The Snake Cord

December 4, 2008

Reading Time: 16 minutes.

A year ago I wrote an Off The Wall piece about the climbing know-all’s favourite piece of gear: the cordelette (cut to an Aussie at Tremadog arriving at someone else’s belay: “Call that a sling” he says walloping what looks like a spare rope clipped to the back of his alligator skin harness). In that feature, I touched upon something I called the Snake Cord, something I felt was an improvement over the standard cordelette or 16ft slings and so in this piece, I’m going to tell you why.

The king of all slings

Once upon a time in the dim and distant past, there existed such things as Snake Slings, incredibly useful pieces of gear and vastly superior to looped slings in many ways. The difference was that instead of being formed from a loop of sewn tape, the Sling was a single length with a loop sewn into each end, the loop being formed by clipping both loops together with a karabiner (or two karabiners so that you could instantly extend a piece). The beauty of this design was the Sling’s flexibility, as it could either be used as a normal sling, extending runners or for draping over spikes etc, or it could be instantly made double length for really long extensions. It was also much easier to thread or sling objects that would otherwise have required longer slings, such as large chockstones or trees and if more sling was required you could clip together multiple slings, meaning you could go from having two 60cm Snake Slings to having one 240cm sling. Another major advantage was for winter climbing, or when multi-pitching with a ‘sack on, the sling didn’t have to be removed over your head and arm (not an easy manoeuvre if that arm happens to be attached to an ice-axe stuck in the ice). All you had to do was unclip one loop and pull the sling off. Unfortunately, although a great idea and one that I think would have gained a big following if it had stuck around, the Snake Sling fell foul of CE rules in the ‘90s because when used as a single strand they didn’t pass 24kN minimum breaking strain for slings and so they disappeared from UK shops. The only way to get hold of them now is via the States, with the best place to check out being where you can buy Snakes (they call them Rabbit Slings) for as little as £6. What I’d really like to see is if Wild Country or DMM can come up with a homegrown version, after all, if they can make 8mm slings that pass the test then surely they can make a Snake Sling that also does? Interbred sling

I’ve been using these Snake Slings for years and was always impressed by how easy it was to equalize belays with the longer ones. At the same time, I was a big fan of the cordelette and it was only a matter of time before the two somehow meshed.

Now I’ve never been a fan of sewn 16ft slings, both because they are bulkier than cordelettes (which are traditionally tied with 16ft of 7mm cord) and because they couldn’t be untied and used for abseil anchors (you can cut up a sling, but it’s an expensive option). One problem with even the cordelette is that it’s still bulky when clipped to the back of the harness. In order to overcome this, I started using the best aspects of the Snake Sling and the cordelette, creating the Snake Cord. With this I could carry half the cord, reducing weight and bulk, while still maintaining the same equalizing coverage (the combined distance from every anchor point to the power/load point). Added to this I could use the cord to thread or lasso really large objects, such as fridge-sized boulders. Once I’d finished using the cord it could be quickly and easily stowed away and live happily on my harness until I needed it next. Growing your own

How long?

Like all these slings you’ll either find it too long or too short about 90% of the time, but the beauty of it is that they can be extended easily or made shorter with a simple knot, but a good length to start off with is five metres for most trad climbers (instructors and guides may want a longer length).

Cord type

Now the obvious cord type most climbers would go for is Spectra, after all, isn’t it the strongest cord on the planet? Well, the problem is that although in a tensile strength it’s very strong, once you add knots and wear and tear the strength is reduced in some cases to the level that it’s no stronger, or even weaker than plain perlon accessory cord (for more information on this check do a word search for ‘cordelette’ at Another problem with Spectra or Dyneema cord is that it’s not cheap, meaning it won’t get replaced nearly enough. In order to maintain a high strength cord, you should replace it at least once a year with moderate wear and twice as often if you are a heavy user, especially if used in high UV situations.

The only cord to use is standard 7mm perlon (£1.25/40g per metre), which has a strength of 15kN (reduced to around 10kN when tied with a figure of eight) when new. One suggestion, both to reduce wear and tear and to identify the ends, is to thread some flexible plastic tubing on to the loop when tying (that transparent tubing you can buy from DIY stores). When tying the knot make sure there are at least five centimetres of the tail to the knot. If you like the idea but would prefer something off the shelf, Yates make some very long Dyneema slings that do the same job. Racking and mating your cord with the right krab

The best way to rack the cord is to match it with the largest and strongest forged HMS krab you can buy (needs to have the maximum gate open strength), with something like the DMM Boa, BD Minipear or HB Hi-Spec HMS being perfect. The reason for using an HMS becomes apparent in a self-rescue, exiting a hanging belay, or when hauling a rucksack. You see the beauty of an HMS is that if you use this as your master point - the focus of equalization and the load point - is that by clipping into this karabiner, say leader and second, magic plate etc, you can easily unclip and unweighted karabiner even if there is another karabiner or rope under tension clipped into the krab, something impossible with a D-shaped karabiner, where everything bunches up. This means if you need to escape the belay doing so will be much easier - especially so if you’re also using a magic plate. The main point is that when you are swapping over belays everything is much easier, plus if you need to bail due to a problem, your ropes are all free. The strength of the karabiner is important because the HMS design is far weaker than a D-shaped karabiner, as the loading isn’t down the spine of the krab. For this reason, the HMS must have the maximum gate open strength (which is around 10kN for the best designs) just in case the gate is open in the worst-case scenario. Personally, I also use an auto-locking design for that extra safety margin, although some won’t find this works for them if they can’t work it one-handed and behind their back.

To rack just clip both end loops into the HMS, pass the loop through the karabiner, creating three loops, tie a loose figure of eight into the middle and clip the bottom into the HMS.

Using the Snake Cord

The most important thing to remember when using this Cord is that if you use just a single strand of it alone it’s only good for 10kN. What you’re aiming for is to have a double strand of cord going from the primary protection pieces to the master point HMS, in order to give you maximum strength. Due to the way the cord works, you will always have at least one doubled strand and ideally, you should have two. Like a cordelette, once you have the cord set through the anchor and directionally correct and equal, tie a figure of eight knot and clip in your HMS.

The diagram above shows an ideal belay set up, with the diagram below-showing something a little more radical. Unless you’re on a bolted route, no two belays will be the same so just use the sling to get the most out of each one.

Belay positioning

When setting the belay, attempt to set the master point at chest height, as this puts the nuts and bolts where you can see them, avoiding fumbles and missed clips. If you’re using a magic plate this is the ideal situation if using it in the auto-locking mode (for bringing up the second), as you can pull the rope down through the device while remaining straight-backed (not bent over and uncomfortable). This is especially important for the older climber. It is best to attach each climber to the master point via their rope (or daisy chain or sling), clipping it off with a screwgate. The leader’s rope can be clipped to the belay as the first runner (either to the master point or the highest anchor in the belay, perhaps with a shock-absorbing sling if it warrants it), reducing the shock loading on the belay (instead of falling straight on to the belay plate they will fall on to the runner and pull the belayer upwards - dissipating some of the energy). Other uses

As I have said earlier a Snake Cord can be used for many sling-like tasks, plus because it’s cheap it can be easily sacrificed (you are effectively maximizing the usefulness of your abseil tat). It is perfect for equalizing a group of spaced runners on a pitch so that you can bring them all to one point so as to reduce drag. On routes that require you to haul your ‘sack the Cord can be used to rig the ‘sack so it hangs correctly, you can use it as a makeshift prusik loop and it also makes a good washing line at Base Camp. When to use a Snake Cord

Obviously, the most solid way of setting up a belay is via your ropes and the same goes for the fastest way also, just plug in two pieces and clip in via a couple of clove hitches. Often things aren’t so straightforward and not everyone’s got a brain that can work out how to employ their ropes to build a perfect belay and so it’s in these grey areas where the Snake Cord comes into play.