QC LAB : CORDES TORDUES

La fameuse corde qui vrille, c’est le cauchemar de tous les grimpeurs. Pourquoi ta corde s’emmêle, comment ça arrive, et quels risques tu prends quand ça t’arrive en pleine grimpe.

T'es déjà monté une voie et tu t'es retrouvé avec une vraie queue de cochon de corde tordue sur ton harnais ? Moi, oui. Et ça me rend dingue. Ça m'est arrivé que je sois en tête ou en seconde, avec des cordes simples, des demi-cordes ou des cordes jumelles — neuves comme vieilles. Le syndrome de la corde torsadée existe depuis que les grimpeurs s'attachent des cordes. On va voir pourquoi ça arrive, comment ça arrive, comment éviter que ça se produise, et s'il y a des risques à avoir des cordes avec trop de torsion.

CAUSES OF A TWISTY ROPE

I’m sure there are more, but I’ve narrowed it down to four main reasons that can cause a twisty rope:

1. coiling/uncoiling
2. lowering – anchor placement
3. lowering – tight radius
4. using a Munter hitch while rappelling.

1) Coiling/Uncoiling

Up until fairly recently, ropes came “old-school” factory coiled from almost every rope manufacturer. Sure, some came loose in bags (which actually avoided coiling and uncoiling issues) but most were coiled similarly to the way you wrap an orange extension cord around your upper arm or shoulder and hand. Think Mountaineers Coil.

Jusqu'à récemment, les cordes étaient enroulées de façon « old-school » par presque tous les fabricants. Certes, certaines venaient en vrac dans des sacs (ce qui évitait en fait les problèmes d'enroulement et de déroulement), mais la plupart étaient enroulées de la même manière que tu enroules un câble d'extension orange autour de ton bras ou de ton épaule et de ta main. Pense à l'enroulement des alpinistes.

Pendant de nombreuses années, et même encore aujourd'hui avec beaucoup de cordes, il existe une « méthode suggérée » pour dérouler une corde neuve. Utiliser la méthode du déroulement bras par bras, suivi simplement de faire passer l'extrémité de la corde dans tes mains plusieurs fois, revient essentiellement à inverser la bobine formée à l'usine — le résultat final étant une corde sans torsion.

De nombreux fabricants de cordes ont récemment mis à jour leur procédé d'enroulement en usine en adoptant un enroulement « lap coil » ou « climb ready » – qui NE génère PAS de torsion pendant le processus. Et comme il n'y a pas de torsion pendant l'enroulement, il n'est pas nécessaire d'inverser le processus lors du déroulement. Avec ces cordes, tu peux sortir directement une corde de son emballage et commencer à grimper, sans trop risquer d'avoir une corde tordue. Génial ! Même si cela ne semble pas énorme, c'est en fait une véritable innovation dans les cordes d'escalade qui a non seulement éliminé le redouté syndrome de la corde tordue, mais qui permet aussi de gagner du temps.

gauche: New School “Climb Ready” Factory Coil

droite: Climb Ready Coil = Bon pour y aller

2.) Descente – Pose d'ancre

Lorsque tu descends d'une voie, l'orientation des placements des ancrages peut avoir un effet important sur ta corde. Idéalement, il y a deux ancrages bomber, équilibrés à l'aide de quicklinks, d'anneaux de rappel ou de chaînes. Quand les deux ancrages convergent en un point focal (c'est-à-dire que la corde prend la forme d'un V) et que tu es descendu, l'effet sur la corde est minime.

Gauche et droite : bon placement de l'ancre

Cependant, si les ancrages sont placés à distance, ce qui fait que la corde monte, passe par-dessus et redescend, cela peut considérablement tordre la corde. Dans ce cas, il est presque toujours préférable de redescendre en rappel.

left and right: Not ideal anchor placement

3.) Lowering – Tight Radius

Have you ever wrapped a birthday present, getting all fancy with some ribbon, and use scissors and the pressure of your thumb to slide down the ribbon and cause it to be all curly and fancy?

Eh bien, c'est similaire à ce qui peut arriver si tu descends en utilisant un mousqueton à petit rayon isolé. La plupart des mousquetons, quicklinks et maillons de chaîne ont un rayon suffisamment grand pour éviter ce problème, mais avec un mousqueton de faible section, un maillon de chaîne ou, le plus grand coupable, un mousqueton rainuré pour corde, cela peut faire enrouler la corde.

4.) Rappelling with a Munter

This doesn’t happen too often nowadays as most folks are using belay devices of one sort or the other. But be warned—if you rappel a rope with a Munter hitch, it will twist the bejeezus out of the rope.

One way to avoid this is to ensure the ropes are fully free hanging … at least that way, the twist is being driven right to the end of the rope. Another way to deal is to have one person rap with a “left-handed Munter” and the next to rap with a “right-handed Munter.” This will balance out the twists and the net result will be less noticeable.

And once again, the best way to avoid a twisty rope when rappelling with a Munter is to NOT rappel with a Munter.

HOW TO UNTWIST A TWISTY ROPE

There are many theories out there. One is to allow the entire length of the rope to free hang off an anchor, blow in the wind and de-kink. This is a good start, but can be challenging to find the appropriate place. The staple method is to have your rope set up TR style, through two quickdraws, and just pull it back and forth a few times—tugging and pulling. This helps. You can find yourself a nice grassy field and just drag your rope on the ground—basically take it for a walk for a little while—that’ll allow it to un-funk itself a bit. But I find the best way is to run it through an ATC style belay device a few times—either on a route, or on the ground.

A few winters ago I blasted up to Alaska for a quick (failed) attempt on a peak. At the airport hanger in Talkeetna, my buddy and I were racking up—we had just brought a brand new old-school coiled cord for the climb. I was dealing with the rack when I glanced over and was horrified to see my buddy just pulling the factory coil apart with not a thought or care in the world. I knew instantly that our cord was destined for the biggest twisty-kink mess of all time. We ended up taking the rope out and laying it on the snow-covered runway and stretching it out as much as possible. We actually tied it to the landing gear of a plane, put our harnesses on, and walked the entire 70m length backwards while running the rope through our ATC belay devices. We did this three times each and at the end of it all, we had worked out the kink-mess pretty well and proceeded with our unsuccessful climb.

RISKS?

Other than the frustration of a twisty pig’s tail at your harness, perhaps getting tangled in quickdraws as you’re seconding or trying to clip while leading, I had always wondered if there was a risk with dynamic loading on an overly twisted rope. Could the act of falling on a twisty rope cause the rope to core-shot itself? We headed down to the drop tower with a bunch of different ropes to find out.

TESTING

We decided to test in two main scenarios—leading and seconding.
We pre-twisted the ropes to fairly excessive levels prior to each drop.

TESTS

We kept the loads on the slightly harsh side mainly by having a static belay:

1. A typical top rope fall with a bit of slack in the system – static (i.e. no slip) belay

2. A lead fall onto a quickdraw, fall factor > 1.0, with a static belay

Samples

We grabbed some ropes from around the office, both new and old of varying diameters.

Results

CONCLUSION

Based on our limited, though semi-extreme testing (both high level of twistiness, as well as high loads), it appears unlikely that falling on a pig-tailed rope will cause the rope to core-shot, though a more used rope did show more signs of “damage” (excessive flattening and starting to show signs of possible core shot) during twisty loading than new or less-used ropes.

BOTTOM LINE

Well, finally I can rest easy. As I’m struggling to second a pitch that my rope-gun wife has led, and I’m about to pitch onto a pigtailed twisty rope mess at my harness, I need not worry as the chance of said rope mess causing anything funky to happen is unlikely. Whew.

When lowering from a route (or top-roping), lower off quickdraws when possible to save the anchors—ensure quickdraws (gates opposed) are equalized at one focal point to eliminate the chance of the rope twisting—and when it’s time for the last person to get down, notice the anchor orientation. If the anchors are spread a distance apart, it may be time to rap to avoid twisting your rope.

When working on your sport proj that you and many others have been failing on at that same stopper move and are lowered to the deck in frustration, have a look at that draw you’re being lowered off. If the biner is getting significantly rope-grooved, do your part and donate a new one to the cause. It’ll help avoid your and other’s ropes from getting twisty, prematurely worn or worse.

And finally, remember when you’re about to use a brand-new rope, it’s always best to spend the time to uncoil properly. If it’s factory coiled, use the arm-over-arm method. If it’s ready-climb coiled then you’re good to go.

Be safe out there,