Review: Petzl Shunt

Following on from my post yesterday on the Ascension rope ascending device which I use to go up ropes whilst strapped into my climbing harness or for hauling things as part of a pulley system along with the gear in my in-car bug-out-bag I thought I would tell you a little bit about another piece of cool climbing tech that I acquired to give me some safety and utility whist getting into tall places, out of deep holes and spanning chasms. So, here we go: this is the Petzl Shunt rope clamp. Another piece of excellent engineering from these people, it's frame is made from machined aluminium, and the internal smooth, sprung cam is likewise aluminium.This means the whole piece only comes in at 188g, for those conscious of how much gear they are hauling. The Shunt is designed to be either a one or two rope device, but Petzl make no bones about the safety precautions around this. it will take a 10-11mm single rope, or 8-11mm double rope.The ropes must be the same diameter, and either be a loop of the same rope, or a single strand. Hooking onto two different ropes is highly discouraged in their safety guide. They also recommend that a figure-8 ring is applied above the Shunt by  double carabiner-ended quickdraw webbing, giving you a two-stage system.

 So, here's how it works. Rope is fed into the device by pulling the sprung "tongue" out of the body, and into its almininium shell such that the tongue will be facing "in" towards the wearer. The "tongue" can then be released and will snap closed. A carabiner is then fitted through the large hole, and attached directly to your harness in most instances. When a load is applied to the carabiner, the rounded cams bite down onto the rope, pinching it and providing a hands-free stoppage on the rope. I use 11mm static rope, as I generally use it as a fixed line and not as a free-climbing top-roping safety line type deal. Petzl tell us that the Shunt will hold a static load of 3Kn (which apparently equates to 305kg(force)) on a single rope and 7.5kn (760kg(force)) on a double strand of 11mm rope before slipping.

In dynamic situations, it fares worse, with a 60-70cm slippage at 3-3.5kN on a single 11mm rope and a potentially unstopped slip at 1-8kN under testing conditions of a 2m, Fall Factor 1 drop for a me-sized 80kg accroding to Petzl. Sobering, but remember, this is a locking ascension device, rather than a dedicated fall-arrester, it is designed to slide up a rope, then hold you before the next slide up. That said, in the event of a slip and drop, it will take the weight , pulling the cam tight against the rope and doing its job to the best of its ability, as long as you just LET GO and let it, Likewise, it will NOT work if the "tongue" is impeded by your body, a wall, or anything else, it must be free to pull down to work. This has a cool feature in reverse, though, in that it will allow you to descend in a controlled fashion by squeezing the body of the Shunt towards you, releasing some of the tension of your load on the "tongue" and the rope will slip through. Letting go again will halt your descent. Again, combined with a figure-8 this allows secure, controlled movement on a rope. I also use mine in combination with my Ascension rope ascending device. (Shh, don't tell Petzl)

There is a small hole in the back of the "tongue" that I have attached a dummy-cord through, because, let me tell you, the springs in this are snappy, and I have had the misfortune of it "sproinging" out of my hands as I was getting ready to fit it to a rope. Fortunately for me this happened whilst I was testing the unit and familiarising myself with its use, rather than dangling from the sky somewhere. Better for me, better for whoever might be below me. Again, this is a really useful piece of kit, not without limitations, as the manufacturer very diligently points out in their manuals (PSA: read them, pay attention and familiarise yourself with all climbing kit before putting yourself or those around you at risk). I've had a lot of fun with this, without yet dropping out of a high-hide like Ian Malcolm.