Catching high fall factor falls - back up knot(s)?

In a couple recent threads on belaying ( mountainproject.com/v/not-a…) and belay devices ( mountainproject.com/v/alpin…) there has been repeated comments, especially from rgold, but also from others about the difficulty of catching high-fall factor falls on a traditional tube device (e.g. an ATC), or even a more recent (nominally) higher-friction device such as an ATC-XP or ATC-Guide.

So, if you have chosen to use such a device for belaying a multi-pitch climb (cost, weight, usability as a rappel device, or other such reasons), might the choice of tying one or more backup knots below the belay device help with this? They would limit how far the leader could fall, should the belayer lose control of the brake strand in a high-fall factor fall. Of course, the clearest disadvantage I see would be the belayer needing to untie the knot (or knots) as they approach the belay device.

Without knowledge of the exact length of the upcoming pitch, the risk of having to untie the knot while the leader is cruxing out or something similar seems like it would negate the value of this. The tying and untying certainly decreases your ability to give an attentive belay as well.

I think it's something to be ready for with your belay skills, and to keep in mind when building belays by setting a piece to protect the belayer against an inevitable upward pull to prevent a hand being jammed in the first piece or slammed into the wall.

I think the hassle/difficulty/complexity/potential danger of untying a knot while trying to pay out slack to a leader makes this a bad idea.

If weight is the primary concern, what about the mammut alpine smart? Semi-auto-locking, same-ish weight as an ATC.

High impact falls do get caught on tube style devices. Typically the issue isn't the device & rope diameter mis-match, but whether the belayer was wearing gloves at the time. Not to take away from the valid point that if you go with a smaller diameter rope and keep the same tube device/out of spec, you lose some ability of rope control.

At some point, you are in area where falling isn't an option if we are talking about this situation. To go back and scrutinize the equipment, which belayers have used with success, seems like splitting hairs to me. Adding back-up knots is just going to make the situation worse.

High fall-factor falls definitely get caught on tube-style devices; I caught one (around FF 1.8) a few years ago with a Reverso on a single 8.5mm strand. The problem is that there are a very large number of variables, and the tubes are probably not up to the worst-case scenarios for most belayers. Certainly belaying without gloves increases the chances of belayer injury and loss of control.

All that said, I think stopper knots would be a nightmare and might damage the rope.

Taking another tack, I'm not at all sure that the climbing community (at least in the US, where research $$$ are almost nonexistent) has paid enough (or any) attention to techniques that might help with big falls.

For example, we have known for many years that the first thing that happens in a big fall, before the rope slips through the belayer's hand, is that the hand gets pulled to the device. I think we should be using this so-called inertial stage for all it is worth. The belayer should begin the catch (if they have any warning) with their hand as far away from the device as possible, meaning straight back as if doing a dumbell kickback. This gives about two feet of brake strand that can be pulled through the device with the belayer resisting, absorbing some fall energy before the hand gets to the device and slippage through the hand is the only option if the load is still too high.

Almost all the belayers I see have their brake hand inches from the device, so they've forfeited almost all the energy-absorbing potential of the inertial phase. How much does this matter? I don't know, but it seems worth some testing to see if the loads can really be reduced this way.

A second thing is role of the non-braking hand. With current technique, not only does it contribute almost nothing to the fall arrest, but it is also at a even greater risk for rope burns than the brake hand. It seems to me that in a high-impact situation, you'd want to get both hands on the brake strand. We don't seem to have any good protocols for this at the moment.

David Gibbs wrote:In a couple recent threads on belaying ( mountainproject.com/v/not-a…) and belay devices ( mountainproject.com/v/alpin…) there has been repeated comments, especially from rgold, but also from others about the difficulty of catching high-fall factor falls on a traditional tube device (e.g. an ATC), or even a more recent (nominally) higher-friction device such as an ATC-XP or ATC-Guide. So, if you have chosen to use such a device for belaying a multi-pitch climb (cost, weight, usability as a rappel device, or other such reasons), might the choice of tying one or more backup knots below the belay device help with this? They would limit how far the leader could fall, should the belayer lose control of the brake strand in a high-fall factor fall. Of course, the clearest disadvantage I see would be the belayer needing to untie the knot (or knots) as they approach the belay device.

You must be joking, right??? Please tell me you are joking. Could you imagine the nightmare it would be to untie and retie stopper knots while belaying someone?? This is probably the worst idea I have heard for a problem that isn't really a problem. And that my friend is saying something for MP. I learned a trade secret long ago for catching big falls. It's really easy if you just man up......... and wear some fucking belay gloves!!

OMG talking about big whips and not being able to catch them without gloves on is a mtn proj classic. of course it is mid winter...

carry on.

A large part of a climber's ability to hold a large whipper involves the fall distance. A fall factor 1.75 10-foot fall has less energy involved than a fall factor 1.5 30-foot fall, and the 30-foot fall would be harder to catch. You can catch high-fall-factor falls with a tube belay device if the fall distance is short. But if you try to catch a high fall factor fall with a large fall distance, the energy involved in the fall starts to become a concern for traditional belay devices. Your best direct defense would be to wear full fingered gloves, and ask the leader to climb in a manner as to limit the fall distance as much as possible (e.g. place lots of pro).

For what it is worth, I caught a 40' FF 1.7ish fall on the WFLT, but I was using a Cinch. The experience was pretty rough, and it would have not been fun to do with an ATC.

MJMobes wrote:OMG talking about big whips and not being able to catch them without gloves on is a mtn proj classic. of course it is mid winter... carry on.

Ok, but only since you suggested it. If you haven't gotten burns, it is because you haven't had to catch a really severe fall, which in fact extremely few people have to do. "Really severe" means more than the fall height and/or fall factor. Some climbers don't realize is the critical role of rope against rock and carabiner friction, which mitigates what the belayer has to hold. It isn't just about the whipper, its about the whole configuration of rock, rope and protection involved. It is a rare situation when the rope path is straight and there is no rock friction, but not an impossible one. When all that extra friction is gone, remember that if you clamp down so that there is only 1/4 second of slippage, you'll still have 4 feet of rope go through your hand. You can pull four feet of rope fast through your hand with the other hand and get a burn, no leader fall required.

So yeah, I know all about climbing N years and never getting burned. I'll see most people their N years and raise them quite a few, double many of the posters here. I never got burned either. But if the rope never slipped, all it means that none of the falls caught transmitted much more than about 600 lbs to the belay, because most climbers grip strength does not exceed 120 lbs and most belay devices don't multiply this by more than about five.

If and when (and I hope it never happens) you get an impact above 1000 lbf, there will be rope slippage through the belay. This has been tested and demonstrated over and over again by the Italian Alpine Club Materials Section and they have high-speed video to prove it.

In addition to friction in the system that prevents high loads from reaching the belayer, there are other variables, such as rope type, treatement, diameter, and condtion and belay device type. Not all belay devices are the same in terms of their force multiplication value.

And grip strength itself is a variable. It is quite variable in the general population; presumably climbers are, at least after years of climbing, at the upper end. But that doesn't mean there aren't substantial differences. Light people can perform on climbs at the same level as much heavier people even though the lightweights have much lower grip strength. But the lower grip strength will show up in the belay context, which is absolute rather than relative.

Another variable with tube-style devices is braking angle. Sometimes the belayer is in an awkward position, and sometimes they have adopted a comfortable position, say seated, that makes it impossible to get the standard 137 degree braking angle. In that case, they will be getting less friction from their device than they may be used to.

I have caught a factor-2 fall, but it was with a hip belay and an 11mm rope, a combination that might have provided more friction than we currently get with most belay devices, which are designed and purchased more because of their rope-handling characteristics than their force-multiplying factors. I've also caught a factor 1.8 fall on an 8.5mm rope with a modern Reverso (not the original version, which had one of the lowest force multiplication factors ever). I didn't get burned on either of these, but I had gloves on for both.

Because I learned to climb in the Pleistocene era, I have caught scores of falls in the UIAA test range with the rope running through a single biner and no other sources of friction. Of course, a weight was used for these belay tests, making them more severe than a corresponding human-body event for the same weight. Still, anyone who has had this experience would never assert that all falls can be stopped without rope slippage.

Modern day tube-type devices cannot stop severe low-friction falls without slippage and indeed include that fact as part of their advantages. This is why Grigris produce higher loads than tubes---the rope slips in tubes. So I wear gloves when belaying with tubes. I know the probability of needing their protection is very low, and that many climbers have full careers without ever getting hand burns. But I dislike the idea of being unprepared for possible scenarios that occur in principle on virtually every climb, scenarios that would result in in rope running. Burns are bad enough and may be far more than a minor first-aid event, but the potential for losing control of the belay is even worse.

I've climbed for the same N years (N=56 in my case) without ever getting hit by a rock. But now that hard hats don't weigh a ton, I wear one, as do many others. The reasoning is that the probability is very low but the consequences of a head injury are very high. Belay gloves are in exactly the same category: you may never need them, but if you do and don't have them, the consequences may be severe indeed (e.g. 1 month for new skin to form, and one year for hand to fully heal, and whatever damage you may have done the person who trusted you to belay).

Untieing -- yes could be awkward. Hopefully the belayer will have enough communication with the climber that this can be done at a point where the climber isn't in the middle of a hard move. And, again, if a crux section is approaching, hopefully the belayer can have any knot untied before that section is entered.

Rope damage -- sure it could happen. But I'd rather have my rope damaged, and catch that fall then not catch the fall.

Using gloves will prevent or reduce rope-burn for the belayer. But, I don't think they will do much to increase the grip-strength the belayer can provide, and may (in fact) slightly reduce the grip strength. (A glove thick enough to provide good protection may be thick enough to be stiff enough to resist closing force from the hand, and so reduce closing force.)

A backup knot also deals with belayer hit by rock factor the way an auto-blocking device does.

rgold wrote: It is a rare situation when the rope path is straight and there is no rock friction, but not an impossible one.

I would argue that is the most likely scenario for catching a high fall-factor fall. These types of falls typically occur shortly after exiting the belay station, with little to no pro in (thus minimal drag), with little rope out, and frequently on steep (and difficult) terrain. In my experience, the times my partner or I were closest to taking a serious fall were on climbs that were very steep and very hard right out of the belay, and the climber was directly overhead, usually with a single bolt for pro, or two bomber cams right next to each other.

Probably so, but climbers, to their credit, don't fall much in those circumstances and so belayers and their devices are very rarely tested.

Meanwhile many of the "whippers" people talk about catching with no slippage have plenty of rock and rope friction to help the belayer, even if the fall itself is pretty big.

Finally, there can be considerable friction help even on factor-two falls, for example if the rope bends over the edge of the belay stance as the leader falls past it.

1. In general knots would be just too difficult to do and untie I think without introducing inattention. Although one knot a long way down the rope might be used to protect one hard high FF move. I have done this a couple of times.
2. I have thought for a long time that it might be possible to invent some kind of ball/spring/something that is on the rope and can slide but would get trapped in a belay device if someone let go. But it might introduce other dangers.
3. as rgold points out, most high FF falls are not so high because of friction etc. so on modest routes this is less of an issue than most people think. To get a high FF it needs to be steep.
4. Possible solutions other than knots are: use a grigri if it steep, or gloves (why aren't these more common? Uncool?), or consider a direct belay on the anchors with a munter just for the steep pitch in question, or use a chariot belay for the pitch (this is where the belayer is parked several metres below the anchors and the anchors used as a piece, so a high FF near the belay cannot happen.

David Coley wrote:4. Possible solutions other than knots are: use a grigri if it steep, or gloves (why aren't these more common? Uncool?), or consider a direct belay on the anchors with a munter just for the steep pitch in question, or use a chariot belay for the pitch (this is where the belayer is parked several metres below the anchors and the anchors used as a piece, so a high FF near the belay cannot happen.

I am going to have to disagree with you on the gri gri. Unless on sport, I will not use a gri gri.
The reason Why: geir.com/mythbuster.html . Go down to number 7 on his myth list. Basically It states that because gri gris lock up automatically they put more force on the ropes than a tube style device. Minimal, Yes. Arbitrary, maybe, but hey we are talking a bout high FF falls, and that could possibly be the difference in gear pulling out.
Just my thoughts.

Matty H wrote: . Arbitrary, maybe, but hey we are talking a bout high FF falls, and that could possibly be the difference in gear pulling out.

Except this thread is about belay control loss from catching a high FF on an ATC, which is far worse than ripping gear. I would rather take a fall being belayed on a GriGri knowing the gear might rip and I might FF2 as opposed to falling with the possibility that my partner is going to melt his hand and drop me the full 60m of the rope. It has happened before. There is a video on here of some guy being dropped the entire length of his rope (although not from taking a high fall factor fall).

This just popped into my head and I don't know if it would work, but what about using a prusik or another friction hitch above the tube-style ATC while belaying? You could keep it loosened with your upper hand while letting out or taking in slack, but it would catch the rope in the case of the belayer getting hit by a rock or letting the rope slip due to a high FF fall.

For some configurations I think it's a lot more than 5. For example an ATC-XP in high friction mode with a 10.5mm rope. When doing a long rap with this configuration I don't even move at the top unless I lift up on the ropes with my brake hand to reduce the force just from the weight of the rope.

rgold wrote: But if the rope never slipped, all it means that none of the falls caught transmitted much more than about 600 lbs to the belay, because most climbers grip strength does not exceed 120 lbs and most belay devices don't multiply this by more than about five.

20 kN wrote:A large part of a climber's ability to hold a large whipper involves the fall distance. A fall factor 1.75 10-foot fall has less energy involved than a fall factor 1.5 30-foot fall, and the 30-foot fall would be harder to catch.

Really? Physics and math are definitely not my forte at all, and that does make sense intuitively, but I thought that the impact force of the fall depends entirely on the fall factor? Or am I confusing two separate concepts?

Emil Briggs wrote:For some configurations I think it's a lot more than 5. For example an ATC-XP in high friction mode with a 10.5mm rope. When doing a long rap with this configuration I don't even move at the top unless I lift up on the ropes with my brake hand to reduce the force just from the weight of the rope.

Yes, my mistake. The old Reverso had a force multiplication of 5. The ATC-XP has a force multiplication factor of 11 for a 9.7mm rope, so even higher for a 10.3. These results from Manin et al., Rock climbing belay device analysis, experiments and modelling, Engineering of Sport 6, pp. 69-74, 2006. The force multiplication factor may not fully explain not moving on rappel, because of the difference between sliding and static friction.

A multiplication factor of 11 gives the climber with the 120lb grip the ability to hold nearly 6 Kn, much better than what I said above but still not enough for a FF 2 fall and probably not enough for a UIAA test type fall through a protection point.

tie all the knots you want, but for the love of Gawd don't use an assisted braking device like a Gri Gri or Smart. Your leader WILL die!

assquack wrote:This just popped into my head and I don't know if it would work, but what about using a prusik or another friction hitch above the tube-style ATC while belaying? You could keep it loosened with your upper hand while letting out or taking in slack, but it would catch the rope in the case of the belayer getting hit by a rock or letting the rope slip due to a high FF fall.

I'd thought about this before as well assquack. It should work in theory with minimal clusterfuckedness.
I'm curious if anyone's tried this method? Similar to using a prusik back-up for rapelling I would imagine.