physics of Half rope method

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Chicken Skinner

Trad climber
Yosemite
May 24, 2009 - 01:29am PT
Smartass answer. Shorter pitches.

Ken
old toad

Trad climber
yosemite, Ca.
May 24, 2009 - 11:58am PT
WBraun

I climb on a single 9.2mm rope now....

Werner, you don't need a rope!!!
jstan

climber
May 24, 2009 - 01:22pm PT
And here I thought this was going away. This isn't about physics. It is about
whether you will need protection at the level of the UIAA drop test.

What seems to be happening here for simple technical rock is the UIAA is
counting on the other half rope as a backup for those cases where a half rope
fails a standard 80Kg. single drop test.

If so then anyone who actually needs protection at that level also needs to think
carefully as to whether the half rope setup is right for them. For now you have
to start worrying about placement positions and/or clipping as a twin.

For simple technical rock where you really are accepting these kinds of falls use
two singles. In alpine climbing where rope cutting and weight are issues and
there is not much protection to start with the logic might tend to weigh in on
the twin or half rope side where being able to rappel long distances is also a
big plus.

Bottom line, a purely technical rock climber whose eyes are not crossed can
make some use of this alpine technology.

If your eyes are crossed, think twice.

Seems to me.
jiimmy

Boulder climber
san diego
May 25, 2009 - 05:24pm PT
sounds like wisdom is .4mm
GreatLakes

Trad climber
Chicago, IL
Sep 10, 2010 - 09:54am PT
Being completely new to the sport and also an engineer....a certain calm comes over me when I explore the different ropes and techniques. I can't seem to find the answer to one question though. How do I tie a half rope system into my harness? I'm assuming two figure 8's would put a torque on the harness and could cause a dangerous situation. Please let me know what knots and how you tie in using half ropes and twin ropes if it differs. Thanks in advance for the insight.

I would also appreciate any names of reference books/websites that detail out the half rope system.
rhyang

climber
SJC
Sep 10, 2010 - 10:54am PT
You just tie in each rope (whether half or twin) to your tie in points the same way you tie in with a single. Though with half ropes you want to pay attention to left vs. right ropes being tied in the same way for both leader & follower. Not sure about reference books .. I learned from more experienced partners.
GreatLakes

Trad climber
Chicago, IL
Sep 13, 2010 - 01:27pm PT
Top roping question: When taking my wife and kids out Iíd like to top rope with two ropes.
1. Should I set up two separate anchor systems?
2. I weigh 230lbs so the rope is being punished when Iím in the air but does it really matter if I use a single(double), half(double) or twin(double) for top roping?

Leading:

3. When leading, why canít I just use two singles while using half rope technique? If I stager the protection shouldnít the load mainly be on one rope anyways?
taptaptap

Trad climber
mass.
Jan 14, 2014 - 01:41pm PT

For the physics minded, the journal article about double ropes has been written:
B. Ernst & W. Vogel, "Determination of the redistribution shock load in climbing double rope system"
http://www.sciencedirect.com/science/article/pii/S1350630708001246
If you don't want to pay the big bucks for the article, see if you can get a free copy through your local library.

Regarding the question about the use of multiple "single" ropes, the question becomes one of finding a sweet spot where everything works OK. For ropes to work, they must simultaneously not stretch too much, must keep the force on the anchor & the deceleration of the arresting climber down to a dull roar, and not sever during fall arrest. The use of multiple "single" ropes will increase the force on and the deceleration of the arresting climber. If handled intelligently dual "single" ropes will PROBABLY work out without surprises for a top-rope situation where the anchors are reliable. BUT, it is possible that such a system will push things outside the sweet spot where everything works OK and challenge the anchor and/or the climber with unexpectedly high forces. Hence, no "sound practice" can recommend dual "single" ropes.
rgold

Trad climber
Poughkeepsie, NY
Jan 14, 2014 - 02:30pm PT
It is worth noting that the article referenced appears, from the list of figures, to deal with one strand of a twin rope system failing. It does not (for good reason) consider the multitude of scenarios that might arise in half rope technique.
Big Mike

Trad climber
BC
Jan 14, 2014 - 09:12pm PT
First of all, thank you for the very interesting discussion. Lots of interesting info here.

I've been climbing for more than fifty years and I think I need rope stacking lessons. When I flip one of those piles, I get the mother of all Gordian knots half the time.

I got a little rope trick for anyone who has ever had this issue. I simply stack both ropes over my personal anchor,starting with really long loops, which each loop progressively shorter than the next. This way, the next loop you stack won't cross under the previous loop which is what causes snags.

So start with six or seven foot loops (or longer if you can) and work your way down to six inch loops by the time your partner reaches the belay. If you do this correctly the rope will flip perfect every single time. The most important part is paying attention to the length of the loops as you belay.

This trick works real nice for single ropes too.

Also never stack the ropes seperately. Treat them as one.
Big Mike

Trad climber
BC
Jan 15, 2014 - 11:15am PT
Bump
Doug from Hobart

Trad climber
Tasmania
Mar 5, 2014 - 01:33am PT
I also use your "rope trick" Big Mike. Works well as long as you are careful with the stacking, otherwise you can end with a monumental mess.

On another note, I'm looking at getting a new set of half ropes. Currently using 8.0 mm Mammut Pheonixes which I've had for a few years and been very happy with, but they are about ready for replacement.
Pluses: at 42 gms/m they are the lightest ropes I've found; they've been pretty durable despite their thinness; less bulky in the pack.
Minuses: They do seem to tangle more easily than previous ropes I've used; fall rating is lower than other half ropes.
Anyone out there got any comments/suggestions? Anything new on the market I should look at?
briham89

Big Wall climber
santa cruz, ca
Nov 29, 2014 - 05:40pm PT
Half rope noob in the house!!!! WOoooo!!

So....

Let's say I lead a single pitch of ice using two half ropes. I then get to the top and want to set an anchor for top roping for my partner / group of friends that want to TR the climb. Should the two ropes be run through the master point biners together and everyone ties into both ropes when they climb? I know a single half is ok for top roping but the stretch will be large which could result in a ground fall if someone blows it say 3m up. So is using two the way to go? Or drop the halves and just use a single instead for this scenario?
Big Mike

Trad climber
BC
Nov 29, 2014 - 06:36pm PT
I also use your "rope trick" Big Mike. Works well as long as you are careful with the stacking, otherwise you can end with a monumental mess.

Yeah you do! But when you get it right it works great.

Brian- yeah, just clip both strands through the master point. That's what we always do.
briham89

Big Wall climber
santa cruz, ca
Nov 29, 2014 - 09:38pm PT
Thanks Mike! I'm going to try your stacking suggestion as well. That's a good idea. Hope you're doing well up there, and getting some snow!!
perswig

climber
Nov 30, 2014 - 04:21am PT
Haha!
Buried in the morass was this gem from Rgold. Worth reading the whole thread just to see the context.

The UIAA rating for half-rope logging is only for non-snagging applications.



Dale

rgold

Trad climber
Poughkeepsie, NY
Nov 30, 2014 - 11:56am PT
RG: I've been climbing for more than fifty years and I think I need rope stacking lessons. When I flip one of those piles, I get the mother of all Gordian knots half the time.

BM: I got a little rope trick for anyone who has ever had this issue. I simply stack both ropes over my personal anchor,starting with really long loops, which each loop progressively shorter than the next. This way, the next loop you stack won't cross under the previous loop which is what causes snags.

So start with six or seven foot loops (or longer if you can) and work your way down to six inch loops by the time your partner reaches the belay. If you do this correctly the rope will flip perfect every single time. The most important part is paying attention to the length of the loops as you belay.

Thanks Big Mike. I've known about this stacking trick for many years. By the way, if you are going to be flipping the stacks, which is what the comment referred to (and because the same person is leading consecutive pitches), then you have to do the opposite of what you posted, which is to say start small and make bigger and bigger loops.

My problem is I can't seem to manage to make the graduated loop system work all of the time, and one bad tangle wastes more time than restacking every pitch. The only time I can consistently get it right is when I belay with a guide plate off the anchor, which I'm not a fan of in general but which does free you up (at the expense of an ideal belay for the second, no matter what anyone says) to fuss with the loop lengths.

Even when you get the loop lengths right, flipping the pile can change things enough to create tangles. Yes, I know about getting the new belayer tie-in right next to and parallel to the current belayer's tie in to that the pile can be flipped without having to be carried. I've still had bad tangles.

I've started to wonder whether it might be better to stack with short loops all of the same length. One of the problems with the graduated loop method is if something goes wrong with a loop six feet below you, there isn't much you can do about it.
Big Mike

Trad climber
BC
Nov 30, 2014 - 12:32pm PT
Hey Brian! I'm doing real good these days, thanks for asking. Snow is coming! But sun and cold are dominating again for the next couple days, so climbing is on my mind..

By the way, if you are going to be flipping the stacks, which is what the comment referredl to (and because the same person is leading consecutive pitches), then you have to do the opposite of what you posted, which is to say start small and make bigger and bigger loops.

No sir! This is probably where your tangles happen. It's way easier to start long because the loops will stay on your tether while you're looking down at your second. If you start short, they can slip off without you even noticing, or if you do, then you have to fix it which takes longer!

You can still get a few tangles when you flip if you drop a couple of the short loops in the transfer, but at least they will be towards the end of the pitch when the belayer has less rope to deal with and will easily be able to sort it out.

I also typically belay halfs with my atc guide in autoblock mode which like your plates makes handling the ropes easier.

I used to have seconds complain about rope snarls all the time, but now i never hear a peep after I flip the rope, and all my leads are clean sans rope snarls.
rgold

Trad climber
Poughkeepsie, NY
Nov 30, 2014 - 12:51pm PT
Hmmm. There is some kind of communication error here. You don't flip a stack at all when alternating leads, the short loops are on top for the person who will become the leader. The only time to flip stacks is when the same person is going to lead consecutive pitches. If you don't flip the stack in that case, the leader's rope will be feeding off the bottom. If you stack loops small to big and then flip the stack, the new leader will be pulling out the big loops before the small loops, a recipe for a guaranteed tangle.
Big Mike

Trad climber
BC
Nov 30, 2014 - 02:45pm PT
Right. I don't know where you got alternating leads from? I am talking specifically about the situation you mentioned, when one person is leading all the pitches and one person follows them all.

Start long, work progressively shorter. Just try it out.
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