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yokese
Dec 5, 2007, 2:11 AM
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andrewbanandrew wrote: Given that I am talking about sport climbing, I don't really care about the impact force so much as the potentially for smacking the wall. For a discussion of belaying a trad leader it would probably be important to consider, though.
Totally agree. Giving some slack to reduce the angle of impact with the wall and, more importantly, avoiding a roof-lip is a common and logical practice, I wasn't trying to argue against it. Also, I'm aware that the model is very simplistic and doesn't take into account the reduction of dynamism due to the friction with the biners, especially the top one.
But, funny enough, I never tried to calculate the impact factor with vs without slack, wrongly assuming that the increase in the fall length would be compensated by the increase in the active rope length.
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davidparks21
Dec 5, 2007, 2:14 AM
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Great stuff here, I have a couple of questions/thoughts on this.
First, I'd love to know if there are any solid numbers on the difference between a dynamic belay (e.g. a jump) with a gri-gri vs. a similar dynamic belay with an ATC. I saw someone post numbers for the difference between jumping and hunkering down, that was great. However, it's not quite natural for me to think that the impact force is significantly reduced if you jump using an ATC vs. using a gri-gri, so I'd like to see, or hear of, some solid tests that back up this hypothesis.
Secondly, on a multipitch route, I commonly tie in using the rope and will give myself a few feet of slack so I can move around comfortably at the anchor. This provides flexibility for me to provide a dynamic belay most of the time (all dependent upon having the right anchor configuration, and as was stated before, you have to do what is right for the situation). This necessitates that you think very carefully about placing those first pieces of pro because a fall on anchor would yank the belayer down a few feet (I often clip the anchor or a piece of the anchor right away and place a piece very shortly after this as well).
Any thoughts on that practice? This brings me back to the gri-gri question, if you are doing this and providing a dynamic body belay I wonder whether a gri-gri is a valid option on trad? If the body belay provides a good dampening the gri-gri is a safer option (among other things it gives a safer option for bailing off the side if taking slack over a ledge is critical). Note that I currently use an ATC for this, but worry about an anchor fall or need to bail off the side, so I constantly wonder if I'm better off with the gri-gri.
I saw a reference to the Italian study (which I'm not familiar with) that suggested that the ATC is always softer than the gri-gri, but it didn't address my question directly. I'd love some hard facts on it, and I'd love to hear peoples opinions.
Dave
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jules
Dec 5, 2007, 2:32 AM
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I've found that weighing 100 lbs is a surefire way to give a dynamic catch every time.
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blueeyedclimber
Dec 5, 2007, 2:33 AM
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Travis, I enjoyed that. Belaying is a pet peeve of mine and I have started a couple threads over the years on this subject, though none were as eloquent as yours.
One thing that I feel a few people still are not getting is that "dynamic belaying" depends on the angle of the climb. Vertical to overhanging. The more overhanging the more dynamic you should be. There is one thing that trumps the dynamic belay, however, and that is a ground or ledge fall. If my climber is in danger of hitting the ground or a ledge then they will be receiving a hard catch.
For slightly older discussion on belaying (and to toot my own horn a little bit), check out:
http://www.rockclimbing.com/...0to%20belay;#1408752
Josh
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andrewbanandrew
Dec 5, 2007, 2:56 AM
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jules wrote: I've found that weighing 100 lbs is a surefire way to give a dynamic catch every time.
Then I'll begin the 'half a grape and a bottle of laxatives' diet plan immediately...
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jt512
Dec 5, 2007, 3:42 AM
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yokese wrote: Interestingly, I just scrapped some numbers on a piece of paper and I got to the (possibly wrong) conclusion that leaving some slack will actually increase the impact factor of the fall. The only exception is when trying to avoid a factor 2 on multipitch routes. Please, let me know if I'm wrong:
You're close.
In reply to: Being y the distance from the belayer to the last piece of protection and x the distance of the climber above the last protection: FF1 = 2x / (x+y) Now if we add some slack (s): FF2 = (2x + s) / (x+y+s) FF2 > FF1 except when 2x > x+y (which would be decking on a single pitch climb).
To simplify the algebra, let's reparameterize the problem, using the definition of fall factor, d/r, where d = (your) x = the distance the climber falls with no extra slack in the rope, and r = (your) x+y = the amount of rope out with no extra slack, and we'll keep your s = extra slack added by the belayer. Now,
FF1 = d / r, and
FF2 = (d + s) / (r + s)
We want to know when FF2 > FF1.
FF2 > FF1 => (d + s) / (r + s) > d / r => dr + sr > dr + sd => r > d => d / r < 1.
But d / r is the fall factor with no extra slack in the rope. Call this the "initial fall factor." So FF2 > FF1 => initial fall factor < 1. And it is clear that FF2 < FF1 when the initial fall factor > 1, and FF2 = FF1 when the initial fall factor = 1.
We can see this directly by taking the limit of FF2 (which is monotonic), as s goes to infinity. If you know how to work with limits, you can show that
s -> infinity => FF2 = (d + s) / (r + s) -> 1, for any values of d and r. That is to say, no matter what the initial fall factor, adding slack makes the actual fall factor closer to 1. So, adding slack to "usual" falls (those < fall factor 1) increases the fall factor, whereas adding slack to severe falls (fall factor > 1) decreases the fall factor.
Jay
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chilli
Dec 5, 2007, 6:04 AM
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davidparks21 wrote: ...Secondly, on a multipitch route, I commonly tie in using the rope and will give myself a few feet of slack so I can move around comfortably at the anchor. This provides flexibility for me to provide a dynamic belay most of the time (all dependent upon having the right anchor configuration, and as was stated before, you have to do what is right for the situation). This necessitates that you think very carefully about placing those first pieces of pro because a fall on anchor would yank the belayer down a few feet...
this (multipitch), in my opinion, is the perfect case in which i try to avoid the whole jumping bit, because i find the quick pay of some slack as the leader falls to be just as (and actually more) effective, and much safer. i've used it a few times and it's done a stellar job. why the preference for hopping around to provide dynamic belay? or have i misinterpreted your statement?
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Basta916
Dec 5, 2007, 4:01 PM
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andrewbanandrew wrote: --I'd always get sucked up about three feet and he never tapped the wall. Maybe I got fatter?
There is a lot of factors, and couple lb shouldn't be one.... I see a lot of guys do a same thing because they tense up and lean back to catch a fall ( it's a great way to make a static catch), so next time try to relax and it could help your partner with a softer stop
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dingus
Dec 5, 2007, 4:18 PM
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chilli wrote: why the preference for hopping around to provide dynamic belay?
Grigri lockup fears mostly.
DMT
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climb_eng
Dec 5, 2007, 5:48 PM
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It's rare that you see such a simple and logical explanation related to the physical principles of climbing. Thanks a lot Jay!  .
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dingus
Dec 5, 2007, 5:57 PM
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He's had 15 years practice, witnessed SO MANY physics wannabes decking on the cold hard floor of internet forums - this is a distillation of wisdom.
Jay has a lot of this sort of experience and relatabilty in him. He's damn well earned his right to be crabby with people though. The place where he grew up in the interwebs was so much more unforgiving and you couldn't go back and edit your idiocy into something more palatable (once it was pointed out to you that is).
Jay is one internet authority, in my experience, that backs up his advice with real experience, thought and science. He rubs some the wrong way because he speaks that authority and when pressed, can defend it quite well.
Always right? I doubt it. Always informed? Mostly. Able to explain when he wishes? YOU BET!
Cheers
DMT
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Basta916
Dec 5, 2007, 6:06 PM
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dingus wrote: chilli wrote: why the preference for hopping around to provide dynamic belay? Grigri lockup fears mostly. DMT
Dingus, you have a lot of good points, but I don't agree with you on GriGri( I know you don't like them) If you feel better with ATC, then that's what you should use.....anyways, I don't think it's a grigri lockup. The idea is that you jump( not like a dyno jump, just a hop) when your partner is starting to put tension on the rope. If done correctly you act as almost a counter balance softening the catch. Correct me if I'm wrong......
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dingus
Dec 5, 2007, 6:11 PM
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Basta916 wrote: dingus wrote: chilli wrote: why the preference for hopping around to provide dynamic belay? Grigri lockup fears mostly. DMT Dingus, you have a lot of good points, but I don't agree with you on GriGri( I know you don't like them) If you feel better with ATC, then that's what you should use.....anyways, I don't think it's a grigri lockup. The idea is that you jump( not like a dyno jump, just a hop) when your partner is starting to put tension on the rope. If done correctly you act as almost a counter balance softening the catch. Correct me if I'm wrong......
Sounds right to me, cept for my alleged grigri-hate. Don't hate em at all and use one quite frequently.
I don't dispute the effect you describe. I still think the jumping thing became accepted because of grigris and feeding issues.
Cheers dude!
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Basta916
Dec 5, 2007, 6:22 PM
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dingus wrote: Basta916 wrote: dingus wrote: chilli wrote: why the preference for hopping around to provide dynamic belay? Grigri lockup fears mostly. DMT Dingus, you have a lot of good points, but I don't agree with you on GriGri( I know you don't like them) If you feel better with ATC, then that's what you should use.....anyways, I don't think it's a grigri lockup. The idea is that you jump( not like a dyno jump, just a hop) when your partner is starting to put tension on the rope. If done correctly you act as almost a counter balance softening the catch. Correct me if I'm wrong...... Sounds right to me, cept for my alleged grigri-hate. Don't hate em at all and use one quite frequently. I don't dispute the effect you describe. I still think the jumping thing became accepted because of grigris and feeding issues. Cheers dude!
ohhh sorry, didnt mean hate for grigri...more like dislike, but I must have mixed you up with someone else...my bad
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davidparks21
Dec 5, 2007, 7:17 PM
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chilli wrote: this (multipitch), in my opinion, is the perfect case in which i try to avoid the whole jumping bit, because i find the quick pay of some slack as the leader falls to be just as (and actually more) effective, and much safer. i've used it a few times and it's done a stellar job. why the preference for hopping around to provide dynamic belay? or have i misinterpreted your statement?
I'm 150 lbs, so unless the fall is near the protection piece I'm always pulled up. I've never tried paying out slack during a fall, that seems like a complex task, especially since you don't always know a fall is coming (if the climber is out of view). I'm not confident that I could rely on such a technique.
Even if a don't jump (for example if I don't see the climber and don't anticipate the fall), the fact that I'm pulled up say 5 feet as a counter weight seems like it's a load limiting factor.
What I wonder is how different a gri-gri is vs. an ATC in such a case (where the belayer acts as a counter weight).
Hmm, does anyone know a cheap way to calculate loads? I have a rope I'm about ready to retire and I'd be intrigued enough to try this out myself if I could find a way to calculate the impact forces.
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blueeyedclimber
Dec 5, 2007, 7:44 PM
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davidparks21 wrote: I'm 150 lbs, so unless the fall is near the protection piece I'm always pulled up. I've never tried paying out slack during a fall, that seems like a complex task, especially since you don't always know a fall is coming (if the climber is out of view). I'm not confident that I could rely on such a technique.
Then you probably shouldn't. My feeling, and i believe the purpose of this thread is to continue to refine your belaying technique as you do with your climbing. As you climb harder, steeper stuff and as you get into more complex climbing situations, your belaying should have improve at an equal rate.
In reply to: What I wonder is how different a gri-gri is vs. an ATC in such a case (where the belayer acts as a counter weight).
An ATC will allow rope to slip through whereas a grigri won't, therefore with a grigri, you need to worry more about being active as a belayer to soften the catch.
In reply to: Hmm, does anyone know a cheap way to calculate loads? I have a rope I'm about ready to retire and I'd be intrigued enough to try this out myself if I could find a way to calculate the impact forces.
If it's a rope that's ready to retire, then it probably doesn't have much stretch left to it and it won't tell you much as far as a real world fall on a more dynamic rope.
Josh
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chilli
Dec 6, 2007, 12:58 AM
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davidparks21 wrote: ...I've never tried paying out slack during a fall, that seems like a complex task, especially since you don't always know a fall is coming (if the climber is out of view). I'm not confident that I could rely on such a technique.
it's actually a lot simpler than you think. with practice, it's very fluid and natural. judging a fall for a jump or slipping some slack through an ATC are really very similar whether you see the climber or not, and so is the reaction time and effect (i haven't had any problems with a quick slack slip when climber isn't visible - though it was only a couple times that i encountered the case). i like it (paying some quick slack) for all potentially swinging overhanging cases, but it's an especially important tool when you don't find yourself in a jumping situation. if you're comfortable with jumping, and it sounds like in many cases you don't have the option, then that's ok. i would suggest that you look into integrating this technique into your 'toolbox' as well. i missed it earlier, but tenn dawg gives a good explanation for using an ATC for this purpose.
like i said, i'm NOT a fan of grigri's for this technique (or many uses for that matter, as a personal preference). i definitely like to stay away from them for trad work (in reference to your earlier question). however, one can use a grigri for slack-pay (squeeze, release, brake). i have, and i didn't like it (compared to ATC), but it did the job. i would think that using a grigri would also defintely make it tougher when you can't see the climber (i have not used one in such a case).
at any rate, for a good description of both dynamic techniques, see tenn dawg's earlier posts.
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lena_chita
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Dec 6, 2007, 4:45 PM
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First of all, thanks for a GREAT math explanation for the effect of slack on FF.
And also bringing up stuff from a long time ago...
[quote "jt512"]Paradoxically, it is the light climbers that tend to take the hardest falls. Light belayers get pulled up and give their heavier partners soft catches automatically. Heavier partners, who always get a soft catch, don't realize that it's important to dynamically belay their lighter partners. Since heavier climbers don't get pulled up, their lighter partners get hard catches. As a lighter climber, you'll find that, as a matter of self-preservation, you'll have to train your heavier partners to dynamically belay you. Expect resistance, especially from old-timers.
-Jay[/quote]
I wanted to say that YES, it pretty much summs my experience. When I started climbing, my belayers were either just as new as I was, or climbers who have climbed for a long time but never really had this issue b/c they did not have interest in pushing the limits to the point where they would be experiencing hard falls themselves.
So my partners were getting pretty soft catches due to the fact that the outweigh me by 40-50 pounds, so jumping up happened pretty naturally with me, and I never realized than my poor 100lb self was getting super-hard catches from people who, with every good intention, kept as little slack as possible in the system.
Until, that is, I started climbing with people who were used to working routes and taking lots of falls-- as well as belaying for partners who did the same.
WOW, it was a revelation, the first time I had a soft catch. I have learned so much from these people. Now, the hard part: getting ALL my belayers to use the same technique.
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Thoughtbubbles
Jan 25, 2012, 4:34 PM
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I've hear rumors of your version of a running belay and I'll credit the occasional application as being a much better solution than taking a 100' whipper. However (and perhaps I'm incorrect), where I'm from the term running belay is used interchangeably with the term simul-climbing. The technique in which both partners climb simultaniously on a shortened length of rope, in order to decrease the amount of time spent building anchors on long routes.
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blueeyedclimber
Jan 25, 2012, 4:58 PM
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Thoughtbubbles wrote: I've hear rumors of your version of a running belay and I'll credit the occasional application as being a much better solution than taking a 100' whipper. However (and perhaps I'm incorrect), where I'm from the term running belay is used interchangeably with the term simul-climbing. The technique in which both partners climb simultaniously on a shortened length of rope, in order to decrease the amount of time spent building anchors on long routes.
I always enjoy reading this thread whenever it comes up every few years. As to your question, Freedom of the Hills defines the "running belay" as you do; simul-climbing. The Stone Mountain Running Belay is a specific belay technique that involved actually running, and has nothing to do with the more generic term.
Whatever happened to tenn_dawg, anyways?
Josh
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olderic
Jan 25, 2012, 6:41 PM
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And then someone should bring up the origin of the word "runner' and the thread could deviate into "trad draw" vs. "sport sling".
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cracklover
Jan 25, 2012, 8:04 PM
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Not to mention the definition of "running belay" meaning "a piece of protection that is part of the protection between a leader and the belay."
GO
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olderic
Jan 25, 2012, 8:23 PM
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Original definition of 5th class climbing.
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bearbreeder
Jan 25, 2012, 8:30 PM
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A
fall on static rope with little elongation and a fixed anchor point will generate much higher impact forces
than a fall on dynamic rope using a running belay.
http://www.sterlingrope.com/...ument/techmanual.pdf
sterling rope uses running belay as to mean dynamic belay .... as does the UIAA
good enuff for me .... though maybe not for RCers 
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