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Brandon Lampley
Mountain climber
Boulder, CO
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Apr 13, 2009 - 02:34pm PT
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All sorts of technical speculation going on here. One thing thougn needs to be clear. ALL double ropes on the market today are NOT RATED AS TWINS. Some may not be because they didn't go through the twin certification process. But, some, like the 9.0 doubles from some manufacturers, have been through the twin tests, and FAILED because of high impact forces.
Clipping both doubles to a single piece after spearating them early in the pitch... This is a different scenario force wise than clipping them like twins from the get go.
Clipping your fat doubles like twins on a bolted pitch, no big deal. Bolts are strong. Clipping your fat doubles like twins on a straight tips crack pitch with rps and micro cams, not for me.
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dirtineye
Trad climber
the south
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Apr 13, 2009 - 02:53pm PT
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well I hope yo uare not referring to my post, because I did not mention clipping unrated for both as both. That could be bad, of course.
Also for the tech side, Rgold did good explanation of clipping two NOT creating the same thing as just doubling the effect of clipping one. Maybe he will post it again for your amusement.
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PP
Trad climber
SF,CA
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Apr 13, 2009 - 02:54pm PT
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I love double ropes it gives you alot of creative options when weird things happen. They worked really great on inverted stair case on Fairview.
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Brandon Lampley
Mountain climber
Boulder, CO
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Apr 13, 2009 - 03:07pm PT
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No dirt, tradmanclimbs is sharing lots of cool practical observations, but also incorrect factual information.
Rgold has been clearing things up though.
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tradmanclimbs
Ice climber
Pomfert VT
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Apr 13, 2009 - 03:24pm PT
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yer right , Some of what I say is probobly against the rules but in the practicle sense of how it actually works I feel that I am dead on most of the time. Why is it not safe to clip both of my 1/2 ropes to a single biner if the little pictuer on the card that comes with the ropes shows a pitcuer of both ropes running straight clipped to the same biner and a happy face. No skull and crossbones like the pictuer with the ropes all twisted to crap, seperated and then stuffed back into the biner. Regardless of what the pictuer says I seem to recall my partner clipping the bolts on Total Recall just like she was useing twins, then she greased off for a 20 footer. Sterling 8.8 maratrhons. resulting catch was light as a feather. Didn't yank me any more or less than catching simeler falls on single rope. Real life ain't a theory ;)
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tradmanclimbs
Ice climber
Pomfert VT
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Apr 13, 2009 - 03:31pm PT
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PP I like the system otherwise I wouldn't use it. I am just willing to concede that the single rope system has its merits as well. There must be a reason that the doubble rope system never really dominated the Yosemite scene where as in the east, doubble ropes have had a pretty strong showing.
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rgold
Trad climber
Poughkeepsie, NY
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Apr 13, 2009 - 03:32pm PT
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Blah: In the last few years, I've read posts of several UIAA single rope drop tests applied to one of a pair of half ropes. Not quite factor 2, but close enough at factor 1.78. 80 kg weight, not 55 kg. My memory is that you get about three such drops before the half rope breaks, which is not enough to earn a UIAA single rope certification.
Edit: Half ropes do not break on the first UIAA single-rope drop test. Consider this in view of
Number of Rope Failures amongst German and Austrian Mountaineers and Climbers since 1968
by Pit Schubert
Because the fall on the Dodero-test-machine is much stronger than in practice, it is not possible (in practice no rigid falling mass, no strictly static belay) for a rope which holds one fall on the Dodero-test-machine to break in practice - not in knot, not in the running belay, not at the belaying device, only when the rope is loaded over a sharp edge, normally a rock edge. And this happens as the table shows very, very seldom.
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tradmanclimbs
Ice climber
Pomfert VT
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Apr 13, 2009 - 03:35pm PT
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I posted that up thread with the unscientific disclaimer. they break!
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rgold
Trad climber
Poughkeepsie, NY
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Apr 13, 2009 - 03:48pm PT
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As for the comparison with the tag line, I'm at a loss to see much of an advantage. The weight is about the same I think. The tag line could be used to haul up gear (its original use), but that seems unnecessary except on wall climbs. Seems like twins would make much more sense if you don't want the hassles of alternate clipping.
The main drawback of the tag line rappel system and, to a lesser but not insignificant extent, twins, is that most people set it up to pull the tag line (to prevent the uneven running that is typical if the set-up is to pull the main rope). This means that if the rappel rope hangs up after it releases from the anchor, the party will be left with only the tag line to try to extricate themselves, rather than with a rope that can be lead on with some confidence and rappelled on without high anxiety and extremely low friction.
As someone who had exactly this type of rappel snag happen a year ago, I wouldn't go anywhere even slightly remote with a single rope and a tag line.
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rhyang
climber
SJC
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Apr 13, 2009 - 04:14pm PT
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So here's a (barely-related) question: does anyone have Edelweiss Dynamic 8.3's ? As I understand it, they are now rated as half ropes and twin ropes. But as of several years ago, they were only rated as half ropes. As far as I can tell, the older ones have the same impact force (5.8 kN as halfs), elongation, etc. as the current model.
Does anyone know if the current edelweiss dynamic 8.3's are simply the same ropes as before, just with new testing / marketing / labels as the previous model ?
I also have a set of pmi verglas 8.1's, but have only used them for ice climbing. They are also getting a bit old (bought in 2005), though they haven't seen much use. Wondering if I should just retire them in 2010 .. I can't see myself tr'ing on them.
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rgold
Trad climber
Poughkeepsie, NY
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Apr 13, 2009 - 04:26pm PT
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rhyang, I don't know whether the ropes are different or not, presumably they have to be. What would have to have changed is not any of the stats you mentioned, but rather how many UIAA drops with an 80 kg weight are held. I think the standard is 5 drops. The earlier versions of the rope couldn't hold 5 drops and the newer, presumably improved versions can. Whether this is due to a change in construction or in, say, heat-treating I do not know.
Edit: My bad. I didn't read your statement carefully enough and thought you were referring to the ropes passing a single-rope test when used individually.
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Jim E
climber
away
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Apr 13, 2009 - 04:31pm PT
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Half ropes are drop tested with 55kg on a single strand. Twins are tested with 80kg on two strands.
The addition of the 'twin' rating is probably due to the manufacturer deciding to have the rope tested as both. It's the 'in' thing.
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tradmanclimbs
Ice climber
Pomfert VT
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Apr 13, 2009 - 04:40pm PT
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Jim. so glad you showed up! Didn't you tell us awhile back that a single rope has a lower impact force than a 1/2 rope? Also remember something about elongation being not what most folks assume?
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tradmanclimbs
Ice climber
Pomfert VT
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Apr 13, 2009 - 04:55pm PT
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Rgold, I agree with you 100% on the tag line system. The times that I have used that system, IC and aid climbing etc. I use one of my 1/2 ropes as the tagline. I know i can lead on it and use it for a rescue. The 1st time I went out west RR, Zion, Etc. in 86 we led on a 50m 11mm and we had a 50m X11mm tag line. THAT was HEAVY setup! We were cutting edge modern at the time as those 11mm ropes were the latest rage ;) Back home in the east I usually did multi pitch with a single 11mm X 50m, no tag line and just hoped that nothing went wrong. We allmost never rapped... We allmost allways hiked off the top.
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murf02
climber
NYC
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Apr 13, 2009 - 04:55pm PT
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" As long as the rope runs relativly straight and are relativle close to each other you can fall all day on them and it won't matter one tiny little bit that both strands are clipped to the same draw. I have tested this very thouroghly."
This suggest that clipping both double ropes to the first piece off the belay would not only reduce the factor 2 on a single rope but friction and melt shouldn't be an issue as well?
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rhyang
climber
SJC
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Apr 13, 2009 - 05:03pm PT
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Wow, thanks for that link. Totally debunks what I had believed about doubles and impact force =:-O
The dynamic 8.3's seem to be rated at 10 UIAA falls for both the new and old models. With the older (non-twin-certified) model, it sounds as though using them as twins on bolts is probably ok, but maybe not such a great idea if on trad pro ..
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jbar
Social climber
urasymptote
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Apr 13, 2009 - 10:32pm PT
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rhyang - Not to be judged but I have an old 8.3 I bought to cut down on weight for an alpine trip I took years ago. Ended up leading a few sport routes and top roping a couple of climbs because it was all I had. Didn't take any extreme falls on it but it handled the use fine. Best I can remember it was rated at 7 falls so it may be different than the new one.
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Dr.Sprock
Boulder climber
Sprocketville
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Apr 13, 2009 - 11:38pm PT
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here is a real simple math approach to the falling aspects,
might get you in the ball park.
if the lines twist and form a "braid" while falling, the straight fiber count approach goes out the window as the sheaths will bind at some point, right?
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