New study shows anchor belay having lower force than harness belay in high energy falls

Saw this video today, and according to it, the ENSA (French mountain guide school) study found that putting the belay directly on the anchor generates the lowest force, presumably lower than if one were to belay off their harness. The video only talks about FF 0.3 falls but I would think they would do more thorough testing than only FF 0.3 falls if they were going to publish a conclusion that goes against conventional wisdom, but I don't know for sure as I couldn't decipher the full report which is in french.

This conclusion doesn't really make sense to me so I'm wondering if any physicists or engineers might be able to weigh in and clarify my understanding of the physics involved in this type of scenario.

In the ENSA gym tests, the lowest forces were with the anchor on the wall (Munter hitch used) and - importantly - the belayer let some rope run through the hitch as they caught the fall i.e. an old school dynamic catch.

Another explanation (that wasn't apparent to me until the final outdoor scene): when a Munter hitch on the anchor is loaded upwards i.e. catching a leader fall, if the belayer's hand holds the brake strand downward (as he did), this puts the Munter in a "low friction mode". The Munter is capable of generating at least as much braking force as an ATC (some say even more than an ATC), but only when the brake strand is held parallel and along the load strand. The catch demonstrated doesn't do this, hence the soft catch using this setup.

I don't know that I've ever seen anyone in the US belay with a Munter directly on the anchor; this video makes a good argument for doing so.

Gunkiemike wrote:

In the ENSA gym tests, the lowest forces were with the anchor on the wall (Munter hitch used) and - importantly - the belayer let some rope run through the hitch as they caught the fall i.e. an old school dynamic catch.

Another explanation (that wasn't apparent to me until the final outdoor scene): when a Munter hitch on the anchor is loaded upwards i.e. catching a leader fall, if the belayer's hand holds the brake strand downward (as he did), this puts the Munter in a "low friction mode". The Munter is capable of generating at least as much braking force as an ATC (some say even more than an ATC), but only when the brake strand is held parallel and along the load strand. The catch demonstrated doesn't do this, hence the soft catch using this setup.

I don't know that I've ever seen anyone in the US belay with a Munter directly on the anchor; this video makes a good argument for doing so.

I caught the "belayer let rope run through the device" comment, but most climbers nowadays wouldn't be able to do that without burning their hands, if at all. So I'm a bit confused why they make the claim that the anchor belay is the best option or even the lowest force option.

I think the deal with the high impact force on the belay with the belayer in the system is that the belayer was connected to the load cell with directly to his harness.  That is a very static connection.  So the belayer got accelerated upwards by the force of the falling climber, then stopped immediately thus causing a high load.  This is analogous to falling on the belay with a PAS or similar static material.  I think Jim Titt said that the acceleration imparted onto the belayer could be something like 4 Gs; possibly in a different situation.  That high of a acceleration could certainly cause a high load on the belay when the belay is stopped in a very short distance.

With the off the anchor belay there is no acceleration of the belayer's mass and so the load is limited by the rope. 

Gunkiemike wrote:

In the ENSA gym tests, the lowest forces were with the anchor on the wall (Munter hitch used) and - importantly - the belayer let some rope run through the hitch as they caught the fall i.e. an old school dynamic catch.

Another explanation (that wasn't apparent to me until the final outdoor scene): when a Munter hitch on the anchor is loaded upwards i.e. catching a leader fall, if the belayer's hand holds the brake strand downward (as he did), this puts the Munter in a "low friction mode". The Munter is capable of generating at least as much braking force as an ATC (some say even more than an ATC), but only when the brake strand is held parallel and along the load strand. The catch demonstrated doesn't do this, hence the soft catch using this setup.

I don't know that I've ever seen anyone in the US belay with a Munter directly on the anchor; this video makes a good argument for doing so.

The strands parallel with the Italian Hitch hasn´t been taught for many years, it´s strands opposed to make the belayers action the same as with an ATC or whatever. There isn´t really that much difference in the force generated, I´ve some test figures somewhere and it´s not as much as one was led to believe.

I tested with the brake strand in the opposed position and the DAV as well, which the French used I don´t know but it always gives more braking power than a conventional plate and especially so with thinner ropes.

eli poss wrote:

I caught the "belayer let rope run through the device" comment, but most climbers nowadays wouldn't be able to do that without burning their hands, if at all. So I'm a bit confused why they make the claim that the anchor belay is the best option or even the lowest force option.

The belayer was wearing gloves as recommended by most rope/belay device manufacturers and thus able to give a dynamic (sliding) belay.

climber pat wrote:

I think the deal with the high impact force on the belay with the belayer in the system is that the belayer was connected to the load cell with directly to his harness.  That is a very static connection.  So the belayer got accelerated upwards by the force of the falling climber, then stopped immediately thus causing a high load.  This is analogous to falling on the belay with a PAS or similar static material.  I think Jim Titt said that the acceleration imparted onto the belayer could be something like 4 Gs; possibly in a different situation.  That high of a acceleration could certainly cause a high load on the belay when the belay is stopped in a very short distance.

With the off the anchor belay there is no acceleration of the belayer's mass and so the load is limited by the rope. 

Well the acceleration is just a function of the belayers weight and the braking force they can generate. With the conventional belay set-up the belayer can try to give a dynamic belay but is likely to lock down on the plate as they start to lift off then impacts onto the belay with considerable force and this is going to be transmitted up to the runner since the plate is now locked, direct off the belay the belayer is in a better position to control the dynaamic aspect of the belaying.

eli poss wrote:

Saw this video today, and according to it, the ENSA (French mountain guide school) study found that putting the belay directly on the anchor generates the lowest force, presumably lower than if one were to belay off their harness. The video only talks about FF 0.3 falls but I would think they would do more thorough testing than only FF 0.3 falls if they were going to publish a conclusion that goes against conventional wisdom, but I don't know for sure as I couldn't decipher the full report which is in french.

This conclusion doesn't really make sense to me so I'm wondering if any physicists or engineers might be able to weigh in and clarify my understanding of the physics involved in this type of scenario.

The Italian hitch is outdated in favor of a locking device making a anchor direct belay kinda funky. Unless there's a device that would work well directly off the anchor? The belayor would have to be in just the right position in order to feed well.

Looks like another lab experiment that doesn't really translate to the real world very well.

Tradiban wrote:

The Italian hitch is outdated.

huh?
Did the laws of physics change? -- without holding public hearings first!

What's outdated I'd say is the use of the phrase "Italian hitch".

Not sure where the French video got that from. There's a perfectly good French term for it: "demi-cabestan".
. . . (related to the French word "cabestan" for USA "clove hitch").

The usual USA name is "Munter hitch" -- which was short for "that so-useful knot which that visiting Swiss guide Munter showed us".

And a nice German word "halbmastwurf", and another (overly long?) one for the belay method used as recently as last year by my German physicist partner when I visited -- "halbmastwurfsicherung" -- so it has an abbreviation I thought was "HMS".

Guess I haven't checked recently enough, but think there are respected climbing-equipment manufacturers who sell an "HMS karabiner". Like here's a web search for
. . . Black Diamond HMS carabiner 

? Time for them to start educating their customers ?

Ken

P.S. I'll guess the French video used the translation words "Italian" and also "Eastern Alps" to avoid the mentioning explicitly that the two practices investigated in the video are favored by some German climbers, and not to raise the question of why the video was not mentioning previous research on this done by German engineers.

Well, somehow in forty-three years of hip belaying and belaying of the harness catching endless falls and lots of hard falls, what's described and shown in the video has never been my experience or the experience of any my partners that I know of. Maybe physics work differently in the EU or we're just too damn good as belayers - nah, that ain't it.

Well quite. The guy who gets slammed into the wall is clearly standing way too far left and not tight to the anchor so it's hardly surprising 

I think this only works with anchors composed of omni-directional pieces like bolts or pitons.  If you have trad anchor with one or more nuts in constrictions, I feel like you'd need to place a fourth piece in many contexts to control the upward pull.  But then you have the equalization problem - if the sling flips up in a fall, and you have a four piece anchor, I don't think a sliding x or similar would equalize quickly enough.  If that's the case, this setup would rely on that single piece placed for an upward pull.  

kenr wrote:

huh?
Did the laws of physics change? -- without holding public hearings first!

What's outdated I'd say is the use of the phrase "Italian hitch".

Not sure where the French video got that from. There's a perfectly good French term for it: "demi-cabestan".
. . . (related to the French word "cabestan" for USA "clove hitch").

The usual USA name is "Munter hitch" -- which was short for "that so-useful knot which that visiting Swiss guide Munter showed us".

And a nice German word "halbmastwurf", and another (overly long?) one for the belay method used as recently as last year by my German physicist partner when I visited -- "halbmastwurfsicherung" -- so it has an abbreviation I thought was "HMS".

Guess I haven't checked recently enough, but think there are respected climbing-equipment manufacturers who sell an "HMS karabiner". Like here's a web search for
. . . Black Diamond HMS carabiner 

? Time for them to start educating their customers ?

Ken

P.S. I'll guess the French video used the translation words "Italian" and also "Eastern Alps" to avoid the mentioning explicitly that the two practices investigated in the video are favored by some German climbers, and not to raise the question of why the video was not mentioning previous research on this done by German engineers.

The munter still works but there's actual belay devices now that obvious provide a better belay.

kenr wrote:

huh?
Did the laws of physics change? -- without holding public hearings first!

What's outdated I'd say is the use of the phrase "Italian hitch".

Not sure where the French video got that from. There's a perfectly good French term for it: "demi-cabestan".
. . . (related to the French word "cabestan" for USA "clove hitch").

The usual USA name is "Munter hitch" -- which was short for "that so-useful knot which that visiting Swiss guide Munter showed us".

And a nice German word "halbmastwurf", and another (overly long?) one for the belay method used as recently as last year by my German physicist partner when I visited -- "halbmastwurfsicherung" -- so it has an abbreviation I thought was "HMS".

Guess I haven't checked recently enough, but think there are respected climbing-equipment manufacturers who sell an "HMS karabiner". Like here's a web search for
. . . Black Diamond HMS carabiner 

? Time for them to start educating their customers ?

Ken

P.S. I'll guess the French video used the translation words "Italian" and also "Eastern Alps" to avoid the mentioning explicitly that the two practices investigated in the video are favored by some German climbers, and not to raise the question of why the video was not mentioning previous research on this done by German engineers.

Originally it was called the "Mezzo Barcaiolo" (which is the Italian equivalent of halbmastwurf) and introduced by a guy called Mario Bisaccia who developed the karabiner required. The UIAA tried to claim it as their own and originally proposed "UIAA Hitch" but this got shouted down and Italian Hitch was generally agreed with. The actual Munter Hitch was an appalling idea, so much so that after Werner Munter had recovered from the injuries sustained demonstrating his idea he widely promoted the Italian Hitch. Werner Munter is still alive and fairly recently retired from being a leading the Swiss avalanche researcher.

Thanks for the history.
I once studied the "Munter method" for avalanche hazard, and wrote an analysis / critique. The reasoning that led him to the method was more influential for my own future practice, since his approach was very different from what was being taught in USA back around 1990. I think most smart people I know who (as I still do) ski lots in avalanche terrain, follow more his approach (but without his numerical calculation).

Then I also used to the HMS lots for climbing -- in USA it was then as now called "the Munter hitch" -- Never any awareness in USA of some "Italian" origin.

But never occurred to me that it was the same Munter person.

I think I'm one of the minority of USA climbers who knew that a person named "Munter" did not invent the knot, and that "Munter hitch" was not the standard term internationally.

Even funnier to learn that Munter himself originally proposed a different knot -- which didn't work.

Guess it shows that sometimes _caring_ about the problem and a new solution approach is what matters. Like I never used his avalanche calculation formula, but his caring about the new paradigm changed my ski mountaineering.

Ken

I rank belaying with a munter right up there with dulfersitz rappelling - did it once, thought it completely sucked and never did it again.

I did a modified Dulfersitz rappel just in April.
Didn't much like it, but it was a good choice for the great route we did. Hope to do the route again, and will plan to do the use the Dulfersitz again (perhaps on other routes now too).

Munter hitch? In addition to my German physicist partner using halbmastwurf HMS / Munter to belay me, I've used it to belay Sharon in the last two years (and expect to do it again).

Funny that a key reason I do not use the HMS / Munter hitch much for belaying any more is because of rappeling -- I find it usually twists the rope when rappelling. So if I know I'm going to do more than one rappel/abseil on a day out, I bring a rappel device -- and then I might as well use it for belaying also.

When I did my tests of rappelling on a super-thin rope (and posted the results on MP), I did test HMS / Munter (both double-strand and single-strand) in addition to mechanical devices.

At the very least, it's smart to learn and practice HMS / Munter hitch just in case drop your belay/rappel device.
. . . (I once met someone who routinely climbed multi-pitch carrying the weight of a second rappel device, just in case they dropped one).

Ken

kenr wrote: Thanks for the history. I once studied the "Munter method" for avalanche hazard, and wrote an analysis / critique. The reasoning that led him to the method was more influential for my own future practice, since his approach was very different from what was being taught in USA back around 1990. I think most smart people I know who (as I still do) ski lots in avalanche terrain, follow more his approach (but without his numerical calculation). Then I also used to the HMS lots for climbing -- in USA it was then as now called "the Munter hitch" -- Never any awareness in USA of some "Italian" origin. But never occurred to me that it was the same Munter person. I think I'm one of the minority of USA climbers who knew that a person named "Munter" did not invent the knot, and that "Munter hitch" was not the standard term internationally. Even funnier to learn that Munter himself originally proposed a different knot -- which didn't work. Guess it shows that sometimes _caring_ about the problem and a new solution approach is what matters. Like I never used his avalanche calculation formula, but his caring about the new paradigm changed my ski mountaineering. Ken

Here´s a link to an e-book where it´s described as the UIAA Belay Method.

While it doesn´t go ito the gory details it is correct when the write "This principle of belaying involves the use of the braking action of the Munter hitch on the body of the carabiner" as the "original" involved tying the hitch around ones body, more exactly the leaders rope going over the shoulder, down behind the back and the half-hitch being formed around the chest. You can easily viualise the consequences of a hard fall!

There´s a photo of it somewhere but I can´t remember exactly  where it was, there was a long article on the history of Italian Hitch in one of the German publications some time ago.

kenr wrote:

At the very least, it's smart to learn and practice HMS / Munter hitch just in case drop your belay/rappel device.

Did a couple of climbs Saturday and somehow managed to leave my ATC in the car between climbs. Ended up hip belaying with a single non-locking biner for five pitches - so much better than the whole HMS/Munter nastiness.

eli poss wrote:

the ENSA (French mountain guide school) study found that putting the belay directly on the anchor generates the lowest force . . .

The main problem I have with applying this video is _not_ the concern about using the "out of date" Munter hitch.

. . . (If only someone had told them, then that ENSA team could have known to switch to a current device).
. . . (Hopefully they've learned better for their next research: Ask on MountainProject Forum first).

. . . (Perhaps they found this 2017 book, and made the mistake of trusting that as not out-of-date).

rather ... seems like in my climbing I'm almost never in a situation any more where minimizing the impact force on the anchor _matters_.

Ken

kenr wrote:

The main problem I have with applying this video is _not_ the concern about using the "out of date" Munter hitch.

. . . (If only someone had told them, then that ENSA team could have known to switch to a current device).
. . . (Hopefully they've learned better for their next research: Ask on MountainProject Forum first).

. . . (Perhaps they found this 2017 book, and made the mistake of trusting that as not out-of-date).

Seems like in my climbing I'm almost never in a situation any more where minimizing the impact force on the anchor _matters_.

Ken

Clearly you've never climbed on choss. Why don't you do some climbing in the san jauns. And secondly, while yes your anchor should be bomber enough anyways, I don't see a reason why not to try to reduce the impact force on the anchor, provided it isn't super cumbersome or time consuming.