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Jim E

climber
away
Aug 18, 2010 - 01:34pm PT
yes.

http://www.dmmclimbing.com/news.asp?nid=293&ngroup=1
http://www.dmmclimbing.com/video.asp?id=5


edited to get the correct link
Studly

Trad climber
WA
Aug 18, 2010 - 01:38pm PT
You're fine Coz. You would have to work pretty hard to figure out a scenario when you could shock load a dyneema sling out climbing enough to break it.
Jaybro

Social climber
Wolf City, Wyoming
Aug 18, 2010 - 02:38pm PT
Yeah, pretty unlikely that you'd break 'em. But why not just use real slings?
ontheedgeandscaredtodeath

Trad climber
San Francisco, Ca
Aug 18, 2010 - 02:56pm PT
Has anyone ever scooched above a rap anchor to deal with some clusterf#@$ or another? I reckon I have. If'n I slip while so doing, would I generate enough force to break these slings or cause my guts to shoot out my anus?
Seamstress

Trad climber
Yacolt, WA
Aug 18, 2010 - 03:10pm PT
Back injury/discomfort most likely. Breakage possible. Testing was persuasive to me.
Wade Icey

Trad climber
www.alohashirtrescue.com
Aug 18, 2010 - 03:32pm PT
guts shooting out of one's anus would be pretty persuasive..
Seamstress

Trad climber
Yacolt, WA
Aug 18, 2010 - 03:58pm PT
http://www.blackdiamondequipment.com/uploads/black-diamond/files/MM5824_C%20Runner-DBone%20WEB.pdf

Sewn slings do not stretch and will not
absorb energy during a fall or shock-load situation. Climbing
and mountaineering require the use of dynamic rope to absorb
energy during a fall.

I didn't find the "words" or test results that go along with the warnings, but the pictures clearly indicate that you should not tie into an anchor with it and girth hitching reduces strength to 35%. That is weaker than I remembered.
Ksolem

Trad climber
Monrovia, California
Aug 18, 2010 - 03:58pm PT
I think it would be hard to match the kind of shock load in the tests (a clean dead vertical drop) in a climbing situation. For example if you step up above a rap station to fiddle with something and fall, you will probably fall out from the rock some amount and swing back in as you load the sling on a curve.

That said, those tests and results are sobering.

"Guts out the anus..."

Classic!
charlie.elverson

Trad climber
St. Paul, MN
Aug 18, 2010 - 03:58pm PT
So why doesn't BD report the problem.

Some one should correct me if I'm wrong, but I was under the impression that although just as strong as a nylon runner, they're (almost) completely static. Where a nylon sling would stretch a (tiny) bit when loaded, a dyneema one won't. This means identical falls on a dyneema vs. nylon sling will generate greater forces because there is greater acceleration. Therefore, a dyneema sling is more easily broken in a fall straight onto it.
Seamstress

Trad climber
Yacolt, WA
Aug 18, 2010 - 04:16pm PT
Exactly. Thus the article a few years back in the climbing mags warning about clipping direct to anchors with the new fangled materials, and the continued reliance on nylon/perlon in the mountain rescue rigging practices.

I thought there was some good stuff on the Petzl or BD sites, but of course I can't find it when I want to.
aliebling

climber
San Francisco, CA
Aug 18, 2010 - 04:27pm PT
A newbie question:

If I'm using a taut dyneema sling (or the likes of a Metolius Personal Anchor System) as well as being tied in short to the anchor and am belaying from my harness when the leader takes a large fall, the force is going to be transferred to the anchor through the sling (since it is shorter than my rope tie in which has some slack in it).

Is this a problem? Will larger (potentially dangerous) forces be transferred to the anchor because of this? Do I need to ensure that my rope tie in (using a figure 8 on a bight) will be absorbing the fall and not a sling?

After reading:

http://wallrat.com/PDF_Files/forcesinleadfalls.pdf

I'm assuming that this case is not overly dangerous, as the force acting upon the belayer is generally pretty low...far less than that created by a factor 1 or 2 fall on to the sling itself. Again, my main concern is the danger of blowing the anchor due to forces being transmitted through the (comparatively static) sling and not the sling itself blowing (since I'm always tied in with the rope as well).

So, should I be making sure that while belaying any force transferred from belayer to anchor is through the rope tie in and not the sling or is this a non-factor?
Studly

Trad climber
WA
Aug 18, 2010 - 04:37pm PT
I usually find it advisable when multipitch climbing, to tie off with the lead rope to the anchor with a clove hitch and equalize it to my daisy. That way you are dynamically roped in, equalized and backed up double.
If the leader were to take a fall with gear in, your weight acts as a counter weight and so the force is not so much taken by the anchors, but by you being pulled up in the air. If the leader were to fall directly on dyneema clipped off to the anchors, the stretch in the rope should not static load the dyneema or the anchors.
If you are worried about breaking dyneema slings, I suggest clipping off in your harness to a bouldering wall and trying to break the dyneema sling by climbing above it and jumping off, static loading the sling. It quickly becomes apparent that you do not normally put yourself in a situation belaying or climbing where you are going to be able to break the dyneema.
Brokedownclimber

Trad climber
Douglas, WY
Aug 18, 2010 - 04:39pm PT
I recently bought some Dyneema slings for tying off chickenheads, since they are narrower and would more easily conform to the rock without slipping off when using a chickenhead knot. This use would involve the dynamic stretch of the rope, but now I'm wondering if I wasted a lot of money?
aliebling

climber
San Francisco, CA
Aug 18, 2010 - 04:52pm PT
Studly, I quite like the idea of the clove hitch equalized to the daisy chain, thanks! Seems like the best of both worlds. My biggest issue with the figure eight on a bight was the difficulty in adjusting its length when needed.

BDC: I don't think dyneema slings are an issue when used attached to pro and taking falls, as the dynamic rope prevents their being shock loaded. For what it's worth, we use 8mm dyneema slings and have had no issue with leader falls.
Thorgon

Big Wall climber
Sedro Woolley, WA
Aug 18, 2010 - 04:53pm PT
BDC, in a dynamic Leader Fall scenario, the rope absorbs the impact force. That is what ropes are designed to do, hence "Dynamic Rope", the problem with Dyneema and Spectra is a fall scenario directly onto the sling! Some n00b (or anyone) girth-hitches a couple together at the belay and slips with slack in the system! Then, like the DMM video shows, the impact force can break the sling, due to Dyneema and Spectra's rigid properties! This can be avoided by simply keeping "slack" out of your anchor system... I have taken some big leader falls on BD Dyneema slings, with no problems and I weigh 220 lbs.!! The rope groans a little, but no problem with the slings!! Hahaha


Climb on,
Thor

Dyneema & Spectra are like using a swaged cable in their inherent properties!
Brokedownclimber

Trad climber
Douglas, WY
Aug 18, 2010 - 05:45pm PT
Thor-

That's what I surmised initially. I'm reserving them specifically for City of Rocks chickenheads, with my Edelweiss 10 mm rope.
Gary

climber
Desolation Basin, Calif.
Aug 18, 2010 - 05:48pm PT
An "authority figure" told me he'd use them for biner to biner only.
orsemaj

Gym climber
SD
Aug 18, 2010 - 06:13pm PT
After watching all the guides in France climb with dynamic tethers, my wife and I started thinking about the idea.

Then on a burly decent in less than good weather, I jarred an old pin anchor pretty hard when a snowbridge collapsed on a couloir we were rapping. That really freaked me out. I only fell about one foot, but it really shocked the hell out of the system.

The next day we bought two DYNADOUBLECLIPs ( http://www.bealplanet.com/portail-2006/index.php?page=longes&lang=us);

I am very happy with the upgrade from all the other attachement systems I have used in the past.
bergbryce

Mountain climber
Oakland
Aug 18, 2010 - 06:28pm PT
Interesting video at DMM.

How do you store one of those Dynadoubleclips on your harness?
orsemaj

Gym climber
SD
Aug 18, 2010 - 06:41pm PT
I primarily use the full length attachment and have it set up with a key lock locker. I pull it around my waist all the way to my haul loop or the third rear gear loop (crossing over the haul loop). I've also gone to the second gear loop but it hangs down a bit too much for me.

The only trick is getting all of ones gear or draws to lie on top of it. But this is pretty easy.

I've come to like this system quite a bit. WHen I was using daisies or the PAS, I would have to double up the sling on the biner and found that to be a hassel at times.
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