Thoughts on Girth Hitch Equalisation

There is no "moment arm" at work in an ADT (or any climbing anchor made from soft goods).  

Thanks for the correction with thorough explanation, Kyle, appreciate ya

Kyle Tarrywrote:

DMM video: https://youtu.be/Vrgadjo9niY?si=qhLaCAMUWp_tLlnz

This video has caused a lot of confusion and misinformation over the years.  It presents large falls with a completely static mass (steel weight) and no dynamic connection whatsoever.  It is not representative of real climbing scenarios, as leader falls involve a length of dynamic rope, and personal tether falls involve a squishy human.

There's a discussion of how it's been misleading here: https://youtu.be/Fh30kHXfVm4?si=YTQuM8oV2wFsgkhD

HowNot2 took some (shorter) human falls onto static slings and the forces were like 2 kN: https://youtu.be/nr3YBDnOI8Q?si=VvtkDJtHrZM8-Wdr&t=692

Agree, it is not representative of climbing situations per se, but it is utterly accurate in the proportional reduction in forces by dynamic materials in anchor construction (up to 50% or more depending on just what materials it is compared to).

There is no misinformation presented in the video as they are very upfront as to the difference between their tests and a climbing scenario. I can certainly see why some might misinterpret what they are presented.

It's also weird, how you selectively choose the HowNot2 videos when you like them but ignore them when they debunk your myths.

Hamster Boondogglewrote:

Agree, it is not representative of climbing situations per se, but it is utterly accurate in the proportional reduction in forces by dynamic materials in anchor construction (up to 50%).

I already covered why this is incorrect in my previous post.  In a leader fall (the specific scenario you were talking about) there is already a dynamic rope in the system. You can't directly compare that to the DMM tests that went from a static system to a dynamic one.

It's also weird, how you selectively choose the HowNot2 videos when you like them but ignore them when they debunk your myths.

Post a link to whatever video you're thinking of and explain how it contradicts anything that I said, I'd be happy to discuss it.  I think this is a straw man, just like you've been doing to Glowering and others in this thread.

If you're referring to their video on the ADT, their data is in good alignment with the theory.  See screenshot below as an example.  The same applies to their 40 degree anchor at 11:02 in the video, which also is well aligned with the theory.

In the end, it's not really worth trying to "discuss" this with you because you're just going to repeat the same things, misrepresent what other people are saying, and resort to insults.  I have quoted specific statements that are technically false and explained why, I have zero interest in interacting with you beyond that.

Kyle Tarrywrote:

I already covered why this is incorrect in my previous post.  Feel free to post any actual math, theory, or test data.

Post a link to whatever video you're thinking of and explain how it contradicts anything that I said, I'd be happy to discuss it.  I think this is a straw man, just like you've been doing to Glowering and others in this thread.

In the end, it's not really worth trying to "discuss" this with you because you're just going to repeat the same things, misrepresent what other people are saying, and resort to insults.  I have quoted specific statements that are technically false and explained why, I have zero interest in interacting with you beyond that.

"Using a short piece of climbing rope in the anchor will not reduce the force of a FF2 fall by "up to 60%" or "1000+ pounds."  This claim is erroneous, and not backed up by any math or test data."

This is precisely the data that is presented in the DMM video where the dynamic materials in the anchor greatly reduce the forces on it. 

It doesn't matter how much weight is used or the nature of the mass (floppy v rigid). The extra length of dynamic material and the knots reduce impact force on the anchor by a very significant amount directly proportional to the max load irrespective of its source.

As well, you cite HowNot2 videos to support your conclusions in one post yet ignore their and other's debunking of the ADT myth when it suits you.

ps. the 60% number is glowering's number.

Kyle Tarrywrote:

I already covered why this is incorrect in my previous post.  In a leader fall (the specific scenario you were talking about) there is already a dynamic rope in the system.  Since there is already a dynamic rope in the system, you can't directly compare to the DMM tests that went from a static system to a dynamic one.  I can't tell if you actually don't understand this concept, or if you do but you're arguing anyway, but neither scenario is very conducive for a productive conversation.

Post a link to whatever video you're thinking of and explain how it contradicts anything that I said, I'd be happy to discuss it.  I think this is a straw man, just like you've been doing to Glowering and others in this thread.

If you're referring to their video on the ADT, their data is in good alignment with the theory.  The data in this screenshot is actually slightly worse:

In the end, it's not really worth trying to "discuss" this with you because you're just going to repeat the same things, misrepresent what other people are saying, and resort to insults.  I have quoted specific statements that are technically false and explained why, I have zero interest in interacting with you beyond that.

Who in the hell is advocating a 130 degree set up like this? Mine is 30 degrees tops and for belaying a second FFS.

Talk about a Straw Man.

What you are confused about is that the forces in the DMM video may be higher than real world given the absorption of the human body, but that does not mean for a second that it is misleading and that short falls onto static slings (ie PAS of all types) are a very bad idea. DMM is perfectly clear about that and the video is a good watch for anyone questioning whether dynamic materials in the belay are of limited value. They are not of limited value but very useful, but we tolerate our current methods of static materials for anchor construction because such severe events are rare and most don't know better.

The above is however very close to the situation if Mark's central anchor failed....

• Kyle Tarrywrote:

DMM video: https://youtu.be/Vrgadjo9niY?si=qhLaCAMUWp_tLlnz

This video has caused a lot of confusion and misinformation over the years.  It presents large falls with a completely static mass (steel weight) and no dynamic connection whatsoever.  It is not representative of real climbing scenarios, as leader falls involve a length of dynamic rope, and personal tether falls involve a squishy human.

There's a discussion of how it's been misleading here: https://youtu.be/Fh30kHXfVm4?si=YTQuM8oV2wFsgkhD

HowNot2 took some (shorter) human falls onto static slings and the forces were like 2 kN: https://youtu.be/nr3YBDnOI8Q?si=VvtkDJtHrZM8-Wdr&t=692

Hi Kyle, I just finished watching all three videos. You have some valid points. I just took the DMM video for what it was. The opening statement in it does address some of the things you mention, but using my own imagination I can see how people might come away from watching it with misconceptions. Misconceptions that in fact I have fought against since my first year, in 1983, teaching and guiding rock climbing. As one example of that, second day students at the Yosemite Mountaineering School were introduced to chock placements,  and belay anchor construction and how those things relate to belaying followers and leaders. In my classes the energy absorption properties of both the rope and the human body were explained, and the importance of it. 

Unfortunately, all testing scenarios I am aware of are flawed, they all are missing one thing or another from real world scenarios. It is thus left up to those who have both substantial experience and a good brain (for this sort of thing) to put testing results into proper perspective. It can be a difficult task. Perhaps the most important statement in all 3 videos is in JB's, at about 14:50 into it. His whole video is good. 

Thank you for bringing to light the issues with the DMM video. I will delete my post recommending it.  Viewers can read about it in your post, where a more complete picture is painted. 

The problem with the ADT is the pulley action at the corners. Mark's big wall anchor doesn't have that, even if the central bolt fails, since each anchor point has its own knot. 

If one is tempted to use an ADT, adding a clove hitch at even one corner will increase its safety. Ideally you clove both corners. Doesn't take much more rope or time.

James -wrote:

The problem with the ADT is the pulley action at the corners. Mark's big wall anchor doesn't have that, even if the central bolt fails, since each anchor point has its own knot. 

If one is tempted to use an ADT, adding a clove hitch at even one corner will increase its safety. Ideally you clove both corners. Doesn't take much more rope or time.

"Ideally you clove both corners."

But then you aren't using an ADT.  

Instead you have a very safe equalized redundant anchor, especially if you can pull enough slack down in the middle to create a masterpoint between the cloved anchors.

Hamster Boondogglewrote:

Ok, if that's how you interpret it then you have my sincere apologies. I honestly regret when these discussions turn prickly.

With all due respect, for someone who regrets discussions going the wrong way you do a lot of contribute to it.

Let's focus on the most important things in my opinion:

1. In the example I provided for belaying a second with one large figure 8 between two close bolts any additional forces from this narrow angle "ADT" are more than made up for by dynamic materials. Regardless, the forces are all negligible regardless of method for belaying a second off the anchor. Strong placements are all that is required. Virtually any redundant connection with proper knots (ie figure 8 etc not just simple knots that no climber would use) connecting strong placements with dynamic materials is perfectly safe as demonstrated by lab testing. There is no magical huge amplification of forces that make a reasonable angle ADT unsafe per se other than one static sling never being recommended. Redundancy of slings or the climbing rope by itself is required, imo.

What myself and other are doing here is using extreme examples to help illustrate the best way of doing things. Would I use an ADT on bolts if I was setting up an emergency rappel anchor and I only had a short length of rope? Yes, and I'd trust it 100%. But would I use an ADT for a multipitch anchors with two cams? Never. I could use an ADT for two bolts on a multipitch anchor but why? As mentioned above throw two cloves hitches in at the bolts and you solve the issue, but then it's not an ADT any longer. I functions as a V anchor at that point.

2. For belaying the leader, dynamic connections as much as is practical are superior for energy absorption. All connections should be redundant. If you belay off of an adjustable tether it should incorporate dynamic materials and the connection to the anchor should be redundant (ie a secondary tie in for safety as FF2 forces on these tethers can be dangerous).

I only belay the leader from using the rope as my tether. But if I used something else I'd probably agree. 

No method (even sliding X's) will equalize forces on the anchor. Strong placements and redundancy are essential to your safety. Expect one anchor point to bear all the load.

3. Static slings (of any configuration) do not equalize forces as perfect leg length, orientation and perfect tightness of the legs is not achievable in the widely varying conditions of belaying a leader or follower. Dynamic materials are superior for building anchors to reduce forces.

I agree with your previous assertions that equalization has been overblown in the past, and I think I previously stated that. However a quad DOES come close to equalizing forces if the placements are horizontally separated, it makes intuitive sense and that's what I remember testing revealed (and a sliding X can come a little less close) As I stated I don't use a quad for that I use it, but as Nick mentioned he uses it for ice climb (I've only ice climbed a few times) and it' makes sense for that. Ice screws aren't nearly as confidence inspiring as cams/nuts/bolts and it would be nice to easily stand side by side with your partner. 

Yes, static slings with knots (e.g. girth hitch anchors) don't equalize. But as you mention equalization is not needed. I'd rather make an anchor out of one solid cam than two iffy cams with any method of tying them together. 

But the length of the material in the parts of the anchor being static or dynamic probably doesn't make much difference. Earlier I wrote:

Let's hear your math. I think a dynamic rope decreases the force by 60% while a wide ADT could put 380% of force on each anchor point.

But again this was an extreme example. If a leader takes a FF2 on a dynamic rope I "think" from what I remember it decreases the force by 60%. And the 380% is for a very wide angle probably no one would be dumb enough to use. But you shouldn't be falling on an anchor. The biggest forces would come from a leader on the next pitch falling and ripping out their first piece and coming onto the belayer/anchor. In that case there should be fair amount of the lead rope out, that's what's reducing the force. Not the 2 feet of material between the belayer and the anchor points that should already be tight and not have any slack in it to allow the belayer to "fall". I agree that all things being equal it's a better for force reduction to use dynamic rope in the anchor than static slings, but it's such a small real world difference for that application it doesn't matter to me, and as I mentioned by tether is always dynamic anyway, and is a single rope, so that's going to reduce the force more than two strands of rope in an anchor.

James -wrote:

The problem with the ADT is the pulley action at the corners. Mark's big wall anchor doesn't have that, even if the central bolt fails, since each anchor point has its own knot. 

If one is tempted to use an ADT, adding a clove hitch at even one corner will increase its safety. Ideally you clove both corners. Doesn't take much more rope or time.

I have to agree I overstated Mark's case (simple error) as the pulley action is not there, however the distance and angle are great which would increase forces.

Regardless, I simply posted a very narrow angle large loop on closely spaced bolts for fixing a rope or belaying a second. There is absolutely nothing wrong or dangerous about this though some are upset by it.

But I was clearly wrong to equate apples to apples Mark's "failure mode" with an "ADT" per se.

Gloweringwrote:

With all due respect, for someone who regrets discussions going the wrong way you do a lot of contribute to it.

What myself and other are doing here is using extreme examples to help illustrate the best way of doing things. Would I use an ADT on bolts if I was setting up an emergency rappel anchor and I only had a short length of rope? Yes, and I'd trust it 100%. But would I use an ADT for a multipitch anchors with two cams? Never. I could use an ADT for two bolts on a multipitch anchor but why? As mentioned above throw two cloves hitches in at the bolts and you solve the issue, but then it's not an ADT any longer. I functions as a V anchor at that point.

I only belay the leader from using the rope as my tether. But if I used something else I'd probably agree. 

I agree with your previous assertions that equalization has been overblown in the past, and I think I previously stated that. However a quad DOES come close to equalizing forces if the placements are horizontally separated, it makes intuitive sense and that's what I remember testing revealed (and a sliding X can come a little less close) As I stated I don't use a quad for that I use it, but as Nick mentioned he uses it for ice climb (I've only ice climbed a few times) and it' makes sense for that. Ice screws aren't nearly as confidence inspiring as cams/nuts/bolts and it would be nice to easily stand side by side with your partner. 

Yes, static slings with knots (e.g. girth hitch anchors) don't equalize. But as you mention equalization is not needed. I'd rather make an anchor out of one solid cam than two iffy cams with any method of tying them together. 

But the length of the material in the parts of the anchor being static or dynamic probably doesn't make much difference. Earlier I wrote:

But again this was an extreme example. If a leader takes a FF2 on a dynamic rope I "think" from what I remember it decreases the force by 60%. And the 380% is for a very wide angle probably no one would be dumb enough to use. But you shouldn't be falling on an anchor. The biggest forces would come from a leader on the next pitch falling and ripping out their first piece and coming onto the belayer/anchor. In that case there should be fair amount of the lead rope out, that's what's reducing the force. Not the 2 feet of material between the belayer and the anchor points that should already be tight and not have any slack in it to allow the belayer to "fall". I agree that all things being equal it's a better for force reduction to use dynamic rope in the anchor than static slings, but it's such a small real world difference for that application it doesn't matter to me, and as I mentioned by tether is always dynamic anyway, and is a single rope, so that's going to reduce the force more than two strands of rope in an anchor.

Ok, now we are finding common ground rather than outright rejection of something perfectly safe for what I stated was it's purpose: Belaying a second from closely spaced bolts or fixing a rope from those same close bolts.

I'm well aware of other options as I even posted another picture of one example. The point was that given two closely spaced bolts fixing the rope or belaying a second can have virtually any quick and dirty solution if it suits you and be perfectly safe. The worries about the "ADT" have been debunked to my satisfaction for my conservative purposes, decide whatever you choose my friend. :)

Otherwise, (anyone) tell me what is wrong with this picture beliow? The horrid "ADT" is not putting remotely significantly more pressure on the anchor points and you need extreme angles (ie kyle's straw man example) to do so (and I personally would not use it for that purpose):

Seems perfectly safe to me. Super good enough for fixing a rope or belaying a second where the forces are similar to this diagram. Remember, the anchor will fail at 25-30kn. This is more than a 10 fold safety margin.

We can also debate whether the standard sling with master point is any better or not, given that it never equalizes, puts 100% of the load on one piece and a master point may be questionably redundant if the sling were to fail (ie failure at ~50% at the knot can be catastrophic and it nearly always fails there). Lastly the placements of whatever type will have variable direction forces on it inevitably regardless so ultimately, all pieces in the anchor need to be safe in multiple directions and there is no way to get around that, that I know of. Ultimately, it's going to come down to personal comfort level as to what choices we make. I will use my big 8 for fixing lines whenever I deem it suitable for my needs. I don't use slings on bolts, as they are pointless, imo.

Lastly, I think in some old discussion with Jim Titt he stated that testing showed that even a foot or two of dynamic connection to the anchor significantly reduced forces on the anchor ie IF a FF2 and max impact force was applied to the belayer the anchor still had lower forces due to dynamic connection that last few feet. If the entire anchor was built of dynamic materials then the reduction should be even greater of course. 

I'll see if I can bribe Ryan and Bobby to put some dynameter numbers to that assertion. :) 

Ps. 

1. My good friend Kyle Terry pointed out that the sum of the forces WAS greater as I was neglecting the 0.91KN across the top. That means this anchor would be ~130% more force on the bolts or ~100lbs. I was totally wrong to suggest there was no difference at all.

2. The purpose I posted this for was for fixing a rope or belaying a second off of 2 closely spaces bolts which would break at 6000lbs force. This method is "super good enough" for that.

3. An extra 100lbs ie 350lbs v 250lbs on a 6000lb anchor? I am not remotely concerned about that nor should anyone be. There literally is at least a ~10x safety factor.

4. Extension? This anchor (if one of the anchor points failed) would extend by 2 feet tops. Again, no one should care that this would hurt anything or anyone or that would remotely ever happen. A little pantie soilage is the worst that would occur.

5. If you are belaying a leader, then tether or anchor with dynamic rope. Anything else puts dramatically higher forces on your anchor and makes these concerns about miniscule increases in forces by some well-meaning types about this narrow case as to be ridiculous.

Peter Bealwrote:

"Ideally you clove both corners."

But then you aren't using an ADT.  

Instead you have a very safe equalized redundant anchor, especially if you can pull enough slack down in the middle to create a masterpoint between the cloved anchors.

Never forget, Peter, that your "master" point does not equalize forces and inevitably focuses the energy on one piece. Particularly as your angle to the climber is never set up perfectly and often changes during their climb. Virtually no one builds it perfectly for forces when catching a second, and essentially never for the leader except by luck.

If you really wanted to share load then the clove method and a sliding anchor point is better (at the risk of extension if one piece fails). But then "shock loading" is minimal at most as testing has shown us.

Maybe tie a quad out of those new dynamic slings the manufacturers are making these days. I bet the ice climbing boys would be interested. Nuts.

You guys need to get a life....

Nick Goldsmithwrote:

You guys need to get a life....

This sort of stuff is a bookmark to that life.

Nah,, go climb a fucking cliff

and don't stress over weather or not the gear is perfect... get the best gear you can and don't fall ;)

How'd this all turn out BTW? Was hillbilly Tut right about everything? Did he get a red hat saying as much? 

Brandon Rwrote:

How'd this all turn out BTW? Was hillbilly Tut right about everything? Did he get a red hat saying as much? 

We seemed to agree it was a kerfuffle about nothing for fixing a rope or belaying a second, but it's not everyone's cup of java. 

On the other hand, I did find this though:

Which is for Beal's dynamic 120cm sling. So, the benefits of even short lengths of dynamic cord seem pretty worthy with quite substantial reductions in peak forces. However, these seem to be drops straight onto the anchor (given the super high loads for static materials).

I'm hoping to get some actual testing done to confirm that in close to real world tests it's actually worth it or not.