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bearbreeder
Dec 24, 2012, 3:07 AM
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you really cant see anything from the photo ... but i believe that they mean it was clipped above the leg loop, not within it at all ... the autoblock would not hold and will probably go right against the ATC ...
if you are going to clip a backup, do so on the INSIDE of the leg loop, not the buckle side if it has speed buckles ..
even better extend the atc off a sling and clip the backup to your belay loop
failure to test and poor rappel technique is the root cause of the accident IMO
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billl7
Dec 24, 2012, 3:25 AM
Post #27 of 63
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bearbreeder wrote: you really cant see anything from the photo ... but i believe that they mean it was clipped above the leg loop, not within it at all ...
That's what I initially thought too. I later realized for me the word "above" was misleading. The marked-up photo from the forum link is pretty clear though. I've embedded in this photo the related text from the forum. The biner was clipped back to the leg loop.
(This post was edited by billl7 on Dec 24, 2012, 3:26 AM)
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milesenoell
Dec 24, 2012, 6:47 PM
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If that's the case then let me venture the question: How likely is a correctly rigged autoblock to fail?
Whether it was rigged correctly or not, I thought they were always suspect, but I've never heard anybody try to quantify it.
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billl7
Dec 24, 2012, 6:51 PM
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On the topic of whether the autoblock might have ridden up agains the ATC and so been pushed down by the ATC during the fall:
The autoblock was a rather tight assembly down at the leg loop; the shiney cylinder is the biner clipped to the leg loop and the yellow is the autoblock cord:
Here's a cleaner shot of part of unfortunately just part of the rig:
At the beginning of the fall, it appears to be appreciably below the ATC; he's already let go of the break strand:
Well into the fall, the autoblock still appears to be appreciably below the ATC. If one imagines where the inflection point of the rope is behind his arm, that is about where the ATC is:
I'm willing to assume there was sufficient separation between the ATC and the autoblock ... although I'm thinking more separation would be better.
Bill L
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billl7
Dec 24, 2012, 7:20 PM
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milesenoell wrote: If that's the case then let me venture the question: How likely is a correctly rigged autoblock to fail?
Good point. At the same time, it's one thing to say that a bowline is correctly tied. Or a double fishermans is correctly tied. An autoblock has variables (some listed below) that necessitates something more than "is this the config I am used to seeing?"
(above, I'm probably saying things that you already include in "correctly rigged" - just want to be explicit.)
In my limited experience with an autoblock, it seemed to be a kind of balancing act between too loose to catch and too tight to be smoothly slid down by the hand. The consequences of too loose are obvious. For too tight, it's both an annoyance and a distraction during the rap. Maybe this balancing act is why some in this thread have emphasized testing the set up to see if it seems to catch (albeit in the config of a given pre-rap test) - to get the balancing act just right.
Assuming the ATC didn't push the autoblock down during this fall, perhaps the failure here has to do with one or more of the following - any of which will reduce the chance that the autoblock is going to grab on its own:
* the number of wraps around the rope being too few (perhaps combined with the ends of the cord not being held in close proximity or crossed (akin to kleimheist)?);
* the relative diameters of the cord to the rope; the author of the video indicated the rope was a 9.0 mm rope; the coils of an oversized cord will not cinch down on a relatively small diameter rope as readily as a cord of lesser diameter;
* the type of rope; Blue Water Canyon Line spec info indicates it has a 100% Technora Aramid sheath for excellent cut resistance (relatively slick?);
* edit to add: too short of a cord may cause the biner to be in contact with the rope - perhaps that could hinder the autoblock from grabbing on its own; perhaps this in itself is a good reason to wrap towards the ATC and then clip back on the opposite side of the girth hitch.
Is there something else (again, assuming the ATC did not push down the autoblock)?
Bill L
(This post was edited by billl7 on Dec 24, 2012, 7:24 PM)
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bearbreeder
Dec 24, 2012, 7:49 PM
Post #31 of 63
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a correctly tied and spaced autoblock once weighted should not "fail" below the device as the weight it needs to hold is minimal ... but as everyone knows when yr shifting around hands free, things can get caught or bumped ...
the autoblock is one of the easier friction hitches to release ... so be aware of that ... if you are truly going hands free a quick overhand knot will prevent you from going SPLAT !!!
also remember on a single strand that youll need more wraps ...
IMO a kleimheist is a "better" knot for this as you can easily tie it with slings ...
the "best" way to use a fiction hitch is to extend the rappel on a sling (use a knot to shorten it) and put the hitch on the belay loop ... this makes the spacing much easier, helps prevent you from screwing up your clipping, and should you be totally and utterly stupid and screw up your rappel setup, the hitch MAY hold you without inverting ...
its also much easier to control the hitch and keep BOTH hands below the device this way ...
personally i use a mammut alpine smart these days ... 
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cracklover
Dec 24, 2012, 8:00 PM
Post #32 of 63
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billl7 wrote: Edit: P.S. It took about 3 seconds (maybe 2) from the time the person rapping first slips to the sound of the splash when he decks. Three seconds seems a long time. But I still doubt that's enough time for a person belaying below and relying on the common instinct to a) realize it's time to engage the fireman's / caver's belay (first second); b) realize that gripping the rope isn't helping (second second), and c) realize that just gripping the rope harder also is not doing the job (third second).
I'm sorry, but that's complete nonsense. Anyone with experience giving a fireman's belay to a rappeller can stop a falling climber in way less time than that. I've only needed to put the breaks on someone once - it was an inexperienced climber doing around a 30 foot rappel. She lost control of the rope just as she was going over an awkward lip. I caught her so fast that I think that by the time she got her hand back on the device a split second later, she wasn't entirely sure she had ever lost control. Of course that might have been plenty of time (especially with falling out of control and the loss of sense of what's where that would follow) that had I not braked the line she may never have regained control before decking.
Bottom line is that for a fully competent person giving a fireman's belay, keeping your partner off the ground is totally trivial.
GO
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billl7
Dec 24, 2012, 8:04 PM
Post #33 of 63
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cracklover wrote: billl7 wrote: Edit: P.S. It took about 3 seconds (maybe 2) from the time the person rapping first slips to the sound of the splash when he decks. Three seconds seems a long time. But I still doubt that's enough time for a person belaying below and relying on the common instinct to a) realize it's time to engage the fireman's / caver's belay (first second); b) realize that gripping the rope isn't helping (second second), and c) realize that just gripping the rope harder also is not doing the job (third second). I'm sorry, but that's complete nonsense.
Bill L
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socalclimber
Dec 24, 2012, 9:04 PM
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bearbreeder wrote: socalclimber wrote: It's simple. Close the system. If I even think that going over the edge is going to be tricky, I just pull up 10 feet of rope and tie a knot in it. That way if I blow it on the edge, I'm not going very far. i believe the guy was down more than 10 feet when the fall happened ...
Well, then you pull up more than 10 feet. Anything to keep you off the deck.
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billl7
Dec 24, 2012, 10:03 PM
Post #35 of 63
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Occasionally I'll tie off with a mule knot and overhand, slip over the edge until hanging, and then release it to then rap.
Reading the linked canyoneering forum, some are suggesting taboggan'ing down as in sit on your butt or hip and slide on rappel. For raps on a wet & polished slot canyon, that doesn't sound too bad in terms of stability.
(This post was edited by billl7 on Dec 24, 2012, 10:03 PM)
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socalclimber
Dec 24, 2012, 10:30 PM
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I agree, that's not a bad idea. I'm still baffled why people cannot seem to understand the concept of closing the system when necessary.
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marc801
Dec 24, 2012, 11:31 PM
Post #37 of 63
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socalclimber wrote: I'm still baffled why people cannot seem to understand the concept of closing the system when necessary.
Here's a hint: learn how to rappel correctly.
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socalclimber
Dec 24, 2012, 11:39 PM
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marc801 wrote: socalclimber wrote: I'm still baffled why people cannot seem to understand the concept of closing the system when necessary. I'm baffled by the amount of analysis and navel gazing over secondary crap like autoblocks in this thread for an accident that is the result of pure incompetence. Here's a hint: learn how to rappel correctly.
Yeah, well that would include closing the system when required.
(This post was edited by socalclimber on Dec 24, 2012, 11:48 PM)
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billl7
Dec 25, 2012, 12:41 AM
Post #39 of 63
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marc801 wrote: I'm baffled by the amount of analysis and navel gazing over secondary crap like autoblocks ...
Folks commonly use backups to rappel. This one failed to perform in circumstances that would lead most who use them to rig one. Seems natural to want to understand the rigging mistakes which were poorly understand from at least 10 months ago up until as recently as about 10 posts ago (some would probably argue the problem is still not well understood and may never be).
Edit: The above statement that the rigging mistake was poorly understood 10 months ago may be wrong; see this post for tests that demonstrate the effect of clipping before or after the girth hitch.
marc801 wrote: ... for an accident that is the result of pure incompetence.
Right. Folks shouldn't overlook the fact that Matt was not ready to do that particular rap without active control by a competent person.
Perhaps RC.com needs a crusade regarding threads that present pure incompetence, that they must stay on topic. I'm sure the rest of us would be fine with starting a separate thread to dig into the details.
Bill L
(This post was edited by billl7 on Dec 27, 2012, 5:28 PM)
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cracklover
Dec 25, 2012, 1:00 AM
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billl7 wrote: cracklover wrote: billl7 wrote: Edit: P.S. It took about 3 seconds (maybe 2) from the time the person rapping first slips to the sound of the splash when he decks. Three seconds seems a long time. But I still doubt that's enough time for a person belaying below and relying on the common instinct to a) realize it's time to engage the fireman's / caver's belay (first second); b) realize that gripping the rope isn't helping (second second), and c) realize that just gripping the rope harder also is not doing the job (third second). I'm sorry, but that's complete nonsense. In light of what I underlined above, what part of the above is complete nonsense? Bill L
Just what I said - you see the person start to fall, so you pull on the rope. It's nearly instantaneous from the moment you notice something wrong up above you. Really from the moment you start pulling, they'll start slowing down.
I don't understand what you mean about realizing that gripping the rope (or gripping the rope harder) isn't working. If the person knows how to give a fireman's belay, why would they think that how hard they grip the rope has anything to do with anything? When you're giving a fireman's, you always have a full grip on the rope until the person's safe or asks you to get off fireman's.
GO
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billl7
Dec 25, 2012, 1:50 AM
Post #41 of 63
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The difference is you are talking about the person who has thought about it and keeps those thoughts in mind while providing a cavers belay. Or someone who has a strong mechanical understanding during each situation regardless of their experience level.
I refer to the person who hasn't really thought about the difference between i) a caver's belay and ii) belaying a climber or stopping their own rap. Sure, they've seen someone hold the rope but that is all.
The term myopic comes to mind. But that is not totally fair. In a moment of panic - when your partner has lost control on rap, folks who haven't thought it out are likely to fall back to the more exercised instincts (i.e., that you just need to keep the rope from moving).
I'll confess that my concerns about this may have been warped over years of teaching folks new to multi-pitch. Most of them were doing it for a one-time experience and were in various states of just learning how to belay and rappel. Perhaps a steady diet of that takes its toll.
Bill L
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milesenoell
Dec 26, 2012, 4:00 PM
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The one time I have actually stopped someone with a fireman's belay was with a BIG guy on a brand new and pretty skinny line so I opted to loop the end under my butt and sit into the loop for tension. While I've never really examined this approach for weaknesses it does seem to make it very intuitive, since any motions the person on the ground makes to get out of the way of the way results in tension to stop the fall.
Sorry if this is taking us off subject, but I figured I'd toss it out there to see what you folks make of it.
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6pacfershur
Dec 26, 2012, 6:04 PM
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where was all the criticism and analysis a few weeks ago when well-known rockstud john long fucked up the fundamental procedure of tying in? i look forward to many pages of validation, rationalization and self-justification.............
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bearbreeder
Dec 26, 2012, 6:15 PM
Post #45 of 63
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there was plenty of that and death of the bowline stuff on the web ...
in this case a simple test of the rap prior and proper rap technique will help ya
in mister longs case there was a total failure of the self/partner check ... and getting distracted likely by hawt chicks
you can "learn" by screwing up yourself .. or from other peoples screw ups
yr choice
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billl7
Dec 26, 2012, 6:19 PM
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milesenoell wrote: The one time I have actually stopped someone with a fireman's belay was with a BIG guy on a brand new and pretty skinny line so I opted to loop the end under my butt and sit into the loop for tension. While I've never really examined this approach for weaknesses it does seem to make it very intuitive, since any motions the person on the ground makes to get out of the way of the way results in tension to stop the fall.
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jcrew
Dec 26, 2012, 9:13 PM
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marc801 wrote: namoclimber wrote: Is this a common practice to not use double rope rap when available. In canyoneering, a double rope rap is almost never used except by the clueless. .
guess i'm clueless,......why the hell was he only on 1 wet strand of rope? why is it so cool to rap 1 strand in a canyon?
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billl7
Dec 26, 2012, 10:05 PM
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In the linked forum, he said they did a single-line rap so that the more experienced one (with the camera), could ascend the free line if his partner got stuck and needed help.
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billl7
Dec 26, 2012, 10:57 PM
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To look at how sensitive the french-prusik autoblock might be to number of wraps, I did some testing. I tried to be as close as practical (for me) to reproducing their rope and cord diameters:
* 9.2 mm Sterling Nano vs. their 9.0 mm Blue Water Canyon Line;
* 6 mm perlon accessory cord vs. their unknown dia cord although ratio of cord to rope looks about right for 6 mm in their images,
Edit: The scope of the testing was increased from that shown below. All current results are shown here.
To summarize: five wraps of the autoblock would stop a drop of a 34 pound weight (via bathroom scale). Four wraps would not stop the same drop, albeit with travel limited to about 2 feet. Each autoblock config was tried 5 times to check reproducability - results were reproducable. And for each drop I would lock off, push the autoblock down about an inch, and then let go.
Interestingly, both configs could hold the weight if the autoblock was pre-tensioned.
This was with 22 1/2 inch stretched-out loop (~45" circumference). loop girthed to leg loop behind buckle (Petzl Adjama), wrap towards load, clip leg loop rear-ward of the girth. It was probably a longer loop than Matt's and would require extending the rap device to avoid interference.
Can provide more details of the tests if folks are interested.
Bill L
(This post was edited by billl7 on Dec 27, 2012, 4:04 AM)
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patto
Dec 27, 2012, 12:54 AM
Post #50 of 63
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jcrew wrote: guess i'm clueless,......why the hell was he only on 1 wet strand of rope? why is it so cool to rap 1 strand in a canyon?
A secondary benefit is that it makes rescues easier, particularly if the FIRST person needs rescuing from above.
That said it does seem that single rope raps in canyoning are used excessively. There certainly is some people other there prefering double rope raps.
I'm leaving tomorrow for an 8 day canyoning trip. I'm using a tube device, most of the others will be using a figure-8.
billl7 wrote: To look at how sensitive the french-prusik autoblock might be to number of wraps, I did some testing. I tried to be as close as practical (for me) to reproducing their rope and cord diameters:
Excellent! Great to see some testing! Also 6mm is likely a little too fat for 9mm rope.
Personally I do not like the reliance on the french-prusik aka the "autoblock knot". IF I am going to use a prusik for backup then I'll use a klemheist or a traditional prusik with the rap device extended.
I find this an absolutely reliable system. I don't normally use rappel backups but if I am I don't see the point in using any system that is not extremely reliable.
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