Pros and cons of simul-rappelling

Walker Treleasewrote:

A broken gri gri is not a belay device. If the cam fails, you may not be able to brake with your hand alone.

Not weighing in on how likely it is the grigri fails, but it isn’t redundant.

Well, "redundant" in itself doesn't mean much - redundant to what makes more sense. An atc rappel + prussic is redundant to the atc failling or you letting go of the brake stand, but not to the rope being cut or the top anchor failing.

Similarly, a grigri alone is redundant to you letting of the brake strand. It is not redundant to the device failing, as you rightly pointed out. So the atc is redundant to more failure modes, but a grigri is still redundant to some.

Walker Treleasewrote:

A broken gri gri is not a belay device. If the cam fails, you may not be able to brake with your hand alone.

You definitely can still arrest the rope with your hand if the cam fails. With the handle fully open, the rope geometry of a grigri is similar to an ATC and works similarly, too. I've done it plenty. Just need a rope within the specs of the device.

 (I'm assuming the failure you mean has the cam completely open, i.e. the position when the handle is fully open. If we are talking about grigris with exploding parts, then I'm far more concerned about whatever caused that explosion.)

Derek DeBruinwrote:

You definitely can still arrest the rope with your hand if the cam fails. With the handle fully open, the rope geometry of a grigri is similar to an ATC and works similarly, too. I've done it plenty. Just need a rope within the specs of the device.

 (I'm assuming the failure you mean has the cam completely open, i.e. the position when the handle is fully open. If we are talking about grigris with exploding parts, then I'm far more concerned about whatever caused that explosion.)

Maybe it's because of different ropes, etc, but this has definitely not been my experience. With the cam completely open, I find a gri gri very hard to control when used the same way as an ATC. 

Also, even though they both go through two "bends", the specific geometries of the friction points are pretty different between ATC and gri gri. 

Wonder if anyone (Jim Titt?) has data on this.

I’ve rappelled thousands of times and can’t remember ever simul rappelling. 

So many other ways to save time on a climb.    I’ve stopped this practice.

mike hwrote:

Maybe it's because of different ropes, etc, but this has definitely not been my experience. With the cam completely open, I find a gri gri very hard to control when used the same way as an ATC. 

Also, even though they both go through two "bends", the specific geometries of the friction points are pretty different between ATC and gri gri. 

Wonder if anyone (Jim Titt?) has data on this.

I did some tests on this.  I posted photos many years ago.  A wide open gri gri has a lot less friction than and atc.

Listen to the old dudes on this one. Unless you are trying to race a storm off a big ass mountain don't simul-rap.

"In climbing, it only takes one mistake to die".

                 -Tradiban

Franck Veewrote:

Well, "redundant" in itself doesn't mean much - redundant to what makes more sense. An atc rappel + prussic is redundant to the atc failling or you letting go of the brake stand, but not to the rope being cut or the top anchor failing.

Similarly, a grigri alone is redundant to you letting of the brake strand. It is not redundant to the device failing, as you rightly pointed out. So the atc is redundant to more failure modes, but a grigri is still redundant to some.

I don’t think your first premise is correct, redundancy means something very clear, that there are no single points of failure. The top anchor (should) already be redundant by having multiple bolts or slings. A rope is somewhat redundant in that it is really many many smaller ropes wound together and protected by a sheath, and all must fail for the rope to fail. The belay system (ie whatever is holding you to the rope) is then the last system that needs to be redundant for the entire rappel to be considered so (no single points of failure, other than the rope which is a unique case).

Redundancy doesn’t work one way. One single point of failure is better than two, but redundancy means none.

I've simul rapped a few times it's not worth what you think is a time saver it's way more dangerous than just rapelling on your own one at a time.  Even if there was lighting all around I wouldn't simul rappel.  Tells who's the gumbies are right away...... 

Two bodies weight of different weights stressing the anchor and the rope.....Those that choose to rap that way are chosen by their decisions....

And gravity is always waiting......

Reduce the links in the chain of things to go wrong or fail.   There is no true redundancy in rappelling, you are ALWAYS relying on a single point somewhere in the system but that’s just the way it is, the biner connecting your device to your harness, your belay loop, the single ring on some rap stations.  The key is to reduce the number of possible failure points as much as possible but you can never totally eliminate all of them.  Simul rapping just doubles the links in the chain of possible failures. 

Derek DeBruinwrote:

You definitely can still arrest the rope with your hand if the cam fails. With the handle fully open, the rope geometry of a grigri is similar to an ATC and works similarly, too. I've done it plenty. Just need a rope within the specs of the device.

 (I'm assuming the failure you mean has the cam completely open, i.e. the position when the handle is fully open. If we are talking about grigris with exploding parts, then I'm far more concerned about whatever caused that explosion.)

You definitely MIGHT be able to arrest the rope with your hand if the cam fails (yes, I mean open not exploded). I can also usually hold someone on top rope with just my hands, that doesn’t mean I’d ever considered skipping a belay device.

To be very clear though, the rope geometry of a grigri is quite different to an ATC. The difference in how tight the bends are is everything. With an ATC the bends are much tighter, and produce significantly more friction than the much softer bends through a grigri with the handle fully open. Not only this, but the bend geometry of an ATC makes it positively reinforcing, meaning provided there is enough brake force to initiate, then the harder the load end pulls on the ATC the harder the ATC locks out, so even with mild brake force the rope can’t slide through the device. This is not true with a cam open grigri, where the harder the rope pulls the harder you must brake to lock it out.

Doing it plenty when it is Intentional is also no where near the same as doing it plenty when the cam failed unexpectedly. It’s also not really great evidence of safety when we are considering failures that are are this low probability/ high consequence, bit like saying “I speed all the time and have never crashed, therefore we don’t need speed limits.”

Kevin Mokracekwrote:

Reduce the links in the chain of things to go wrong or fail.   There is no true redundancy in rappelling, you are ALWAYS relying on a single point somewhere in the system but that’s just the way it is, the biner connecting your device to your harness, your belay loop, the single ring on some rap stations.  The key is to reduce the number of possible failure points as much as possible but you can never totally eliminate all of them.  Simul rapping just doubles the links in the chain of possible failures. 

Technically you are correct, however I think it’s worth drawing the distinction that some single points of failure are intentionally designed so the chance of failure is virtually non existent, such as your belay loop and biner. I more or less agree with you, true redundancy something we (I hope) aim for and everyone sets their own bar as to how close to it they are willing to accept. I’m not trying to tell anyone where to set their own bar, but I want them to have access to as much information as possible so they may make an informed decision.

While I wasn’t actually referring to simul rapping specifically, I would point out it’s not just doubling the links. It also doubles the consequences, and the added complexity also makes some of those links less reliable.

Walker Treleasewrote:

I don’t think your first premise is correct, redundancy means something very clear, that there are no single points of failure. The top anchor (should) already be redundant by having multiple bolts or slings. A rope is somewhat redundant in that it is really many many smaller ropes wound together and protected by a sheath, and all must fail for the rope to fail. The belay system (ie whatever is holding you to the rope) is then the last system that needs to be redundant for the entire rappel to be considered so (no single points of failure, other than the rope which is a unique case).

Redundancy doesn’t work one way. One single point of failure is better than two, but redundancy means none.

Well, maybe your personal perspective on redundancy means that, but not from an engineering perspective. E.g. taking the definition of redundancy itself (wikipedia):

In engineering, redundancy is the duplication of critical components or functions of a system with the intention of increasing reliability of the system, usually in the form of a backup or fail-safe, or to improve actual system performance, such as in the case of GNSS receivers, or multi-threaded computer processing

Hence my comment - just saying a grigri or an atc is "redundant" or not doesn't make much sense. One needs to specificy wrt to what. Yes, an atc + prussic provides more redundancy (in that it protects against more failure modes) than just a grigri. But the grigri still offers some redundancy (against failure to hold the break strand).

Few systems are entirely redundant - you'd need to duplicate the whole system to achieve that, which is sometimes not possible (say, the crew quarters in a spacecraf like Crew Dragon, yes it has many redundant systems but it is not redundant say to a structural failure from stress of re-entry), and sometimes not desirable/deemed necessarily.

Many things in climbing are not redundant - you're belaying a single belay look, you use a single rope (however much you may twist things to consider that a rope is actually many ropes.... still, if you core run hard over an edge an cuts, it's gone), we sometimes use a single thether, etc. You use a single belayer for that matter.

Simulrappelled a couple of times when I started climbing. Was totally sketch.  

Rappelling is the 2nd greatest cause of climbing deaths for a reason. Why tempt fate and make it even riskier to save maybe 25% of the time?

I would rather take the extra time and improve my odds of climbing another decade or two…

We'll probably be simul-rapping through someone's rappel station this weekend.. "Coming through, Bud!" 

They'll likely be rigging a fourth hand, chatting about how many guides they know and letting that Clif Bar wrapper blow away accidentally. 

That's the only thing they brought to eat all day, too

mike hwrote:

Maybe it's because of different ropes, etc, but this has definitely not been my experience. With the cam completely open, I find a gri gri very hard to control when used the same way as an ATC. 

I've taught many beginners to use a grigri in the last decade and a half. The easiest way to get them to lower smoothly? Open the handle completely. Start by adding a back up belayer and slowly remove the assistance over progressive practice. Works with grigri 1, 2, 3, or +.

I also didn't say it was exactly the same, nor easier than with an ATC. Finding it more difficult to control than an ATC is an anecdotal use case and not terribly relevant, much as I was rebuked in the speeding car analogy (below).

Also, even though they both go through two "bends", the specific geometries of the friction points are pretty different between ATC and gri gri. 

For sure. That's why I said "similar" and not "same."

Greg D wrote:

I did some tests on this.  I posted photos many years ago.  A wide open gri gri has a lot less friction than and atc.

Agreed, but not inadequate friction for rappelling.

Walker Trelease wrote: 
You definitely MIGHT be able to arrest the rope with your hand if the cam fails (yes, I mean open not exploded). 

Yep, I might. Thankfully haven't had to test that yet, but my prior experience with the device fully open helps my chances. Of course, with a tube and friction hitch back up, you MIGHT be able to arrest the rappel if you lose control, but there's testing that indicates otherwise.

I can also usually hold someone on top rope with just my hands, that doesn’t mean I’d ever considered skipping a belay device.

Sure, makes sense. But that's not exactly what we are discussing.

Doing it plenty when it is Intentional is also no where near the same as doing it plenty when the cam failed unexpectedly. It’s also not really great evidence of safety when we are considering failures that are are this low probability/ high consequence, bit like saying “I speed all the time and have never crashed, therefore we don’t need speed limits.”

There's some pretty reasonable arguments to be made about getting rid of speed limits. But yes, fair point about intentional use very unexpected use.

More to the point, this is a comparative discussion with respect to a tube belay device backed up with a friction hitch (presumably below the device). Pragmatically, what's being missed is the potential failure methods and the security we are gaining or losing. Note that redundancy is a specific type of increased security (or reliability if you will). I can make a system more secure by using locking carabiners in place of non-locking carabiners. I can make a rope more secure by using cut resistant materials in the sheath. Neither increases redundancy specifically (as Franck noted).

How would the cam on the grigri fail? If the spring on the cam is no longer functional, the grigri would still lock (it would be similar to a Grillon:  https://www.petzl.com/US/en/Professional/Lanyards-and-energy-absorbers/GRILLON ). If somehow the cam where jammed into the open position, this should be uncovered prior to use during a safety check (since the grigri wouldn't lock). (This assumes we are being congruent and safety checking both the grigri and tube prior to use.) The only remaining failure short of mechanical failure (the exploding cam I mentioned earlier) is the device becoming held in the open position by an outside force. I'm having a hard time understanding a realistic scenario for what that force would be while rappelling, but I'd welcome examples (other than panic pull, which I'll discuss below).

A tube and friction hitch, has its own failure mechanisms. If the rappel device isn't extended, a friction hitch on the leg loop can fail from poor body position. If the rappel device is extended, that's great, but the extension can still be rigged improperly, as could the friction hitch. More to the point, unless appropriate technique is used with the friction hitch (and in my experience most people do not use appropriate technique), initial loss of control is unlikely to be arrested due to the same panic grab problem many attribute to the grigri. That is, when sliding too fast, most folks instinctively grab more tightly. If the hand is positioned on the friction hitch back up (in order to tend it open while rappelling), this just further defeats the friction hitch. A better technique is to place the hand on the rope just above the friction hitch and tend it with the little finger, with the second hand placed below the friction hitch. The instinct to grip more tightly is more likely to be effective in that case.

I hope we agree that either a grigri or an ATC plus friction hitch will grab the rope if the rappeller loses consciousness (because they both will and have equivalent security in that case). If the concern is loss of control, neither system is fool proof (and equivalent in my thinking). Therefore, I'm having difficulty seeing the difference in security.

Derek DeBruinwrote:

I've taught many beginners to use a grigri in the last decade and a half. The easiest way to get them to lower smoothly? Open the handle completely. Start by adding a back up belayer and slowly remove the assistance over progressive practice. Works with grigri 1, 2, 3, or +.

forgive me if I'm wrong but doesn't the grigri + have a panic function where the cam re-engages when the level is pulled fully open? Otherwise your point stands and actually sounds like a good idea for noobs.

Christian Heschwrote:

forgive me if I'm wrong but doesn't the grigri + have a panic function where the cam re-engages when the level is pulled fully open? Otherwise your point stands and actually sounds like a good idea for noobs.

It does, but you can defeat the panic function by pulling harder still. So, in truth, there's a bit more nuance when teaching on the +. 

nice, maybe I won't throw mine away yet... :) 

To play devils advocate here, adding a reepschnur to the system not only makes one side totally independent,  if you and your partner are tethered together it protects the rappellers on the knot side of the reepschnur from rapping off the end as well as protects them in the event of a rope failure on their strand of rope.  Adding a reepschnur takes seconds and does not have to be redone each rappel,  it can stay tied as you feed the rope for the next rappel.  

For those rapping on two ropes tied together, the knot will naturally jam in most anchor setups, no reepscchnur necessary. 

Likewise,  a tether between rappellers does not have to be redone at each station.  We usually tether to a quad and never undo them,  that way, only each leg of the quad need be connected to the anchor on bolted routes, instead of two tether for each partner or a non redundant connection of one tether to one bolt for each partner,  which I see frequently.  

Simul rapping is an advanced technique. A competent party rappelling traditionally will always outpace an inefficient simul rapping team.  You have to ask yourself are you adding additional risks for a marginal reward in time savings,  and 'is it worth it',  are there are parts of a traditional system you can become more efficient without the need for simuling?