Forums: Climbing Information: General:
Quick and dirty test: What happens during shockloading?
RSS FeedRSS Feeds for General

Premier Sponsor:

 


USnavy


Dec 25, 2012, 9:40 PM
Post #1 of 80 (7863 views)
Shortcut

Registered: Nov 5, 2007
Posts: 2664

Quick and dirty test: What happens during shockloading?
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (3 ratings)  
Can't Post

Today I performed a quick, dirty and non-scientific test for a highline article I am writing, and I came across some results that may interest climbers. There is a lot of talk about how a short fall on a Dyneema sling can cause the sling to fail, but drop testing fabrics can be a bit abstract, and it can be hard to visualize what is actually going on within the sling during a fall. This quick and dirty test may help make it easier to visualize a shockloading scenario from the viewpoint of the sling.

In the photo below you can see a load cell connected to a bolt and to a 1” nylon webbing sling tied in a sliding X. Attached to the sling is a steel ring that weighs 12 lbs. I picked the ring up and dropped it 20” onto the cell.



Load weight: 12 lbs.
Fall factor: 1
Fall distance: 20”

Dynometer scan rate: 520Hz / 1.92ms per reading
Peak load: 457 lbf. / 2.03kN*
50 lbf to 50 lbf load duration: Approximately 24ms



*The scan rate of my dynometer was actually too slow, and so the dynometer was not able to capture the true peak. Therefore, the actual peak load of this fall is actually slightly higher than what the dyno measured. If you look closely at the graph you will notice that top of the peak is flat. The start and end points of the flat section of the peak is actually the duration between two individual samples!

To further emphasize the short duration of a static fall like what I tested, let us compare it to the graph below. The graph below represents three lead falls in a typical climbing scenario. The load cell was placed on the protection bolt.



The fall above had a duration of around 2,500ms which is obviously far longer than the 24ms the static fall drop test took.

In conclusion, this quick test, which involved a 20” fall of a 12 lb. steel weight, produced a peak load increase of over 3,800%. Although this test is not analogous of a typical climbing shockloading fall due to a lack of a fleshy mass, it still emphasizes how relatively short falls on static materials can produces insane peak loads. I suspect that if the load weighed 80kg, I would have broken the bolt in the ceiling and exceeded the weight limitation of my load cell.


JAB


Dec 27, 2012, 5:45 AM
Post #2 of 80 (7743 views)
Shortcut

Registered: Apr 26, 2007
Posts: 373

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (2 ratings)  
Can't Post

OK, this is nice and everything, but really adds nothing we already didn't know. What would be much more interesting, is if you now did the same test on yourself, as in a real world scenario. I.e. put on harness, girth hitch sling to it, other end to bolt, and then drop the 20". Compare results.

Now everybody knows that the human body, harness, loose knots etc all help to reduce the load, but nobody can say by how much.


ObviousTroll


Dec 27, 2012, 6:08 AM
Post #3 of 80 (7736 views)
Shortcut

Registered: May 29, 2012
Posts: 90

Re: [JAB] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (2 ratings)  
Can't Post

JAB wrote:
OK, this is nice and everything, but really adds nothing we already didn't know. What would be much more interesting, is if you now did the same test on yourself, as in a real world scenario. I.e. put on harness, girth hitch sling to it, other end to bolt, and then drop the 20". Compare results.

Now everybody knows that the human body, harness, loose knots etc all help to reduce the load, but nobody can say by how much.

I triple doggy dare you.


acorneau


Dec 27, 2012, 6:19 AM
Post #4 of 80 (7731 views)
Shortcut

Registered: Feb 6, 2008
Posts: 2889

Re: [ObviousTroll] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

ObviousTroll wrote:
JAB wrote:
OK, this is nice and everything, but really adds nothing we already didn't know. What would be much more interesting, is if you now did the same test on yourself, as in a real world scenario. I.e. put on harness, girth hitch sling to it, other end to bolt, and then drop the 20". Compare results.

Now everybody knows that the human body, harness, loose knots etc all help to reduce the load, but nobody can say by how much.



I triple doggy dare you.


I accidentally did this a long time ago when I was a snot-nosed kid new to climbing.

At the time the sliding-x was a very popular method of rigging a top rope. I thought if it was good enough for a TR then it was good enough for my anchoring tethers, so I put a locker on my harness and rigged a 4' Titan sling in a sliding-x with biners on each end.

I lead a sport climb and barely made it to the top, clipped the first biner on one hanger and the other was just a few inches short. As I stretched to clip the second bolt my arm holding me up gave out and I fell directly on the sling, roughly 24" worth.

It completely wrenched my back and hurt like a beyotch! I managed to get back up and finish up the rigging but the drop messed with my back the rest of the day.


patto


Dec 27, 2012, 7:45 AM
Post #5 of 80 (7710 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

And I bet that ceiling flexes alot more than solid rock!


PeteF


Dec 27, 2012, 1:33 PM
Post #6 of 80 (7650 views)
Shortcut

Registered: Jan 14, 2012
Posts: 20

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

In reply to:
In conclusion, this quick test, which involved a 20” fall of a 12 lb. steel weight, produced a peak load increase of over 3,800%. Although this test is not analogous of a typical climbing shockloading fall due to a lack of a fleshy mass, it still emphasizes how relatively short falls on static materials can produces insane peak loads. I suspect that if the load weighed 80kg, I would have broken the bolt in the ceiling and exceeded the weight limitation of my load cell.

Thanks very much for going to the trouble of doing that and putting it up here. For those of us new to climbing it's a good reminder.

Since you have all the gear there handy, is there any chance of repeating the experiment with a comparison between otherwise identical components but one static while the other is dynamic? For example two different ropes. I would be interested to see the difference in results over a short drop like this.


Syd


Dec 28, 2012, 11:35 AM
Post #7 of 80 (7566 views)
Shortcut

Registered: Oct 25, 2012
Posts: 300

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

The main peak load occurs over 85ms (that is, the width of the peak above the final base load). The most extreme part of the peak load happens in a shorter period. It is interesting to consider this in relation to active dynamic belaying. It is claimed that if the belayer jumps or steps or actively initiates a moves in some way, when a climber falls, he can reduce the peak loading on the climber. It takes an absolute minimum of 200ms for a person to react to some stimulus (such as hearing a yell "falling" or seeing a fall), and generally this time is much longer. Further time is then required for the belayer to flex in some way. To reduce the peak load on the climber, the belayer's jump would then have to be precisely synchronised with the 85ms peak load. To me, this seems almost impossible.

Any "dynamic" effect by the belayer is simply the belayer being lifted off the ground by the impact of the fall. It is virtually impossible for the belayer to actively contribute to any impact reduction.

Many people consider that dynamic belaying is an essential part of good belaying but actions other than allowing some rope slip through the belay device at the moment of impact and an indirect or semi direct belay, seem futile.


(This post was edited by Syd on Dec 28, 2012, 11:41 AM)


redlude97


Dec 28, 2012, 11:45 AM
Post #8 of 80 (7559 views)
Shortcut

Registered: Aug 27, 2008
Posts: 990

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

Syd wrote:
The main peak load occurs over 85ms (that is, the width of the peak above the final base load). The most extreme part of the peak load happens in a shorter period. It is interesting to consider this in relation to active dynamic belaying. It is claimed that if the belayer jumps or steps or actively initiates a moves in some way, when a climber falls, he can reduce the peak loading on the climber. It takes an absolute minimum of 200ms for a person to react to some stimulus (such as hearing a yell "falling" or seeing a fall), and generally this time is much longer. Further time is then required for the belayer to flex in some way. To reduce the peak load on the climber, the belayer's jump would then have to be precisely synchronised with the 85ms peak load. To me, this seems almost impossible.

Any "dynamic" effect by the belayer is simply the belayer being lifted off the ground by the impact of the fall. It is virtually impossible for the belayer to actively contribute to any impact reduction.

Many people consider that dynamic belaying is an essential part of good belaying but actions other than allowing some rope slip through the belay device at the moment of impact and an indirect or semi direct belay, seem futile.
You got it all wrong. First a dynamic rope spreads the peak load out farther. Second, to give a dynamic belay you just have to time your jump so that you are moving upwards at point the rope catches. you are in the air for 1-2 seconds which is pretty easy to time with the fall once you get used to it. Just wait until you just feel the rope tension and jump. It works. Period.


healyje


Dec 28, 2012, 1:16 PM
Post #9 of 80 (7546 views)
Shortcut

Registered: Aug 22, 2004
Posts: 4199

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

I see a balcony in that photo - surely you can come up with a more realistic test...


Syd


Dec 28, 2012, 2:26 PM
Post #10 of 80 (7523 views)
Shortcut

Registered: Oct 25, 2012
Posts: 300

Re: [redlude97] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

redlude97 wrote:

You got it all wrong. First a dynamic rope spreads the peak load out farther. Second, to give a dynamic belay you just have to time your jump so that you are moving upwards at point the rope catches. you are in the air for 1-2 seconds which is pretty easy to time with the fall once you get used to it. Just wait until you just feel the rope tension and jump. It works. Period.

You've totally missed the point. Try jumping off the ground and staying in the air for 1-2 seconds as you claim. A belayer is PULLED into the air.
Do you really think you can time your little jump accurately to 85 milli seconds ?


redlude97


Dec 28, 2012, 2:33 PM
Post #11 of 80 (7519 views)
Shortcut

Registered: Aug 27, 2008
Posts: 990

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

Syd wrote:
redlude97 wrote:

You got it all wrong. First a dynamic rope spreads the peak load out farther. Second, to give a dynamic belay you just have to time your jump so that you are moving upwards at point the rope catches. you are in the air for 1-2 seconds which is pretty easy to time with the fall once you get used to it. Just wait until you just feel the rope tension and jump. It works. Period.

You've totally missed the point. Try jumping off the ground and staying in the air for 1-2 seconds as you claim. A belayer is PULLED into the air.
Do you really think you can time your little jump accurately to 85 milli seconds ?
You don't get it. You don't have to be accurate to within milliseconds. The catch just has to occur while you are still moving up during your jump. You also aren't just guessing. You jump when you start to feel the tension.


(This post was edited by redlude97 on Dec 28, 2012, 2:43 PM)


petsfed


Dec 28, 2012, 3:54 PM
Post #12 of 80 (7498 views)
Shortcut

Registered: Sep 24, 2002
Posts: 8595

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

Shock loading is what we call sudden increase of load to the point that, in comparison to the scale of the entire event, it acts like a delta function in time. There's nothing fancy about that. Its just verbal short-hand. Moreover, because of the extremes that necessitate the delta-function approximation, the actual behavior of the system is not, strictly speaking, predictable.

You want to impress me with your greater understanding, then show me if your loading profile exhibits marked asymmetry, periodicity, or multiple peaks. Then, talk to me about cyclic loading and relaxation time.

As it stands, you've used more words than normal to express what's been known for better than 60 years by engineers around the world, some of which happen to be climbers.


dan2see


Dec 28, 2012, 8:22 PM
Post #13 of 80 (7460 views)
Shortcut

Registered: Mar 28, 2006
Posts: 1497

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

To JAB and petsfed, here's two juicy Tongue Tongue
for your negative comments that belittle USNavy's demo.

To Syd and redlude97, here's two more juicy Tongue Tongue
for changing the subject from "static anchor" to "dynamic belay".

To USNavy, thanks for the demo. I like to see these experiments that verify, extend, or negate stuff everybody knows everything about.

This week-end I will be playing with anchors and belays. So I will keep your findings in focus, while I'm messing around with my gear, on the rocks, with my delicate body.


(This post was edited by dan2see on Dec 28, 2012, 8:23 PM)


JimTitt


Dec 28, 2012, 10:05 PM
Post #14 of 80 (7434 views)
Shortcut

Registered: Aug 7, 2008
Posts: 986

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

Syd wrote:
The main peak load occurs over 85ms (that is, the width of the peak above the final base load). The most extreme part of the peak load happens in a shorter period. It is interesting to consider this in relation to active dynamic belaying. It is claimed that if the belayer jumps or steps or actively initiates a moves in some way, when a climber falls, he can reduce the peak loading on the climber. It takes an absolute minimum of 200ms for a person to react to some stimulus (such as hearing a yell "falling" or seeing a fall), and generally this time is much longer. Further time is then required for the belayer to flex in some way. To reduce the peak load on the climber, the belayer's jump would then have to be precisely synchronised with the 85ms peak load. To me, this seems almost impossible.

Any "dynamic" effect by the belayer is simply the belayer being lifted off the ground by the impact of the fall. It is virtually impossible for the belayer to actively contribute to any impact reduction.

Many people consider that dynamic belaying is an essential part of good belaying but actions other than allowing some rope slip through the belay device at the moment of impact and an indirect or semi direct belay, seem futile.

Even in the shorter falls used in lab experiments which are the only ones we get full data for the time from initially tensioning the rope to the peak force is substantially longer than you are talking about, around 200ms is probably reasonable. From the point of falling where a reasonably alert belayer has clues to prime his movement you´d have about 400ms.
If you look at US´s lower graph (which is a longer, lower FF)you´ll see the belayer had about 500ms from tension to peak and probably over a second if he saw the fall.
If the time from tension to peak was a short as you think then the impact force would be horrific!


USnavy


Dec 28, 2012, 11:51 PM
Post #15 of 80 (7418 views)
Shortcut

Registered: Nov 5, 2007
Posts: 2664

Re: [petsfed] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

Syd wrote:
The main peak load occurs over 85ms (that is, the width of the peak above the final base load).
No it does not, look again. From 50lbf to 50lbf the load duration is 24ms.


petsfed


Dec 29, 2012, 10:33 AM
Post #16 of 80 (7371 views)
Shortcut

Registered: Sep 24, 2002
Posts: 8595

Re: [dan2see] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

dan2see wrote:
To JAB and petsfed, here's two juicy Tongue Tongue
for your negative comments that belittle USNavy's demo.

Dan, with respect, I don't see how USNavy's demo is at all useful. If you want a useful illustration of shock loading, look at a hammer and nail. If you swing the hammer, you drive the nail. If you apply the same impulse (that is, change in momentum for the hammer over some distance) over a longer time, you don't drive the nail.

That's shock-loading, and perfectly illustrates why we need to worry about it. That said, its not clear how much of an issue that is with a dynamic rope, so these tests are not at all informative.


Syd


Dec 29, 2012, 12:19 PM
Post #17 of 80 (7351 views)
Shortcut

Registered: Oct 25, 2012
Posts: 300

Re: [JimTitt] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (2 ratings)  
Can't Post

JimTitt wrote:


Even in the shorter falls used in lab experiments which are the only ones we get full data for the time from initially tensioning the rope to the peak force is substantially longer than you are talking about, around 200ms is probably reasonable.

Based on ? I have seen a graph but I'm damned if I can find it.

In reply to:
If you look at US´s lower graph (which is a longer, lower FF)you´ll see the belayer had about 500ms from tension to peak and probably over a second if he saw the fall.

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.


jt512


Dec 29, 2012, 3:09 PM
Post #18 of 80 (7338 views)
Shortcut

Registered: Apr 11, 2001
Posts: 21893

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

Syd wrote:
JimTitt wrote:


Even in the shorter falls used in lab experiments which are the only ones we get full data for the time from initially tensioning the rope to the peak force is substantially longer than you are talking about, around 200ms is probably reasonable.

Based on ? I have seen a graph but I'm damned if I can find it.

In reply to:
If you look at US´s lower graph (which is a longer, lower FF)you´ll see the belayer had about 500ms from tension to peak and probably over a second if he saw the fall.

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.

You don't know what you're talking about. But you're right about one thing: if you're too uncoordinated to time the jump properly, you're better off just standing there and locking off, since jumping too early results in a harder catch than if you just stand there like an idiot and lock off.

Better yet, offer to let someone who knows what they're doing belay.

Jay


(This post was edited by jt512 on Dec 29, 2012, 3:10 PM)


Syd


Dec 29, 2012, 6:26 PM
Post #19 of 80 (7304 views)
Shortcut

Registered: Oct 25, 2012
Posts: 300

Re: [jt512] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (3 ratings)  
Can't Post

jt512 wrote:

But you're right about one thing: if you're too uncoordinated to time the jump properly, you're better off just standing there and locking off, since jumping too early results in a harder catch than if you just stand there like an idiot and lock off.
Jay

Another fellow conned by the dynamic belay myth. How high do you think you can you jump while belaying ... 4 inches maybe 6 ? Or do you think you can equal the athlete maximum 28 inch vertical leap? I'm talking about actually jumping your CG up instantaneously from a resting, unprepared stance. How does your 4 to 6 inches, compare to a typical fall of 20-30 ft or more ? That is, there is at least 40 to 90 TIMES AS MUCH energy in the fall as your pathetic bunny hop !
... and you think you can time your little bunny hop accurately to a small fraction of a second !? A mis-timing of 200 milliseconds and you add to the impact ... not that the falling climber would notice your tiny bunny hops. The falling climber will rip you off the ground as the rope tensions and you will be fooled into thinking you have done wonders.
You are dreaming if you think it helps.


shotwell


Dec 29, 2012, 7:28 PM
Post #20 of 80 (7292 views)
Shortcut

Registered: Jan 5, 2009
Posts: 366

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (3 ratings)  
Can't Post

Syd wrote:
jt512 wrote:

But you're right about one thing: if you're too uncoordinated to time the jump properly, you're better off just standing there and locking off, since jumping too early results in a harder catch than if you just stand there like an idiot and lock off.
Jay

Another fellow conned by the dynamic belay myth. How high do you think you can you jump while belaying ... 4 inches maybe 6 ? Or do you think you can equal the athlete maximum 28 inch vertical leap? I'm talking about actually jumping your CG up instantaneously from a resting, unprepared stance. How does your 4 to 6 inches, compare to a typical fall of 20-30 ft or more ? That is, there is at least 40 to 90 TIMES AS MUCH energy in the fall as your pathetic bunny hop !
... and you think you can time your little bunny hop accurately to a small fraction of a second !? A mis-timing of 200 milliseconds and you add to the impact ... not that the falling climber would notice your tiny bunny hops. The falling climber will rip you off the ground as the rope tensions and you will be fooled into thinking you have done wonders.
You are dreaming if you think it helps.

Remind me to NEVER let you belay me.


jt512


Dec 29, 2012, 7:34 PM
Post #21 of 80 (7291 views)
Shortcut

Registered: Apr 11, 2001
Posts: 21893

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

Syd wrote:
jt512 wrote:

But you're right about one thing: if you're too uncoordinated to time the jump properly, you're better off just standing there and locking off, since jumping too early results in a harder catch than if you just stand there like an idiot and lock off.
Jay

Another fellow conned by the dynamic belay myth. How high do you think you can you jump while belaying ... 4 inches maybe 6 ?.

You're arguing theory in the face of decisive contrary empirical evidence, and you're arguing with people who on a day in and day out basis continue to generate that evidence. When an overwhelming amount of data contradicts your theory, then your theory is wrong. The zillions of real climbers who give and receive well-executed dynamic belays every time we're out climbing can assure you that dynamic belaying is no myth. In fact, it is a relative simple skill to master, and a vitally important one. I'm about a decade and half past trying to convince the minority of climbers who cling to the paradigm of dynamic belay denial. I simply refuse to climb with deniers, as do many of my partners.

Shut up and learn how to belay already.

Jay


dan2see


Dec 29, 2012, 8:22 PM
Post #22 of 80 (7285 views)
Shortcut

Registered: Mar 28, 2006
Posts: 1497

Re: [jt512] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

shotwell wrote:
... Remind me to NEVER let you belay me.

jt512 wrote:
... Shut up and learn how to belay already.

Oh yeah? Well your mother wears army pants! Tongue
Both of you! Tongue

The thing is, it's fun to be more right than the other guy. But it's another thing entirely to figure out how things work, and what you should do about it.

For myself, the only "rule" for my belayer is "Never let go of the break brake strand".

Petzl (I think) once had a page of advice, related to lead techniques. In the paragraph about anchors, their advice was "... Clip your sling to the anchor, sit in your harness, and ..."

So you guys, you don't have to be more scientific, or more experienced, than the OP. But it's silly to argue about how to belay.

---o---o---

Some time ago, I asked a couple of friends about that short phrase "sit in your harness", but nobody had noticed it. One guy said "Well that's what I always do" and another said "Huh? What?" but nobody had a reason.

Although plenty of folks I climb with today know that a short fall off your anchor produces a high fall-factor that can injure you. These same guys will get very nervous if anybody climbs above the top anchor.

(Edit ...)
Oops not "today"! Everybody I know is skiing, or climbing ice today. Well I never learned to ski, and I'm staying off the ice-climbs for this winter.
But I'm still messing around on snow and rock and scree and other silliness.


(This post was edited by dan2see on Dec 29, 2012, 9:36 PM)


patto


Dec 29, 2012, 9:04 PM
Post #23 of 80 (7265 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

Syd wrote:
The main peak load occurs over 85ms (that is, the width of the peak above the final base load). The most extreme part of the peak load happens in a shorter period. It is interesting to consider this in relation to active dynamic belaying. It is claimed that if the belayer jumps or steps or actively initiates a moves in some way, when a climber falls, he can reduce the peak loading on the climber. It takes an absolute minimum of 200ms for a person to react to some stimulus (such as hearing a yell "falling" or seeing a fall), and generally this time is much longer. Further time is then required for the belayer to flex in some way. To reduce the peak load on the climber, the belayer's jump would then have to be precisely synchronised with the 85ms peak load. To me, this seems almost impossible.

Any "dynamic" effect by the belayer is simply the belayer being lifted off the ground by the impact of the fall. It is virtually impossible for the belayer to actively contribute to any impact reduction.

Many people consider that dynamic belaying is an essential part of good belaying but actions other than allowing some rope slip through the belay device at the moment of impact and an indirect or semi direct belay, seem futile.

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. If you are doing it to make you and you partner more comfortable on repeated sport climbing falls then I don't see a problem. In steep over hangs more slack or dynamic belays can avoid ankle damaging pendulums.

If you think it is an essential part of safety in TRAD climbing then you are misguided. The difference between a grigri and a ATC is far bigger. But unless you are frequently leading very tiny pieces then I don't believe dynamic belays are important. (Even when I've lead X rated climbes with RPs and ultra micro cams I've never felt the need for a dynamic belay. Personally I want a reliable catch and in the event of piece failure a reliable FF2 preventative measures.)


Certainly amongst MY local TRAD community dynamic belays are never emphasised.


dan2see


Dec 29, 2012, 9:39 PM
Post #24 of 80 (7258 views)
Shortcut

Registered: Mar 28, 2006
Posts: 1497

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

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.


bearbreeder


Dec 29, 2012, 10:10 PM
Post #25 of 80 (7250 views)
Shortcut

Registered: Feb 1, 2009
Posts: 1960

Re: [shotwell] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post



Dynamic belaying

Some think it is difficult to belay dynamically with the GRIGRI. But it is the belayer, not the belay device, that plays the primary role in dynamic belaying.

The key to dynamic belaying: step or make a small jump forward when the climber falls. We also stress that dynamic belaying does not mean keeping 3-4 m of slack in the climber’s side of the rope: this does not reduce the force of a fall. In addition, in the case where the climber has not gained enough height, it increases the risk of a ground fall.

In any case, it is necessary to be attentive and vigilant while belaying, so that potential falls can be anticipated. Remember that where there is a risk of a ground fall, or striking a ledge, a dynamic belay should not be used.

It takes practice to master dynamic belaying. To practice, start with falls sufficiently high relative to the ground (for example, when the climber is nearing the end of a pitch)


http://www.petzl.com/...erience#GE-dynamique


its that simple folks Wink


JimTitt


Dec 29, 2012, 10:49 PM
Post #26 of 80 (3050 views)
Shortcut

Registered: Aug 7, 2008
Posts: 986

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

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 don´t jump, don´t recommend it and don´t expect anyone to do it. Nor would I teach it. That was USNavy´s idea and how he achieves this I have no idea, he´s 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 I´m 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 don´t bother since the bottom of the cliffs where I mostly climb are an upward slope which makes things awkward and anyway I´d 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 it´s a whole different concept and process (and belay device generally).


(This post was edited by JimTitt on Dec 29, 2012, 10:51 PM)


csproul


Dec 30, 2012, 4:35 AM
Post #27 of 80 (3020 views)
Shortcut

Registered: Jun 4, 2004
Posts: 1768

Re: [dan2see] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

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.


dan2see


Dec 30, 2012, 4:38 AM
Post #28 of 80 (3020 views)
Shortcut

Registered: Mar 28, 2006
Posts: 1497

Re: [JimTitt] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

JimTitt wrote:
... Mostly I don´t bother since the bottom of the cliffs where I mostly climb are an upward slope which makes things awkward and anyway I´d 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"! Tongue !! Tongue !!!


(This post was edited by dan2see on Dec 30, 2012, 5:14 AM)


dan2see


Dec 30, 2012, 6:11 AM
Post #29 of 80 (3001 views)
Shortcut

Registered: Mar 28, 2006
Posts: 1497

Re: [csproul] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

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.


Syd


Dec 30, 2012, 12:28 PM
Post #30 of 80 (2982 views)
Shortcut

Registered: Oct 25, 2012
Posts: 300

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (2 ratings)  
Can't Post

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.


jt512


Dec 30, 2012, 1:12 PM
Post #31 of 80 (2972 views)
Shortcut

Registered: Apr 11, 2001
Posts: 21893

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (2 ratings)  
Can't Post

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


redlude97


Dec 30, 2012, 4:03 PM
Post #32 of 80 (2959 views)
Shortcut

Registered: Aug 27, 2008
Posts: 990

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (4 ratings)  
Can't Post

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.
Seriously. STFU with your theory. At 180lbs, belaying girls on a regular basis means dynamic belays are a necessity. Otherwise quite the slam results. I would estimate 99% of the hundreds of falls I've caught I've timed the jump correctly. You have no idea WTF you are talking about.


csproul


Dec 30, 2012, 4:19 PM
Post #33 of 80 (2954 views)
Shortcut

Registered: Jun 4, 2004
Posts: 1768

Re: [dan2see] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

dan2see wrote:
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.
I wasn't addressing the OP, genius, I was addressing you. If you can read the highlighted and underlined sentence above, YOU are talking about a dynamic belay and how you've "never seen anyone do a dynamic belay in your local sport climbing community". And my original statement stands. Either you are not paying attention to your local sport climbing community or you don't have one. Dynamic belays are commonplace at every sport climbing crag I've ever seen and they are effective. Period.


(This post was edited by csproul on Dec 30, 2012, 5:09 PM)


dan2see


Dec 30, 2012, 6:39 PM
Post #34 of 80 (2935 views)
Shortcut

Registered: Mar 28, 2006
Posts: 1497

Re: [csproul] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

csproul wrote:
...
I wasn't addressing the OP, genius, I was addressing you. If you can read the highlighted and underlined sentence above, YOU are talking about a dynamic belay and how you've "never seen anyone do a dynamic belay in your local sport climbing community". And my original statement stands. Either you are not paying attention to your local sport climbing community or you don't have one. Dynamic belays are commonplace at every sport climbing crag I've ever seen and they are effective. Period.

Tongue Tongue Tongue

<Phew> I feel better already!


Syd


Jan 1, 2013, 4:38 PM
Post #35 of 80 (2861 views)
Shortcut

Registered: Oct 25, 2012
Posts: 300

Re: [jt512] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

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.


jt512


Jan 1, 2013, 5:07 PM
Post #36 of 80 (2858 views)
Shortcut

Registered: Apr 11, 2001
Posts: 21893

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

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


csproul


Jan 1, 2013, 5:19 PM
Post #37 of 80 (2853 views)
Shortcut

Registered: Jun 4, 2004
Posts: 1768

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

You're either substantially heavier than most of your partners or you don't fall very often.


notapplicable


Jan 1, 2013, 5:24 PM
Post #38 of 80 (2852 views)
Shortcut

Registered: Aug 31, 2006
Posts: 17768

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

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.


USnavy


Jan 3, 2013, 10:42 PM
Post #39 of 80 (2775 views)
Shortcut

Registered: Nov 5, 2007
Posts: 2664

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

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.
Maybe research done by high school kids. Any reputable research done by anyone that knows what they are doing will show the opposite of what you claim, except in extremely low fall factor scenarios.
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 .
That is completely incorrect. You are overthinking it. Dynamic belaying is not as much of a precision art as you believe it is. Close is good enough. You dont need to time things to the millisecond.

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.
Allow me to show you what actually happens when you give a dynamic belay and when you dont. I tested this at my local crag using standard belaying techniques found in use by any experienced sport climber.



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 3, 2013, 10:49 PM)


patto


Jan 4, 2013, 12:41 AM
Post #40 of 80 (2758 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

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!


redlude97


Jan 4, 2013, 1:15 AM
Post #41 of 80 (2755 views)
Shortcut

Registered: Aug 27, 2008
Posts: 990

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

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!
An 18% reduction in peak is negligible?

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, 1:53 AM)


bearbreeder


Jan 4, 2013, 2:20 AM
Post #42 of 80 (2742 views)
Shortcut

Registered: Feb 1, 2009
Posts: 1960

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

patto wrote:

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!


First of all, just to clear-up a few myths, the following is not dynamic belaying:

1) Dynamic belaying involves giving lots of slack - FALSE!

The more slack there is in the system, the further the climber will fall before the rope can start to do its job and the more force will need to be absorbed. Unless there is an obvious hazard that you need to steer the falling climber away from, give only enough slack to allow freedom of movement.


http://www.ukclimbing.com/...les/page.php?id=1844


We also stress that dynamic belaying does not mean keeping 3-4 m of slack in the climber’s side of the rope: this does not reduce the force of a fall. In addition, in the case where the climber has not gained enough height, it increases the risk of a ground fall.


http://www.petzl.com/...erience#GE-dynamique


http://bealplanet.com/...ervir-corde-page.php


patto


Jan 4, 2013, 2:39 AM
Post #43 of 80 (2737 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [bearbreeder] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

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! Crazy

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.


bearbreeder


Jan 4, 2013, 2:46 AM
Post #44 of 80 (2736 views)
Shortcut

Registered: Feb 1, 2009
Posts: 1960

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

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! Crazy

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 Wink

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 Tongue


(This post was edited by bearbreeder on Jan 4, 2013, 2:52 AM)


patto


Jan 4, 2013, 5:02 AM
Post #45 of 80 (2719 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [bearbreeder] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (2 ratings)  
Can't Post

bearbreeder wrote:
are you whinning about UKclimbing confusing stuff for ya Wink

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 Tongue

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. Crazy


(This post was edited by patto on Jan 4, 2013, 5:08 AM)


redlude97


Jan 4, 2013, 5:13 AM
Post #46 of 80 (2712 views)
Shortcut

Registered: Aug 27, 2008
Posts: 990

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

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! Crazy

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.
The difference is that using slack to decrease the pendulum effect comes at a cost of much farther fall to achieve the same affects as dynamic belaying. You still have the higher overall impact forces as well. Dynamic belaying results in all the benefits and no drawbacks.


patto


Jan 4, 2013, 5:29 AM
Post #47 of 80 (2710 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [redlude97] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (2 ratings)  
Can't Post

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. Wink


redlude97


Jan 4, 2013, 6:22 AM
Post #48 of 80 (2703 views)
Shortcut

Registered: Aug 27, 2008
Posts: 990

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

patto wrote:
So a foot of dynamic jumping is so much better than a foot of slack in reducing the pendulum! Crazy Laugh

patto wrote:
So a foot of dynamic jumping is so much better than a foot of slack in reducing the pendulum! Crazy Laugh
Yes, by a long shot.

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. Wink
You are still missing the point.The impact force rating of the rope has a marginal effect on the pendulum effect.
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.


wivanoff


Jan 4, 2013, 7:09 AM
Post #49 of 80 (2693 views)
Shortcut

Registered: May 23, 2007
Posts: 144

Re: [Syd] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

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.


csproul


Jan 4, 2013, 7:46 AM
Post #50 of 80 (2687 views)
Shortcut

Registered: Jun 4, 2004
Posts: 1768

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

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, 9:22 AM)


bearbreeder


Jan 4, 2013, 9:08 AM
Post #51 of 80 (3009 views)
Shortcut

Registered: Feb 1, 2009
Posts: 1960

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

patto wrote:
bearbreeder wrote:
are you whinning about UKclimbing confusing stuff for ya Wink

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 Tongue

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. Crazy

i think yr making things up to cover up ... ALL i care about is not getting SLAMMED into the wall ... regardless of whatever "forces" on gear ... i did say SPORT after all Wink

a highly experienced climber like you doesnt even know how to give soft catches ???

good thing you arent belaying me ... because id hate to get SLAMMED into the wall just because someone doesnt know how to catch sport whippers over and over again ... and is too "proud" to admit it

Tongue

from redpoint by doug hunter and dan hague




(This post was edited by bearbreeder on Jan 4, 2013, 9:11 AM)


patto


Jan 4, 2013, 9:21 AM
Post #52 of 80 (2997 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [bearbreeder] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

bearbreeder wrote:
a highly experienced climber like you doesnt even know how to give soft catches ???
Who said I don't know how to dynamic belay? What I'm arguing here are the exaggerated benefits.

bearbreeder wrote:
good thing you arent belaying me ... because id hate to get SLAMMED into the wall just because someone doesnt know how to catch sport whippers over and over again ... and is too "proud" to admit it
Sport whippers!? Isn't that an oxymoron? Wink

Anyway I'm done talking about dynamic belays. Like myself and others said earlier it has very little to do with this topic. I should have bowed out earlier. Angelic


(This post was edited by patto on Jan 4, 2013, 9:26 AM)


bearbreeder


Jan 4, 2013, 9:27 AM
Post #53 of 80 (2989 views)
Shortcut

Registered: Feb 1, 2009
Posts: 1960

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

patto wrote:
bearbreeder wrote:
a highly experienced climber like you doesnt even know how to give soft catches ???
Who said I don't know how to dynamic belay? What I'm arguing here are the exaggerated benefits.

bearbreeder wrote:
good thing you arent belaying me ... because id hate to get SLAMMED into the wall just because someone doesnt know how to catch sport whippers over and over again ... and is too "proud" to admit it
Sport whippers!? Isn't that an oxymoron? Wink

if you took a 5-10+ whippers a day, 2-3 times a week, 52 weeks a year ... you wouldnt think they were exaggerated

all it takes is one hard catch that tweaks your ankle to realize this ... of your friend getting slammed by someone who didnt understand the concept, and not being able to climb for a year because of someones ignorance ...

its that simple Tongue


redlude97


Jan 4, 2013, 9:38 AM
Post #54 of 80 (2982 views)
Shortcut

Registered: Aug 27, 2008
Posts: 990

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

patto wrote:
bearbreeder wrote:
a highly experienced climber like you doesnt even know how to give soft catches ???
Who said I don't know how to dynamic belay? What I'm arguing here are the exaggerated benefits.

bearbreeder wrote:
good thing you arent belaying me ... because id hate to get SLAMMED into the wall just because someone doesnt know how to catch sport whippers over and over again ... and is too "proud" to admit it
Sport whippers!? Isn't that an oxymoron? Wink

Anyway I'm done talking about dynamic belays. Like myself and others said earlier it has very little to do with this topic. I should have bowed out earlier. Angelic
You keep saying this but don't provide any evidence whatsover.


jt512


Jan 4, 2013, 10:14 AM
Post #55 of 80 (2971 views)
Shortcut

Registered: Apr 11, 2001
Posts: 21893

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

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!

You are never belaying me.

Jay


patto


Jan 4, 2013, 10:27 AM
Post #56 of 80 (2966 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [redlude97] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

redlude97 wrote:
You keep saying this but don't provide any evidence whatsover.
Evidence? I have settled on reason which has been discussed earlier.

The "evidence" used to argue the opposite has simply been people bragging about their whippers. Laugh

jt512 wrote:
You are never belaying me.
Who said I had offered? Besides you continue to confuse technical discussion with actual belay techniques. Crazy

The real world is quite varied. If you can't think and alter your behaviour to the present situation then you may end up in an unsafe situation.

As I found out earlier in the week, even something as simple as a fireman's belay can be difficult and ineffective if somebody simply relies on rote technique.


(This post was edited by patto on Jan 4, 2013, 10:35 AM)


redlude97


Jan 4, 2013, 10:45 AM
Post #57 of 80 (2957 views)
Shortcut

Registered: Aug 27, 2008
Posts: 990

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

patto wrote:
redlude97 wrote:
You keep saying this but don't provide any evidence whatsover.
Evidence? I have settled on reason which has been discussed earlier.

The "evidence" used to argue the opposite has simply been people bragging about their whippers. Laugh

jt512 wrote:
You are never belaying me.
Who said I had offered? Besides you continue to confuse technical discussion with actual belay techniques. Crazy

The real world is quite varied. If you can't think and alter your behaviour to the present situation then you may end up in an unsafe situation.

As I found out earlier in the week, even something as simple as a fireman's belay can be difficult and ineffective if somebody simply relies on rote technique.
patto wrote:
Syd wrote:
The main peak load occurs over 85ms (that is, the width of the peak above the final base load). The most extreme part of the peak load happens in a shorter period. It is interesting to consider this in relation to active dynamic belaying. It is claimed that if the belayer jumps or steps or actively initiates a moves in some way, when a climber falls, he can reduce the peak loading on the climber. It takes an absolute minimum of 200ms for a person to react to some stimulus (such as hearing a yell "falling" or seeing a fall), and generally this time is much longer. Further time is then required for the belayer to flex in some way. To reduce the peak load on the climber, the belayer's jump would then have to be precisely synchronised with the 85ms peak load. To me, this seems almost impossible.

Any "dynamic" effect by the belayer is simply the belayer being lifted off the ground by the impact of the fall. It is virtually impossible for the belayer to actively contribute to any impact reduction.

Many people consider that dynamic belaying is an essential part of good belaying but actions other than allowing some rope slip through the belay device at the moment of impact and an indirect or semi direct belay, seem futile.

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. If you are doing it to make you and you partner more comfortable on repeated sport climbing falls then I don't see a problem. In steep over hangs more slack or dynamic belays can avoid ankle damaging pendulums.

If you think it is an essential part of safety in TRAD climbing then you are misguided. The difference between a grigri and a ATC is far bigger. But unless you are frequently leading very tiny pieces then I don't believe dynamic belays are important. (Even when I've lead X rated climbes with RPs and ultra micro cams I've never felt the need for a dynamic belay. Personally I want a reliable catch and in the event of piece failure a reliable FF2 preventative measures.)


Certainly amongst MY local TRAD community dynamic belays are never emphasised.
Except your agreement is based on completely flawed theory by Syd. Your "reason" refers to some "evidence" that the reduction is minimal. Care to provide it? Evidence provide here through actual testing and theoretical calculations shows significant decrease in both peak loads and pendulum velocity. Yet you are going to keep sticking by your vague "reason" with "evidence" that isn't to be seen? Are you being deliberately obtuse in your old age?


(This post was edited by redlude97 on Jan 4, 2013, 10:46 AM)


bearbreeder


Jan 4, 2013, 10:48 AM
Post #58 of 80 (2955 views)
Shortcut

Registered: Feb 1, 2009
Posts: 1960

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

patto wrote:
The "evidence" used to argue the opposite has simply been people bragging about their whippers. Laugh
.

petzl, beal, ukclimbing, redpoint by the same authors of self coached climbing ...

thats just the start ...Tongue

go climb sport at your limit for a few months ... take the falls over and over again ... and youll see

let me ask you this ... how many whippers do ya catch in a day on 11+ sport routes, and how many falls a year ... i mean you are obviously so knowledgeable that you MUST have a massive amount of experience catching falls on hard sport climbs ... Wink

an experienced belayer MUST have alot of experience catching falls ... they need to know WHEN to give a soft catch, when to sit right down, judge the effects of their catches on traverses and overhands, etc ... not just hold the rope and give a static belay ...

any belayer who doesnt have real world experience catching falls over and over again ... will be the one that gives you the wrong catch at the wrong time ... and youll get hurt

the person i WILL NOT climb with is the person who says "hey i will ignore everything from petzl, beal, and other sources because i dont believe dynamic belay works since i cant ADMIT im wrong .... who cares if you break your ankle since im ALWAYS RIGHT"

Crazy


Partner cracklover


Jan 4, 2013, 11:32 AM
Post #59 of 80 (2941 views)
Shortcut

Registered: Nov 14, 2002
Posts: 10054

Re: [jt512] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

jt512 wrote:
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!

You are never belaying me.

Jay

It is quite possible that I have partners who, without me being aware of it, are as inept as Patto. However, I don't have any that are as proud or as stubborn about their own failings. For that reason alone, Patto can add to me to the list of folks who will not climb with him.

GO


patto


Jan 4, 2013, 3:17 PM
Post #60 of 80 (2912 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [cracklover] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

bearbreeder wrote:
the person i WILL NOT climb with is the person who says "hey i will ignore everything from petzl, beal, and other sources because i dont believe dynamic belay works since i cant ADMIT im wrong .... who cares if you break your ankle since im ALWAYS RIGHT"

Sigh. Unsure

Since my comments are being frequently misrepresented and twisted into something that is entirely different from what I have said I see no use in debating.


cracklover wrote:
It is quite possible that I have partners who, without me being aware of it, are as inept as Patto. However, I don't have any that are as proud or as stubborn about their own failings. For that reason alone, Patto can add to me to the list of folks who will not climb with him.

Having offensive people suggest the wont climb with my certainly isn't a problem for me! Cool

However having people use this as a debating tool based on false interpretations of what I have said is a problem.


There is no use continuing when I'm continually being accused of saying things I have not.


bearbreeder


Jan 4, 2013, 4:20 PM
Post #61 of 80 (2901 views)
Shortcut

Registered: Feb 1, 2009
Posts: 1960

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

patto wrote:

Sigh. Unsure

Since my comments are being frequently misrepresented and twisted into something that is entirely different from what I have said I see no use in debating.

your comments were quite clear ... despite clean evidence by multiple reputable manufactures, authors and sites

in addition multiple posters who climb sport have told you that dynamic belaying is effective for preventing your climber from slamming into the wall ... yet you insist on going off about who knows what about how it ...

heres another one from "how to climb HARD TRAD" by britains best trad climber , dave macleod

If there is enough height to manage it, get the belayer to give you a dynamic belay.
This basically means the belayer slows the rate at which the rope comes tight,
spreading the load out over time and lowering the peak forces on the gear. This is
really effective both for preventing gear failing but also for lessening violent swings
into the crag, which do cause some really bad injuries, even on apparently safe
routes.
There are a few techniques for dynamic belaying. The most obvious one is
to let the rope run through the belay plate, gradually closing grip until the rope stops.
In practice this is very difficult to do, so is best avoided for short routes. If you must
use it, practice on some long sport routes first. The second is to belay slightly away
from the crag and ‘run with’ the rope as it comes tight for a few steps. This might be
a bad idea if the gear includes poor wires, where standing as close to the wall as
possible is best. In this case, jump upwards with the rope as it comes tight, or use a
bombproof runner close to the ground to redirect the rope.



but then i suppose you know better than him Tongue

as to "misconstrued" ... your the pot trying to call the kettle black

its quite obvious from this and other threads that some RCers dont understand, care or practice dynamic belays ... this is a serious hazard should you ever need to catch vertical to overhanging "clean" falls ... having your ankle or other extremity busted from slamming into the wall or other such that could be prevented with a dynamic belay is a VERY COMMON injury ....

and people say intraweb forums is a "good" place to learn basic safety advice

Tongue


(This post was edited by bearbreeder on Jan 4, 2013, 4:24 PM)


JimTitt


Jan 5, 2013, 4:35 AM
Post #62 of 80 (2867 views)
Shortcut

Registered: Aug 7, 2008
Posts: 986

Re: [bearbreeder] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

Dynamic belaying is a requirement for international competition climbing.

Prior to the event belayers are required to "Train in stopping a competitor's fall dynamically." (ISFC) or show they can belay dynamically (various national federations intepretation of this for selecting belayers.

During the event belayers are required to:-
"Absorb the fall dynamically which is not synonymous to a long fall.
Absorb the fall safely – sometimes a longer fall is needed in order to avoid hitting a roof edge, etc." (ISFC)

Automatic or semi-automatic belaying devices are not allowed. (ISFC)


patto


Jan 5, 2013, 11:57 AM
Post #63 of 80 (2833 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [JimTitt] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

I am not against people using a dynamic belay. Yet somehow people continue to twist my comments despite my pointing this out. Crazy

(Not directed at you JimTitt)


JimTitt


Jan 5, 2013, 12:20 PM
Post #64 of 80 (2823 views)
Shortcut

Registered: Aug 7, 2008
Posts: 986

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

I always get a dynamic belay anyway, I weigh over 200lbs!


USnavy


Jan 5, 2013, 8:47 PM
Post #65 of 80 (2802 views)
Shortcut

Registered: Nov 5, 2007
Posts: 2664

Re: [JimTitt] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

JimTitt wrote:

Automatic or semi-automatic belaying devices are not allowed. (ISFC)
Well that should be easy considering not a single automatic or semi-automatic handheld belaying device exists, with the exception of roped soloing devices.


(This post was edited by USnavy on Jan 5, 2013, 8:47 PM)


JimTitt


Jan 6, 2013, 1:26 AM
Post #66 of 80 (2790 views)
Shortcut

Registered: Aug 7, 2008
Posts: 986

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (2 ratings)  
Can't Post

USnavy wrote:
JimTitt wrote:

Automatic or semi-automatic belaying devices are not allowed. (ISFC)
Well that should be easy considering not a single automatic or semi-automatic handheld belaying device exists, with the exception of roped soloing devices.[/quote

Halbautomat is widest used description of this kind of device in Europe and translates as semi-automatic. The IFSC is not part of the UIAA and don´t give a shit about whatever terminology they use this week, nor what you call them either.


USnavy


Jan 6, 2013, 5:02 AM
Post #67 of 80 (2767 views)
Shortcut

Registered: Nov 5, 2007
Posts: 2664

Re: [JimTitt] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

JimTitt wrote:
USnavy wrote:
JimTitt wrote:

Automatic or semi-automatic belaying devices are not allowed. (ISFC)
Well that should be easy considering not a single automatic or semi-automatic handheld belaying device exists, with the exception of roped soloing devices.[/quote

Halbautomat is widest used description of this kind of device in Europe and translates as semi-automatic. The IFSC is not part of the UIAA and don´t give a shit about whatever terminology they use this week, nor what you call them either.


You mean this crude Mammut Smart? http://www.youtube.com/watch?v=0mgXCDkDOh0


(This post was edited by USnavy on Jan 6, 2013, 5:02 AM)


JimTitt


Jan 6, 2013, 6:10 AM
Post #68 of 80 (2758 views)
Shortcut

Registered: Aug 7, 2008
Posts: 986

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

No


USnavy


Jan 6, 2013, 8:56 PM
Post #69 of 80 (2724 views)
Shortcut

Registered: Nov 5, 2007
Posts: 2664

Re: [JimTitt] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

Do you have a link?


JimTitt


Jan 6, 2013, 11:43 PM
Post #70 of 80 (2715 views)
Shortcut

Registered: Aug 7, 2008
Posts: 986

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

Do I have a link to what?


Partner cracklover


Jan 7, 2013, 8:54 AM
Post #71 of 80 (2678 views)
Shortcut

Registered: Nov 14, 2002
Posts: 10054

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

patto wrote:
Since my comments are being frequently misrepresented and twisted into something that is entirely different from what I have said I see no use in debating.


cracklover wrote:
It is quite possible that I have partners who, without me being aware of it, are as inept as Patto. However, I don't have any that are as proud or as stubborn about their own failings. For that reason alone, Patto can add to me to the list of folks who will not climb with him.

Having offensive people suggest the wont climb with my certainly isn't a problem for me! Cool

However having people use this as a debating tool based on false interpretations of what I have said is a problem.


There is no use continuing when I'm continually being accused of saying things I have not.

I'm sorry you find me to be offensive. If there's something I've said here that you find objectionable, please do point it out, and I'd be happy to address it, or, if I was in the wrong, apologize.

As for misrepresenting you, all I've said is that you seem to me to be both proud and stubborn about your method of belaying, which, unless I'm mistaken, is to give extra slack as opposed to a soft catch. You also have a variety of arguments, none of which are convincing to me, to back up this choice.

GO


6pacfershur


Jan 8, 2013, 7:15 PM
Post #72 of 80 (2615 views)
Shortcut

Registered: Jun 22, 2010
Posts: 223

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

patto wrote:
Since my comments are being frequently misrepresented and twisted into something that is entirely different from what I have said....

thats what this forum does best!!!!


USnavy


Jan 8, 2013, 10:12 PM
Post #73 of 80 (2602 views)
Shortcut

Registered: Nov 5, 2007
Posts: 2664

Re: [JimTitt] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

JimTitt wrote:
Do I have a link to what?
I misread. I thought the halbautomat was a specific device. Now I see it is just German for semi-automatic.


(This post was edited by USnavy on Jan 8, 2013, 10:13 PM)


Partner rgold


Jan 9, 2013, 9:45 AM
Post #74 of 80 (2569 views)
Shortcut

Registered: Dec 3, 2002
Posts: 1801

Re: [USnavy] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (4 ratings)  
Can't Post

I've used the jump dynamic belay in a gym setting and the leaders involved have the impression of a softer catch. This corresponds to the extensive experience of the climbing community, as evidenced by the quotes from various sources posted by Bearbreeder and the IFSC regulations posted by Jim (English version of site at http://www.ifsc-climbing.org/). We have US Navy's test (one trial?), in which an 18% load reduction strikes me as better than one can expect in general, and the abstract of more extensive and probably more reliable testing by Walter Nachbauer posted by Magid, http://www.rockclimbing.com/...post=1899631#1899631 (the link there is broken and I haven't been able to find the paper), which observed a 12% reduction over a Munter hitch belay. Other reported results are very interesting---have a look!

The substantial experiential evidence and such tests as we have indicates that the millisecond arguments are wrong, probably because of assumptions that do not correspond to proper belay technique. The belayer has to be ready, standing with knees bent and a slight forward lean. The jump happens from this position as soon as rope tension is felt at the belay; there is no critical "timing" involved and it is not hard to get it right. Moreover, there is no danger of a premature jump (which could make for a very nasty catch), the worst outcome being loads no better than those from a standing belay.

These actions typically produce a catch that most leaders perceive as more comfortable. Whether this perception corresponds to a significant reduction in physical injuries is, as far as I know, unknown. We also don't know what physical aspects of the system, modified by the dynamic belay, contribute to the perception of a softer catch (which is to say that maybe we don't really know what a "soft catch" is). The studies tacitly assume that reduction in peak load is the governing parameter. With dynamic belaying, that reduction is associated with a lower rate of load increase (smaller maximum "jerk") on the way to the peak load. From a physiological point of view, I don't know which, if either, of these factors is more critical.

Almost every bit of research that has involved human belayers has noted a broad range of belayer reactions to identical stimuli, often broad enough to overwhelm the effects of the phenomena that were supposed to be tested. This being the case, it is reasonable to assume that belayer behavior with respect to dynamic belaying will be inconsistent, and so the importance of correct technique is to insure outcomes no worse than a standing belay.

Another issue for hard routes that involve multiple leader falls is that the rope gets progressively stiffer with each successive catch and so the impact forces rise on each successive fall, even with a dynamic belay. Those tweaked ankles could be a result of not switching ends after a few falls rather than whatever actions the belayer did or did not take. Old worn ropes will also be stiffer than less-used ones.

I think Patto is right to emphasize that issues associated with pendulums are not necessarily the same as the question of peak load reduction and that the discussion has been confused on this issue.
Bearbreeder mentions dynamic belays in relation to "tweaked" ankles and some of the posts mention things like "smashing into the rock." This is usually a pendulum question, although a dynamic belay that plops the leader onto a ledge could also lead to injuries, and the ledge doesn't have to be very big if the wall is merely vertical. However, the typical scenario for a pendulum impact is a short fall on an overhanging wall. The leader pendulums in and smacks the wall hard, possibly injuring one or both ankles.

The problem here is that the small amount of rope out for a short fall determines, at the moment the pendulum begins, a relatively large initial angle and so relatively large amplitude---the leader "wants" to swing approximately as far to the other side of the pendulum point, but of course the wall is there to stop them. The solution to this problem, as Patto says, is lengthen the leader's fall. With more rope out, the pendulum effect engages with a smaller initial angle and so a smaller amplitude, and in addition the overhanging wall is moving away from the leader. The combined effect is that either the leader doesn't hit the wall at all while swinging, of if so hits with reduced horizontal velocity on the upward part of the pendulum motion.

The jump dynamic belay and the simple addition of slack to the belay both achieve this end. Adding slack to the belay increases the peak load, so is less desirable than the jump---assuming the belayer gets the jump right, and assuming that the three feet or so obtained from the jump is enough extra slack to produce a suitable reduction in the pendulum. These assumptions indicate that there is uncertainty that cannot be removed in any practical situation.

I think the uncertainty about the value of this process increases as the wall becomes less overhanging. Climbers, consciously, unconsciously, or because of the dynamics of the moment of release, end up falling way from vertical walls and so are subject to pendulum impacts when they swing back in. The biggest advantage in the overhanging case, that the wall is moving away from the climber, is no longer present, and the climber is going to hit the wall with some horizontal velocity from the pendulum effect no matter what. Moreover, as mentioned above, relatively small features on a vertical wall can do a lot of damage if the fall is lengthened and the climber hits them. All of this makes dynamic belaying a much iffier proposition.

I'd be particularly concerned when the belayer is lifted many feet. Tests by the CAI (which did not, however, involve a jump by the belayer) suggested that lifting the belay more than about 8 inches had no further effect on reducing the peak load to the top pro. Belayer lifts of ten feet have been mentioned in this thread (with an implication that the belayer is somehow able to decide on or control how much lift occurs). At some point the dangers associated with the climber hitting something (including the ground) and/or a midair collision of climber and belayer are going to seriously outweigh any advantages of letting that much extra slack run through the system. In this regard, it is important not to automatically equate lifting with load reduction or even with energy absorbtion. In the absence of friction, such a system would attain equilibrium in the form of motion at constant velocity, at which point any further lifting is of no value whatsoever.

In all these situations, the pendulum effect is not particularly great for long falls, and in addition the effects of jumping, both in terms of activating an alternative energy-absorbing mechanism and adding extra rope, will be negligible. It would be nice to have some idea when the effects of jumping really no longer have any useful effect, but meanwhile it is a technique primarily of value for relatively short falls, which are after all the primary type of fall for most sport climbing.

It is important to emphasize that the technique of standing away from the wall and moving towards when the rope tension is felt is, by and large, a sport-climbing technique. The same technique applied in the presence of trad gear risks zippering the pro from the ground up unless a genuinely bombproof directional anchor has been set up as the first piece.


bearbreeder


Jan 9, 2013, 11:28 AM
Post #75 of 80 (2550 views)
Shortcut

Registered: Feb 1, 2009
Posts: 1960

Re: [rgold] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

you can still slam into the wall on dead vertical falls ... i know someome with a broken ankle to prove it ... on a nice shinny rope from the first fall of the day

simply giving slack isnt always practical or advisable depending on the situation

and if a person believe that all they need to do is "give slack" you can still slam a lighter climber into the wall if its slightly slabby to slightly overhangingif you happen to give a very static (fight the fall by sitting back) belay at the moment the rope comes taut .... yes ive seen injuries from that as well

note that most the souces i posted including petzl, ukclimbing, doug hunter/dan hague, the UIAA link jim posted ... as well as all the people here who sport climb alot ... say or imply that simply giving slack isnt the answer ...

its the "trad" climbers that do

Wink


(This post was edited by bearbreeder on Jan 9, 2013, 11:29 AM)


Partner rgold


Jan 9, 2013, 11:34 AM
Post #76 of 80 (739 views)
Shortcut

Registered: Dec 3, 2002
Posts: 1801

Re: [bearbreeder] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (1 rating)  
Can't Post

I don't know who you are replying to but it certainly isn't me. I covered everything you said here.

I see sport climbers leave substantial loops of slack in the belay a lot.

I never see trad climbers doing that.


redlude97


Jan 9, 2013, 12:15 PM
Post #77 of 80 (726 views)
Shortcut

Registered: Aug 27, 2008
Posts: 990

Re: [rgold] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

rgold wrote:
I don't know who you are replying to but it certainly isn't me. I covered everything you said here.

I see sport climbers leave substantial loops of slack in the belay a lot.

I never see trad climbers doing that.
Patto does it....


(This post was edited by redlude97 on Jan 9, 2013, 12:16 PM)


patto


Jan 9, 2013, 3:53 PM
Post #78 of 80 (704 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [cracklover] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

cracklover wrote:
As for misrepresenting you, all I've said is that you seem to me to be both proud and stubborn about your method of belaying, which, unless I'm mistaken, is to give extra slack as opposed to a soft catch.

You are totally mistaken in every facet of that statement.

*I have not expresed pride of stubbornness about my belaying.
*In fact I haven't even discussed my belaying.
*I'm not advocating "giving more slack" to the climber


(This post was edited by patto on Jan 9, 2013, 4:01 PM)


redlude97


Jan 9, 2013, 4:53 PM
Post #79 of 80 (685 views)
Shortcut

Registered: Aug 27, 2008
Posts: 990

Re: [patto] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

patto wrote:
cracklover wrote:
As for misrepresenting you, all I've said is that you seem to me to be both proud and stubborn about your method of belaying, which, unless I'm mistaken, is to give extra slack as opposed to a soft catch.

You are totally mistaken in every facet of that statement.

*I have not expresed pride of stubbornness about my belaying.
*In fact I haven't even discussed my belaying.
*I'm not advocating "giving more slack" to the climber
Sure you haven't directly stated what you do, but what are we supposed to believe when you make statements like this.
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!

patto wrote:
Syd wrote:
The main peak load occurs over 85ms (that is, the width of the peak above the final base load). The most extreme part of the peak load happens in a shorter period. It is interesting to consider this in relation to active dynamic belaying. It is claimed that if the belayer jumps or steps or actively initiates a moves in some way, when a climber falls, he can reduce the peak loading on the climber. It takes an absolute minimum of 200ms for a person to react to some stimulus (such as hearing a yell "falling" or seeing a fall), and generally this time is much longer. Further time is then required for the belayer to flex in some way. To reduce the peak load on the climber, the belayer's jump would then have to be precisely synchronised with the 85ms peak load. To me, this seems almost impossible.

Any "dynamic" effect by the belayer is simply the belayer being lifted off the ground by the impact of the fall. It is virtually impossible for the belayer to actively contribute to any impact reduction.

Many people consider that dynamic belaying is an essential part of good belaying but actions other than allowing some rope slip through the belay device at the moment of impact and an indirect or semi direct belay, seem futile.

I completely agree with this.

Crazy


patto


Jan 9, 2013, 6:14 PM
Post #80 of 80 (674 views)
Shortcut

Registered: Nov 14, 2005
Posts: 1452

Re: [redlude97] Quick and dirty test: What happens during shockloading? [In reply to]
Report this Post
Average: avg_1 avg_2 avg_3 avg_4 avg_5 (0 ratings)  
Can't Post

redlude97 wrote:
Sure you haven't directly stated what you do, but what are we supposed to believe when you make statements like this.
Crazy

You should read and comprehend what the statements DO say and not to jump to conclusions about what they DO NOT say.

rgold wrote:
....

LOTS OF TEXT...
Like usual I feel compelled to agree with Rgold...


rgold wrote:
I see sport climbers leave substantial loops of slack in the belay a lot.

I never see trad climbers doing that.

I've observed this about many gym climbers too. Though I have no reason or desire to fault their belay as it seems to regularly achieve the desirable outcome.

When it comes to trad though, in my experience, the best way for a belayer to reduce the risk of injury to the climber is USUALLY to minimise the fall distance. This normally involve minimal slack, no jumping and standing beneath the first piece. Of course where a pendulum injury is possible or the pro is exceptionally weak then other approaches may be preferable.

For the last big trad fall I caught there was 30m of rope in the system. The leader fell ~7m came within 0.5m of a sloped face beneath her. I would expect that she was glad of a tight belay with minimal slack or jumping. Wink

Of course a belay should be situationally dependent.


(This post was edited by patto on Jan 9, 2013, 6:50 PM)


Forums : Climbing Information : General

 


Search for (options)

Log In:

Username:
Password: Remember me:

Go Register
Go Lost Password?



Follow us on Twiter Become a Fan on Facebook