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JimTitt
Dec 30, 2012, 6:49 AM
Post #26 of 80
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Syd wrote: In fall of 20 to 30 ft, the belayer has about 1300 ms from fall to peak. The point is the time to react and how to precisely synchronise his jump with the peak. As USNavy says, you can define the peak as an even shorter period. Try standing on a flat surface in belay stance and as quickly as possible, jump as high as possible. You might raise your CG by a couple of inches. That is, by a dynamic belay jump, you might be able to reduce the energy of the climber's fall by perhaps 1% or so ... if you time your jump precisely to the millisecond. Belayers are better off forgetting about jumping to give an active dynamic belay, and locking off the rope correctly and focussing on not tripping or hitting the wall if on an indirect belay.
I donīt jump, donīt recommend it and donīt expect anyone to do it. Nor would I teach it. That was USNavyīs idea and how he achieves this I have no idea, heīs probably younger, more athletic and has better reactions than me.
Since I weigh over 200lbs my belayers generally give me a dynamic belay whether they want to or not, when Iīm belaying I try to give a dynamic belay if required by relaxing towards the tension of the rope as shown in the Petzl cartoon. Mostly I donīt bother since the bottom of the cliffs where I mostly climb are an upward slope which makes things awkward and anyway Iīd probably spill my coffee by moving fast.
The amount of movement required is very low to reduce the peak force, six inches or a foot at the belayer end makes a huge difference and probably wants to be given at an early stage in the arrest of the fall. If you timed it to coincide with the absolute peak force then you are far too late as there is a time delay through the whole process.
If I need to give a soft catch to reduce the swing into the rock then itīs a whole different concept and process (and belay device generally).
(This post was edited by JimTitt on Dec 30, 2012, 6:51 AM)
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csproul
Dec 30, 2012, 12:35 PM
Post #27 of 80
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dan2see wrote: patto wrote: ... Certainly amongst MY local TRAD community dynamic belays are never emphasised. And amongst my local sport community, I've never seen anyone do a dynamic belay.
THe point is much less about minimizing peak load than it is about reducing the slam into the wall produced by the pendulum effect. IT's not that hard. You don't have to really "jump" unless you really outweigh your climber. GIve into the pull of the fall and allow yourself to be pulled up. I routinely end up hanging 10 or more ft up when my climber falls.
Unless, of course, there is something to hit below the climber..then that take precedence. Keep the climber from hitting dangerous things 1st, soften the catch 2nd. IF I'm slab climbing, usually with big runnouts, then shortening the fall gets bumped up in priority.
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dan2see
Dec 30, 2012, 12:38 PM
Post #28 of 80
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JimTitt wrote: ... Mostly I donīt bother since the bottom of the cliffs where I mostly climb are an upward slope which makes things awkward and anyway Iīd probably spill my coffee by moving fast...
I'd say that matches the scene where I climb. Don't forget the rubble and talus I'm standing on, too.
But the hard part is, I don't have a load cell. If I did, we could set-up a "quick and dirty" point at the top anchor and record from there. Although I don't know anybody who would volunteer to leave his laptop perched up there, on a ledge (if there is a ledge). And then jump off, for a ff1 fall! With a belayer who'd jump, just before the faller hits the ground? They'd both be crazy!
I agree with JimTitt that a "jump" is not practical and not even practicable (hey! there's a good word!). So I obey my own rule: "Never let go of the brake strand."
And once again, I make the effort to remind everyone here, that the OP's set-up measures a "static anchor", and not a "dynamic belay"!  !! !!!
(This post was edited by dan2see on Dec 30, 2012, 1:14 PM)
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dan2see
Dec 30, 2012, 2:11 PM
Post #29 of 80
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csproul wrote: dan2see wrote: patto wrote: ... Certainly amongst MY local TRAD community dynamic belays are never emphasised. And amongst my local sport community, I've never seen anyone do a dynamic belay. Either you don't have a very sporty "local sport community" or you are not paying attention. Observe sport climbers at any major sport area..think the Red, the New, Obed, Rifle, Rumney (sorry, US-centric I know, but those are the areas that I am familiar with)...and you will observe prolific dynamic belaying in practice. Even here in NC, with very few bolts, I see it all the time. THe point is much less about minimizing peak load than it is about reducing the slam into the wall produced by the pendulum effect. IT's not that hard. You don't have to really "jump" unless you really outweigh your climber. GIve into the pull of the fall and allow yourself to be pulled up. I routinely end up hanging 10 or more ft up when my climber falls. Unless, of course, there is something to hit below the climber..then that take precedence. Keep the climber from hitting dangerous things 1st, soften the catch 2nd. IF I'm slab climbing, usually with big runnouts, then shortening the fall gets bumped up in priority.
No! You are not paying attention!
1. The OP is about measuring a static anchor, not the technique of dynamic belay.
2. I don't live near any of those places. I live near the Canadian Rockies. You know, up there in the great white frozen wasteland?
Anyway it's Sunday now and I'm loading my gear into the car. In a couple of hours I'll be snow-shoeing and scrambling a ridge on Mount Baldy. Tame enough, but it provides plenty of adventure. The rocks aren't too high, but all the features are covered with snow. It's sheltered by forest, so the venue is very pleasant. I'll try to get some snapshots of the static anchors I set up.
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Syd
Dec 30, 2012, 8:28 PM
Post #30 of 80
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patto wrote: I completely agree with this. And I believe there has been other good research to support this. Dynamic belaying was found produce only very minor reductions in peak load.
Thanks patto.
I've done some experiments to support this. The maximum effect of a dynamic belay is the instant the belayer's feet leave the ground. The fastest time I recorded was 800 millisecs from the instant a climber yells or is seen to fall, to the belayer's feet leaving the ground in an active hop. 200 ms later, the belayer is headed for the ground again (unless he is yanked upwards of course). Another 200 ms and the belayer is adding to the impact on the climber.
A "typical" free fall of 20 feet takes 1200 ms. In the next 200 ms, the climber falls another 8 feet. For a dynamic belay to work, the belayer has 400ms to calculate the amount of slack, how far the climber will fall and hence exactly when to jump.
To put things into perspective, "the blink of an eye" is 300 to 400 milliseconds. That is, the belayer must literally do the above calculations in the blink of an eye. If he's a blink of an eye out, he adds to the impact on the climber.
In summary, dynamic belaying is a myth. It might make you feel good in that you fool yourself into thinking you are helping but it's useless.
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jt512
Dec 30, 2012, 9:12 PM
Post #31 of 80
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Syd wrote: patto wrote: I completely agree with this. And I believe there has been other good research to support this. Dynamic belaying was found produce only very minor reductions in peak load. Thanks patto. I've done some experiments to support this. The maximum effect of a dynamic belay is the instant the belayer's feet leave the ground. The fastest time I recorded was 800 millisecs from the instant a climber yells or is seen to fall, to the belayer's feet leaving the ground in an active hop. 200 ms later, the belayer is headed for the ground again (unless he is yanked upwards of course). Another 200 ms and the belayer is adding to the impact on the climber. A "typical" free fall of 20 feet takes 1200 ms. In the next 200 ms, the climber falls another 8 feet. For a dynamic belay to work, the belayer has 400ms to calculate the amount of slack, how far the climber will fall and hence exactly when to jump.
Sorry, but you are completely full of shit. The belayer simply jumps as soon as he feels tension in the rope. It really is that simple.
Jay
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redlude97
Dec 31, 2012, 12:03 AM
Post #32 of 80
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Syd wrote: patto wrote: I completely agree with this. And I believe there has been other good research to support this. Dynamic belaying was found produce only very minor reductions in peak load. Thanks patto. I've done some experiments to support this. The maximum effect of a dynamic belay is the instant the belayer's feet leave the ground. The fastest time I recorded was 800 millisecs from the instant a climber yells or is seen to fall, to the belayer's feet leaving the ground in an active hop. 200 ms later, the belayer is headed for the ground again (unless he is yanked upwards of course). Another 200 ms and the belayer is adding to the impact on the climber. A "typical" free fall of 20 feet takes 1200 ms. In the next 200 ms, the climber falls another 8 feet. For a dynamic belay to work, the belayer has 400ms to calculate the amount of slack, how far the climber will fall and hence exactly when to jump. To put things into perspective, "the blink of an eye" is 300 to 400 milliseconds. That is, the belayer must literally do the above calculations in the blink of an eye. If he's a blink of an eye out, he adds to the impact on the climber. In summary, dynamic belaying is a myth. It might make you feel good in that you fool yourself into thinking you are helping but it's useless.
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csproul
Dec 31, 2012, 12:19 AM
Post #33 of 80
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dan2see wrote: csproul wrote: dan2see wrote: patto wrote: ... Certainly amongst MY local TRAD community dynamic belays are never emphasised. . Either you don't have a very sporty "local sport community" or you are not paying attention. Observe sport climbers at any major sport area..think the Red, the New, Obed, Rifle, Rumney (sorry, US-centric I know, but those are the areas that I am familiar with)...and you will observe prolific dynamic belaying in practice. Even here in NC, with very few bolts, I see it all the time. THe point is much less about minimizing peak load than it is about reducing the slam into the wall produced by the pendulum effect. IT's not that hard. You don't have to really "jump" unless you really outweigh your climber. GIve into the pull of the fall and allow yourself to be pulled up. I routinely end up hanging 10 or more ft up when my climber falls. Unless, of course, there is something to hit below the climber..then that take precedence. Keep the climber from hitting dangerous things 1st, soften the catch 2nd. IF I'm slab climbing, usually with big runnouts, then shortening the fall gets bumped up in priority. No! You are not paying attention! 1. The OP is about measuring a static anchor, not the technique of dynamic belay. 2. I don't live near any of those places. I live near the Canadian Rockies. You know, up there in the great white frozen wasteland? Anyway it's Sunday now and I'm loading my gear into the car. In a couple of hours I'll be snow-shoeing and scrambling a ridge on Mount Baldy. Tame enough, but it provides plenty of adventure. The rocks aren't too high, but all the features are covered with snow. It's sheltered by forest, so the venue is very pleasant. I'll try to get some snapshots of the static anchors I set up.
(This post was edited by csproul on Dec 31, 2012, 1:09 AM)
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Syd
Jan 2, 2013, 12:38 AM
Post #35 of 80
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jt512 wrote: Sorry, but you are completely full of shit. The belayer simply jumps as soon as he feels tension in the rope. It really is that simple. Jay
Pointing out that traditional view are nonsense is like Galileo pointing out the Earth revolves around the sun.
Jt, if you jump as soon as you feel the tension in the rope, your effort is almost a second too late. You will be fooled into thinking you have done something useful because you will be lifted off the ground by the falling climber. If you do nothing, you will be lifted off the ground just the same.
I'm sure all those people dynamic belaying will keep doing it because it feels good to think they might be doing something useful. At least it does no harm. The smarter folk will just smile knowingly.
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jt512
Jan 2, 2013, 1:07 AM
Post #36 of 80
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Syd wrote: jt512 wrote: Sorry, but you are completely full of shit. The belayer simply jumps as soon as he feels tension in the rope. It really is that simple. Jay Pointing out that traditional view are nonsense is like Galileo pointing out the Earth revolves around the sun. Jt, if you jump as soon as you feel the tension in the rope, your effort is almost a second too late. You will be fooled into thinking you have done something useful because you will be lifted off the ground by the falling climber.
You're still arguing theory in the face of overwhelming contrary evidence. As a 135-climber I can assure you that I can feel the difference between when my heavier partners do and do not dynamically belay.
In reply to: If you do nothing, you will be lifted off the ground just the same.
That's patently false when the belayer outweighs the climber or there is substantial friction in the system.
Jay
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csproul
Jan 2, 2013, 1:19 AM
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You're either substantially heavier than most of your partners or you don't fall very often.
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notapplicable
Jan 2, 2013, 1:24 AM
Post #38 of 80
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Syd wrote: jt512 wrote: Sorry, but you are completely full of shit. The belayer simply jumps as soon as he feels tension in the rope. It really is that simple. Jay Pointing out that traditional view are nonsense is like Galileo pointing out the Earth revolves around the sun. Jt, if you jump as soon as you feel the tension in the rope, your effort is almost a second too late. You will be fooled into thinking you have done something useful because you will be lifted off the ground by the falling climber. If you do nothing, you will be lifted off the ground just the same. I'm sure all those people dynamic belaying will keep doing it because it feels good to think they might be doing something useful. At least it does no harm. The smarter folk will just smile knowingly.
When my 210 lb partner falls I get lifted off the ground if I don't jump. When my 120 lb partner falls I remain exactly where I stand if I don't jump. I assure you, their experience during the fall is very different.
As a 155 lb climber who has been belayed by those who weight significantly more and less than I do, I can attest to this fact. A well timed jump makes a tremendous difference.
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USnavy
Jan 4, 2013, 6:42 AM
Post #39 of 80
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patto wrote: And I believe there has been other good research to support this. Dynamic belaying was found produce only very minor reductions in peak load.
Syd wrote: That is, by a dynamic belay jump, you might be able to reduce the energy of the climber's fall by perhaps 1% or so .
Syd wrote: patto wrote: I completely agree with this. And I believe there has been other good research to support this. Dynamic belaying was found produce only very minor reductions in peak load. Thanks patto. I've done some experiments to support this. The maximum effect of a dynamic belay is the instant the belayer's feet leave the ground. The fastest time I recorded was 800 millisecs from the instant a climber yells or is seen to fall, to the belayer's feet leaving the ground in an active hop. 200 ms later, the belayer is headed for the ground again (unless he is yanked upwards of course). Another 200 ms and the belayer is adding to the impact on the climber. A "typical" free fall of 20 feet takes 1200 ms. In the next 200 ms, the climber falls another 8 feet. For a dynamic belay to work, the belayer has 400ms to calculate the amount of slack, how far the climber will fall and hence exactly when to jump. To put things into perspective, "the blink of an eye" is 300 to 400 milliseconds. That is, the belayer must literally do the above calculations in the blink of an eye. If he's a blink of an eye out, he adds to the impact on the climber. In summary, dynamic belaying is a myth. It might make you feel good in that you fool yourself into thinking you are helping but it's useless.
Fall 1: - Dynamic catch 13 total 3.09 kN
Fall 2: - Static catch (belayer just stood there) 10 total 3.75 kN
Fall 3: - Running belay (belayer yanked in slack and ran backwards) 7 total 3.91 kN
(This post was edited by USnavy on Jan 4, 2013, 6:49 AM)
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patto
Jan 4, 2013, 8:41 AM
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Those graphs show quite clearly that the difference between dynamic and a simple belay is negligible.
Also all the comment regarding sport climbing and stopping the pendulum effect miss the point. A dynamic belay is not the best solution to avoiding a pendulum! The best solution is allowing more slack!
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redlude97
Jan 4, 2013, 9:15 AM
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patto wrote: Those graphs show quite clearly that the difference between dynamic and a simple belay is negligible. Also all the comment regarding sport climbing and stopping the pendulum effect miss the point. A dynamic belay is not the best solution to avoiding a pendulum! The best solution is allowing more slack!
In regards to swinging into the wall. It isn't about peak force but rather horizontal velocity that matters. A pretty good discussion from a while back shows the merits of a dynamic belay(as well as initial slack).
http://www.rockclimbing.com/..._reply;so=ASC;mh=25;
"Theory" shows ~40-60% reduction in horizontal energy
(This post was edited by redlude97 on Jan 4, 2013, 9:53 AM)
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bearbreeder
Jan 4, 2013, 10:46 AM
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patto wrote: bearbreeder wrote: First of all, just to clear-up a few myths, the following is not dynamic belaying So instead of clearing up myths you continue to mix up and confuse the issues of reducing pendulums and reducing impact force!  More slack will increase the impact forces, nobody is arguing otherwise. More slack will significantly reduce the pendulum effect. A dynamic belay will normally slightly reduce impact forces. A dynamic belay will slighty reduce the pendulum effect.
are you whinning about UKclimbing confusing stuff for ya 
how many sport whippers do you catch in a day ... 15+ footers? ... a decent sport climber at their limit will easily take 5-10 or more in a day ... and catch that many ...
the effect of a dynamic belay is often more than "slight" ... as anyone who sport climbs a decent amount will know friends that have busted ankles from hard catches
im a wussy climber and i climb sport at my limit indoor and outdoor 2-3 times a week ... 5-10 whippers a day ... basically 1000+ not so short falls a year .... and there are many that take much more than that
if you climbed and fell constantly on sport, all it takes is one hard catch where you tweak your ankle to see what works ... and what doesnt
despite all the RC mumbo jumbo ... thousands of sport climbers understand it .... petzl understands it, beal understands it ...
but RCers dont
(This post was edited by bearbreeder on Jan 4, 2013, 10:52 AM)
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patto
Jan 4, 2013, 1:02 PM
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bearbreeder wrote: are you whinning about UKclimbing confusing stuff for ya
No. In fact I have no confusion regarding the UKclimbing statement. If you had basic skills in comprehension you might realise that.
bearbreeder wrote: but RCers dont
The only person here totally intend on winning the ignorance battle is you.
You continue to confuse and muddle the differences between pendulums and high impact forces on gear.
(This post was edited by patto on Jan 4, 2013, 1:08 PM)
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redlude97
Jan 4, 2013, 1:13 PM
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patto wrote: bearbreeder wrote: First of all, just to clear-up a few myths, the following is not dynamic belaying So instead of clearing up myths you continue to mix up and confuse the issues of reducing pendulums and reducing impact force! More slack will increase the impact forces, nobody is arguing otherwise. Alot More slack will significantly reduce the pendulum effect. A dynamic belay will normally slightly reduce impact forces. A dynamic belay will slighty significantly reduce the pendulum effect.
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patto
Jan 4, 2013, 1:29 PM
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So a foot of dynamic jumping is so much better than a foot of slack in reducing the pendulum! 
I'm not faulting dynamic belays, I'm just saying that they have massively overstated benefits. If you want a softer catch then buy a BEAL rope!
It is far better to use a stretchy rope to absorb energy and reduce a pendulum than doing a little jump.
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redlude97
Jan 4, 2013, 2:22 PM
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patto wrote: So a foot of dynamic jumping is so much better than a foot of slack in reducing the pendulum!
patto wrote: So a foot of dynamic jumping is so much better than a foot of slack in reducing the pendulum!
patto wrote: I'm not faulting dynamic belays, I'm just saying that they have massively overstated benefits. If you want a softer catch then buy a BEAL rope! It is far better to use a stretchy rope to absorb energy and reduce a pendulum than doing a little jump.
The dynamic belay changes the arc of the pendulum significantly enough to decrease the horizontal for by~40%+. This is best illustrated in Blondgecko's image found the thread I posted
That change in trajectory is what saves ankles, not the lower peak impact force. Albeit that is somewhat idealized.
I still don't get why you are arguing this. Sport climbers are literally utilizing this hundreds to thousands of times a day to decrease the pendulum into the wall. It isn't hard to learn, and it can be used in conjuction with slack and low impact ropes to further reduce slams into the wall.
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wivanoff
Jan 4, 2013, 3:09 PM
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IDK. Intuitively, it would seem that jumping to give a dynamic belay would provide some benefit.
Consider a car parked in neutral. I start to push it. It takes a lot of effort to get it moving. But, once I get it moving it takes less effort to keep it moving.
Consider I'm giving a static belay. The rope comes taut and starts to pull me up. It takes effort to get me moving. But, once I'm moving it takes less effort.
Consider I'm giving a dynamic belay. The rope comes taut but I've started moving on my own by jumping. It takes less effort to keep me moving, just like the car.
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csproul
Jan 4, 2013, 3:46 PM
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In reply to: So a foot of dynamic jumping is so much better than a foot of slack in reducing the pendulum! Crazy Laugh I'm not faulting dynamic belays, I'm just saying that they have massively overstated benefits. If you want a softer catch then buy a BEAL rope! It is far better to use a stretchy rope to absorb energy and reduce a pendulum than doing a little jump.
If you introduce slack, the fall distance will be greater, the impact force will be greater, but the pendulum effect will be reduced. A well done dynamic belay will have all of the pluses (reduced pendulum effect) and still reduce impact force. And it is not that hard, it get's done all the time. Being a lighter climber, I can definitely feel when my belayer is soft or not.
The other thing that you're missing that putting slack in the rope gives you no option but to increase the fall distance. If you do not (arbitrarily) introduce slack you can adjust your belay to the situation. If you need to shorten the fall because of a ledge, you do not give the dynamic belay. If you had slack in the system, this is not an option. If there is nothing to hit, you can belay dynamically with all of the benefits as if you had put slack in the system, without having to yard rope in an out to adjust for every changing situation.
If you only get pulled up a foot in your dynamic belay...you are definitely doing it wrong. I routinely allow myself to be pulled up a good 10 ft. So you'd rather I just leave 10 ft of slack in the rope? Let's say my climber has 10 ft of slack in the line and decides s/he quickly wants to step down and hang...if I were prepared for any type of belay, be it dynamic or otherwise (eg no slack!), all I'd have to do is essentially sit down and take. With your 10 ft of slack out I'd have to take all that rope in and then take their weight. No thanks.
(This post was edited by csproul on Jan 4, 2013, 5:22 PM)
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