder, CO · Joined Jun 2008 · Points: 0

+1 on the double bowline-on-a-bight. Mostly I use cordage for just about every anchor, but sometimes--if I'm swinging leads and have plenty of rope left (and won't need all of the rope for the next pitch either)--I'll tie this knot. I leave one of the loops very short and clip a locker to it, and the other quite long and equalize all of my anchor pieces between the piece and the short locker loop. Self equalizing, but it would extend if a piece blew. But since it's self-equalizing, you reduce the chance of that happening... the old debate.

The knot ties very quickly, is quite stable and strong, and unties even after loading quite readily (but not on its own!)

Kevin Craig · · Unknown Hometown · Joined Mar 2002 · Points: 325

+1 (FWIW) on Kelly's set-up. Yeah there's some friction to the equalization and doesn't work if you're leading in blocks, but it's fast, simple, and no extra gear.

I'd still like to see a mechanical engineering analysis of the set-up that Mark/Buff depicts (maybe that's in the paper he refers to?). I'm only a chemical engineer, but it still seems to me like that's a complicated way to set up 2 Death Triangles. I'm willing to be convinced otherwise, but regardless, to my simple brain, complicated is bad especially when I'm tired, dehydrated and maybe gripped.

Mostly, I still use "sliding"-x's (sometimes tied off) and cordalette type set-ups (in combination if I need a bunch of pieces to feel safe) taking into consideration their limitations and lack of perfect equalization (but hey, nothing in life is perfect).

Guess I'm just to old to learn/use the latest equallette-triple-Lutz-with-a-half-gainer which is about how complicated some of these "better" systems seem to me.

Marc H · · Longmont, CO · Joined May 2007 · Points: 265
Kevin Craig wrote:I'm only a chemical engineer, but it still seems to me like that's a complicated way to set up 2 Death Triangles.
That's a good point. I will generally only clips the two bights independent of one another if I'm near 100% sure that nothing's going to blow. In reality, I only use this knot in that configuration once in a blue moon. I use it pretty frequently as a single master point, though.

--Marc
Buff Johnson · · Unknown Hometown · Joined Dec 2005 · Points: 1,145

Kev - poor Johnny for he is no more, for what he thought was H20 was H2SO4! -- I know you've never heard it, right??

The rig I posted just depicts what the op was getting after in their hand-drawn diagram. I don't know if the results were posted, but can certainly jack it and see what the reads are for distribution. I like how it uses nylon all throughout though the load and works away from the x clutch; though I've used it zero times while climbing.

The quicker rope rigs you guys followed up are what I would go with; and I also go with the quick sling or cord overhanded to switch and work at the station. Mainly because of the first rule of fight club: keep moving & don't fall on the f'n anchor!

Kevin Craig · · Unknown Hometown · Joined Mar 2002 · Points: 325
Buff Johnson wrote:Mainly because of the first rule of fight club: keep moving & don't fall on the f'n anchor!
Word!
slim · · Unknown Hometown · Joined Dec 2004 · Points: 1,093

ditto kelly and marc's methods. they work well, quick, and use very little gear.

Mitch Musci · · Laramie, WY · Joined Apr 2002 · Points: 720

Don't forget that a sliding x tied on a single sling with TWO extension-limiting knots (overhand knots on both sides of the sliding x) makes the anchor redundant.

Buff Johnson · · Unknown Hometown · Joined Dec 2005 · Points: 1,145

though, the x would still be similarly "redundant" if it were just an x without any knots, would it knot?

Greg D · · Here · Joined Apr 2006 · Points: 883
Buff Johnson wrote:though, the x would still be similarly "redundant" if it were just an x without any knots, would it knot?
Without the knots, a failure of the sling anywhere means total failure. By tying the extension limiting knots you create two independent strands in the middle. Therefore, failure of one of these strands does not equal total failure. These limiter knots do inhibit the sliding x's ability to equalize somewhat.
Buff Johnson · · Unknown Hometown · Joined Dec 2005 · Points: 1,145

only if failure of the sling (assumed from rockfall) just happened by happenstance outside of the knots assuming the knots themselves would also not be damaged. Failure within the knots would still be failure with a single sling.

The point is you don't really have any more redundancy that you can effectively rely upon, you do have a limiter for mass acceleration that can reduce friction & impact to protection; which if you talk about that, then you must address how loads distribute being more important than what is perceived through redundancy.

Darren Mabe · · Unknown Hometown · Joined Dec 2002 · Points: 3,669
Kevin Stricker wrote:I stay away from any sliding anchor system, and like to use my rope whenever possible to build an anchor. I don't like carrying extra stuff that does not have uses outside of anchor building. I guess a short answer would be .."No"..
i am with kevin. keep it simple!

EDIT: dont know if it has been mentioned, but remember that with the double bowline, a third point can be clipped via cloving the strand that goes down to the follower
Greg D · · Here · Joined Apr 2006 · Points: 883
Buff Johnson wrote:only if failure of the sling (assumed from rockfall) just happened by happenstance outside of the knots assuming the knots themselves would also not be damaged. Failure within the knots would still be failure with a single sling. .
Not so. After tying limiter knots you have two strands between the knots. Both strands would have to fail (provided you rigged it as a sliding x). Hence, redundancy. I agree that load distribution is very important, thus, reducing that chance of failure of any one component in the first place. This is why I don't use the typical cordalette rig anymore. Very poor load distribution with the slightest change in direction and/or varying lengths of "arms".
Guideline #1: Don't be a jerk.

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