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Carnage


Jan 28, 2011, 9:38 AM
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Jim, thanks for your input. I guess i'm pretty much dead wrong.


caughtinside


Jan 28, 2011, 10:25 AM
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That is some good info. I often use a grigri for single pitch trad climbing, mostly on granite but some at Indian Creek. I've thought the jump was an adequate force reducer on the gear, but I guess not?

Probably caught 100 or so falls on gear on the grigri, only one piece pulled.

Not sure yet if I'll switch devices, been nearly clanged a couple times by the leader kicking something off.


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Jan 28, 2011, 10:58 AM
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Re: [caughtinside] Testing a "Dynamic Belay" [In reply to]
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caughtinside wrote:
That is some good info. I often use a grigri for single pitch trad climbing, mostly on granite but some at Indian Creek. I've thought the jump was an adequate force reducer on the gear, but I guess not?

Probably caught 100 or so falls on gear on the grigri, only one piece pulled.

Not sure yet if I'll switch devices, been nearly clanged a couple times by the leader kicking something off.

On routes with small gear near the ground, or really sandy funky rock - be well worth considering.

Cheers,

GO


qwert


Jan 31, 2011, 3:46 AM
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One of the german tests Jim Tit mentioned is probably this one:
http://www.alpenverein.de/...5d9d8468a2e73a1e29d1

I wont translate it, but here is some words about it, and a quick look at some of the numbers they got:

The DAV tested a few belay devices (Tube (looks like it was a classic ATC), various forms of 8s, munterhitch/'HMS, GriGri and TRE) in a factor 0.4 fall.

The fixed the devices to the belay, and belayed with an artificial hand, where they could adjust the hand power, which is - according to a previous study - 209N on average.
so they ran the tests with a hand power of 100N, 250N, 400N and two Persons.

They measured the forces on the top piece and that are the results:

Code
Hand force:       |   100N   |   250N   |   400N   | Person1 | Person2  
Top force GriGri| 5.9kN | 5.6kN | 5.5kN | - not tested -
Top force Tube | 2.7kN | 3.8kN | 5.0kN | 3.8kN | 4.1kN
rope slip GriGri| 9cm | 8cm | 9cm | - not tested -
rope slip Tube | 182cm | 51cm | 22cm | 101cm | 66cm

Obviously this is -as mentioned - a fixed belayer and a small fall factor, but it is safe to assume that those observations also apply for bigger stuff.
The less the belayer grabs the rope, the less force the top piece will see if you are using a dynamic device. If you know how to do this, this can be used to give a soft catch/ help bad protection to stay in.
However if you simply dont have significant force, this might result in uncontroled slipage, that will burn you hand.
On the other hand, if you have strong hands, and simply lock up the rope, you can - if we are ignoring jumping or being pulled up - produce forces quite similar to the grigri.

I would be interested on how some "increased braking strength" tubes like the ATC-XP behave in this test.
I am simply going to claim that this will increase the top force/ reduce the slipage, and that this will reduce the hand force needed to make it static, and thus that there probably are quite a few folks out there who might as well belay trad with a grigri, since it wouldnt make a difference for them anyways.

qwert


(This post was edited by qwert on Jan 31, 2011, 3:50 AM)


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Jan 31, 2011, 8:33 AM
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Interesting study. Since I often belay trad with a TRE, that part was of particular interest to me.

On the moderate fall studied, the TRE (called Sirius in the study) was pretty much equivalent to the Gri Gri. This is not surprising, since it is supposed to lock down and slip at around 3.5 to 4 kN, which is above the amount felt by the belayer in this fall.

So, for the severity of fall studied, the TRE performed as advertised. But I would have liked to see if there *was* in fact this divergence for harder falls - since this is one of the pluses to me in using the TRE.

GO


qwert


Jan 31, 2011, 8:38 AM
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I didnt include the values for the TRE, since this thread is about the GriGri, but yeah, you're right, additional tests with higher fall factors would have been nice.

But unfortunately they havent done them.

qwert


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Jan 31, 2011, 8:57 AM
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Re: [qwert] Testing a "Dynamic Belay" [In reply to]
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qwert wrote:
I didnt include the values for the TRE, since this thread is about the GriGri, but yeah, you're right, additional tests with higher fall factors would have been nice.

But unfortunately they havent done them.

qwert

As a TRE user, I did find one other reference interesting. If I translated correctly (and my German isn't so great these days, so who knows) - they imply that due to the results of the study, they don't recommend belaying a leader directly off the anchor with the GriGri or the TRE. And they explicitly state that while Petzl actually does not endorse such a method, TRE does.

I only ever belay with my TRE direct off the anchor when bringing up a second - never for a leader. And again, with harder falls, there might be more of a divergence between TRE and GriGri. But it's still worth keeping in mind, in case one is ever in a situation where it's tempting to belay the leader directly off the anchor.

I know there are other users of the TRE on this forum, so - sorry for the thread hijack - but I thought it might interest others too.

GO


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Jan 31, 2011, 9:02 AM
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Re: [JimTitt] Testing a "Dynamic Belay" [In reply to]
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JimTitt wrote:
This is in fact why the Petzl calculator is useful as it allows for this to some extent.

Hi Jim,

About a year ago the link I had been using to get to the Petzl calculator stopped working, and I have been unable to find the calculator anywhere on their site.

Do you have a new link to the calculator, or do you know if it still exists anywhere on the web?

Thanks,

GO


JimTitt


Jan 31, 2011, 12:47 PM
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The company is called TRE and the device the Sirius just to clear things up!
TRE published some test graphs for the Sirius where it was a bit less powerful than an HMS but they didn´t give any test details so that isn´t very helpful. We don´t know if the impact force is for the device alone or with a top runner, if it was tested alone then the lower impact force (than the HMS) corresponds with the findings of the DAV with a higher force because the rate of force rise for the Sirius is considerably higher than the HMS. (A bit complicated but due to the stretch in the rope, damping and friction on the runner the steepness of the force curve has a lot of influence on the peak forces further down the rope.)
Anyway your Sirius must be so worn out now it wouldn´t stop a falling raindrop!
The real objection from the DAV is that with both the Grigri and Sirius and a fixed belay the belayer has no control over the braking and cannot influence whether the climbers hits the rock hard or not.

The `high power´devices aren´t really that much more powewrful despite the attempts of the marketing guys! An ATC XP has been shown time and again to be about 20-30% more powerful than an normal ATC but the exact value depends on the drop.
One probem is that it is all so variable, one of the farm mechanics by my workshop can defeat a Grigri with one hand using an ATC XP because he is a monster whereas one of my climbing partner gives me a gentle stop with a Grigri because I´m 90kg and she is 55kg.
As we see it the desirable position is to have a more powerful device than a standard plate (we use the ATC XPfor this) which is easy to regulate which will allow for progressive stops no matter what the fall and also cover a greater range of ropes and belayers.
However it´s not so easy, we made a plate with 50% more power (than an XP) but then abseiling and lowering started getting a bit clunky with thicker ropes and we though customers wouldn´t like it so detuning was called for!

Jim


Partner j_ung


Jan 31, 2011, 1:12 PM
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Jim, does the Chicane address some of these issues, and if so, how? What are are its trade offs?


healyje


Jan 31, 2011, 1:35 PM
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Those ATC rope slip numbers look outlandish and like someone doesn't know how to belay with one. I've never had rope slip anywhere near those numbers in thirty-six years of climbing with either a hip belay or an ATC of any style/make and find them quite unbelievable.

Edit: Ah, 'artificial hand' - got it - ridiculous test design.


(This post was edited by healyje on Jan 31, 2011, 1:36 PM)


JimTitt


Feb 1, 2011, 12:10 AM
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Hmmm, since in that particular test they (the DAV) also used two human belayers and the results where almost identical or even slightly worse then I think it is fair to accept they are right and you are wrong.
However it is possible that your 35 years climbing has given you higher than average hand strength in which case the slip will decrease dramatically, 400N which an old guy like me with 42 years experience can reasonably achieve gives 22cm slip. And it´s unlikely that in your 35 years of climbing you have been holding falls using a brand new 9.6mm rope every time, if you use a furry monster the slip will be negligable!

250N artificial hand - 1.7kN 51cm
Test belayer 1 - 1.7kN 66cm
Test Belayer 2 - 1.5kN 101cm

Using a different design of hand which measured the force a different way and a lower FF and braking force Manin of the CMT (Italy) got 1.26kN and 86cm

Black Diamond and I test by pulling and so we have to calculate the slip from the power ratio and for the DAV fall we get 57cm and 52cm.

The climbing industry and the powers-that-be are kind in that they not only consider the capabilities of hairy assed old men with decades of experience but have to look after the interests of weak and feeble beginners and even `gasp´ delicate members of the opposite sex with their delicate, callus-free moisturised palms!

Jim


JimTitt


Feb 1, 2011, 12:16 AM
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The Petzl calculator was pulled off or moved when then re-designed their site and I´ve not seen it since though to be fair I didn´t use it a lot since I can usually find the info another way.


healyje


Feb 1, 2011, 12:18 AM
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JimTitt wrote:
Hmmm, since in that particular test they (the DAV) also used two human belayers and the results where almost identical or even slightly worse then I think it is fair to accept they are right and you are wrong.

Then the test design and belaying methods used therein were obviously faulty as given a rope of any diameter and a correspondingly appropriate-sized ATC there is no way for slippages like those to occur unless you are incompetent (i.e. faulty test design).


JimTitt


Feb 1, 2011, 12:41 AM
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The prototypes where running over 50% more power than an XP and with thick ropes this was a pain, the impact forces where getting higher than we´d like and lowering and abseiling a problem with light people and double ropes. Conversly with thin ropes the performance was brilliant so what I did was reduce the thick rope force while trying to keep the thin rope performance which I more or less achieved.

The trade-off is you need to be more alert to the climber weight or any friction when you are going to be lowering, the difference between the high and low power sides is much more noticeable than usual so for lighter climbers and easy angled stuff you really want to be going to the low power setting or the rope feed is a bit jerky. Or you just tilt the plate with your thumb!

Publishing our internal test results is a bit of a difficult issue and we´ll probably have to wait for someone independent to do the tests.

Jim


qwert


Feb 1, 2011, 1:59 AM
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healyje wrote:
JimTitt wrote:
Hmmm, since in that particular test they (the DAV) also used two human belayers and the results where almost identical or even slightly worse then I think it is fair to accept they are right and you are wrong.

Then the test design and belaying methods used therein were obviously faulty as given a rope of any diameter and a correspondingly appropriate-sized ATC there is no way for slippages like those to occur unless you are incompetent (i.e. faulty test design).
From what you are saying, it seems like you think that all slippages they measured are too high. So either you dont know what kind of length a cm is (its much less than an inch!) ;) or you have big hand strength and always lock up your ATC.
Obviously the 180cm are critical, especially when you are trying to hold that without gloves, but the 22 to 51 cm range seems realistic to me.
Thats about the range i let trough the device, if i try to actively give a soft belay.
Also i do not really see where their test design is faulty.
Yes - an artificial hand (which seems to be some kind of pulley thingy, if you look at the pic in the report) will never grab the rope just the same as a real hand, but thats probably what makes it usefull. With a real hand you might have all kinds of factors that will affect the holding power of said hand (smooth skin vs. rough calluses vs. leather glove; chalked hands vs. sweaty hands; slightly different position of the rope in the hand and of the hand compared to the belay device; etc.), independent of how much N the testee can produce.
And many of these factors will probably vary between test falls, even if you always use the same testee.
And with the artificial hand, you at least get compareable numbers between devices, and personally i think it is safe to assume that those numbers would translate to the real world to some amount.
The question is just how much. For example i have never seen slip like the 180cm, even when kids belay, but then its mostly ATC XPs (that do seem to have more holding power, although probably not as much as the marketing would make one belief), thicker or older ropes, and fall wheights under 80kg.

qwert


healyje


Feb 1, 2011, 2:58 AM
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I'm talking about a fall happens and you lock up the ATC. In that instance if 8-20" of rope is streaming through the ATC then something is dreadfully wrong with the belaying in anything but an unexpected, unannounced, out-of-sight fall. Oh, and hand strength plays very little into the matter; in fact, if you're depending on 'hand strength' as a substantial factor in the belay you're kind of screwed up front. It's a matter of proper pairing of ATCs-to-diameter. I don't trad lead on single ropes smaller than 9.8 personally, but that's me and use a Kong Ghost on my 9.x cords and a Bug or Reversino on my 7.8 twins - no problem with slippage on any of them regardless of hand strength.

If you are talking about deliberately paying out slippage (which by and large I think is a bad idea in trad climbing except in rare situations), then anything is possible given how badly the demographic belays in general. Teaching people to pay out slippage? Again, by and large a lousy idea - better to teach them to use a screamer on any piece they are that concerned about it.

Hell, I've held solid lead falls on a 9.8 with a hip belay through a single non-locking biner going to the leader and not had any appreciable slippage - something's just not right or someone's not doing it right if they are getting those slippage rates when trying to lock it up - either that or the general situation out there is worse than I imagined.


(This post was edited by healyje on Feb 1, 2011, 3:04 AM)


JimTitt


Feb 1, 2011, 3:31 AM
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There is NO lower force limit where slip does not occur. The rope slips in all belay devices and methods, alone the stretch in the rope between the belayers hand and the device takes care of that!
Hand strength (more exactly the ability to grip a particular rope diameter) IS the determining factor in a given devices performance. The relationship between hand strength and braking force is almost perfectly linear.

Advising use of a screamer on anything but an extremely mild fall is incorrect.

Jim


healyje


Feb 1, 2011, 3:38 AM
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We will have to agree to disagree.

And I'm not speaking of rope stretch - I'm speaking of brake hand position/distance from the device being unchanged and zero rope slip through the hand. If you are encountering either your hand moving towards the device or the rope slipping through your hand then something is wrong.

Grip-to-diameter is strictly a matter of appropriately sizing the rope to the device. Properly sized the diameter decrease shouldn't require more hand strength.

Any time there is concern about about a piece ripping then the answer should be put a screamer on it - not attempt a 'dynamic' belay unless you are a highly experienced and very competent belayer and even then I'm going with the screamer every single time.


qwert


Feb 1, 2011, 4:25 AM
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healyje, so what you are saying is that you have a specific device for every rope size you use?
While it should be obvious to anyone that "extremes" such as using a fig8 with a single 8mm rope, or a reversino with a fuzzy 11mm rope should be avoided, This becomes less obvious with "normal" rope sizes between say 9.5 and 10.5mm, and the additional "holding power" their fuzziness will introduce.
Yes, i know that manufacturers normally rate their devices only for specific thickness rates, but this is somewhat irrelevant if we are going to take stuff like dry treatments, thight sheats and wear into account.
Essentially those factors can cause a 10mm rope to be harder to hold than a 9mm rope. Obviously its the beleayers responsibility to assess the rope, and belay accordingly, but since the handling of a rope can change even during a single climb, a device (and a belayer) should be able to handle a certain range of ropes.

I am going to side with the DAV (and jim Tit) here, and believe that the rope slip has to do with the hand force.
I do not know you, but i wouldnt be surprised if you hand force is simply above average and thus you lock up the device with no slip, essentially turning it into a static belay device.

And something on the screamers:
(slightly of topic, but since we are talking about a DAV paper, i think it should be mentioned)
It seems to me that screamers are strictly an american thing. I only hear about using screamers here, even to the point that people use only screamers instead of quickdraws while ice climbing.
I have never seen a screamer in real life - neither on the racks of my friends, nor on the racks of other climbers i encountered, no matter if those encounters where on trad, alpine or ice.


qwert


healyje


Feb 1, 2011, 5:04 AM
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If you mean I use different ATCs for 10.x, 9.x, and sub-9.0 ropes then the answer is absolutely. It is critical to pair the device to the rope diameter and I personally don't really buy the idea that brake-side 'grooving' and groove texturing makes up enough of a difference compared to a properly [down]sized device. I also don't consider sub-9.8 cords 'normal' , but rather recent innovations whose use with an inadequate device (autoblocking or ATC) is just a bad idea in the hands of most of today's demographic.

Overall I don't use cords that 'fuzz' for the most part and don't consider fuzz / coating in the equation except relative to my roped-soloing device (Eddy) and there I'm exceptionally picky about my ropes and stiffness/fuzz/coating do get taken into account.

In the end I just can't and don't ascribe to the 'range of rope sizes' or 'one-size-fits-all' school of belay device selection. In fact, I think it's a poor idea in general and one borne of misplaced convenience.

In reply to:
I am going to side with the DAV (and jim Tit) here, and believe that the rope slip has to do with the hand force.

It definitely is if you are using the wrong size device.

Hey, I have completely average hand strength, again, it's all about careful device/rope pairing. And that's something that doesn't really happen much these days which I consider somewhat unfortunate as folks gravitate towards smaller and smaller cord diameters (usually for no good reason relative to the routes they are doing or their climbing level).

Screamers in the US are mainly only seen in aid and ice climbing and most screamered falls are probably by aid climbers. But I have a long history of free climbing over what most people would consider very marginal pro - stacked passive pieces, skyhooks, Crack 'N Ups, #1-3 Loweballs, and equalized RP nests. I've blown dozens of screamers taking repeated falls onto placements working some cruxs where the pro for sure wouldn't have held without them. On really delicate placements I pre-slice the screamers at an steep angle with a razor blade in order to flatten out their loading curve so it's less jarring. Overall, I wouldn't trust any of those screamered placements to the unpredictable vagaries of attempts at a 'dynamic' belay - I want the belayer to just lock it up and I'll take care of the 'dynamic' protection of my placements if they need it.


(This post was edited by healyje on Feb 1, 2011, 5:31 AM)


Partner j_ung


Feb 1, 2011, 5:50 AM
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JimTitt wrote:
The prototypes where running over 50% more power than an XP and with thick ropes this was a pain, the impact forces where getting higher than we´d like and lowering and abseiling a problem with light people and double ropes. Conversly with thin ropes the performance was brilliant so what I did was reduce the thick rope force while trying to keep the thin rope performance which I more or less achieved.

The trade-off is you need to be more alert to the climber weight or any friction when you are going to be lowering, the difference between the high and low power sides is much more noticeable than usual so for lighter climbers and easy angled stuff you really want to be going to the low power setting or the rope feed is a bit jerky. Or you just tilt the plate with your thumb!

Publishing our internal test results is a bit of a difficult issue and we´ll probably have to wait for someone independent to do the tests.

Jim

When are they available? I'd love to review one.


qwert


Feb 1, 2011, 6:19 AM
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healyje wrote:
Overall I don't use cords that 'fuzz' for the most part and don't consider fuzz / coating in the equation except relative to my roped-soloing device (Eddy)...
where do you get that ropes? I want them!
I have managed to turn thin, slippery ropes that where really hard to hold into fuzzy fatties that got hard to feed through the device quite fast.

In reply to:
In the end I just can't and don't ascribe to the 'range of rope sizes' or 'one-size-fits-all' school of belay device selection. In fact, I think it's a poor idea in general and one borne of misplaced convenience.
One size fits all is surely a bad idea (though stuff like the edelrid zap-o-mat might lead to a "solution"), but you have to have some range, if you dont want to end up with 100 devices.

In reply to:
I want the belayer to just lock it up and I'll take care of the 'dynamic' protection of my placements if they need it.
So why do you not just give you belayer an autoblock, which us just as safe as an ATC or similar device, with the added safety function that it will still stop you fall if your belayer got knocked out due to rockfall or something similar?

I am not trying to start an internet argument, i am just curious, since i think i remember you as an oponent of autlockers.

qwert


hafilax


Feb 1, 2011, 7:40 AM
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Re: [qwert] Testing a "Dynamic Belay" [In reply to]
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qwert wrote:
One of the german tests Jim Tit mentioned is probably this one:
http://www.alpenverein.de/...5d9d8468a2e73a1e29d1

I wont translate it, but here is some words about it, and a quick look at some of the numbers they got:

The DAV tested a few belay devices (Tube (looks like it was a classic ATC), various forms of 8s, munterhitch/'HMS, GriGri and TRE) in a factor 0.4 fall.

The fixed the devices to the belay, and belayed with an artificial hand, where they could adjust the hand power, which is - according to a previous study - 209N on average.
so they ran the tests with a hand power of 100N, 250N, 400N and two Persons.

They measured the forces on the top piece and that are the results:

Code
Hand force:       |   100N   |   250N   |   400N   | Person1 | Person2  
Top force GriGri| 5.9kN | 5.6kN | 5.5kN | - not tested -
Top force Tube | 2.7kN | 3.8kN | 5.0kN | 3.8kN | 4.1kN
rope slip GriGri| 9cm | 8cm | 9cm | - not tested -
rope slip Tube | 182cm | 51cm | 22cm | 101cm | 66cm

Obviously this is -as mentioned - a fixed belayer and a small fall factor, but it is safe to assume that those observations also apply for bigger stuff.
The less the belayer grabs the rope, the less force the top piece will see if you are using a dynamic device. If you know how to do this, this can be used to give a soft catch/ help bad protection to stay in.
However if you simply dont have significant force, this might result in uncontroled slipage, that will burn you hand.
On the other hand, if you have strong hands, and simply lock up the rope, you can - if we are ignoring jumping or being pulled up - produce forces quite similar to the grigri.

I would be interested on how some "increased braking strength" tubes like the ATC-XP behave in this test.
I am simply going to claim that this will increase the top force/ reduce the slipage, and that this will reduce the hand force needed to make it static, and thus that there probably are quite a few folks out there who might as well belay trad with a grigri, since it wouldnt make a difference for them anyways.

qwert
It's interesting that the top piece peak force goes down with increased hand strength using a GriGri. I wonder if pulling on the GriGri somehow keeps it from locking up as quickly?

I haven't looked at the paper but I'm assuming that the belay device is rigidly anchored in the tests. This might account for the discrepancy that healyje is talking about. The forces involved are more than enough to move a person around and, if the impulse is long enough, lift them. If the belayer is free to move I would bet that the slip figures get far smaller. I know that top roping, a lot more rope slips through when I'm anchored than when I'm not, especially with heavy climbers.


JimTitt


Feb 1, 2011, 11:26 AM
Post #50 of 55 (2888 views)
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Registered: Aug 7, 2008
Posts: 980

Re: [j_ung] Testing a "Dynamic Belay" [In reply to]
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No idea about the marketing but I´ll be seeing the guys at a trade show on Tuesday and ask, I´ll try and score a few for selected testers as well.

Jim

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