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wootles
climber
Gamma Quadrant
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Jan 16, 2007 - 08:19am PT
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God knows I don't want to get too deep in this topic again but...
There's been a few statements about shock loading and the dangers there of. First we need to define what a shock load is and that's not as easy as it sounds. A simple answer is rapid loading. But how rapid? In normal UIAA drop tests the peak force occurs in roughly 0.11 to 0.17 seconds on the first drop with a new rope. Each successive drop the peak force occurs earlier than the previous. So I would think that shock loading would have to occur sooner than that but then again how high does the force need to be to be considered in the definition of shock load?
I performed tests specifically looking for the theoretical shock loading. I think it's in Largo's book, though I have to confess I have not read it entirely. I feel the tests showed quite conclusively that shock loading from extension is a myth. There are only two dangers I see in regards to extension: potential loss of control of the belay due to redirection and if the belayer is easily startled loss of control of the belayer's bowels. Yes there is a transfer of the force but it does NOT exceed the total sum of the force, obviously. There are far too many variables to calculate what the final force would be but for certain if you are tied to the anchor with a dynamic rope there is no shock loading. That said, I did not test using static lanyards such as daisy chains or Dyneema/Spectra slings. I, and some other people, have conducted other tests that show direct connection with static lanyards is a bad practice. You may be better off with nylon slings but ultimately the rope is your safest option.
So then back to the rapid loading. I'm working from memory here but during the shock loading tests I recall the second peak, the one resulting from the transfer, occurred at a time point roughly equal to twice the time it took to reach the first peak. The first peak occurred earlier than the normal UIAA drop test because of the test method. The method was to use a 'fuse' on one leg of the anchor that would blow before what would have been the normal peak force. For example the first peak would occur at roughly 0.07 seconds and the second, and lower peak, would occur at roughly 0.14 seconds. Those might seem to be super fast but the forces were quite low, under 3kN if I recall. I wish I could find the data. Sterling moved to a new building back in August and the computer that has all that stuff in it somehow got damaged and I haven't tried to retrieve anything from it.
Now for the curve ball... All of this goes out the window in rescue scenarios. When hauling litters extension is potentially a really bad thing. WBraun can probably address this more.
If this horse was the son of God we would be celebrating Easter all year long.
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Largo
Sport climber
Venice, Ca
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Jan 16, 2007 - 11:49am PT
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Gee Willikers, am I really diving back into this . . . again??
Jim wrote: "I performed tests specifically looking for the theoretical shock loading. I think it's in Largo's book, though I have to confess I have not read it entirely. I feel the tests showed quite conclusively that shock loading from extension is a myth."
Maybe a better term is "load multiplication," meaing that somehow in the time that the first piece blows, to the time (fractions of a second) that the second piece starts absorbing the load, said load does not magically increase. In fact, it decreases relative to the amount of energy absorbed by the first piece before it blew out. Meaning if you had initial loading of L3 on the anchor, one piece blows out and absorbs L1, then extends to the second piece, the second piece would be subject to L2 of loading, almost to the pound according to the testing.
The whole thing goes out the window with rescue work because there is no tube/crimp belay device in the equation (through which the load is greatly diminished through rope slippage), no body to fold and give and absorb energy, and most of all, no dynamic rope that stretches upon loading. Here (as is probably the case with big haul bags tethered with static lanyards) it is almost certain that you'd see, not load multiplication, but shock loading, meaning the sudden decelleration of a litter or haul bag could quite possibly bust biners and rip anchors.
JL
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wootles
climber
Gamma Quadrant
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Jan 16, 2007 - 12:07pm PT
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Thanks John. That was a much better explanation than mine. Yeah I forgot to mention the energy absorption of the piece blowing out. I'll keep looking around for the data but I'm pretty sure it's locked up in my computer bone yard. My drop tower and slow pull computers didn't survive the move.
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mingleefu
climber
Champaign, IL --> Denver, CO
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Jan 16, 2007 - 12:54pm PT
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WBraun wrote: "make your anchors 10 to one safety factor"
Are you just being facetious, or is this actual practice in your line of work? How does one go about conceptualizing what a 10:1 safety factor looks like? Or do you just build the anchor ultra-beefy until you have that "feel good" fuzzy inside?
Curious about the concept.
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TradIsGood
Happy and Healthy climber
the Gunks end of the country
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Jan 16, 2007 - 01:07pm PT
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Largo, that explanation of loads and energies is pretty confused.
Meaning if you had initial loading of L3 on the anchor, one piece blows out and absorbs L1, then extends to the second piece, the second piece would be subject to L2 of loading, almost to the pound according to the testing.
Load would certainly be a measurement of force and not energy. The idea that L3 = L1 + L2 is vague as to the definitions of the L's, and likely not right with any reasonable definitions even if you define them to be energy instead of forces.
Measurements are important. One thing that changes after the first piece blows is the elasticity of the rope. It is now "less dynamic", since it will not immediately shrink to its unstretched length.
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Ed Hartouni
Trad climber
Livermore, CA
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Jan 16, 2007 - 10:40pm PT
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god knows I never get this stuff right the first time, but I did do an analysis of the cordolette and the "magic x" equalization of two points and got what I thought was something consistent with the drop tests that wootles did.
My main conclusion from that was basically, don't use stiff slings... nylon slings, as with nylon ropes, have a lower bulk Young's modulus which lowers the force considerably. The difference of lenghts of the arms of the cordolette will cause differnt forces for each of the pieces of protection they are attached to, thus defeating the idea of equalization. However, if you keep this in mind, and if you make sure that the arms are long, rather than short, the differences may be within the margin that your anchors might be able to take.
What you have to be aware of is the cordolette does not equalize.
What I take to be shock loading is simply that the dynamic forces generated have to do with the change of momentum:
F = dP/dt
where P is the momentum... P = m*v and the difference in the momentum is proportional to the velocity that gets stopped, and the time it takes to stop it. This is the same force calculated in the "force factor" equations, so you can get an idea of the dt by first calculating that force, then calculating the change in momentum, and solving the above for dt:
dt = dP/F
When you have a failure of an anchor at some force, some amount of momentum is decreased, which means the falling person has a lower velocity... this sets an upper limit on the force the next anchor will be subject to. This force will be less than the force that would have been generated if the piece that blew wasn't there in the first place.
Anyway, I've had way too much to drink tonight to be at all coherent... another way of thinking about shock loading is to consider how a hammer works. If you push on a nail with the same force you would swing a hammer, you would not press the nail into the wood. But the hammer generates a lot of force because of the the change of momentum over a very short time. F = dP/dt...
That's going to happen in a belay situation. It is possible that practically it is not an issue for blown pieces on a set of closely spaced, closely coupled anchors, but if you had a very long sling connecting the pieces it might be more of an issue.
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GOclimb
Trad climber
Boston, MA
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Jan 17, 2007 - 05:39pm PT
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>> I wrote:
>> There were several excellent solutions proposed on
>> that thread which, while untested by JL's crew, showed
>> slightly more promise than the "accepted" method proposed by
>> JL. Of course, they won't sell any books - which must be why
>> they're considered impertinent. Apparantly the fact that they
>> just might save lives seems not to be as important.
> To which RG responded:
> Perhaps this is what Joe was warning about when he suggested
> not opening this can of worms again. I'm always astonished
> when people pretend to know other people's motives, especially
> when they are ready to ascribe the basest motivations to
> people they don't know for actions they have no basis for
> judging. I hope you find yourself able to apologize for this
> one Gabe, it is way out of line, and contributes nothing but
> rancor to a discussion that might otherwise be useful.
I didn't say he thought the discussion was impertinent, he said that. As for why he would be so dismissive of all ideas but the one presented in the book, I admit - I really can't (and shouldn't presume to) answer that question. But I sure do find the idea of tarring the entire discussion with the dismissive word "impertinent" to be a bit galling. Still, I'll try to remain productive, despite the fact that many find any input (by better minds than mine) so completely valueless.
And by the way, in regards the importance of factoring in the force a falling belayer creates when a piece extends, I could not agree more. As it happens, I introduced that question in the original thread, and (perhaps too) strenuously argued about its importance. I even suggested what I thought was a reasonably simple change to the testing environment to measure this factor. More impertinence on my part, no doubt! ;)
> healyje wrote:
> Wanna share which ones? Preferrably with a pic of each (if you
> can find them). And if you were posting over on the rc thread
> were you doing it under GoClimb there as well (sorry, my
> memory isn't what it used to be...)?
The moniker GOclimb was taken on rc.com, so I'm Cracklover over there.
Here are the ones I'm most taken with for a typical three point anchor. The pros and cons of each are all available in that thread, though I also have my own views on them after using them for a season:
The Mooselette:
The CharlesJMM anchor:
And the two crossed slings:
Werner I ain't, and greater minds and more experienced climbers seem to want this conversation to end, so I'm not going to take the time to detail my thoughts on these unless requested. Briefly, my preference goes from top to bottom, with the Mooselette equalizing the best and being quickest to set up (once you get accustomed to it, and in situations where it's appropriate), CharlesJMM rig being in the middle, and two crossed slings taking the longest to set up, and equalizing the worst.
Cheers,
GO
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rgold
Trad climber
Poughkeepsie, NY
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Jan 17, 2007 - 07:52pm PT
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GoClimb wrote: I didn't say he thought the discussion was impertinent, he said that.
The I-word wasn't used by Largo. It was Wootles who said
...as much as you all love to bust on rc.com everything is pretty well covered over there, that is if you can wade through the 1000 or so impertinent posts.
GoClimb wrote: As for why he would be so dismissive of all ideas but the one presented in the book, I admit - I really can't (and shouldn't presume to) answer that question.
Since the quote isn't from Largo, you are relieved of even presuming to to figure out why he said it. Meanwhile you have let stand your claim
Of course, they won't sell any books...Apparantly the fact that they just might save lives seems not to be as important.
which says that Largo, who never said what you say he said, is by virtue of those misappropriated words more concerned about book sales than human life.
Moreover, even though they aren't Largo's words, the quote itself, far from being dismissive, clearly expresses the author's appreciation for the rc.com thread, even in the face of this site's reflexive inclination to denigrate anything from rcNOOB.com. The I-word supplies a touch of irony and can hardly be read as a "tarring of the entire discussion."
Largo obviously could care less, but I still think a real apology would still be the decent thing to do here, not that decency is particularly high on any list of internet discussion desiderata.
..........
By the way, to return to the topic at hand and highlight a point Largo made previously, in 49 years of climbing I've had to hold one factor 2 fall directly onto the belay. The anchor was a single 1" angle, pounded zealously into a perfect horizontal crack. The belay was, of course, a hip belay.
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healyje
Trad climber
Portland, Oregon
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Jan 17, 2007 - 08:02pm PT
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"By the way, to return to the topic at hand and highlight a point Largo made previously, in 49 years of climbing I've had to hold one factor 2 fall directly onto the belay. The anchor was a single 1" angle, pounded zealously into a perfect horizontal crack. The belay was, of course, a hip belay."
I can't speak to the fall factors involved, but I've held a few hard drops directly on to hip belays. I'm always categorically stunned - stunned - at the number of [smart, experienced] folks who have never hip belayed who don't consider it a "real" belay. For the uninitiated, hip belaying when done right is highly effective, can be fairly technical and is best considered integral with a more technical perspective on stancing than is commonly in evidence today.
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WBraun
climber
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Jan 17, 2007 - 08:20pm PT
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Well ....
To tell you the truth, I'm so glad I don't have to hip belay no more. You have to be so damn attentive to the point of being anal to do it properly so that if a fall does occur that the rope doesn't rip out of my hands.
So glory hallelujah rgold, the one f'ckin pin held. Why did we all even live through that crazy sh#t we did back then?
Now I'm scared to belay without my grigri and have to tie off 10 twigs instead of just one .......
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maldaly
Trad climber
Boulder, CO
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Jan 17, 2007 - 08:25pm PT
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With all due respect....I'm starting to feel like I'm over at rc.com.
Lot's of good stuff here but I'm with nutjob, despite the unfortunate handle. If the rock is good and the anchors sound, I place two down (EQ'd) and one up. Tie in with the rope, twnsion with a clove hitch and swing leads.
I'm not dead yet.
Mal
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rgold
Trad climber
Poughkeepsie, NY
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Jan 17, 2007 - 08:29pm PT
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Now I'm scared to belay without my grigri and have to tie off 10 twigs instead of just one .......
Y'know, I recently tied off ten twigs for a belay anchor and caught a load of flak for it. Man, those twigs were bomber!
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andanother
climber
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Jan 17, 2007 - 08:44pm PT
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Hi,
My name is overkill. I like to beat dead horses.
LOOOOOONG after they are dead I can be found beating their rotting carcasses. That's my thing.
I also like to over-analize the sh#t out of everything. I don't actually climb much, but I spent 2 hours building an anchor in my backyard just so I could post pictures for you guys. Hope you like them. I analyzed them for hours. Then I over analyzed them even more. That's what I do.
I'm the guy that turns 3 pitch climbs into overnight epics. I've had to rappel off of every single grade III I've ever attempted. It gets expensive, but I make some pretty sweet rap anchors. I have photos of every single one of them. I took photos from all different angles so that I could over analyze them upon returning home.
In my world, grade IV doesn't exist. If it's longer than 3 pitches, it is automatically grade VI. I can often be seen hauling 60 pounds of gear up Nutcracker.
Still haven't finished that one. Is the mantle as scary as they say?
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GOclimb
Trad climber
Boston, MA
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Jan 17, 2007 - 09:17pm PT
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> RG wrote: The I-word wasn't used by Largo. It was Wootles who said ...
Yes, it's Wootles who I'm referring to. If that wasn't clear, I apologize. At the time I made my post, I don't believe that JL had even waded back into this morass, so I thought it clear who's post I was referring to.
And I read the statement "...as much as you all love to bust on rc.com everything is pretty well covered over there, that is if you can wade through the 1000 or so impertinent posts. "
As saying: In case you don't want to buy the book, JL, Healyj, RG, and I pretty well spelled out all the research we did in that thread on rc.com. Too bad it was mucked up by all those other impertinent posts.
> RG also said: Since the quote isn't from Largo, you are
> relieved of even presuming to to figure out why he said it.
> Meanwhile you have let stand your claim
>> Of course, they won't sell any books...Apparantly the fact
>> that they just might save lives seems not to be as important.
> which says that Largo, who never said what you say he said, is
> by virtue of those misappropriated words more concerned about
> book sales than human life.
Okay, I apologize for suggesting that. In fact, I was quite impressed that JL came right out and said he felt responsibile for selling an idea that he now believes to be flawed, and he clearly put a huge amount of work into getting this new research done, and promulgating a new idea anchor system that we can all agree is superior to the standard cordelette method. So far as I'm concerned, JL's heart is clearly in the right place. Absolutely no question about it.
I'll just let it go at that.
GO
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Largo
Sport climber
Venice, Ca
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Jan 17, 2007 - 09:20pm PT
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"As for why he would be so dismissive of all ideas but the one presented in the book, I admit - I really can't (and shouldn't presume to) answer that question. But I sure do find the idea of tarring the entire discussion with the dismissive word "impertinent" to be a bit galling. Still, I'll try to remain productive, despite the fact that many find any input (by better minds than mine) so completely valueless."
I think this deserves a sober response. I stated in the new anchor book that the equalette was simply the first of many new possible innovations that tried to address the problem of extension and equalization. I fully expected, and encouraged others, to keep the discussion going in the hopes of fathering new rigging strategies. I recommended the equalette and the quad simply because those were the ones we were able to devise and test (Wottles work here)–both in the lab and in the field–in the limited time we had. The claim that I, personally, consider new wrinkles on this basic strategy as "completely valueless" is something that, apparently, only you believe.
I've stated many times that little if anything in any of my books is catagorically definitive, rather it's merely the most up to date information that I know of per what should and must remain an ongoing investigation.
The other issue is that I am somehow discouraging the climbing community from embracing strategies other than those shown in my books for the fear that such an endorsement would affect book sales. That's an awfully tough pill to swallow, especially considering that the anchors books are speciality items that might, at best, sell about 20,000 copies over a decade. Per hours spent in the research and writing and profits received from such sales, my rate would work out to around 10 bucks an hour, and zero bucks an hour to important contributors like Rich and Craig, as well as many others. I'm glad that for every book sold, perhaps ten or even twenty people read it. That's the point–to get the knowledge out there. It's basically my other work that allows me, and pays for me, so to speak, to work on books (such as Climbing Anchors) that would put me in the poorhouse and my family on the street if I was relying on them for my livelihood.
JL
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GOclimb
Trad climber
Boston, MA
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Jan 17, 2007 - 09:22pm PT
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Andanother: I'm not a particularly fast climber by anyone's measurement, but after placing the gear, this anchor takes me the same length of time to build as a standard cordelette.
GO
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healyje
Trad climber
Portland, Oregon
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Jan 17, 2007 - 09:27pm PT
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Well, 100 posts and not out of the rough quite yet...
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GOclimb
Trad climber
Boston, MA
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Jan 17, 2007 - 09:30pm PT
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Largo, I tremendously appreciate the time, effort, and money put in by you, Wootles, RG, Chiloe, Sterling, etc, for that effort, and also your role in the discussion around it, which I found extremely valuable. I said as much to Jim when I ran into him last year. In fact, IIRC, I volunteered to put in some time in some testing he was talking about doing this winter.
The fact that I found some elements of that discussion extremely frustrating does not in any way reduce my appreciation for your work.
GO
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WBraun
climber
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Jan 17, 2007 - 10:06pm PT
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GOclimb
I'm glad for your input as it brings out good discussion and analysis. You never know what people come up with. There's always subtle nuances that appear in these analysis that surprise us.
In YOSAR, we've tested and analyzed many types of rigging and anchor systems over the years, and I'm always surprised by some of the many different nuances that come up.
I like learning all the stuff there is.
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Rags
Trad climber
Sierra foothills, CA
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Jan 17, 2007 - 10:45pm PT
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Largo wrote, "I fully expected, and encouraged others, to keep the discussion going in the hopes of fathering new rigging strategies.
John, thanx for the work you have done on anchors, and to further the sport and address safety, something many of us consider worthy of discussion. I would hope that you and wootles continue to be available for comment. You are by virtue of your testing, possibly the closest thing to "experts" on the subject.
Discussions such as this might actually stimulate new thinking on an old topic. However, this become tedious because the discussion gets perforated by those that think it a waste of time. In this regard, it is the very act of interjecting meaningless drivel, irrelavant to the topic, that hobbles an intelligent and worthy discussion. Even the marginally relevant misunderstandings detract from the otherwise intelligent analysis and exchange of ideas. If you have nothing of value to add, have some consideration and respect for others, exhibit some self-control, and post to the "nothing thread".
Back to your regularly scheduled program--------------
The point that I find curious is the suggestion that a sliding X or W assumes that all pieces are bomber and won't blow. The ASCA website has this, "While the sliding X does equalize the pieces, it assumes that neither could break, since if one does break, there is severe extension in the system - enough that it would likely cause the carabiners to break."
Obviously the testing has proved this to be a myth. However, it has been my practice to use this arrangement, and the "W", in most of my anchors, including an arrangment that utlized a marginal piece. A knot to shorten extension always seems the simple solution. Since shock loading is now a marginalized concept, why are there still concerns regarding extension at all?
As someone pointed out, a fall of factor 2 is highly unlikely. Redirects and practicing a "soft belay" in the event there is a possibility would seem to mitigate the risk even further. I am suggesting that our techniques are as important as our mechanics.
"How we do" with "what we have" ultimately dtermines the net risk. There needs to be an integration of both in the learning process and evaluation process.
Thanx to all that have "contributed" to the discussion.
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