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Rope belaying

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lynx23. 08. 2013 09:54:00
primoza: the one in kibuba is also tested and says it withstands 6 falls.
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Zebdi23. 08. 2013 09:58:39
lynx, you sure? I found this on Simond website:

"8.2mm dynamic rope, designed for summer hiking and ski touring.
For use as a safety line only: not designed to withstand falls from a height.
Lightweight and compact, you'll forget it's in your backpack.
Unique tracking number.
Available in 3 lengths: 20m, 30m and 40m.
Warning: this rope is NOT suitable for climbing or mountaineering use."

I might use it for some abseil, but not for more. I'd rather take something else mežikanje

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neph23. 08. 2013 10:07:52
Jedriličar, some time ago I read articles on the topic but can't find them now... At the start we understood correctly, but according to my info, twin rope shouldn't be used as half, because advantages of twin are lost and problems with too high impact force arise. Not sure if clipping twin into same quickdraw is dangerous or not, so correct me if wrong.

In practice many clip twin together into same device. Personally wouldn't use twin as half.

ps. Juš, good rope right? velik nasmeh
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jedriličar23. 08. 2013 10:19:07
@Neph: but according to my info, twin shouldn't be used as half...
Yes, main advantage of twin over half is that with twin you can climb triple, with half you cannot, meaning twin rope 'stronger' than half, actually yes, one twin can hold one climber alone, one half cannot (actually yes as second, but no one writes that nor tests, so forget it)
This means if you use twin as half no problem if you follow ALL quickdraw clipping rule, if reverse (half as twin) then problem you can disappear. Of course no smart person uses half as twin, didn't buy it for that, I just noted the possibility and dangers if misused, but seems I caused confusion... so use twin by twin rules, half by half rules...velik nasmeh
Anyway, I use BEAL ICELINE 8.1 mm, excellent rope for all purposes....
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neph23. 08. 2013 10:21:33
Jedriličar, thanks for explanation, found also official Mammut explanation, adding as interesting:


"The CE- Standard for Half- and Twin Ropes is different regarding the testing: twin ropes are always tested both pairs clipped into one biner (80kg mass, 12 falls), half ropes are... tested as a single rope with a 55kg mass (5 falls required). So the standard for half ropes is tougher than the one for twin ropes as half ropes also offer a great safety margin as a single rope (only to be used to belay two second climbers from an anchor). Therefore, half ropes can always be used in twin rope technique as well (whereas the other way round, twin ropes can not be used in half rope technique). The impact force is not affected by clipping one or two half ropes through the same biner."

So we got to the bottom of it. velik nasmeh
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JusAvgustin23. 08. 2013 10:23:03
And hit the bottom of the barrel! nasmeh
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lynx23. 08. 2013 10:28:12
Zebdi: didn't say it's for climbing. mežikanje On the package data for falls too.
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jedriličar23. 08. 2013 10:30:41
@Neph: there, correct explanation from authoritative source... think even saw pic explaining it somewhere... anyway, glad we all agree... velik nasmehvelik nasmehvelik nasmeh no more zmedenzmedenzmeden
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Bobaje23. 08. 2013 20:47:55
Twin and double rope are basically intended for climbing, i.e. always in pairs, hence smaller diameter. When using two ropes in climbing, a fall factor "2" can occur. Which means you climb 50m above the belay and fall 50m below belay without intermediate protection. That means you fell 100m on a 50m long rope. Height/length is Fp=2. Even a single rope over 9.5mm withstands that. Using only one rope from twin or double rope doesn't guarantee safety for falls at Fp=1. To put it simply, using only one rope from twin or double rope or thinner ropes is limited to belaying the second in the team or abseil, where the rope is more or less always tensioned, preventing long falls. Well if you ask me with such rope even Fp=0.5 fall is not recommended. If you like yourselves buy single over 9.5 and you'll be completely and above all safe with proper use. If anyone interested in fall factors type into google and will know what I'm talking about.
And one more: watch when buying ropes not to buy static rope which despite thickness is deadly dangerous for climbing.
That's it, hope understandable.
Lp Jure
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Keko23. 08. 2013 21:06:46
I think Bobaje explained the difference between ropes and their proper use most nicely and most vividly. It was explained to us something like that in alpinism school.
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jedriličar24. 08. 2013 08:04:51
@Bobaje: there is no rope that would hold a fall factor 2 as you describe, in such a fall everything would fly down (belay stance, second climber, and it would also rip out intermediate protection if any), for the simple reason there is not enough rope in the system for fall amortization (50 m free rope means only 10 m left for fall amortization, if it is stretched at all) ...
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jedriličar24. 08. 2013 08:23:44
If you mean these new pendulum jumps, the thing is a bit different; it's hard to talk about the fall factor there: namely, the jumper goes far enough to the side from where the swing is performed so that the rope tenses and then jumps, so there is minimal free fall there, the rope is already tensioned. For a vertical fall (the factor is not important now) of any length, first you have a free fall twice as long as the rope length between the climber and the last intermediate protection, then when the climber falls below the last intermediate protection by the length of the free rope, only then does amortization start, in a way that the point of the last intermediate protection suffers and the rope stretches along its entire length, from the stance to the climber. However, the smaller the fall factor, the greater the amortization and the greater the probability that the fall will be stopped. In the example that bobaje gave, there is simply no chance that such a fall could be amortized; the following would happen:
- very likely the falling climber would break his spine from the violent jerk at the end of the fall
- the highest intermediate protection would be ripped out
- then further intermediate protections would be ripped out in a zipper-like chain
- finally, it is questionable whether the stance and the belayer on it would hold under such forces
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Bobaje24. 08. 2013 08:28:43
Jedriličar, obviously you still have a lot to learn, so read some professional literature first, so I don't come off as smart. A proper rope normally holds such loads. I didn't talk about the stance, nor about bouncing off rocks during the fall, and we know how that ends.
"from simple reason because there wouldn't be enough rope in the system for fall amortization (50 m free rope means only 10 m left for fall amortization, if stretched at all) ..."
But I don't get that at all.
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jedriličar24. 08. 2013 08:34:11
I think you don't understand fall factors at all, but that's your problem; I just wanted to point out your wrong thinking in good faith, but it's your thing. Look at the pictures you can find in any good mountaineering literature about what the fall factor is, and everything will be clear to you (fall length/stretched rope between belayer and climber).
Lp and have a nice weekend.
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Bobaje24. 08. 2013 09:01:03
Well, Jedriličar, you have no idea what you're talking about. That's exactly why you climb with dynamic rope, so that there is no spine breakage. I don't know what isn't clear to you. I have a feeling that for you climbing with dynamic rope is the same as climbing with a sling.
Somewhere I read that on this forum users are being misled; well, this post by Jedriličar is one such, but here thank God for ignorance.
I'll explain once more: the human body during a fall withstands an impact force of 15G or translated 13kN of force. At this force, injuries already occur that are still compatible with life. Of course, I'm talking about a fall onto the rope, without hitting rocks etc. In a fall onto dynamic rope (height doesn't matter at all) at Fp=2, the force on the body is between 6 and 8kN, well below the injury threshold. Whether the stance holds or not has nothing to do with it, because we're talking about ropes. A fall onto static rope at Fp=2 means a force on the body of 17kN!!! So you're definitely dead or at least seriously injured. That height doesn't matter is shown by the fact that these anomalies, i.e., forces, start appearing already at 1 meter height. Now the best thing, which I often see on via ferratas. Securing with an auxiliary cord. Example: Auxiliary cord (elasticity somewhere between dynamic and static) is about 0.5m long. The hiker, clipped in vertically with a karabiner, climbs from piton to the next piton 10m and falls just below the latter. Fp=fall height/rope length=10/0.5=20!!
So fall factor 20!!!! Nobody survives that. Now it will probably be clear to you why there are so many problems because of ferrata kits. Lately, quite a few systems have been withdrawn from sale. With such a factor, it's an art to make a system that reduces the deadly force to a survival force. Jedriličar, google and surf, you'll find everything.
That's enough. Oh, and this: dynamic rope has about 12% stretch, static 5%, auxiliary somewhere in between.
Be safe!
Lp Jure
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jedriličar24. 08. 2013 09:06:40
Now you explained everything nicely so we can focus on climbing ...
Lp
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Bobaje24. 08. 2013 09:15:40
http://www.youtube.com/watch?v=2kfZ85Ks170

http://www.youtube.com/watch?v=GTC0dNG4Ygg

Jedriličar, watch the videos. Obviously even at Red Bull they have no clue!
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jedriličar24. 08. 2013 09:26:58
Look, friend, obviously you got hurt that I dared to write something to you because your ego is too big, but since you nicely found the videos (the second with fall factor is important, the first one is ???), nicely study them, then look at your first post, the one I referred to, and the nonsense you detailed there .... and again I say, it was well-meant, take it as you want. And once more, I wish you a nice weekend
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Bobaje24. 08. 2013 09:58:28
I hope you don't believe a word I wrote. Yeah, sometimes I'm just rude. Hats off to some experts.
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Keko24. 08. 2013 10:27:12
Guys, so you don't argue, it's best to check the thing from a physical standpoint. For the calculation I used fall factor 2 and fall depth 100m on 50 meters of rope. For the test I took an equipped alpinist with total weight 100 kg, and used rope:
http://www.kibuba.com/Plezalna-oprema/Vrvi/Enojne?pID=3742
The result I got is that the rope holds such a fall. The rope will stretch 29.4% in a dynamic fall, which is still within limits, as the rope handles dynamic stretch 35%. Some ropes list only static stretch, which is much smaller.
It needs to be remembered that in such a fall, per manufacturer instructions, the rope must be discarded, as it was overloaded and in the next similar fall its arrest force will no longer be adequate.
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