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tradmike
Jun 7, 2004, 3:35 AM
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Sorry for your loss. Let this be a lesson to us all. Ropes under tension can cut easily. I almost lost my life on a Mammut. An edge caught my rope in a very short fall and cut my Mammut 10.5 half way through. Nothing wrong with Mammut but I now use Edelweiss.
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pedro_burrito
Jun 7, 2004, 4:36 AM
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I read the accident report. This is what struck me:
"2.8 Fault Tree Analysis
The investigators developed a fault tree which includes both potential root causes and possible
contributing factors of the accident. The purpose of this analysis is to develop a list of all reasonable
influences, examine them, and include or exclude each in turn based on available evidence. Only
accidental causes were considered, since the Lake County Sheriff's Office determined there was no
evidence of criminal activity related to the incident. Additionally, the investigators found no
indications of any inappropriate behavior by the subject group."
The investigators were told to look only at accidental causes. That appears to severely restrict the investigation. They really found nothing that they could prove cut the rope. Yes, they found that some things can get into the grigri and tear up the sheath but they could not reproduce the sequence completely where the rope is cut. The whole preliminary investigation by the Sheriff's department appears to be a Keystone Kop kind of deal. The first thing that all police are supposed to be trained in is to secure the area. No one did that. Someone walked up to the scene and cut the other end of the rope! That's called destroying evidence.
The Midwest Technical Rescue Training Associates investigation was severely hampered. There are far too many unknowns for them to do a thorough investigation plus they were told to ignore anything that wasn't an accident. By the same entity (the Sheriff's Office) that screwed up the preliminary investigation. I'm not a conspiracy theorist but the Sheriff's Office would look very bad if the Midwest Technical Rescue Training Associates investigation came back and said that there was foul play involved.
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papounet
Jun 7, 2004, 7:59 AM
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dear
I read Rescueman's intial points again and checked Sandstone's test, and read the thread twice to make sure I understood.
Would it be possible for the 2 of you to agree you are not talking about the same thing ?
Rescueman talked about autoblock knots testing under rescue load and high fall conditions. Under those conditions, knots appear to slip for a certain distance (which may cause the material to start melting, utlimately leading to failure under extreme conditions).
the facts that the knots slipped doesn't say that they didn't grab instantly. It just say that wether or not the knot grabbed the rope instantly, it took x cm fo rope to for the knot to halt the fall.
I would think that Rescueman refered to
http://cmru.peak.org/...july97_drop_test.htm
where the load was 210 and 300 kg , the fall is 1 on 3 meter of used static line (ff is .33)
Sandstone's are very interesting (thanks a lot , or as some write on the forum a lot of thnacks), and describe a different setup: normal climber weight, small fall. Under those conditions, the knot does not slip, aka, grabs instantly.
All autoblocks knot are not equal see for example the slippage of a Kleimheist in
http://www.xmission.com/...ull_tests_11_98.html
A physicist could probably attempt to compute the speed at which the rope retracts from being previously under tension against the acceleration of the falling climber pulling on the knot.
But I am so far convinced that under normal climbing conditions a properly done autoblock knot (not a prussik, rather this one
http://www.ffme.fr/...oquant/francais0.gif would do fine.
Thanks again to sandstone.
Now wether I put it above or below, I prefer above as I was witness once of a the troubles of a too long prussik going into the descender, no dire consequence, just a big mess that took long to address).
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rescueman
Jun 7, 2004, 2:35 PM
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In reply to: Rescueman talked about autoblock knots testing under rescue load and high fall conditions. Under those conditions, knots appear to slip for a certain distance (which may cause the material to start melting, utlimately leading to failure under extreme conditions).
Thanks for a reasoned and reasonable response. Interesting that it takes a Frenchman to be a peacemaker here - just as France refused to go along with the beligerance of the US toward Iraq.
While one thread in this convoluted discussion has touched on rescue loads, the more important point I've been trying to make is that for one person rappels, an above-the-descender prusik backup has been problematic and occassionally fatal.
In reply to: All autoblocks knot are not equal
Quite right. But, for clarification, I was using the term "autoblock", not in the generic sense that you do, but to describe the specific friction hitch which has become the standard for below-the-device rappel backups:
http://www.geocities.com/...Autoblock-sketch.jpg
In reply to: A physicist could probably attempt to compute the speed at which the rope retracts from being previously under tension against the acceleration of the falling climber pulling on the knot.
Actually, any theoretical calculations would be completely useless in the field because the functioning of a prussik depends on:
- the relative size of the cord compared to the host rope
- the relative stiffness of the cord compared to the host rope
- the weave of the sheath
- whether it's dry, wet, dirty, muddy, or icy
- how well the knot was dressed and set
- and, of course, how the loop was tied
Because of the many variables involved in the safe applicaiton of prusiks, the EU has pretty much eliminated them for rope access and rope rescue.
In reply to: But I am so far convinced that under normal climbing conditions a properly done autoblock knot (a kleimhiest not a prussik) would do fine.
In reply to: Now wether I put it above or below, I prefer above as I was witness once of a the troubles of a too long prussik going into the descender, no dire consequence, just a big mess that took long to address).
I think many of us tend to make decisions based on either anecdotal evidence or a single experience that left a mark on our memory, such as the one you describe.
But there is a huge difference between "no dire consequences, just a mess" with an autoblock getting sucked up into a descender and the cases of climber/caver deaths due to use of a prusik "safety" above the descender.
An additional negative to using an above-the-device friction hitch is that it requires two hands to manage the rappel (one on the hitch and one on the brake) leaving no free hand to fend off obstacles or keep from spinning or swatting mosquitoes. The autoblock below requires only one hand to operate safely, has only to hold the significantly reduced load on the brake side and is hence both more reliable and much easier to break free under tension.
To avoid the problem of interefence between the autoblock and the descender, simply extend the descender away from the harness with a short (or doubled) sling.
- Robert
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sandstone
Jun 7, 2004, 4:08 PM
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Rescueman wrote:
In reply to: ...all you've proven is that you're willing to accept whatever coincides with your own misperceptions and choose to argue, like sandstone, against whatever contradicts your preconceived notions and limited experience.
I have not accepted either your misconceptions or my own assumptions. Assumptions and misconceptions are killers, that's why it's important to shine the light on them when you see them. Asking you to back up your bad assumptions is not "arguing" at all -- it's just the simple process of separating the wheat from the chaff.
In reply to: And what's most peculiar, is that sandstone is going to such great lengths to "prove" the reliability of a technique that he very specifically doesn't recommend.
What great lengths? As I stated before, all I did was stroll back to the wall and do a quick and simple test. Everything I needed was already there, it was no big deal.
You completely miss the point of my test -- I was not trying to prove the reliability of a technique.
My purpose was bringing to light the fact that you are posting bad assumptions. You write in a "voice" of authority and knowledge, yet when I put one of your proclamations to a simple test I found it to be complete b_llsh_t. People need to know that.
In reply to: What's the point of continuing to offer my knowledge, insights and experience when the most vocal on this forum are the ones least interested in learning?
Rescueman, let's test that theory ("...least interested in learning"), with me as the guinea pig.
I learned from this thread that there is a very small chance that the debris I generate when cleaning a route could fall into my Gri-Gri and sever my rap rope. Even though the risk is very small, I changed my backup technique (rather than use knots on the rap rope below the Gri-Gri, I now use knots on a separate rope).
I learned that you are perfectly willing to try to pass off your personal opinions and bad assumptions as facts in a public climbing forum. I learned to treat everything you say as suspect information.
It's just my opinion of course, but it sure looks like I'm willing to learn.
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sandstone
Jun 7, 2004, 4:43 PM
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In reply to: I read Rescueman's intial points again and checked Sandstone's test, and read the thread twice to make sure I understood....Would it be possible for the 2 of you to agree you are not talking about the same thing ?
Yup, that's definately the case. This discussion was about a climber being lowered on a dynamic rope (the original post about the accident), and this sub-discussion was about a slow stop and go rappel (for cleaning a route).
In reply to: Rescueman talked about autoblock knots testing under rescue load and high fall conditions....where the load was 210 and 300 kg , the fall is 1 on 3 meter of used static line (ff is .33)
It's obvious Recueman was referencing a completely different scenario. That's why I had a problem with what he was posting, he was assuming the system would behave the same under completely different conditions. That's a very bad assumption.
I think the lesson here is don't assume anything, even when someone makes an authoritative proclamation. If it smells bad, peel back the lid far enough to see if it's really just a can of b_llsh_t.
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alpnclmbr1
Jun 7, 2004, 4:50 PM
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In reply to: In reply to: I posted my original message so other people who are cleaning routes would get a "heads up", and maybe re-think their backup strategy as I did. My goal was just to try to help out some folks. Rescueman, I have no idea what your goal is. Wow! Sandstone, your posts were a clear demonstration of experience, logic, and an open mind. I hope you continue to post on this site. Thank you for going through the time to do that test; I've never been an advocate for above the device rappell back ups, but I'd always wondered if they would lock up quickly enough. Rescueman, you're an arrogant azzhole.
That works for me.
Welcome to the site Sandstone.
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stickclipper
Jun 7, 2004, 7:22 PM
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In reply to: What are some problems with rappel backups done on the "above the device" side of the rope? I assume by "above" you mean the loaded side of the rope? I've heard this before and usually have used a bachman knot (I think that's the name...) off my legloops on the non loaded side of the rope, but I haven't heard a cogent discussion of the reasons. UB
My understanding is that the three main problems with it above the device (yep, loaded side) are the following:
1. The knot can lock up out of reach, leaving you stranded with no way to unload it (and a much heavier load it is, compared with below the device). Either in John Long's Climbing Anchors or in a book called Knots for Climbers it is stated that climbers have died because of this - eventually passing out and then dying quickly from harness hang syndrome.
2. As Rescueman pointed out, the tendency to grab the rope in front of your face (thus grabbing the prussik) would cause it to fail to engage.
3. As Rescueman also pointed out, having the knot above requires both hands to be in use during a rappell, while below allows you a free hand.
Damn, I guess Rescueman uttered something true. Hm. Well, even a blind squirrel finds a nut every once in awhile.
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timstich
Jun 7, 2004, 7:30 PM
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In reply to: Well, even a blind squirrel finds a nut every once in awhile.
But a blind squirrel finds his own nuts every time if he doesn't bathe.
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pneumoped
Jun 7, 2004, 8:17 PM
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In reply to: Holy Moly Batman, ...
Dear Robin,
Batman here! I hope that you and sandstone will feel good in knowing that I have spent the better part of today LMAO. In fact this whole weekend was a treat as I sat back and watched the fireworks. Before I enter the fray with my own opinions and references, I have one question (for anyone to answer).
How does one properly rig an autoblock knot below a rappel device? Specifically an ATC (which is what I use)? AND, which autoblock knot (used below the rappel device - the unloaded part of the rope) would you recommend and why (since I've seen reference to another type of autoblock knot that I'm unfamiliar with in this thread)?
Thanks,
Pneumoped
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moondog
Jun 7, 2004, 9:29 PM
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Another quality of the GriGri and similar autolock devices is the "complacency tendency" that's created by the assumption that the device is "fail-proof" or "automatic" and requires less attention from the belayer.
"Complacency tendency" is clearly not a quality of the Grigri or any other thing. It is a specifically human thing (if it even exists). The idea that a device automatically makes one complacent is iffy. Does wearing a seat belt cause one to drive carelessly?
Yeah, I'm being a mite picky 'cuz I'm real tired of hearing about the mysterious persuasive powers of Grigris and other doodads :wink:
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pneumoped
Jun 7, 2004, 10:21 PM
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In reply to: And the most commonly used backup device is the Petzl Shunt. - Robert
First, I better lay out the exact scenario before I pose my questions and opinions about the Petzl Shunt so we have an idea of what the circumstances are.
I’ve just finished climbing Kor Ingalls on Castleton Tower in Moab with my partner (nice route by the way). We climbed on a 9.8 mm by 60m rope and tailed a smaller diameter 60m rope for the double rope rappel and a haul line. We tailed a smaller diameter rope to reduce weight during the 4 pitch climb. In order to avoid rapping down on top of the hoards of other climbers coming up behind us, we decided to rap off the North chain anchors which required us to tie the two ropes together and thread 3 separate rap anchors on our way down. To my knowledge, there is no way to do this rappel from this anchor with just one 60m rope without leaving it and end up stranded on the first ledge down. The first rap anchor consists of 3 bolts on the horizontal surface of the top of Castleton Tower about 14 inches from the edge (forgive me if I don’t get it exactly right). To each bolt is attached a chain and the three chains come together about 6 inches over and down the face of the cliff and are connected with a typical rappelling ring(s) of some sort (I can not remember exactly). It’s a long way down, a sobering test of complete trust of ones equipment, competence, and anchors placed by unknown people. To get on the first rappel safely, I scooted up the anchor and clipped in with my daisy chain for safety. I was the last one off in my party. Then, I pulled on the chains, hauling the rappel ropes up to me. I set up my rappel (an ATC) and left enough space between the rappel and the anchor to also set up a prusik backup (about 4 inches) on the to be loaded side of the rappel. I tightened the prusik knot as best I could. I unclipped my daisy chain since once over the edge I would not be able to reach up to unclip it. Then, with a good 15 to 20 pound pack on and using both hands, I turned myself around to face the wall and lowered my self down with my hands on the cliff edge until the slack of rope between my ATC and the anchor were taken up. While holding the cliff edge with one hand, I adjusted the chain anchor so the chains were not crossed and everything looked good before grabbing the brake line and loading the rope. I felt that having a prusik backup would be a good idea in case my hands slipped while lowering off.
If there is a better way to backup in this scenario, I’m more than willing to know. I’m curious about this autoblock knot below the rappel device and how to set it up. However, a Petzl Shunt would not have been a good idea (in my opinion) in this case for several of the following reasons:
First, according to Petzl’s technical notice, the Shunt is only approved for use under two rope setups; A) a single fixed rope 10-11 mm, or B) a single 8-11mm rope doubled over through a rap anchor. They are very addament that with a double rope rappel, the two rope strands are the same rope. Other types of rappel setups are cautioned against with skull and crossbones in their technical notice, including using it on a rappel with different diameter ropes as described above and I can clearly see the reason why. If the two rope strands were different sizes, then the larger strand would get cinched in the devince and leave room for the smaller strand to slip - truly a recipe for disaster.
Second, assuming I was using one rope for a double rappel, by setting up the Shunt using their diagrams, I would have had too much slack between the anchor and my harness as I lowered off with my hands. I suppose I could have grabbed the chains and lowered off a bit more, or even grabbed the rope, but I try to avoid those kinds of things whenever possible.
Next, the technical notice cautions that the Shunt will not work if you don’t let go of it in a fall:
In reply to: Attention! It is essential to let go of the device in the event of a fall. Nothing must be allowed to impede the movement of the handle (carabiner, rope, lanyard,…)
So, is the climber that panics and does not let go of the prusik the same climber that does not let go of the Shunt? Or is there something unique about the Shunt that eliminates that problem. Also, the diagram in the technical notice shows the climber holding the brake lines with his left hand and the Shunt with his right hand. One of the criticisms of the prusik that was pointed out in this forum tread is not having one hand free.
Finally, the Shunt is 198 grams. I’m looking for a device or method that is safer than a prusik backup (considering what "a recipe for disaster" it is), is about as light as a prusik, can be used to ascend a rope, can be used to slide equipment up or down a rope, and in emergencies can be used to build an emergency rap anchor along with a couple of rap rings.
FYI, here is the link to the Petzl technical notice for the Shunt:
http://www.petzl.com/...ervices/PS_116_1.pdf
Cheers,
Pneumoped
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pneumoped
Jun 7, 2004, 10:56 PM
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In reply to: When I clean a route from now on I'll be rappelling on one line with my GriGri, and using a second rope for my backup knots.
sandstone,
I think I'm confused how you do this. Are these two fixed ropes? One of which you rap on and the other used for your backup knots? I'm unfamiliar with this technique, can you describe it better? How do you pull down your rappel if they are fixed?
Also - sorry to get you and rescueman in such a debate. I hope you never need to be rescued by rescueman. You might not make it home.
I had no idea that using a prusik backup above the rappel was actually more dangerous than not backing up at all. Before I started using prusik backups, I wasn't using anything at all. I think I got the idea from an accident report in the 2003 Accidents in North America. I'll go back and check.
Cheers,
pneumoped
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sandstone
Jun 8, 2004, 12:05 AM
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sandstone wrote:
In reply to: When I clean a route from now on I'll be rappelling on one line with my GriGri, and using a second rope for my backup knots.
Pneumoped wrote:
In reply to: I think I'm confused how you do this. Are these two fixed ropes? One of which you rap on and the other used for your backup knots? I'm unfamiliar with this technique, can you describe it better? How do you pull down your rappel if they are fixed?
Yes, both ropes are fixed. It's dirt simple, just rap on one line, and occasionally tie and clip into a figure 8 knot on the second line. To get back to the anchor I go back up the rap rope using the Gri-Gri and one ascender (backing myself up by clipping into the backup knots on the second rope). The ropes have to then be re-rigged if I then need to rappel and pull them down.
In reply to: Also - sorry to get you and rescueman in such a debate.
Wasn't your fault. Rescueman just got off on a rant and said some things that weren't quite right. He's just human -- we've all done the same thing in one way or another. He does seem to have a need to feel important (another human trait we all share in one way or another), and I think that's what got him wrapped around the axle.
In reply to: I hope you never need to be rescued by rescueman. You might not make it home.
Rescueman is probably an OK guy in person -- most people are. People tend to make rants and claims on the "faceless" Internet they would not make in person.
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badass
Jun 8, 2004, 1:20 AM
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This is a fact you might not know. Grigri's suck. I know 3 people personally that have been dropped on grigri's because they lower to fast and fight against a persons natural inclination to hold on rather than let go of the lever in a circumstance.
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wedgy
Jun 8, 2004, 1:42 AM
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"I know 3 people personally that have been dropped on grigri's because they lower to fast".Here we go again. You know 3 people who were dropped by idiot belayers. Lets see...if the left hand was holding the black plastic arm what was the right hand holding? If your answer was any thing other than "the rope" you are wrong. You can hold the arm WIDE OPEN and the grigri will still hold like ...well... gee...an ATC, because your right hand is supposed to be on the rope. Yes as you would an ATC. Perhaps such a complicated device is just that...TOO complicated for some to understand.
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badass
Jun 8, 2004, 2:02 AM
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That is my whole point exactly. When you lower with a Grigri one hand is on the lever the other on the rope. Thats only one brake hand. If you lower someone remotely fast the rope can slip out of a single brake hand and then you are forced to let go of the lever which is hard to tell yourself to do in an emergency.
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jt512
Jun 8, 2004, 2:43 AM
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In reply to: That is my whole point exactly. When you lower with a Grigri one hand is on the lever the other on the rope. Thats only one brake hand. If you lower someone remotely fast the rope can slip out of a single brake hand and then you are forced to let go of the lever which is hard to tell yourself to do in an emergency.
I find it almost impossible to believe that someone who claims to have redpointed 5.14a could have written something as idiotic as the above.
-Jay
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sarah
Jun 8, 2004, 2:54 AM
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sorry to hear - i never liked the grigri two friends of mine were dropped with them because of the lever belaying the rope so fast :(
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wedgy
Jun 8, 2004, 3:12 AM
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"That is my whole point exactly. When you lower with a Grigri one hand is on the lever the other on the rope. Thats only one brake hand" How many brake hands do you use to rappel? or belay(a leader ; ie pay out rope with the left, right hand(brake hand) on the rope. "Your whole point exactly" indicates you dont know how to belay. period
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badass
Jun 8, 2004, 3:21 AM
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Hey wedgie ever notice when you're lead belaying with that piece of sh-t grigri that you have zero brake hands when your paying slack. If you do then your probobly shortchanging the belayer. You rappel one handed what are you psycho? Do me a favor next time you pick up your 2 pound grigri. open it up and look at the pathetic pin holding it together. Now try to flex the grigri apart. Don't go looking for it Taylor you may not like what you find. :lol:
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badass
Jun 8, 2004, 3:23 AM
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And Jay, I don't claim to climb 5.14 I did climb 5.14. Grigris suck
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wedgy
Jun 8, 2004, 4:16 AM
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--------------------------------------------------------------------------------
Hey wedgie ever notice when you're lead belaying with that piece of sh-t grigri that you have zero brake hands when your paying slack. If you do then your probobly shortchanging the belayer. You rappel one handed what are you psycho? Do me a favor next time you pick up your 2 pound grigri. open it up and look at the pathetic pin holding it together. Now try to flex the grigri apart. Don't go looking for it Taylor you may not like what you find.
_________________
Slack is paid out just as it is with an ATC, nice and smooth. Perhaps youre a little too nervous or something? no? Yes, I do rappel one handed. How would one expect to free up a rope( it doesnt always fall in a straight line to the next anchor) or clip into the next rap station if both hands are nervously clenched in a death grip (as yours appear to be) on the rope? The grigri is by far the easiest way to clean solo aid pitches. Get this, sometimes I take both hands (yes, right AND left off the rope)! As for the pathetic pin you speak of, its the same pin (only bigger) thats in all your biners. I wouldnt recommend torquing a biners gate off its axis either, but you seem to have a history of not following the manufacturers instructions. Maybe I can buy yours & your friends grigris for cheap? or just give them to me before you guys hurt yourselves any worse.
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rescueman
Jun 8, 2004, 8:20 AM
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In reply to: Another quality of the GriGri and similar autolock devices is the "complacency tendency" that's created by the assumption that the device is "fail-proof" or "automatic" and requires less attention from the belayer. "Complacency tendency" is clearly not a quality of the Grigri or any other thing. It is a specifically human thing (if it even exists). The idea that a device automatically makes one complacent is iffy.
Hank,
I can understand your defensiveness about the Grigri, since its use and misuse has created so many problems. But don't let your loyalty override your objectivity.
Of course no device "automatically" makes anyone act in a certain way, and Petzl has gone to great lengths to downplay the "fail-proof" quality which so many in the climbing community ascribe to the Grigri.
But Petzl didn't create a device to be used without human involvement, and no amount of disclaimers and warnings (how many users actually read the lengthy technical bulletins?) will prevent the all-too-human responses to a device that's intended to "automatically" replace at least a part of the human response mechanism.
Choosing to market a product which feeds the modern human tendency to let technology replace vigilance and effort is to assume responsibility for the inevitable and extensive over-reliance that will result.
One of the most common uses of the Grigri is in indoor climbing gyms because of the assumption that it is safer for use with novices. We know too well that, in the hands of novices, it is often a dangerous device. And experienced users have found methods to override some of its built-in safety (by thumbing the lever), not realizing that they are creating a hazard.
So I stand by my statement that any "automatic" device that feeds the assumption that it is "fail-proof" or "fool-proof" merely invites fools to use it and do foolish things.
Better to take the time to teach safe belaying with simple, easy to understand devices than start people off on complicated autolockers. At Outward Bound, we began all climbers with a body belay, backed up by a rope handler. I think it bodes ill for the sport of climbing that we're introducing so many new people to high-tech equipment before they learn the basics.
And, in fact, the rise in popularity of climbing gyms coincided with a marked increase in the number of climbing accidents on crags.
I would strongly encourage all Grigri users to read this balanced article:
http://www.thebmc.co.uk/.../articles/grigri.pdf
- Robert
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rescueman
Jun 8, 2004, 8:40 AM
Post #75 of 118
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Registered: Mar 1, 2004
Posts: 439
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In reply to: In reply to: And the most commonly used backup device is the Petzl Shunt. - Robert So, is the climber that panics and doesn’t let go of the prusik the same climber that doesn’t let go of the Shunt?
That statement was in response to Sandstone's use of a prusik on a seperate fixed line as a backup. This is the standard for professional rope access work, except a Shunt is used instead of a prusik.
I do not advocate the use of a Shunt in recreational climbing. Though it was marketed as a "mechanical prusik", as you've noted it has a number of limitations and is more likely than a prusik to be rendered useless in a panic.
In reply to: Finally, the Shunt is 198 grams. I’m looking for a device or method that is safer than a prusik backup (considering what "a recipe for disaster" it is), is as light as a prusik, can be used to ascend a rope, can be used to slide equipment up or down a rope, and in emergencies can be used to build an emergency rap anchor along with a couple of rap rings.
There is nothing more versatile and lightweight than a simple prusik sling. It has more uses than any other piece of gear and it's cheap and easily replaced.
I'll say it one more time: For a safer and easier alternative to the prusik rappel backup, use an autoblock below the descender.
http://www.geocities.com/...Autoblock-sketch.jpg
There is a good discussion of rappel backup options at:
http://www.chockstone.org/TechTips/RapBackup.htm
- Robert
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