Discussion Topic |
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| Messages 1 - 9 of total 9 in this topic |
rgold
Trad climber
Poughkeepsie, NY
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Aug 12, 2011 - 05:09pm PT
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They've taken a single (relatively short) strand and doubled it, tying a figure-8 in the bight end. You can't do this with a pair of twins. I guess you could get a 120m twin strand and do this, but roping up would involve threading 60m of rope through the harness and then using the whole pile to tie the figure-8; obviously an absurd procedure.
Carry on with the usual double tie-in; it's fine.
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Ksolem
Trad climber
Monrovia, California
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Aug 12, 2011 - 05:25pm PT
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I would not want to deny myself the option of being able to untie one cord without undoing he other.
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Gene
climber
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Aug 12, 2011 - 05:28pm PT
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^^^^^^^ Very good thought Ksolem. I had never considered that. Thanks.
g
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GreatLakes
Trad climber
Chicago, IL
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Topic Author's Reply - Aug 12, 2011 - 05:32pm PT
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I was thinking of a figure 8 follow through with with the ropes doubled (similar to a normal tie-in but both twin ends in parallel, not on a bite).
I will keep tying in as rgold suggested.
good point Ksolem.
What about the multi directional loads you are putting on the harness? You don't see those as much with halfs because typically only one rope is loaded at a time.
EN 12277- I believe only shows one load....although it is to the belay loop.
http://www.hamradio.si/~s51kq/photo_album/Climbing_and_Mountaineering/pdf_climbing/UIAA/PictUIAA105-EN12277Harnesses.pdf
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rgold
Trad climber
Poughkeepsie, NY
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Aug 13, 2011 - 01:58am PT
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What about the multi directional loads you are putting on the harness? You don't see those as much with halfs because typically only one rope is loaded at a time.
No, no, it is the other way round. Twins are clipped together through every piece, so the two strands will always apply parallel loading vectors. Halfs are potentially a different story. If two pieces are placed at some distance apart but in the same horizontal feature (a pretty common situation in the Gunks, for example), then a fall results in an "M" configuration of ropes and the loads on the harness are multidirectional.
Back in the days of swami belts, this would cause the two tie-in loops to migrate to the climber's left and right sides, thereby supplying opposing loads to the swami with consequent flattening effect on the climber's torso. In order to avoid this, we always used to tie in so that the loops interlocked and so could not separate when pulled in opposite directions.
I used to tie in this way, out of habit, when swami's were replaced by harnesses, but eventually got lazy about it and stopped bothering. I've never seen any evidence of stitch-ripping in the harness tie-in pockets caused by "M" falls, and I've taken a bunch of 'em over the years.
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Ghost
climber
A long way from where I started
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Aug 13, 2011 - 02:46am PT
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A couple of thoughts.
Regarding falls: I think this is a non-issue. I've climbed on doubles/halfs/twins tied separately for 30 years and fallen more times than I can remember. It really just ain't no thing. Fall on both equally. Fall on one a little bit more than the other. Fall on just one. The result is always the same: If the gear holds, you're fine.
Regarding the idea of one long rope vs two shorter ones: what Kris said about being able to untie the ropes independently is important, but you have to realize that when using a single long rope only one end is really affected. Just make sure your partner ties in at the middle and you get the two ends.
There are advantages to using a single long rope, although they're probably not significant enough to make it worth while. I once scored a 100m 9mm rope for an unbeatable price and climbed on it a lot over many years. One thing it was really good for was multiple-rappel descents. Faster and easier than with two ropes. It also offers the possibility of running 100m pitches on moderate terrain, but that's really only a consideration on long alpine routes.
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rockgobbler
Big Wall climber
London, UK
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Aug 13, 2011 - 05:21am PT
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Yea another vote for being able to untie each independently. Great thing is with half or twins you can stay clove-hitched in with the other rope while you do it. Good for sorting out the occasional tangley twited rope on multipitches.
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Bobert
Trad climber
boulder, Colorado
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Aug 13, 2011 - 10:34am PT
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I agree, tying in independently is the ticket. Don't really see any difference when falling on a single rope in a double rope system than when falling on any single rope tied into your harness. While ice climbing I also often go from twin clip-ins to double-rope clip-ins when I have a lot of rope out and a lot of pro (with lots of extra friction). I guess that is not to be recommended with a standard twin, but it does not bother me. I figure my ice pro coming out is the main risk and the softer the fall the better.
Just read about the M falls. Never thought about that. I think my harness is strong enough to take it.
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