New AAC Article on Anchors

wes calkins wrote:

David Coley, 

I am the person depicted in photo "2" that you are talking about and I have in fact been "wrong handed" all of my life. 

:)

By the way, how did you set the anchor up? It really looks like the belay was tied after you were hanging in the air, given the length of the sling to the lowest piece.

Jeremy B. wrote:

Suggested reading: http://people.bath.ac.uk/dac33/high/6TheBelay.htm#swapd

Ok, pretty much what I figured. Is this common practice? It's not hard to understand, but I've never before heard of it being used or described. I want to say even RGold, who is a prominent proponent of rope anchors here, has agreed in the past block leads are an issue, which makes me think the linked method is not a widespread technique.

David Coley wrote:

Hi,

some comments:

1. I'm not sure "Indisputably, anchors fail because the load exceeds the force that the anchor can withstand." covers everything. In that, pieces getting pulled in the wrong direction is a possible reason for failure. This is not mentioned in the list that follows.

2. I might be wrong, but was the photo with the caption "Modern anchors are configured to secure belayers no matter who they are belaying.  They might be belaying a second; they might be belaying a leader." faked? He is hanging from the rope having been dragged up the cliff by the leader falling. However if you imagine him hanging from the belay before the fall the sling to the lower "upward pull" piece must have been 3 times longer than would in truth be. This gives the wrong impression of how this needs to be put together. In addition, he seems to be holding the rope with his hands round the wrong way - his strongest hand (the upper one) is on the wrong side of his body. He seems to like being wrong handed, as he does it again in photo "All these different changes in the direction of load will shift the entire load onto a single component.  "

3. In the photo with the caption "Even the theoretical load distribution of many anchors is not "equal."  This anchor builder intentionally rigged to distribute more load to big pieces and less load to small pieces." At least two of the carabiners are being loaded over an edge. This is really bad as carabiners snap easily it such situations. 

I know the images were meant to illustrate other points, but when producing educational material one needs to understand that the reader might not just focus on what you wanted to, and might well take other messages. This is why for example, even when talking about chalk bags, a photo of a belay locker not done up on a belay plate is unhelpful.

Suprised you haven´t mentioned the two quick links are installed upside down  

Ted Pinson wrote:

 I think that one of the main points brought up in the article/video is that even small amounts of shock load can be dangerous. 

Please define "small amounts of shock load".

E.g: the amount allowed by the limiter knots on a quad.  Watch the video...

Ted Pinson wrote:

E.g: the amount allowed by the limiter knots on a quad.  Watch the video...

I've watched the video.  The video doesn't define it.  Virtually no one that uses the term can define it.  As Jim Ewing of Sterling Ropes has rightly pointed out it is ill-defined and not terribly useful.  Yet it gets used as a justification for anchor designs.  It seems it has some sort of visceral power to create fear.  Maybe it's the climbing version of the word "terrorism"?  ;)

edited to correct attribution

How about "a sudden force applied to an untensioned system"?  You could technically say that lead falls are an example of shock loading, although the dynamic properties of the rope and climbing system negate most of the additional loading.

...and the climbing word for terrorism is "factor 2."

Ted Pinson wrote:

How about "a sudden force applied to an untensioned system"?  You could technically say that lead falls are an example of shock loading, although the dynamic properties of the rope and climbing system negate most of the additional loading.

Ok, we're teasing something out now.  So, now what is a "sudden" force?  How does it differ from a "not-sudden" force?  

I won't say a lead fall is an example "shock loading" as I don't ever use that term. :)  
But what is this "additional loading" you speak of in a lead fall?  Additional to what?

BTW, have you read the discussion on RC.COM? 

David Coley,  I am speaking only for myself here and not for the AAC or the AAC's education director. 

The anchor was NOT constructed after I was hanging on the belay plate. The pic is an example of one way to rig an anchor for a possible upward pull. It was incorporated onto the anchor with a leg of the sling/cordellette that was used for the other 3 pieces. I can assure you that before I was "pulled" upward by the leader that legs of the anchor were being pulled "evenly". (I used quotes on the evenly because I know that that is a myth in climbing, I hope you understand my point.)

Again, I am only speaking for myself here but I think the article explores some truths that we all know or are at least suspicious of. 

1. In anchoring one piece is doing most of the work most of the time.  If you have solid pieces of pro that you are building your anchor with then what has been taught about using a cordellete still works. 

2. If your pieces are not of equal value then prioritizing the best piece to do most of the work makes sense. This can be accomplished with the way the we connect the material to the pieces of pro. 

3. Equalization doesn't exist in the real world. This is hard to prove without actual testing equipment but you can watch this video and it may provide some insights. https://youtu.be/X0SP85S1m4Q Watch the end of the video where the angle of the load changes while the legs are still being pulled taut. 

Further reasons why anchors shouldn't be thought of as equalized:

Pieces aren't of equal value.

Anchor material tying pieces together aren't of equal length. i.e. shortest leg would be pulled the most due to less material available to stretch. 

Any shift in load direction would pull on one of the pieces more than the others, I feel like this is already known by most. 

Skye Swoboda-Colberg wrote:

Does anyone regularily build anchors with only two cams? ..... but a two piece anchor does not seem to be "good enough" unless you really don't have a third option.

I've used two piece anchors in alpine/multipitch situations on a fairly regular basis, particularly if one of them is a bomber nut.  This is especially common when the terrain offers ledges or other good stances.  I'll often add a third piece to protect an upward pull if warranted after the second arrives with more gear.

Skye Swoboda-Colberg wrote:

So in a fall that pulls multiple pieces out, the accelerating object (climber) gains momentum and the force exerted on each subsequent piece increases until a piece is strong enough to arrest the fall. The theory (which I don't agree with) is that the momentum gained as the powerpoint is lowered to the load-limiting knot (due to the failure of the piece connecting that leg to the powerpoint) is greater than any force absorbed by the failure of that piece and can lead to an uncontrolled increase in force on the other piece and lead to anchor failure. Even if the extension is only a few inches.

Your theory (and that of others) is that the failure of one point requires energy (not force) which reduces the energy from the falling climber going into the remaining point and thus reducing the impact force. Technically this is called the work of failure and is extremely variable, the work required to break something ductile or stretchy like a climbing rope is enormous but the work required to chip off the rock crystal holding your cam or nut in place can be minimal. As this is impossible to estimate in normal climbing we consider the work of failure to be zero to always stay on the safe side when looking at the various scenarios or measuring the forces.

The tests by Jim Ewing were adequate in a top-roping scenario but failed to investigate worst-case scenarios such as a direct fall onto a hanging belay in a multi-pitch situation where even relatively short extension gives enormously increased impact forces, so much so that both I and another researcher abandoned drop testing at the point where the sling failed.A common conceptual failure by people who are not directly testing but are simply thinking through the scenarios is to forget that not only the belayer attatched directly to the belay (worst case) is falling but that they are being accelerated downward by the braking force applied to the falling climber by the belay device which under normal circumstances could be around 4kN, in other words the belayer is experiencing ca. 4g not 1g.

Under normal circumstances the ability of an anchor to adjust to a change in direction of the applied force is not required, either the force will come from the last piece of protection or straight down, gravity never changes it´s direction. Even if the climber falls to the side of the belay there is insufficient lateral force to overcome the friction in the system and the master point does not slide.

Another widely-held misconception is that building a multi-piece anchor as an equalising system allows the remaining points to share the load when one point fails. This ignores what happens to the failed piece (karabiner and whatever) which in our testing jams into the supposedly sliding karabiner, prevents any realistic equalisation and places all or most of the impact on one of the remaining pieces.

Building "equalising" anchors is 99.99% of the time providing little or no benefit and is potentially exposing the belay to complete failure.

Excellent post, Jim.  I think that the "even relatively short extension gives enormously increased impact forces" bit would be a good definition of shock loading and where people are seeking clarification/evidence of the mechanisms involved.  Is what you described (belayer falling, breaking force) what creates the "shock load" (for lack of a better term)?

Ted Pinson wrote:

https://americanalpineclub.org/resources-blog/2017/7/31/anchors

https://www.facebook.com/AmericanAlpineClub/videos/10155014157483935/

Found this very interesting, potentially game-changing in terms of how anchors are taught.  Ironically, posters on MP (e.g RGold) have been making these points for years, but it's good to see that the AAC has come around on it.  Maybe we'll see fewer "how to build a quad" videos in the future...kind of surprised there's no discussion/advocacy for rope anchors, however, as this seemed like the most logical solution to the shock loading danger to me.

edit: added video link.

Two questions:

First, in the historical photo, is he belaying with something, or just the ropes in his hands?

Second, the photo with three cams, that someone mentioned had biners loaded on rock, how would you fix that? Hitch a sling onto the cam and skip those carabineers?

Thanks! Plenty to consider, especially with Jim on here, thanks, sir!

Best, Helen

Skye Swoboda-Colberg wrote:

Does anyone regularily build anchors with only two cams? I was told last summer I was "super safe" because I use a minimum of 3 pieces for an anchor, which surprised me. Maybe this is overkill, and an example of redundancy run amok, but a two piece anchor does not seem to be "good enough" unless you really don't have a third option.

Yes. If it's two pieces larger than .75 c4 in a face (not flakes) than I only use two pieces for my anchors. 

If the gear is smaller I'll do 3. If the rock is questionable and there are no other options I've done 4 piece anchors.

Ted Pinson wrote:

Excellent post, Jim.  I think that the "even relatively short extension gives enormously increased impact forces" bit would be a good definition of shock loading and where people are seeking clarification/evidence of the mechanisms involved.  Is what you described (belayer falling, breaking force) what creates the "shock load" (for lack of a better term)?

Well the only place I´d use "shock loading" in climbing gear is analysing the effect of the pin on a karabiner gate impacting the nose itself (a boring subject I investigated once) since that´s the only time the rate of stress and the stress propagation waves start to get interesting, the rest of the time it all happens so slowly in engineering terms that I just use impact like most everyone else as the forces only change by a factor of a few tens.

In tha traditional climbing safety system there is always an impact attenuator in the system to spread the energy over a longer period (the rope) but modern climbing educationalists have decided to introduce systems where this is no longer available to reduce the ultimate impact forces, mainly due to their limited understanding of the mechanics involved and their wish to produce a "new", "slick" system to teach to gullible beginners. Equalising belays and the use of PAS´s as the attatchment to a belay fall into this category.

Are we still trying to figure out how build an anchor using two bolts?

Skye Swoboda-Colberg wrote:

Thank you Jim for clarifying this point of contention. It boils down to the idea that gear doesn't break, rock does. But if that cam or nut really is being held in place by one crystal prone to failure, is it really strong or secure? If equalization is a myth, why can't I find a single reputable study or paper to back up this claim? I'm usually pretty good with google, but have yet to find hard evidence. The posted video doesn't address problems with self-adjusting systems.

That´s your intepretation, not mine. Gear does fail, whether it´s a badly made Alien, a WC rock that crept through the Chinese QC or an Omega Pacific Link Cam loaded sideways as examples. The point is the work of failure for all these and many other possibles is unknown and so cannot be used in a meaningful way to analyse anchor strength.

That a sliding X doesn´t equalise was shown by caving researcher somewhere back like 1986 and a number of others subsequently. Extensive research and published papers are hardly nescessary since a) the concept defies the known laws of friction b) can be shown to be false by practical experimentation by anyone so any paper would be of nescessity extremely short. The best you can hope to achieve is a load split of  1.4:1 or 58%/42% on the pieces which is why most researchers prefer the term load distributing or load sharing and you´ll find more stuff on that. My own research runs to 700 pages and compressed to legibility still is over 30 and requires a good grounding in mechanical concepts which is why it´s easier on a forum just to say "it doesn´t work" and leave it at that.

Dave Kos wrote:

Are we still trying to figure out how build an anchor using two bolts?

More interesting than how to back up an 8ft diameter tree  

wes calkins wrote:

David Coley,  I am speaking only for myself here and not for the AAC or the AAC's education director. 

The anchor was NOT constructed after I was hanging on the belay plate. The pic is an example of one way to rig an anchor for a possible upward pull. It was incorporated onto the anchor with a leg of the sling/cordellette that was used for the other 3 pieces. I can assure you that before I was "pulled" upward by the leader that legs of the anchor were being pulled "evenly". (I used quotes on the evenly because I know that that is a myth in climbing, I hope you understand my point.)

Hi Wes, sorry, looks like I got it wrong. It was just that lower leg was so long. And please don't think I was knocking the article in the slightest - good to see effort being placed into spreading some truths! 

Might there be a rope based belay version coming along soon?

Old lady H wrote:

Second, the photo with three cams, that someone mentioned had biners loaded on rock, how would you fix that? Hitch a sling onto the cam and skip those carabineers?

yep