The benefits of the pre-rigged rappel
Pre-rigging a rappel (known by some as a “stacked” rappel) is a common technique with guides and clients. But, it has some benefits that crossover well to recreational climbers too.
What’s a pre-rigged rappel? It’s when everyone on the climbing team (or, as many of them as can comfortably fit near the anchor) attaches to the rope at the same time with an extended rappel. Learn about the extended rappel in detail here. The extended sling allows the people waiting to rap to be connected to the rope, but not be yanked around by the rope tension from the person on rappel.
A pre-rigged rappel setup. Orange carabiner on right is rapping first. Blue carabiner on left is pre-rigged and ready to rap the moment the first rappeller is done. (Recommended third-hand autoblock is omitted for clarity.)
Okay, got it. So . . . why would you want to do this?
A pre-rigged rappel reduces risk.
1 - We always give our partner a safety check when we’re climbing up. Why not do the same on the way down? With everyone pre-rigged at one time, teammates can give each other a proper safety check of BRAKES (Belay device, Rope, Anchor, Knot, Extension and Safety backup). Compare this to the traditional rappel method, where the last person waiting to rap rigs up completely on their own, with no one there to give them a safety check. This risk can be increased when an inexperienced rappeler is the last person heading down, which is typical in a two person team - the most experienced person would almost always go first, to decluster the ropes, find and rig the lower anchor, or maybe give a firefighter’s belay to the second person down. That’s a reason why guides like this method.
2 - Only one “safety” knot needed. Here’s one other interesting safety consideration. If the first person down ties a single stopper knot in either strand, or connects the end of either strand to their belay loop, there’s no way that they can rappel off the end of the rope. This is because the second rappeller, who is pre-rigged, has the rope essentially locked off in their rappel device. If the first person down were to hit one stopper knot or the end of the rope they’re tied to, the rope strands will not instantly slide through the anchor as with a typical rappel.
Note: just being pre-rigged, without having an auto block on the rope, does not always prevent the rope from sliding. With a skinnier rope, or free hanging rappel, or heavy partner or some combination of the above, the rope might still slip through the device if all the load goes onto one strand. So, if you are rappelling with only one knot in the rope, you may want to add a backup to be SURE the rope doesn't move. A simple one is a double strand bight knot (figure 8, butterfly) tied below the device of the second person. See photo below.
3 - In addition, this technique can reduce risk when doing multiple double rope rappels. A common reason for people to avoid the basic safety practice of “closing the system” and tying knots in BOTH strands on long multiple rappels is that when you thread a lower anchor and then pull the rope, the strand that’s going up to the previous anchor and then falling down obviously cannot have a stopper knot in the end. Pulling this rope strand back up, tying a stopper knot, and then re-throwing it takes time, and for that reason is sometimes skipped. With a pre-rigged rappel, because you only need a “safety” (stopper knot or tied directly to it) in one end, the first person down can thread the lower anchor, tie the one safety knot that’s needed, and then pull the other strand through the top anchor. This lets you rappel with greater speed and efficiency, and still have the assurance of never rapping off the end of your rope.
4 - Finally, if you find you’re rappelling in the dark and only have one headlamp (whoops!), this technique allows both people to set up using the one light. (Yo, you should always have a headlamp!)
A pre-rigged rappel improves speed.
I’ve read a bunch of articles and web discussions on the pre-rigged rappel, and curiously no one seems to mention this benefit. You get everyone down the rappel faster. Why? Because it eliminates the downtime of waiting for climbers to rig the rappel one by one, because several people can rig up at the same time. After rigging up, everyone can be on the tensioned rope (if you have a decent ledge to stand on) without being yanked around because of the extension. The moment the Rapper 1 goes off rappel, they quickly feed a couple meters of rope through their device and Rapper 2 can head down immediately. The movement of climbers down the rope is pretty much constant, with no waiting for someone to rig. (Of course this downtime is much less with skilled climbers, but it can be an eternity with a larger group of beginners.)
To be fair, let's look some potential downsides of pre-rigging.
The first person down can’t do a test pull to see that the ropes pull smoothly, because the person above is essentially locking the rope in place. If you have any doubts about pulling the ropes, you might not want to use this method, because pulling the rope without issue is more important than adding a small degree of speed and reduced risk by pre-rigging.
If you need the full length of the rope, and the exact middle is not on the anchor, and you’re relying on the sloppy technique of your stopper knot hitting your rappel device to move the rope ends while you’re rapping, you may end up short of your anchor. (This is unusual and can be avoided if you use good technique and simply put the middle of the rope on your anchor, but I heard a story of someone having this problem, so I thought I'd mention it.)
If the second person down rigs an extended rappel, but also puts their third hand / autoblock on and clips it to their harness, that usually means the second will be yanked around by the rope under tension. There's an easy solution to this. The second puts their autoblock on the rope, clips the carabiner to it, but does NOT clip it to their harness until the first person is off rappel and feeds some slack.
Should you use a pre-rigged rappel every time you rap? I’ll leave that choice to you, but if you look at the substantial rewards over the small downsides, you may well decide it's a good idea. Many very experienced guides do this as common practice, so you may want to consider it too.
Bonus speed trick: the safer simul rappel
With 3 (or more) people, a pre-rigged rappel lets two people rappel at one time, each on a single fixed strand. This gives pretty much all the benefits of a classic simul rappel with greatly reduced risk. (I learned this clever tip from IFMGA certified guide Rob Coppolillo.)
(Generally, the standard method of simul rappelling is not recommended for lots of reasons, covered in detail at this article.)
Picture this: a party of 3 (or more) is at the top of the route, and you want to get everyone down as quickly as possible. (Let’s assume you have a stout anchor that can easily hold the weight of two people.) Everyone pre-rigs their rappel at the same time.
The last person down rigs for a standard double strand rappel, with an extension.
The other two people (here on Grigris, could be any device) each attach to a separate single strand of rope. These two can rappel at the same time. Because each strand is fixed by the pre-rig of the last person, the risks of a normal simul rappel are pretty much eliminated.
Here's one way to rig it for four people.
Here's how it might look for five people. I think you get the idea.
Obviously, normal precautions need to be taken - knots in the rope ends to close the system, and especially, an anchor that can without question handle the weight of two climbers. Please, this is an advanced technique. Experiment and practice with this on flat ground in you before you ever try it for real.
Caution: stacked rappel with a Grigri(s)
There is a caution on the Petzl website against doing a stacked rappel with a Grigri. From the website:
“With the GRIGRI + from 2017 and on, and the GRIGRI from 2019 and on, unblocking and a consequent fall can occur if the rope is heavily loaded below the user. Unblocking can occur if the rope is loaded with a weight equal to or greater than that of the person rappelling on the GRIGRI.
Examples of dangerous situations:
Multiple people rappelling in sequence, GRIGRIs pre-installed on the rope. If the person waiting in turn to rappel has their GRIGRI pre-installed on the rope, it can be inverted (and thus unblocked) by the weight of the person rappelling below them. So it will not be operational when the second person wants to start their rappel.
Bottom belay: the person performing the belay maneuver must not hang on the rope.
Rescue from below: The rescuer must not ascend the rope of a person who is stuck on rappel.”
Below is a stacked rappel with a Grigri. When the first person down starts loading the rope, (apparently, in some cases) it can cause the rope to invert on the top person. (I tested this briefly and could not cause failure, but I certainly trust the Petzl engineers on this one, so don't do it!
image: https://www.petzl.com/US/en/Sport/Rappelling-with-the-GRIGRI?ProductName=GRIGRI-PLUS
Related to this, Petzl also cautions against a firefighter belay, or someone ascending a rope when someone above them has a Grigri.
image: https://www.petzl.com/US/en/Sport/Rappelling-with-the-GRIGRI?ProductName=GRIGRI-PLUS
Awkward anchor rigging option
The stacked rappel works best when you have a solid anchor that’s about chest height, and a nice ledge to stand on. However, if you have an anchor that's more awkward, or even on the ground, like the base of a tree, here's an alternative way to set it up so the second person doesn't get yanked around.
In some circles, this is known as a “J-rig.”
The second person (top) sets up their rappel.
The first person (bottom) pulls up about 2 meters of slack rope, ties a double strand clove hitch and clips that to the anchor with a carabiner. Here, I'm using the blue wide HMS locker, but it doesn’t have to be a locking carabiner. (You could also use a double stranded bight knot, such as an overhand or figure 8, but those are going to be a bit harder for the second to untie after being loaded.)
This creates an isolated double strand loop, so the second person doesn’t get yanked around.
When the first person reaches the lower anchor, the second person unties the clove and rappels normally.
Lets you rappel single strand with a Grigri
I briefly covered this above, but let's have a closer look. A pre-rigged rappel effectively gives you two independent fixed strands of rope. This means that the first person down can rappel on one strand with a Grigri. (Note, the rappel extension that would normally be on the top device is not shown here for clarity.)
Note, many people think that the rappel device alone is enough to secure the rope, but that's not necessarily true. If the rope is new, thin, slippery sheath, etc. the weight of the first person can creep the rope through the top device. The auto block is important, it prevents rope creep. (You could also tie a BHK, as in the photo above, which will nicely secure the rope.)
This set up is a little unusual; be sure and practice it with your partner on the ground before you try it for real.
Here’s a nice instructional video from the Seattle Mountaineers that covers one way to set up the extended rappel. Start the video at 4:50 to see how a pre-rigged rappel is set up with two people.
