Rappelling on Skinny Ropes Part 2—Tethers and Third Hands

Rappel extensions/tethers and third hands are useful tools in a mountain environment. Photo: Aidan Whitelaw

Continuing our dissection of ski mountaineering rappel systems, we are exploring the various options for rappel extensions/tethers and third hands. There is significant overlap here with standard rock climbing gear and techniques, but our needs as skiers, especially skiers with skinny ropes, are a bit different. 

You can find part one of our rappelling on skinny ropes series here.

Learn more about rappelling for ski mountaineers in this primer from Sam Hennessey here.

Why you should use a tether and third hand

Starting close to square one, why do you want this extra gear in the first place? There is certainly some appeal to my minimalist brain to a rappel kit consisting of a single locking carabiner and a belay device. 

Starting with the tether/extension component, this serves a few main purposes. First, the tether component is what we use to attach ourselves to an anchor. Even with a single rappel and an anchor on moderate or steep snow, it is best practice to tether oneself to the mountain when possible. This secures your stance to assess the anchor, setup the rappel, and test your rappel setup before committing your full weight to it. In a skiing context, I will often stab my poles or an ice tool vertically into the snow and clip my tether in while transitioning from skis to crampons, or vice versa.

An extended rappel offers many benefits over rappelling from the belay loop on your harness. It gives the rappeller more space to hold the brake strands, as well as reducing the force needed to slow/stop the rappel. An extended rappel also makes it easier to pre-rig a rappel–see this excellent post from Alpine Savvy for more on that. 

​​Last, extending the rappel allows us to rig a friction hitch backup off the belay loop, which is especially important given that many ultralight ski harnesses aren’t made with independent load bearing leg loops (a common place to attach a third hand). 

The third hand or friction hitch rappel backup is generally commonplace in rock climbing, but in my view, especially important when skiing. The third hand gives us a backup, such that if the rappeller is disabled in some way during their descent, causing them to lose control of the brake strands, the friction hitch will tighten down and stop the rappeller’s descent. Given the risk of sluffing, avalanches, or rockfall in many places we ski, it is extremely important to minimize the risk of losing control while rappelling.

Tether Options

There are a plethora of super functional tether options out there–whether you want a purpose built, a home-tied cord option, or something fashioned out of a climbing sling. Relative to climbing, there are a few things worth considering for skiing. First off, in a similar way that we talk about ultralight ropes and harnesses in the context that they play a small role in our overall ski day, I often opt for a lighter and more compact tether than I may for rock climbing. The second consideration is the necessary length and adjustability for skiing. With the possibility of skiing into an anchor and having skis in the way of clipping a short tether, or perhaps early season or in a low snow year, the normal anchors in a line are high above the snow surface, a long tether can be super handy. 

Ideally, whatever tether you choose should also have a short attachment to clip in a rappel device for an extended rappel. Around 6” is a good minimum extension, but longer can work well too. The key here is to be sure the device doesn’t interact with the third hand below it, as this can inhibit the “locking” of the third hand. Here are some of the options and techniques I have seen or explored myself:

Double length runner options (L to R): 110cm Blue Ice Alpine Runner, Mammut contact sling 120cm, or Edelrid Sewn Aramid Cord 120cm.

Double Length (120cm) Sling

Lots of options here; from an 18mm nylon runner, slim and lightweight sewn Dyneema runners, to high tech options like the Edelrid Aramid sewn cord sling. Some rock climbers opt for a nylon runner here for a bit more stretch in case of a slip at the anchor–I would simply recommend not putting oneself in the position to take a fall on a static tether, nylon or otherwise. Something like the 8mm Mammut Contact sling is among the lightest options, but can be hard to untie to de-rig. The Edelrid Aramid sling is super durable and very stiff, which makes it easier to untie. 

There are lots of options for rigging a double length runner for a tether/extension—below are some of the options I like.

The basket hitch + overhand method for a double length sling. Perhaps the most simple option, but often the resulting tether is a bit short for reaching ski anchors (especially with skis on).

The girth hitch + overhand on a bight. Dead simple, hard to untie with a dyneema runner.

The ‘bowline method’ for a double length sling tether/extension. A bit tricky to tie, but good for a longer extension. Currently in-fashion.

Blue Ice Alpine Runner

A new option I have been enjoying is the 110cm Blue Ice Alpine Runner. It’s functionally similar to the double length runner options, but rather than an open loop, it has a “chafe cover” that encases both strands and leaves a tight clip in point on either end. This holds carabiners in place and feels a bit more tidy than the open loop style. There are many ways to rig the Alpine Runner, but I prefer simply threading my belay loop and tying an overhand. 

My go to setup for the Blue Ice Alpine Runner, there are a million ways to skin this cat, but this method is quick and effective.

Adjustable “Devices” 

The Kleenex of adjustable devices is the Petzl Connect Adjust, but there are many options like the Camp Swing, Kong Slide or Edelrid Switch. These devices generally come at a significant cost and weight penalty, but offer easy adjustment and often come with very strong, dynamic climbing rope as the tether material.

Standard Petzl Connect Adjust – a bit short for clipping into an anchor with skis on. Strong and reliable but a bit bulky.

I have spent a bit of time and energy trying to find a small diameter cord that works well in the Connect Adjust—it’s a bit finicky, but lightens things up a bit. The Mammut Glacier cord is the best so far, but generally, soft, 6mm+ cords work okay. 

Petzl Connect Adjust with Mammut Glacier Cord. Needs the “right” carabiner to hold, but is more compact and provides a longer max extension.

To rig a rappel extension, I simply attach my device with a clove hitch at the desired extension length. 

Purcell Prusik

A cord-based adjustable tether option, the purcell prusik is a cheaper adjustable option. I would recommend using a 5mm tech cord or 6-7mm nylon accessory cord. Alpine Savvy has a cool single strand option that will reduce bulk.

Downsides of the purcell are that its adjustment range is limited to between half length and full length, and while one can choose any length for the ‘length’ variable, it isn’t easily shortened below half length.

A Purcell Prussik (single strand) with Petzl RAD line. Perhaps a bit “old school”, but it checks the boxes of cheap and effective.

“PAS” Sewn Loops

Perhaps not the most fashionable option, the sewn PAS is a pretty foolproof option here. Adjustment is achieved via choosing a length from a series of clippable loops. The purpose built PAS’s have independent, full strength loops and don’t have the same potential danger of a daisy chain. For a rappel extension, choose a shorter loop and clip in your device. Downsides include bulk and a more complex on-the-go adjustment. 

Third Hand Options

As discussed above, I am firmly of the belief that a third hand is necessary while rappelling in ski terrain. Making a third hand work well with potentially icey, skinny ropes, can be a bit of a challenge. I often opt for either a Autoblock hitch or Klemheist as a friction hitch for my third hand as they are quicker to tie and easier to tend than a prusik.

On skinny ropes, a skinnier cord diameter will generally grip better, but more wraps in the friction hitch are often necessary to get sufficient grip for a true backup. Another skinny rope consideration is the likelihood of having to manage tangles. A hands free backup (tie a catastrophe knot for extended futzing) is key to efficiently managing and solving tangles. I have been experimenting with some homemade, spliced aramid loops for skinny rope specific third hands. Of all my splicing experiments thus far, this seems to be the biggest success so far.

Knotted Cord

The cheapest option that works just fine for rock climbing but potentially less good for skinny ropes – often made with 5-6mm cord. For skinny ropes, a skinny cord would work better, but you quickly end up with a cord that isn’t sufficiently strong (4mm accessory cord is about 4kN – less with wear and tear!). 

Sewn Cord

Sterling and Beal make the popular options here, simply a loop of sewn cord that is bartacked and heat shrunk to achieve lower bulk than a knotted cord. I have had serious durability issues with the core bulging out of the sheath on three different Beal Jammies and prefer the Sterling option. 

Sewn cord rappel backup options—left is the Beal jammy, which I works well but has serious durability issues in the form of the core bursting out of the sheath. On the right is a similar Sterling sewn cord that I have had great luck with, especially on rock climbing ropes.

Sterling Hollowblock

The Hollowblock is a flat(ish) weave aramid loop that is super popular as a rappel backup. The flat, aramid material is heat resistant and increases the contact area between the Hollowblock and rappel rope. There are some videos out there of worn Hollowblocks breaking under low loads – most people will get a few years out of a Hollowblock though.

A few examples of purpose built cords for rappel backups—left is the Grivel Magic Ring which doesn’t require a carabiner, unfortunately the result is a pain in the butt to rig and the cord is too stiff to grab well. Right is the Sterling Hollowblock, which is made from 6.8mm aramid and flat for better friction.

Slings

It is generally acceptable to use a sling as a third hand, though it is good practice to dedicate said sling to that use once it has been subjected to the heat and abrasion of rappelling. I wouldn’t choose a Dyneema sling for this – rather a nylon or mixed Dyneema/nylon option. Again, replace often and keep an eye on wear. I like the 9” Blue Water Titan Sling for a compact option that provides a lot of surface area.

A few alternative options that have worked well for me on skinny ski ropes. Left is a Blue Water Titan sling, with its flat profile and nylon blend, it grabs pretty well on a skinny rope. My current favorite is this 3mm Vectran(Aramid) spliced loop—a 3 wrap autoblock hitch holds perfectly on a single strand of Petzl Pur’line.

Experimental – Spliced 3mm Single Braid Aramid

Similar to Amsteel, a few rope manufacturers make a 12 strand, single braid aramid cord. I have been experimenting (both off the deck and in the mountains) with the 3mm variety spliced into a loop. Some folks on Mountain Project are deeper in this rabbit hole. As discussed in the comments of part 1 in this series, the old rule was half the diameter of the rappel rope for a third hand. The 3mm Aramid has a breaking strength of 993kg—so is plenty strong, in addition to being more heat resistant than Dyneema. This is the only option that has given me reliable hands free holding power on a single strand of skinny ski rope. 

Conclusion

I’ll end with the usual caveat—these are nuanced techniques that should be practiced and understood at home before going out and using them in the field. Making a mistake or misusing any of these techniques or products could kill you. That being said, if you are planning to do any rappelling this ski season, now is a good time to check out your kit and consider adding a third hand and extension to your kit if you don’t already have them.