Crystal clear video and test of dynema cow's tail

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nicolasC

climber
Topic Author's Original Post - Dec 6, 2014 - 05:35am PT
The tests were done by the french Ecole Nationale de Ski et d'Alpinsime (ENSA) the official and only school tasked with training mountains guides in France.

Even with fall factor as low as .3, cow's tail done with dynema slings failed

Whereas cow's tail done with dynamic rope (either sewn or made from regular climbing rope) did not fail even with fall factor 2)

in the last part of the movie, there is a nice demonstration of using a cow's tail to position the belay device midway and connect to the anchor

[Click to View YouTube Video]

stay safe
Bill Mc Kirgan

Trad climber
Cedar Rapids, Iowa
Dec 6, 2014 - 05:57am PT
nicolasC,

Thanks for sharing this. The demo of the rap setup at the end was especially helpful, at least for me. I've never seen that setup before, but it makes sense.

It looks like it really makes a difference using either the sewn or tied cows tail.

http://www.beal-planet.com/2014/anglais/longes.html

http://www.beal-planet.com/2014/anglais/longes-relais.html

I understand the knot (for homemade) or the way the rope is sewn/joined is the key to softening the fall arrest.

The pages I linked, above show the manufactured lanyards in greater detail. I'm looking closely at how the rope is joined.

THANKS FOR POSTING SOMETHING RELATED TO ROCK CLIMBING!!!1!!!
Bad Climber

climber
Dec 6, 2014 - 06:13am PT
Interesting and sobering!

What diameter dynamic cord was the bloke using for his tail?

Opinions on this rap method?

Why is the dudes speakin' gibberish?

BAd
TGT

Social climber
So Cal
Dec 6, 2014 - 08:29am PT
Something I've been preachin' since they came on the scene.

NEVER! tie knots in UHMW Polyethylene (Spectra, Dynemea) slings.
Jaybro

Social climber
Wolf City, Wyoming
Dec 6, 2014 - 08:34am PT
F*#k dynema!
couchmaster

climber
Dec 6, 2014 - 08:36am PT


Like to see a French speaker step in here. Aren't they demoing how guides rap with a client in France? Was it a Beal Joker piece of rope they were comparing?
Bill Mc Kirgan

Trad climber
Cedar Rapids, Iowa
Dec 6, 2014 - 08:58am PT
couchmaster,

I think it was the Joker being demonstrated by the guide.


Does anyone sell 8 to 10 foot lengths of dynamic rope for such a purpose?

All I could find in a quick search earlier were the links I posted above.

I don't think I would want to try this with a rope I retired, but I am practicing the setup a bit to see how it works using a fuzzy old 11mm cord.

Ed Hartouni

Trad climber
Livermore, CA
Dec 6, 2014 - 10:17am PT
thanks for the post,
it would be nice to get a translation of the commentary, but the scenes are pretty self explanatory;
my remnant bits of French help...
rwedgee

Ice climber
canyon country,CA
Dec 6, 2014 - 10:27am PT
I resent animal testing.
Test rig is a guillotine...ironic.
rgold

Trad climber
Poughkeepsie, NY
Dec 6, 2014 - 11:15am PT
I think we've known for quite a while that real falls (ff > 1) on a dyneema sling, especially one with a knot in it, have the potential for failure, although that potential is overemphasized by tests done with steel weights.

I rather doubt than many in the US, even those like me who already use an installed tether, are likely to swap it out for a much bulkier dynamic rope tether, especially in view of the fact that nylon tethers, like the Sterling Chain Reactor, will withstand several factor-2 falls (but will deliver a hell of a body blow in the process, probably 18 kN or more). But still, the tether is primarily used for leaning against and actual falls onto it seem to me to be very uncommon.

By the way, did anyone else find the positioning of the rappel device so far away from the climber to be perhaps unfortunate? When rapping with an extended device, there are sometimes problems going over roofs, and it is helpful to be able to lever the rope away from the cliff to keep the device from scraping down the wall. The further away it is, the harder this becomes. There are also occasionally trick starts or starts with a very low anchor position that would be made harder with the rap attachment point so far away.
redrocks

Social climber
Las Vegas, NV
Dec 6, 2014 - 05:32pm PT
did anyone else find the positioning of the rappel device so far away from the climber to be perhaps unfortunate?

The advantage is in keeping the autoblock away from the rap device. But it did seem farther away than necessary.
Studly

Trad climber
WA
Dec 6, 2014 - 05:37pm PT
What I got from this is don't fall factor onto your daisy. Seems common sense, but why use the short piece of rope for a back up when you can throw a clove onto the anchor with your lead rope and do the same thing? I hang on my daisy all the time but its never shock loaded. I can also put my rap device on my daisy and rap with it extended away from me, why do you need a piece of rope to do that as you are not going to shock load the daisy while you rap?
rgold

Trad climber
Poughkeepsie, NY
Dec 6, 2014 - 06:19pm PT
The advantage is in keeping the autoblock away from the rap device. But it did seem farther away than necessary.

It is way further away than necessary. It is beyond the climber's reach altogether.

why use the short piece of rope for a back up when you can throw a clove onto the anchor with your lead rope and do the same thing?

The primary application is for when you aren't tied into the rope.

I can also put my rap device on my daisy and rap with it extended away from me, why do you need a piece of rope to do that as you are not going to shock load the daisy while you rap?

The rope serves not simply as the extension for the rap device, it is also the tether to the anchor, and it is in its role as a tether that the dynamic rope is suggested.

nicolasC

climber
Topic Author's Reply - Dec 7, 2014 - 10:50am PT
The rope used is most probably the Beal Joker 9.1 which is triple certified (single, double and twin usage) most probably because Beal is a partner of ENSA and they push this rope.

At 38 seconds into the video, they used a cow's tail made of sewn dynamic rope (lanyard) instead (also from Beal).

I have seen this setup used more and more by french guides.
I have tested it with some thin double (iceline 8.1mm) with a butterfly knot midway instead of the bulky fig-8.

I will be using this setup when gearing up someone who is not an expert to go with me on long routes as it makes the safety at the belay station easier to maintain and assert.
Studly

Trad climber
WA
Dec 7, 2014 - 11:56am PT
I don't see the benefit of this system. It does the same thing as a daisy chain or a runner, but its full strength in a situation where you will never need it to be.
redrocks

Social climber
Las Vegas, NV
Dec 7, 2014 - 03:18pm PT
Nicolas, maybe this should be its own thread, but I don't get the multiple certs (single, half, twin). Why would a half rope not be always usable in a twin situation?
Fishy

climber
Zurich, Switzerland
Dec 8, 2014 - 02:08am PT
Extending the belay device by around 2 feet is very widespread over here in the alps.

They seem to like it for attaching to the belay whilst climbing, and because it allows the autoblock/prussic to be attached to the belay loop (rather than leg loop) when descending.

One other key finding of the video - the dyneema sling, tied with knots, nearly fails (one strand breaks) also at low fall factor of 0.3 (see 1.53 in the video).

Take home: dyneema is not a good option, and defintely dont tie knots in it! Even small falls can be catastrophic.
Bad Climber

climber
Dec 8, 2014 - 06:22am PT
RE.tying knots in dyneema is really worth knowing.

Now, would a sewn tubular webbing sling have failed in the same way?

As others have pointed out, however, how often or under what circumstances are slings/tie-ins shock loaded? Every fall I've handled or situation I've encountered has the rope as a mediating factor, adding that crucial dynamic element.

@Ron: I currently use a "web-o-let" which IS KISS. It's so easy and slick to equalize anchors--far quicker and cleaner than sometimes futzing with slings that aren't quite the right length.

I will experiment a little with putting the rap tool further out from my body. It certainly clears the way for the belay knot.

Re. self-belay knots: nylon webbing or round cord? What diameter do you guys like? On short raps I often don't back up with a self-belay, but in more exposed/longer raps, I do, and that has been with some 9/16 nylon tubular.

BAd
jaaan

Trad climber
Chamonix, France
Dec 8, 2014 - 11:02am PT
Aren't they demoing how guides rap with a client in France?

Training and assessing guides is only a part of what ENSA does. They also test every type of system that climbers commonly use - in this instance the cowstail. I agree, it's a bit long. I'd imagine it wasn't intentional. This system is regularly used in France. So much better than the nonsense of the prussik attached to the leg loops, so beloved of the Brits.

There are other ENSA videos that are worth looking out. Some quite sobering, like the crevasse fall and moving together on ice one...
rockgymnast

Trad climber
Virginia
Dec 8, 2014 - 11:42am PT
Just logged onto the ENSA website and looked at some of their instructional videos.

Re: Rappelling - they show tying two ropes together using a "Figure 8" rather than the more common EDK

Is this a dated video? or current accepted practice in France?

Re: glacial travel - they did show an interesting idea for tying the middle climber (in a team of 3) to the rope using a friction hitch rather than a tie in with the rope (alpine knot). When crossing a snow bridge, this allows the middle climber to stay on one side of the bridge (if it is a long one) by sliding the friction hitch allowing only the leader to weight the bridge. When the leader is safely across the middle climber slides his friction hitch along the rope as he travels across.

Thoughts??
Thanks.
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