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tradmanclimbs
Ice climber
Pomfert VT
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May 11, 2010 - 03:09pm PT
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The best way to doubble your brakeing power is to simply add a 2nd locker.
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cleo
Social climber
Berkeley, CA
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May 11, 2010 - 03:10pm PT
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Yes, interesting - the center bar is indeed the only thing keeping the rappel going, when normally it is the thicker ATC walls.
If the center bar fails = disaster.
If the outside (hand side) wall fails = probably disaster.
But one is designed for the load, and the other, presumably, is not.
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High Fructose Corn Spirit
Gym climber
Full Silos of Iowa
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May 11, 2010 - 03:14pm PT
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Cleo- that's the dumbest rigging relating to rappel I've ever seen. Chiloe is exactly right. That would be an emergency-only system. And what would require that? when better options exist. An accident waiting to happen. Wow!
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Edge
Trad climber
New Durham, NH
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May 11, 2010 - 03:18pm PT
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I don't use this method, as I generally climb on doubles or with a similar sized haul line.
It seems to me that if the knot got shock loaded enough to pull through the rap ring, say via an aggressive rappel, bounce, whatever, only then the biner would come into play and prevent tragedy.
But couldn't it also then become damned near impossible to pull it back through to retrieve the line? Especially if it is a full length rap and you are playing against 70m of rope stretch?
Elucidate me.
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cleo
Social climber
Berkeley, CA
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May 11, 2010 - 03:36pm PT
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See, I'm glad I asked and glad I only used it once when I was first starting. Now I can go chat with my (far more experienced) friend who showed this to me in the first place.
I rarely rap on a single line, fwiw. Usually 2 lead lines with a prussik/autoblock or a fireman's belay. Or I find a walk off.
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rockermike
Trad climber
Berkeley
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May 11, 2010 - 03:40pm PT
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I thought Cleos setup was pretty cool. I suppose it depends on which ATC you are using but I can't imagine the crossbar blowing from rapping. Now rapping on a 7 mill. that WOULD get my hair standing on end - though I have rapped with a pig on a single 8 mill. Scary enough.
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Chiloe
Trad climber
Lee, NH
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May 11, 2010 - 04:02pm PT
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I can't imagine the crossbar blowing from rapping.
Your imagination is better-behaved than mine is!
That ATC cross-piece might be strong, but I'm pretty sure they didn't design or test it for direct force like that.
Even the much thicker tube walls of an ATC wouldn't normally have to take the full weight of a rappel or a fall. That's the biner's job.
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High Fructose Corn Spirit
Gym climber
Full Silos of Iowa
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May 11, 2010 - 04:03pm PT
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Cleo- I take my adjective back. Who's to say what "dumbest" is in this sport. Would I bet I could rap your rig 999/1000 times safely? Yes. So would that be dumb? Everything's relative. Who's to say. Not me. I've done dumber things.
EDIT
I can't imagine the crossbar blowing from rapping.
What would concern me is an unforeseen weakness, crack (from metal fatigue, etc) on the crosspiece out of view somewhere and then the crosspiece under load cracking off before my very eyes.
(I already worry about my old ATC in standard mode-- cracking and crumpling in places on rappel-- and what I'd have to do quickly in response, that's enough.)
Much "dumber" is not replacing my ATC every few years.
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rockermike
Trad climber
Berkeley
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May 11, 2010 - 04:09pm PT
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OK, I stand corrected; it appears the original BD ATC has a pretty thin cross-member (as in Cleo's photo). Maybe shaky. For myself, I have a BD Guide,and the middle cross-member is a solid wall. Plus the whole thing is designed to hang off the eyelet when used in autoblock mode. So I still can't imagine... ha
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cliffhanger
Trad climber
California
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May 11, 2010 - 04:12pm PT
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Here's a possible scenario for an EDK: two brand new slick polished shiny new ropes, a wet day, and you just had some salami adding some grease to the equation. You tie the EDK, start your rap, it rolls thru all 18" of the tails. The dirt nap.
You could make the EDK safe by tying a good knot in the tails: Flemish bend, overhand follow-thru (not the EDK), or even a sheet bend.
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Mighty Hiker
climber
Vancouver, B.C.
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May 11, 2010 - 04:16pm PT
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The Petzl diagram of the EDK setup might be improved if the two ropes were differently coloured, and it clearly identified which rope was which in terms of diameter.
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cleo
Social climber
Berkeley, CA
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May 11, 2010 - 04:20pm PT
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What would concern me is an unforeseen weakness, crack (from metal fatigue, etc) on the crosspiece out of view somewhere and then the crosspiece under load cracking off before my very eyes.
I worry about that too in a standard rappel setup. Actually, I worry a lot about that - If those walls blew, you're hosed even with the biner taking some (most?) of the load (does it take most of the load? I'm not so sure...)
I currently use an ATC XP - MUCH thicker walls than the original ATC. Much thicker center cross-piece.
I'm on my 3rd ATC because I worry so much.
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cleo
Social climber
Berkeley, CA
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May 11, 2010 - 04:21pm PT
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ATC XP
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Gene
Social climber
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May 11, 2010 - 04:24pm PT
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The Petzl diagram of the EDK setup might be improved if the two ropes were differently coloured, and it clearly identified which rope was which in terms of diameter.
Agreed. The Petzl diagram shows only a single rope - I don't see any knot connecting two different cords. Why would anyone EVER use this set up with a single rope rappel?
By way of contrast...
g
Pictures lifted from other posts.
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Mighty Hiker
climber
Vancouver, B.C.
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May 11, 2010 - 04:27pm PT
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Appreciating that gene's photo may be for illustration rather than real-world, it's weakness being use of a single link and a single sling. No redundancy. It may be a brand new sling, properly tied, and the link may be a brand-name one, properly closed. And of course sometimes you just don't have stuff to spare. But redundancy is a virtue.
And looking at the knot joining the ropes in the photo - why not use a Flemish bend there, with tails? Seems simpler and more reliable than what is shown.
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Gene
Social climber
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May 11, 2010 - 04:42pm PT
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Mighty Hiker,
Could not agree with you more. I just can't see any benefit to the pull cord method beyond the couple of pounds difference between a 5 or 6 mm pull line and a 8 or 9 mm rope. Not enough to satisfy the risk/reward equation.
As I understand it, the set up involved in the fatality lacked the figure 8 on the pull side and the biner attached to the rap side line. So sad.
Quoting shipoopoi
whatever system you are using, i encourage a ritualistic approach to setting up rappels, where one is in the zone, not talking to anybody, and making the system from start to finish without interuption.
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Jay Wood
Trad climber
Fairfax, CA
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May 11, 2010 - 04:52pm PT
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Rapping a single skinny cord, a munter hitch would be probably be safer and better control.
Maybe add an extra turn around the spine of the biner.
That atc setup gives me the willies.
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cliffhanger
Trad climber
California
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May 11, 2010 - 05:01pm PT
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Werner made an excellent post, one of the best so far and bears repeating:
Werner Braun: I rapped with 7mm for 20 years with the 7mm thru the anchor and always pulled the lead line. There's no slippage if you use a figure 8 correctly with an added friction biner. Those new fangled rappel gadgets might be a problem though and that's why I still use a figure 8 today.
Always be alert to potential problems and have for-thought before you do anything is the motto.
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Gene
Social climber
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May 11, 2010 - 05:04pm PT
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What about this for a single skinny cord set up?
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climbingcook
Trad climber
sf
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May 11, 2010 - 05:06pm PT
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The Petzl diagram shows only a single rope - I don't see any knot connecting two different cords. Why would anyone EVER use this set up with a single rope rappel?
The illustration has no EDK or flemish bend because it's showing only one rope. They're illustrating how to rappel safely using a grigri.
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