Critique my rappel extension

Ricky Harlinewrote:

The best solution would be for everyone to buy a Smart Alpine, but Mammut apparently thought it would be fun to tease us with the finest rappelling device known to man and then discontinue it. 

But anyway, the extended rappel is hardly any more work and is slightly safer than the third hand through the leg loop method. I know multiple people who accidentally let go while they were rappelling (in each case they bumped their elbows hard which they say caused an involuntary opening of their hand on the brake strands) and only avoided accidents because of the third hand. Using some form of a third hand if you use a non auto locking rappel device is now taught as standard operating procedure from every climbing educator that I know of, and the rappel extension is taught alongside it because it is safer than the leg loop method and significantly more convenient and enjoyable to use during rappel as well. 

Ricky you gotta try the alpine up… I’ll let you give mine a test drive this fall!

Wren Cooperriderwrote:

For the people taking the stance that going without a third hand is dangerous... here are my thoughts about it:

• Rigging the rap is slower and so is actually rapping- I often climb in a party of 3 so this is compounded here, and especially if you have many raps or one climber is particularly slow at doing their third hand, they can just not be first and not use one. Spending hours getting down a rap route can be dangerous too...

Tie an alpine butterfly on a locker on a bolt, first two go down on Grigris, third undoes butterfly and comes down using third hand or fireman's belay as they prefer. You should be able to rap in a party of 3 <10% slower for sure with this method. 

Jared: don't know much about it. Stoked to try it out for sure!

Wren Cooperriderwrote:

For the people taking the stance that going without a third hand is dangerous... here are my thoughts about it:

• Rigging the rap is slower and so is actually rapping- I often climb in a party of 3 so this is compounded here, and especially if you have many raps or one climber is particularly slow at doing their third hand, they can just not be first and not use one. Spending hours getting down a rap route can be dangerous too...
• It is more difficult to rescue a person if they somehow get stuck partway down (yes, unlikely to happen but worth considering if you tend to take inexperienced climbers with you)
• Unless you're the first person down, someone can give you a fireman's which is just as safe, simpler, and generally faster

I'm pro-extension though since I also like to pre-rig my raps.

I rapped for 10 years without a third hand and still do it on occasion (e.g. I'm rapping a TR I just setup with no chance of rockfall). So I don't think of it as dangerous, just not as safe as a method with a backup. I think of it as 1. insurance (rockfall, wasps nest, slamming against the wall and 2. convenience, if the rope is hung up or tangled it's way easier to deal with with a third hand. I agree with using a fireman's and often use that after the first person down, especially with novices. But I don't know if using a third hand is any slower. 1. you can rig the third hand first when getting ready to rap (I use an autoblock which is super quick) then pull up slack and put on the belay device easily, so you're never having to rig something while the whole weight of 2 ropes is pulling down. 2. with an autoblock I can rap as fast as I want and generally limit my speed to keep the ATC from getting too hot, so I go the same speed with or without the third hand. Also with a third hand it's easier to rig up a way to ascend back up the ropes while you're hanging if needed. I've done 15 raps with a partner in 2 hours with third hand raps, so 4 minutes each per rap.

Shane Fwrote:

I think that a point of clarification is needed in a lot of the center of mass commentary. None of you are thinking in the correct reference frame. With respect to the ground when one is standing, the location of the rappel device is meaningless. However, when you are on rappel, the device is the reference point. Think about a free hanging rappel, all the forces are going through the device and up the rope. In this scenario, extending the rappel device will increase the distance between the device and your bodies center of mass. This increase in distance will make it so that your body will hang directly below the device in a more comfortable manner. Both extended and off the belay loop are fine in most situations. Learn what the odd situations are, like having a heavy pack, and learn to mitigate against their pitfalls, like extending your rappel or tethering the pack below you.

The rappel device is not the reference point but the focal point. When it comes to a person's center of mass and rotation there are two critical points, the pivot point (belay loop), and the focal point (belay device). 

The distance between the belay loop and rappel device is moot when as it pertains to a person's center of mass and rotation. That is because regardless of distance the pivot point (belay loop) does not change. 

What changes with the distance between the belay loop and rappel device is the focal point. Extending the rappel device moves the focal point away from the pivot point and perhaps above one's center of mass. Doing so makes it easier to control the rotation about the pivot point. Especially because one can have two hands on the rope.

An example, if one sits on a swing, holds on to the rope where it connects to the seat, and leans back it is easy to flip backwards. If one sits on a swing, holds on to the rope a chest level, and leans back, the ability to flip backwards is greatly reduced. If one sits on a swing, holds on to the rope above their head, and leans back, if is difficult to flip backwards. That is the affect of moving the focal point above one's center of mass. 

I like extending for multiple rappels. Especially in alpine settings. Keeps the device away from my jacket. The device being higher gives me more room to hold the rope and provides more space between the third hand and the device. 

I always use a third hand for rappelling first on less than vertical terrain. Often the ropes don't toss clean and you have to straighten them out or get them unstuck. It's great to just be able to let go without having to wrap the rope around your thigh.

Second can forgo the extension and third hand if they want. Fireman's is an option. Discuss with your partner beforehand. But it's easier in my mind if both people use them. 

I think the extension and third hand save time in the end. 

Eric Craig wrote:

Treating your climbing guests like cattle is downright shitty guiding. One way or another.  Except maybe in a real emergency.  And that too, is likely the result of shitty guiding. 

I'm just gonna leave the rest of this discussion alone.

So is getting your client killed. 

Eric Craig wrote:

And what the fuck do you think you know about guiding? 

Quoting before you delete it.

Eric Craig wrote:

I think not. If I get in trouble, oh well. It may be rudely phrased,  but, under the circumstances, it is a legitimate question. 

It really depends on what the clients reason for hiring a guide so, doesn’t it? Some people really want to learn how to climb/plug gear/rappel/rope systems so they can go out and do it themselves. Some people just want to go on an adventure and not worry about the dangerous and confusing parts. Also some people are just plain stupid. I wouldn’t be trusting the latter two groups to set up their own rap without supervision

I’m happy with interesting thread drift and useful discussion but please keep it civil. Completely unnecessary to be a dick. 

Eric Craig wrote:

Treating your climbing guests like cattle is downright shitty guiding. One way or another.  Except maybe in a real emergency.  And that too, is likely the result of shitty guiding. 

I'm just gonna leave the rest of this discussion alone.

I guess I’m a little confused by this position…. Generally the rap setup is supervised by the guide before they rap down. This is to reduce the likelihood that a rap error gets made. Mistakes can get made by anyone and the strategy is adding a “partner check” type step will decrease the chances of an accident.

This doesn’t necessarily mean people are being treated like cattle. I guess it could look like that, but if it feels like that, it’s got more to do with the guide and less to do with the system.

It’s sop in a lot of places because it’s a low cost way to reduce risk. I see how the system could be used in lazy or “shitty” guiding, but that’s really not the intention. 

Bb Cc wrote:

It took about 50 raps before my wife was comfortable using the “3rd Hand” (set up, management, extra kerfuffle). Practicing before need is paramount.

Sometimes I use a VT hitch above the device (ATC), it releases very easily under load. If I need to undo my tangles from a bush I then also tie a catastrophe knot.

I have used a clove hitch on my Petzl Connect as an extension method. This limits the adjustability as a tether.

At the local crag: 3 people, one rope, 2 raps: often send first 1-2 folks down a single fixed strand and then one of us does the 2 raps. Of course, we could just do the walk-off but how would we practice and review effectively?

As for the double-ended-bowlins-on-a-bight tether? I have taught my daughter that an overhand is a very effective knot especially when untie-ing it is not the issue. She asked the name (again), I said it’s called a fkn knot. Simple.

Yup. After all the faffing around the girth hitch overhand tether extension is still the best. Ockhams razor and KISS for the win. I just like experimenting sometimes. I’m no guide but I do occasionally take folks/friends of varying experience levels out, and have found a long locker draw is a great extension, which doesn’t need any knot knowledge, with a girth hitched sling for tether. 

I haven’t seen it mentioned, but if rappelling without a third hand and you need to go hands free to fix the ropes or whatever, you can also use the method grandpa still uses sometimes: wrap the dangling part of the rope around your leg a few times. 

Eric Craig wrote:

I guess I would like to add "center of effort" to "braking angle" and "braking lever arm"  to a list requiring, for me anyway, further explanation. I am at a loss trying to understand an application of these terms to the subject at hand. ??????.

If you still care…(I said I’d come back and post a diagram).

the “center of effort” is just the point at which you are applying your counter-rotational forces (hands and belay device) on the rope that keeps you from flipping upside down due to the difference between the “center of gravity” at the time and the “center of rotation” - your harness tie in point.   In most cases, the CoG is pretty dang close to the CoR, but the longer the distance the CoE is from CoR, the more leverage you have and the easier effort of staying upright.   Same with the braking angles Allen was describing.  

In short, an extension just makes everything easier, but doesn’t change the CoG.  You can change the CoG with body positioning and equipment positioning, but the key is to reduce horizontal distance between CoG and CoR to eliminate rotational moments.  Or give yourself more leverage with higher CoE.

Mark Pilatewrote:

If you still care…(I said I’d come back and post a diagram).

the “center of effort” is just the point at which you are applying your counter-rotational forces (hands and belay device) on the rope that keeps you from flipping upside down due to the difference between the “center of gravity” at the time and the “center of rotation” - your harness tie in point.   In most cases, the CoG is pretty dang close to the CoR, but the longer the distance the CoE is from CoR, the more leverage you have and the easier effort of staying upright.   Same with the braking angles Allen was describing.  

In short, an extension just makes everything easier, but doesn’t change the CoG.  You can change the CoG with body positioning and equipment positioning, but the key is to reduce horizontal distance between CoG and CoR to eliminate rotational moments.  Or give yourself more leverage with higher CoE.

Mark. That’s an awesome diagram, and a fantastic explanation. Thank you so much! This is really really cool. Fascinating to see it actually mapped out rather than just “oh it gets easier when it’s extended” kind of thing.

Mark Pilatewrote:

If you still care…(I said I’d come back and post a diagram).

Mark great diagram and explanation. Much better than mine from last night and why I added the example of swing and holding on to the rope.

Mark Pilatewrote:

If you still care…(I said I’d come back and post a diagram).

the “center of effort” is just the point at which you are applying your counter-rotational forces (hands and belay device) on the rope that keeps you from flipping upside down due to the difference between the “center of gravity” at the time and the “center of rotation” - your harness tie in point.   In most cases, the CoG is pretty dang close to the CoR, but the longer the distance the CoE is from CoR, the more leverage you have and the easier effort of staying upright.   Same with the braking angles Allen was describing.  

In short, an extension just makes everything easier, but doesn’t change the CoG.  You can change the CoG with body positioning and equipment positioning, but the key is to reduce horizontal distance between CoG and CoR to eliminate rotational moments.  Or give yourself more leverage with higher CoE.

This was confusing because you mention lots of things, but don't emphasize that actual difference between the scenarios.

It's all about letting the brake hand position be higher, so it can more effectively contribute to keeping you upright, correct? And nothing else changes?

Or did I still misunderstand?

Austin Donisanwrote:

This was confusing because you mention lots of things, but don't emphasize that actual difference between the scenarios.

It's all about letting the brake hand position be higher, so it can more effectively contribute to keeping you upright, correct? And nothing else changes?

Or did I still misunderstand?

Nope, you understood.  Maybe this explains better?   Shows the differences better and the direction and a bit of magnitude of the forces in addition to the moment arms.

Yeah that's better.

It also explains well why once you start flipping upside down it becomes hard to stop it, since both moment arms are changing to make it harder.

I was really thrown off by "but the key is to reduce horizontal distance between CoG and CoR to eliminate rotational moments", but I realize now that was an independent thing.

Wren Cooperriderwrote:

• Rigging the rap is slower and so is actually rapping- I often climb in a party of 3 so this is compounded here, and especially if you have many raps or one climber is particularly slow at doing their third hand, they can just not be first and not use one. Spending hours getting down a rap route can be dangerous too...

A small time savings is to pre-rig the friction hitch onto the ropes and just leave it hanging there until ready to rappel, then just clip it onto the belay or leg loop and let 'er rip.  This can be done while the first person is rappelling, which should be plenty of time for even the slowest autoblock wrapper.

• Unless you're the first person down, someone can give you a fireman's which is just as safe, simpler, and generally faster

It can sometimes be useful for the first person down to be free to do stuff instead of providing a firemans, especially if there's work to be done setting up the next rap.  They can build a v-thread, pre-thread the ropes, deal with tangles, work on the anchor, etc.  Speeds up the process of the next rap when the last person shows up.

I'm pro-extension though since I also like to pre-rig my raps.

Same same!  Contrary to the weird "cattle" comment by another poster, I think it's really rad to double-check my buddy's rappel setup after a long day (and have him check mine).  I certainly trust my partners to set up a rappel, but mistakes happen (especially on a long day) and a second set of eyes is pretty sweet.  It's cool to make it home in one piece.

I'm as old and crusty as Al, but for better or worse I've kept up with developments.  This is the history as I've experienced it.

Sometime in the 1970's, the conversation started about using a prusik backup for rappels.  The original motivations came from cavers.  At first, it was thought that having a prusik above the device would save a rappeller from going off the end of the rope, but tests by a French caving group demonstrated conclusively that it didn't work, because the rappeller's grip on the prusik kept it from locking, and this proved to be the case even in tests when the rappeller knew they were going to rap off the ends (they still had a separate belay of course).

In Off Belay No. 16, pp. 10-11, Larry Penberthy (founder of MSR) presented the idea of putting the autoblock below the device, originally without an extension, the device on the belay loop and the autoblock on a harness leg loop.  His reasoning was,  "As the climber descends, the rope slides upwards through the security knot, and then through the friction device. If the climber lets go with his braking hand completely, the knot grabs and stops him. If he grips the control knot tightly in panic, the extra braking friction force stops him, assuming the friction device has a high enough friction ratio." Penberthy added,  "CAUTION:
The security knot must not be able to touch the [rappel device].  If it does, the security knot will not grab."

I've read about a few incidents, one involving severe injuries, in which Penberthy's warning came to pass and the rappeller was dropped by their system.  The original setup could be easily released if the rappeller raised the leg whose leg loop held the autoblock, say when cleaning an overhanging route, pivoted sideways so that their body was horizontal.  People who were using the autoblock to go hands-free were suddenly dropped when their body motions released the autoblock.  In any case, the system would fail if the falling rappeller flipped upside-down

Additional problems surfaced with some harnesses with adjustable leg loops.  The autoblock could easily be clipped in such a way that loading it would pull open the leg loop buckle and free the autoblock from its anchored position.

The cure for these issues was the rappel extension.  Put the rap device on a sling extending its position, and put the autoblock on the belay loop.  The extension keeps the autoblock from colliding with the rap device and so solves that problem.  Not one of the original reasons, but the extension allows the brake strand to make a bigger angle with the load strand and so increases the friction capability of the device.  I've found this effect to be noticeable when rappelling with thin ropes.

Something I don't buy is that the extension somehow makes it easier to stay upright. The rappel system, extension or not, makes a straight line to the rappeller's harness. Where the friction device appears along that straight line doesn't have any effect on the rotating moments. It is true that one can use a higher brake hand, but the brake hand is busy with braking and feeding slack and it is the non-brake hand that provides rotational resistance to tipping over. This also corresponds to my experiences with both systems---I've never noticed any less rotational moment with an extension. Another questionable claim is that the extension allows you to use both hands on the brake strand. Yes, but this is also quite possible without the extension.

Ok, now on to arguments about how much sense a backup makes.  Of course we old crusties, who rapped for twenty years before backups became a thing, have been skeptical.  But the rap backup has become an absolute standard world-wide at this point, and any instructor who doesn't teach it would be instantly accused of dangerous incompetence.  As time goes on, the number of climbers who rappel without an extension and backup is becoming vanishingly small, and many would feel suddenly naked if their autoblocks were removed.

There are two things a rappel backup is supposed to counteract. (1) loss of control without letting go and (2) letting go of the brake strand.

(1) Loss of control without letting go. This seems like a very rare occurrence.  If the climber is gripping the knot hard, it won't do anything, so the question is whether their newly-panicked grip will work where their previous grip did not.  All in all it seems unlikely that there will be a consistent benefit.  I do think that many climbers have found themselves in a situation in which it was very hard to control their descent.  Either the rap was on thin ropes that were a bad match for the device or it was a single-strand rappel.  The usual advice is to double the carabiners used for the rap device, but that doesn't address the usual situation, which is that the control problems only emerge after the rappeller is on rappel.  There are simple strategies for adding friction while on rappel, and every climber should know how to do this---an autoblock does not fix the problem.

(2) Letting go of the brake strand.  In this situation, the backup with an extended device will work.  Why would the rappeller let go? There is an occasional advantage in being able to use both hands to get into position on funky take-offs, but for the most part some objective threat like an impact from falling rock or a stinging insect attack.   Well, that used to be the case, but the ubiquitous presence of backups means that the rappeller can let go to scratch their nose.  There is no longer a critical imperative to hold onto the brake strand no matter what, and rappellers drop their brake strands willy-nilly for...whatever.  One consequence is that the climber trained in and habituated to a rappel backup probably shouldn't do without it, because they've developed habits that would be dangerous without the backup.

So my take is the only actual safety function of the backup is to stop the rappeller from falling if some event forces an involuntary release of the rope.  Of course the most severe but possibly the most likely such event would be something that knocks the rappeller out.  

We don't see much discussion about what comes next: the party has an unconscious member hanging part way down the rappel and is faced with a pretty difficult rescue situation.  This led me to propose, many years ago, that only the first person down should use a backup and the subsequent party members should be protected with a fireman's belay from below, which would enable the party to lower an unconscious rappeller who was stuck in mid-rappel by virtue of an activated backup knot. Nowadays it isn't uncommon to see this recommendation, but I should add that no less of an expert than Andy Kirkpatrick, in his book Down (essential reading!) heaps scorn on the idea because he doesn't think anyone will actually do it.

Bottom line, rappel backups with an extended device are here to stay.  They provide protection against certain severe events and beginner mistakes, while on the other hand contributing to a certain amount of complacency about general behavior.