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Equalizing the Middle Anchor Leg

Mathias · · Loveland, CO · Joined Jun 2014 · Points: 306

Jktinst:

Thanks for answering. I think I understand now. If I used the same method on a 4 piece anchor, it'd equalize the load though, right?

jktinst · · Unknown Hometown · Joined Apr 2012 · Points: 55

Yes in theory.

csproul · · Pittsboro...sort of, NC · Joined Dec 2009 · Points: 330
Mathias wrote:Jktinst: Thanks for answering. I think I understand now. If I used the same method on a 4 piece anchor, it'd equalize the load though, right?
If I'm understanding Jim and RGold correctly, only if each arm was exactly the same length, something virtually unobtainable in the real world.
Mathias · · Loveland, CO · Joined Jun 2014 · Points: 306
csproul wrote: If I'm understanding Jim and RGold correctly, only if each arm was exactly the same length, something virtually unobtainable in the real world.
That would be my thinking too. I wasn't suggesting perfectly equal with that question, just far closer than 25/50/25.

(I'm thinking a lityle more cleary now that I'm done putting heat and hammer to things that shouldn't need them, for today anyway)
aikibujin · · Castle Rock, CO · Joined Oct 2014 · Points: 300
Robert Cort wrote:Why don't you just work some of the slack through the master-point knot before you tighten down on the master-point knot. Yes, then you will have unequal loops in the master-point, but that doesn't matter too much, because the load goes through the master-point to the now (hopefully) equalized anchor points. If I understand your question properly, it would result in one of three loops in the master-point being slightly longer than the other two - I wouldn't sweat that.
I think this is worth repeating because it's something a lot of people miss. But please, don't get in the habit of putting a winky face at the end of your post... it has been waaaay over used.

Most people tie the master point by bringing all the strands of the cordelette (ie the strand from A to B, B to C, and A to C) together, make sure all the legs are taut, then pinch all the strands together and tie the knot. However, when you pinch the strands together, you're essentially shortening the strands going to the two outer pieces, leaving slack in the strand to the middle piece after the knot is tied. Like Robert mentioned, the solution is simple: after you pinch all the strands together, make sure you pull any slack in the middle leg through to the loops for the master point. After the master point is tied, one loop may be bigger than the others, but it doesn't matter since you have two other loops.
Jim Titt · · Germany · Joined Nov 2009 · Points: 490
Mathias wrote:Jktinst: Thanks for answering. I think I understand now. If I used the same method on a 4 piece anchor, it'd equalize the load though, right?
You might be able to equalise it manually BUT self-equalising not a chance in hell. Back on one of the ST death threads somebody posted this:-

4 piece anchor

Along with the caption "The Equallette Anchor in Full Form will slide nearly 45 degrees and remain equalized ".
If it has to self-equalise due to the direction of pull changing the friction of the karabiners means it has a calculated load distribution from left to right of 12.9%/21.7%/24.5%/40.9% on the pieces.
I tested it and got a load split of 7.7%/18.2%/30.9%/43.2%. which is worse because as the karabiners slide over the cord under tension it starts introducing twists which jam up.
You can see just looking at the photo that it is nowhere near equalised, drawing a simple vector diagram the left piece appears to get maybe less than 5% and the far right one maybe 70%.
BigCountry · · The High Country · Joined May 2012 · Points: 20

Wow! Greg D thanks for trying and don't know why they won't listen. Pictured above is the worst example of an equallete I've ever seen. So disregard that shit it's just not right. Done properly it's my favorite way to build anchors. And it sure as shit distributes the load way better than master point anchors. Learn it people don't just hate it cause you don't get it.

David Coley · · UK · Joined Oct 2013 · Points: 70
Mathias wrote: I was thinking of a self equalizing anchor that could deal with the load moving from side to side. Applications would include TR anchor
Sounds a bit worrying. A TR anchor that needs to concern itself with trying to equalise forces doesn't sound a good idea.
David Coley · · UK · Joined Oct 2013 · Points: 70
Mathias wrote: Given real world placements, is it ever actually possible (factoring in cord or sling angles and the extra forces they create) to get a system that will actually distribute the load truly equally over all placements?
If you are talking real-world, then a big NO. In the real world in the event of a fall of significant magnitude all the force will most likely be on one arm, however you build the thing. Even if you had a perfect frictionless sliding system.

This is because people build powerpoints, sliding-x's etc. with the misguided idea that the force will be roughly downwards plus or minus whatever angle the sliding X can slide through.

It will only be downwards if the second falls off. If you have rigged a belay that might fail when the second falls, you are on some very extreme ground. Most likely you will have not bothered to use a plate but a waist belay, dug a hole for you bum in the snow, braced your feet and said a prayer.

The fall you build belays to hold is a leader fall. This will be up or sideways and only down if the Jesus piece blows. Which, is likely to be at the top of one arm of the belay - the Jesus arm.

The only way I can see any way these complex systems can work is if you use the powerpoint or X as the Jesus. Otherwise all the force is on the Jesus arm of the anchor. By definition, this means the Jesus piece is lower than it could be (because the PP or X is by definition below the top piece by typically 0.5 to 2m). Hence you increase your fall factor. Which seems a strange thing to do with an anchor that you think could possibly fail.
jktinst · · Unknown Hometown · Joined Apr 2012 · Points: 55
David Coley wrote: If you are talking real-world, then a big NO. In the real world in the event of a fall of significant magnitude all the force will most likely be on one arm, however you build the thing. Even if you had a perfect frictionless sliding system. This is because people build powerpoints, sliding-x's etc. with the misguided idea that the force will be roughly downwards plus or minus whatever angle the sliding X can slide through. It will only be downwards if the second falls off. If you have rigged a belay that might fail when the second falls, you are on some very extreme ground. Most likely you will have not bothered to use a plate but a waist belay, dug a hole for you bum in the snow, braced your feet and said a prayer. The fall you build belays to hold is a leader fall. This will be up or sideways and only down if the Jesus piece blows. Which, is likely to be at the top of one arm of the belay - the Jesus arm. The only way I can see any way these complex systems can work is if you use the powerpoint or X as the Jesus. Otherwise all the force is on the Jesus arm of the anchor. By definition, this means the Jesus piece is lower than it could be (because the PP or X is by definition below the top piece by typically 0.5 to 2m). Hence you increase your fall factor. Which seems a strange thing to do with an anchor that you think could possibly fail.
Many things to disagree with here. I build my belay anchors to be strongest for holding a downward leader fall because that is the worst fall that it might have to hold. It’s great that this happens to give me a solid anchor to bring up the second as well but that is not my primary concern in anchor-building. Of course there are also circumstances where the second could take a fall that is every bit as hard or harder than a leader fall (as you’ve just reported). I don’t neglect upward-pull pros either (or sideways blocking pros for traverses) but I don’t worry about these other pull directions to nearly the same extent because the forces involved will typically be lower.

As I said in that RC.com thread I referenced above, I use as much as possible various belay anchor-setting and belaying approaches that aim to either avoid altogether the possibility of the leader falling directly on the belay anchor or severely reduce the impact of such a fall. However, even with these approaches, failure of the first few progression pros (however unlikely) or some other excessively rare circumstance could still result in the leader falling hard on the belay anchor so I just keep right on building anchors that are strongest against a downward pull.

After reading all the detailed test reports and “no-extension vs equalization” discussions I could lay hands on, I remain quite convinced that I am better off with a fairly narrowly extension-limited, dynamically equalizing belay anchor (although I avoid the looping 3-arm configurations because I strongly suspect that since those require cord to slide with sharp bends through multiple successive biners or rings, they are the ones that result in the greatest friction and more uneven distributions). It follows from this that I am also averse to intentionally risk jeopardizing the balance and collective strength of my belay anchors by clipping one of their pros as a first progression pro (no contradiction here: the approaches I use to prevent the leader falling directly on the anchor also avoid the possibility of a leader fall hitting first a single belay anchor pro).

I suspect that it looks like more people like clipping one of the belay anchor pros as the first progression pro these days because non-sliding anchor rigging approaches also appear to be on the ascendant (at least on the forums). If you’ve already made the decision to build belay anchors that load their pros one at a time (even in a strictly downward pull) by using non-sliding approaches, I can well-imagine that the possibility of ripping one of them off by using it as a Jesus pro doesn’t look nearly so dire.

Of course, as you’ve recently reported as well, on those relatively rare occasions when the leader falls on the anchor-linked Jesus pro, it usually simply holds the fall and everyone can just dust themselves off and carry on like nothing happened.
Mathias · · Loveland, CO · Joined Jun 2014 · Points: 306
David Coley wrote: Sounds a bit worrying. A TR anchor that needs to concern itself with trying to equalise forces doesn't sound a good idea.
I've set up anchors on some routes that traverse a little, which seem as though a fall could potentially cause much more load to certain pieces than other. It's TR so the forces aren't as much as a lead fall, but it also make me wonder if the climber requires a take, could slack develop on some placements and maybe even cause them to shift. I guess the answer is to not TR routes like those in the first place.

I just thought I'd mention, I use a cordelette when building anchors. I was simply curious about some other ideas. But thanks for the input. I'll stick with the cordelette. :)
Jim Titt · · Germany · Joined Nov 2009 · Points: 490
Mathias wrote: I've set up anchors on some routes that traverse a little, which seem as though a fall could potentially cause much more load to certain pieces than other. It's TR so the forces aren't as much as a lead fall, but it also make me wonder if the climber requires a take, could slack develop on some placements and maybe even cause them to shift. I guess the answer is to not TR routes like those in the first place. I just thought I'd mention, I use a cordelette when building anchors. I was simply curious about some other ideas. But thanks for the input. I'll stick with the cordelette. :)
Due to the friction on the sliding karabiner you have to offset the force by roughly 13° before it even starts moving which in a top-roping situation is usually a considerable distance sideways. Then the force required to slide the anchor has to be less than the force required to move the faller across to under the anchor for an equalising anchor to be any use for an offset fall, a couple of simple force diagrams show this is extremely unlikely/will never occur.
Stick with the cordelette or whatever, top roping it´s pretty irrelevant really.
eli poss · · Durango, CO · Joined May 2014 · Points: 525

I'd wouldn't really worry about it. statistically, you're much more likely to die from rappelling off the end of the rope than from your anchor failing

Guideline #1: Don't be a jerk.

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