Anchors Away

Using personal anchor tethers for climbing safely

Traditionally, climbers have anchored to the belay by tying in directly with the rope. Now, many prefer the convenience of personal anchor tethers specifically designed for this purpose for belays, as well as for cleaning the top anchor on a sport climb or anchoring during multi-pitch rappels. When used properly, these systems can be safe and strong, but when used improperly, they can lead to fatal accidents.A 2007 incident on the Grand Capucin near Chamonix, France, exemplifies the danger: A climber fell less than two feet onto the Dyneema sling attaching him to his anchor; the resulting impact broke the anchor sling, and the climber fell to his death. Ledges break, climbers slip—and the result can be dynamic loading of an anchor.

All climbing cord and webbing was once made from nylon, which stretches slightly, absorbing energy. Stronger materials such as Spectra and Dyneema now allow climbers to save weight, but lack the ability to absorb energy through stretch. When used in systems with an energyabsorbing component—such as in quickdraws, where the dynamic rope clipped to the draws absorbs energy—these materials excel. When they’re used in a system with no energy-absorbing component, any dynamic event results in extremely high impact forces.

Drop tests demonstrate the danger. DMM tested an assorted batch of Dyneema and nylon slings, using a 176-pound weight in fall-factor 1 (120cm drop on 120cm sling) and fall-factor 2 (240cm drop on 120cm sling) scenarios (www.dmmclimbing.com/video.asp?id=5). Even when the Dyneema slings did not fail, the impact force (18–22+ kN) delivered to the climber likely would have resulted in massive or fatal injury.

Rigging for Rescue also tested a variety of personal lanyards and anchors, using 176-pound and 220-pound loads (riggingforrescue.com/relanyards1.html). Spectra daisy chains began to fail at a fall factor of 0.25: a 220-pound weight dropped nine inches on a 36-inch daisy chain. At a fall factor of 0.5 (18-inch drop on a 36-inch daisy), virtually every daisy chain failed.

Consider the personal anchor systems that climbers are using today:

DAISY CHAINS

These are aid climbers’ tools, used to link one’s harness to aiders or ascenders, but they’re commonly and improperly used as personal anchor tethers. Daisy chains should not be used as anchoring systems, for two important reasons. First, the best-case scenario for a climber dynamically loading a daisy chain is a perilously harsh impact that could break the daisy, rip the anchor, or injure the climber. Second, it is extremely easy to clip a daisy chain in such a way that you are clipped through loops that only are designed to hold body weight.

ANCHOR TETHERS

Specially designed tethers—such as the Metolius PAS, Blue Water Titan, and Sterling Chain Reactor—overcome a key weakness with daisy chains: the potential for improper clipping through loops. Still, most are made partly with Spectra or Dyneema (the Chain Reactor is 100 percent nylon), and none is intended to absorb much energy or withstand dynamic loading. During Rigging For Rescue’s drop tests, the PAS withstood a factor-1 fall with a 220-pound weight, but the resulting impact force was 19 kN. The potential for a factor-1 fall occurs when your waist is at the same height as the anchor and the system is completely slack.

If you use an anchor system, be aware of the risks and how to minimize them. Except for daisy chains, which were never designed to be used as personal anchors, tethers are safe, but only if they are never placed in a situation where dynamic loads could occur—the kind of load that could happen in the illustration at left. Keep the attachment weighted at all times! Even a short fall onto an anchor tether, especially if it is made of Spectra or Dyneema, can generate huge forces.I have found that it is impractical to always keep the anchor weighted, and I now use the old-school Purcell, a prusik-based lanyard that offers excellent adjustability and energy-absorption potential, with just a bit more weight and bulk than daisies. The Purcell can be purchased (from Sterling Rope) or easily tied from 6mm nylon cord. The prusik knot will slip under high load, avoiding the extreme impact forces of falls on more static tethers. At any belay stance, you can always back up your tether with the tried-and-true method of tying into at least one anchor directly with the climbing rope.

Comments

I use daisy chains for personal anchors all the time, but I always back it up with 2 QuickDraws. The daisy chain is just my backup. Or I might use my long red sling if I need to move around. I think it's funny when people go off on how dangerous using certain things in certain situations can be. News flash. Climbing is an inherently dangerous sport. Now I don't have any argument against anything anyone says about what not to use because you're probably right. I just think it's a waste of time to figure out exactly the right piece of gear for each situation. ROCK ON BROS.

Austin Sweeney - 10/02/2014 7:33:59

I used daisy chains and or slings for a long time as safeties. For the last few years however i have used the rope for my safety or if working used a length of dynamic rope cut specifically. After doing this for a few years now i believe these to be the safest options.

hugh sutherland - 03/06/2014 9:19:27

Brian - 'that dead guy from Grand Capucin' you referred to was my uncle. In future maybe it's best not to refer to others in such a disrespectful way, anonymity on the internet doesn't excuse you from treating others with the respect they deserve. I was interested to see what this page had to say about the accident, and then I saw your comment. Think before you speak (or write).

Louise - 02/09/2014 9:10:52

If only that dead guy from Grand Capucin hadn't neglected the give in his harness, he'd be alive today. What's just plain stupid is ignoring lessons learned from fatal accidents. That's how safety systems are continuously improved.

Brian - 07/08/2013 6:34:44

pics do not work

Daniel - 05/09/2013 1:01:40

Preach on Joe!

Tim Burke - 04/02/2013 10:36:30

I guided someone out of the US who was taught to use the Purcell Prusik. It's just plain stupid. These short static loads are not allowing for give in the harness and body. Despite being extremely hard to produce on a belay stance. It smacks of rescue specialists trying to fix something that ain't broke.

Joe McKay - 02/25/2013 11:07:56

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