What did I just read?

[driggs]

Part of my argument is that an ascender rated for 4kN is not enough of a safety factor even in a purely static situation. This is roughly 1/6 the strength of a typical carabiner. If this was enough of a safety factor, then we would all be using 5mm cord to rappel (same 4kN rating).

I'm a little surprised there's so much debate over this. I'm all for reviewing and challenging the status quo, but I thought this was a well established standard in all roped vertical work. If ascenders are developed that are rated to 22kN, can never come off the rope when cross-loaded, and won't cut the rope with a fall impact, then perhaps relying on a single ascender will become the new standard practice.

I personally use 10 or 11mm rope versus 5mm cord (or 8mm rope), not for its increased capacity for shock loading, but for its resistance to abrasion and lesser stretch.

I'd argue that shock loading an ascender is one of the least likely potential causes for injury on rope, though this is a "wild-assed guess" with no statistical investigation to back it up. In fact, I'd guess an order of magnitude more importance on preventing errors from failed connections in the situations I outlined previously versus ascenders severing rope... or else we'd all be climbing on knots or steel cable or ladders to prevent ropes snapping left and right.

BUT, it is certainly a real risk, no matter where it ranks on the likelihood scale. So I'm curious if, in a situation where your ascender is shock-loaded at 4+kN, and either the sheath separates or the rope is cut (I believe the former tends to happen with toothed ascenders, right?), is enough energy absorbed by this initial failure that the second ascender on the rope remains safely in place? Has anyone ever done a drop test on two simultaneously attached ascenders to model one of our climbing systems?

[NZcaver]

So I'm curious if, in a situation where your ascender is shock-loaded at 4+kN, and either the sheath separates or the rope is cut (I believe the former tends to happen with toothed ascenders, right?), is enough energy absorbed by this initial failure that the second ascender on the rope remains safely in place? Has anyone ever done a drop test on two simultaneously attached ascenders to model one of our climbing systems?

When I read Derek's earlier comment, I was wondering exactly the same thing. I suppose it would depend on exactly how you load the ascenders for testing, versus how a real world shock loading of 2 ascenders in a personal climbing system might possibly occur. Both loading equally, or one backing up the other? So many variables. My contention is that while a single ascender might be nominally rated at 4kN (depending on the rope and conditions), two ascenders - while providing some redundancy - are not likely to double your MBS and theoretical system safety factor.

[wyandottecaver]

well certainly in the interests of science we would want to accurately document the loads, dimensions, and forces to quantify both the problem and proposed solution. Of course what some see as simple quantitative bodily measures others see as salacious details. I thought the degree of description was beyond what I wanted to envision certainly.

Of course the same is true of a caver at a NCRC weeklong in Carlesbad I observed wearing what appeared to be silver silk shorts and a skin tight bright pink shirt during the mock.....

[NZcaver]

Of course the same is true of a caver at a NCRC weeklong in Carlesbad I observed wearing what appeared to be silver silk shorts and a skin tight bright pink shirt during the mock.....

If you mean the Carlsbad weeklong back in '03, my memory is a blur. I hope that wasn't me.

[Extremeophile]

I'd argue that shock loading an ascender is one of the least likely potential causes for injury on rope, though this is a "wild-assed guess" with no statistical investigation to back it up. In fact, I'd guess an order of magnitude more importance on preventing errors from failed connections in the situations I outlined previously versus ascenders severing rope... or else we'd all be climbing on knots or steel cable or ladders to prevent ropes snapping left and right.

I'd agree with your guess. The actual statistics probably show that most incidents are from human procedural errors rather than straight equipment failure.

[Anonymous_Coward]

I once saw a guy at convention (Sewanee '98) taking down his tent while wearing nothing but a breechcloth made of two yellow rubber dishwashing gloves. One in the front, one in the back, and a thin cord around the waist.

I also like to use spectra cowstails. I find that they work fine if you just go limp like a drunk every time your ascender blows out or the bolt pops out of the wall. (If I had a nickel...)

[Extremeophile]

a breechcloth made of two yellow rubber dishwashing gloves. One in the front, one in the back,

See, sometimes two is better than one.

[Cody JW]

Now that we have all images of butts being weighed out of mind , I would like to give a real life ( or death ) example of the benefits of not being bashful about using a QAS. Some of you may be old enough to remember the death of fellow Hoosier caver Chris Yeager in Cheve, Mexico . In this accident, he fell down a 60 foot (or so) pit during an expedition. It was on the way down and there were no eye witnesses but he was found dead on the bottom of the pit with his descender attached to the rope up top. I am just connecting dots here and speculating but I am guessing he, and his family ( who I have met) and friends and the recovery personnel would of loved it if he had his QAS attached during this procedure of attaching himself to the rope. Can you get by in most situations without it - likely. In this case ,the few seconds it takes to remove the Jumar from the seat accessory loop and attach it to rope would of saved a life and lots of trouble. I read published accident reports and analysis and think " What can I do to keep that same kind of thing from happening to me?", I remember things like that and practice what I have learned resulting in my desire to attach a QAS during any kind of maneuver where climbing/ rappel devices are being removed and attached to the rope where there is exposure.I did not read that in any manual or was taught that by anyone, just common sense.

[Stan Allison]

Why is it that all Cavechat discussions end up discussing QAS's, spectra cows-tails and yellow rubber dishwashing glove breechcloths???

I started caving in Cheve the year after the Chris Yeager fatality. I was a young caver and it was my first 1,000 meter deep cave. My caving mentors on the trip drilled into me a rebelay passing technique that would have prevented Chris' fatality. Every time I pass a rebelay on rappel, I attach my short cowstail to the anchor area and then clip my long cowstail into the rope loop. If for some reason my rappel device were to fail when I remove my short cowstail, I would drop a few feet onto my long cowstail but still be alive. Using a QAS is not a suitable substitute for the long cowstail since you don't ever want to shock load an ascender and it also takes much more time to attach a QAS rather than just clipping a long cowstail into the rebelay loop.

As a refresher on the fatality, Chris was passing an awkward rebelay. When he removed his short cowstail from the anchor his locking carabiner on his rack must not have been locked because it opened leaving his rack on the rope below the rebelay anchor and Chris at the bottom of the drop. If Chris had clipped his long cowstail into the rebelay rope loop this accident could have been prevented.

As for two versus one ascender on rope. I do sometimes climb short handlines that I can free-climb by just attaching my croll to the rope and climbing. I always have two devices attached to a rope when performing changeovers either going up or down. I'm not concerned about ascenders failing or popping off when they are weighted and not being moved up or down the rope. My favorite unconscious pick-off technique is the counterweight method on a long cowstail as on page 277 of Alpine Caving Techniques. Step 7 of this technique does leave both myself and the patient suspended by one pre-weighted ascender until a rappel device is attached. If any of you don't feel comfortable hanging by just one ascender, please let me know and I will leave you hanging on rope unconscious if I should ever encounter you in this situation. We could refer to this is as a DNP order for a Do Not Pickoff order. To be safe, it might be best if you have a DNP order bracelet or tattoo on your chest.

[Scott McCrea]

As a refresher on the fatality, Chris was passing an awkward rebelay. When he removed his short cowstail from the anchor his locking carabiner on his rack must not have been locked because it opened leaving his rack on the rope below the rebelay anchor and Chris at the bottom of the drop. If Chris had clipped his long cowstail into the rebelay rope loop this accident could have been prevented.

If you deconstruct the accident further, the root cause was that he unweighted his rack while disconnecting his safety. Unweighting a rack, or any descender, is a chance for a bad time. A safety that requires the descender to be unweighted to be removed is not safe. The long cowstail that can remain slack and be removed after the descender is loaded is safe. A QAS, above the descender, with a slack lanyard, can be removed without unloading the descender is safe.

We could refer to this is as a DNP order for a Do Not Pickoff order. To be safe, it might be best if you have a DNP order bracelet or tattoo on your chest.

This is good. I might do this.

[Stridergdm]

As a refresher on the fatality, Chris was passing an awkward rebelay. When he removed his short cowstail from the anchor his locking carabiner on his rack must not have been locked because it opened leaving his rack on the rope below the rebelay anchor and Chris at the bottom of the drop. If Chris had clipped his long cowstail into the rebelay rope loop this accident could have been prevented.

If you deconstruct the accident further, the root cause was that he unweighted his rack while disconnecting his safety. Unweighting a rack, or any descender, is a chance for a bad time. A safety that requires the descender to be unweighted to be removed is not safe. The long cowstail that can remain slack and be removed after the descender is loaded is safe. A QAS, above the descender, with a slack lanyard, can be removed without unloading the descender is safe.

We could refer to this is as a DNP order for a Do Not Pickoff order. To be safe, it might be best if you have a DNP order bracelet or tattoo on your chest.

This is good. I might do this.

Well put it on the bottom of your shoe in glow in the dark colors so as the person climbs up to pick you off they can see it before they get to you.

[Extremeophile]

Disclaimer: Debating caving technique with Stan is not advisable. With that said ...

Every time I pass a rebelay on rappel, I attach my short cowstail to the anchor area and then clip my long cowstail into the rope loop. If for some reason my rappel device were to fail when I remove my short cowstail, I would drop a few feet onto my long cowstail but still be alive. Using a QAS is not a suitable substitute for the long cowstail since you don't ever want to shock load an ascender and it also takes much more time to attach a QAS rather than just clipping a long cowstail into the rebelay loop.

I attach my footloop ascender to the down rope just below the knot before moving my descender from the upper rope to the lower rope. If my short cowstail or descender fail for any reason during the transition then this ascender takes the load. Perhaps you could call it a shock load since there's a little slack in the long cowstail attached to this ascender, but it would be a very low FF. The long cowstail in the rebelay loop might be a better choice for absorbing a shock load, but considering the length of the cowstail and the rebelay loop, you might generate up to a FF2 impact force on the long cowstail. Some texts suggest leaving the braking carabiner clipped into the rebelay loop until the descender is moved to the lower rope (that's if you're using a bobbin and not a Freino). I'm not sure any of these techniques are ideal, but they are all backups and all may be adequate to catch a once in a thousand error.

As for two versus one ascender on rope. I do sometimes climb short handlines that I can free-climb by just attaching my croll to the rope and climbing. I always have two devices attached to a rope when performing changeovers either going up or down.

I consider something like a single ascender belay when climbing a ladder or free-climbing to be standard practice. I count ledges, hand/foot holds, ladder rungs, etc., that support body weight, as a point of attachment.

I'm not concerned about ascenders failing or popping off when they are weighted and not being moved up or down the rope.

While I have never had an ascender fail or come off the rope in any way, I still don't consider a single ascender to be strong enough to trust as a sole means of life support. I trust BFRs, trees, 10-11mm rope, maillons, and locking carabiners. For other devices such as non-locking carabiners, bolts, nuts/chocks, and ascenders I'll stick with two.

My favorite unconscious pick-off technique is the counterweight method on a long cowstail as on page 277 of Alpine Caving Techniques. Step 7 of this technique does leave both myself and the patient suspended by one pre-weighted ascender until a rappel device is attached.

I've only ever practiced a pick-off once, and didn't much care for it. The description and diagram in ACT is a little difficult for me to follow, but I'm not sure why it's necessary for the rescuer to detach their footloop ascender before the descender is attached and locked off. My practice when doing something like a changeover is to always move the footloop ascender so that it is just above the Croll before trying to remove the Croll. This generally prevents weighting the long cowstail and maintains a backup until the descender can be tested.

[Anonymous_Coward]

Well Stan, after looking at the diagram of step 7 I think I can see why it would be YOUR favorite!

But really, if you just moved step #3 "I remove my upper ascender from the rope, since I no longer need it." until after the descender was tested, I think it would satisfy everyone's concerns.

Derek, be advised that the only thing more non-advisable than debating Stan is the sacrilege of questioning The Book. ACT will not tolerate dissent.

[Stan Allison]

I attach my footloop ascender to the down rope just below the knot before moving my descender from the upper rope to the lower rope. If my short cowstail or descender fail for any reason during the transition then this ascender takes the load. Perhaps you could call it a shock load since there's a little slack in the long cowstail attached to this ascender, but it would be a very low FF. The long cowstail in the rebelay loop might be a better choice for absorbing a shock load, but considering the length of the cowstail and the rebelay loop, you might generate up to a FF2 impact force on the long cowstail. Some texts suggest leaving the braking carabiner clipped into the rebelay loop until the descender is moved to the lower rope (that's if you're using a bobbin and not a Freino). I'm not sure any of these techniques are ideal, but they are all backups and all may be adequate to catch a once in a thousand error.

Derek makes a good point. No matter what you do to backup passing a rebelay on rappel it is just a backup and in reality either an ascender or a cowstail is probably fine to catch the one in a thousand error. I still stand by my statement that it is less efficient to use an ascender rather than using a long cowstail to quickly clip into the rope. While attaching and detaching an ascender doesn't take much more time than clipping and unclipping a cowstail and this time may not be a significant issue in smaller caves, in caves over 1km deep rigged with mucho rebelays a few seconds add up here and there when you are passing tens to hundreds of rebelays.

I would also recommend if you are going to use an ascender, which I don't recommend, place it on the upper rope where you are less likely to create a serious FF. placing the ascender just below the anchor as Derek does creates more of an opportunity for shockloading the ascender. With very little rope between the anchor and the ascender that possibility exists.

Derek may still not agree with me, but I'm pretty certain that we both agree that the most important thing is to do something to backup the moment when the short cowstail is removed and the rappel device is being weighted. Even if Derek's descender or descender attachment fails and he drops onto his ascender placed below the rebelay anchor, he has a much better chance of surviving than with no backup.

I disagree with Derek's statement that it would be possible to generate up to a FF2 impact on the long cowstail if it failed. If the long cowstail was attached to the bolt and the caver was the length of the cowstail above the bolt it would be possible to create a FF2 impact. However the long cowstail is connected to the loop in the rope which is probably going to be at least 10 feet long even for two tightly placed rebelay. My long cowstail is 2 feet long. Even in the worst situation, I can't see where I would even drop as many as 6 feet onto my long cowstail. Assuming that this extreme 6 foot drop occurred onto a total of 12 feet of rope including the long cowstail and the rope this would only be a FF0.5 even in this extreme example of only ten feet of rope between rebelays. Most rebelays have much more rope between them.

Well Stan, after looking at the diagram of step 7 I think I can see why it would be YOUR favorite!

Andy makes an excellent point. Step 7 offers many opportunities for creative rescuer/patient interactions. ACT gives me permission "to push up on the victim's bottom with my hands and knees". Using the term "victim" also implies that as the pick-offer, I am the "victimizer".

But really, if you just moved step #3 "I remove my upper ascender from the rope, since I no longer need it." until after the descender was tested, I think it would satisfy everyone's concerns.

My long cowstail is my link to my upper ascender. Leaving my upper ascender on rope wouldn't provide any form of backup since I'm using my long cowstail to counterbalance the patient. I've also found that when practicing pickoffs, the more stuff that is hanging on rope, the more likely it is to get tangled, twisted resulting in unwanted friction when counterbalancing and at worst resulting in both the victim and victimizer stuck on rope. To be honest, doing an unconscious patient, single rope pick-off even when I'm rested and hanging on a rope in a warm, dry cave is quite challenging. If I were tired and in a wet, cold cave with even perhaps a rope in water, I would have to seriously think about whether I would even attempt to do so. An extremely competent and experienced Swiss friend of mine died trying to do an unconscious patient, single rope pick-off in a cold, alpine cave in a waterfall. In retrospect, I wish that only one person had died, but understand and respect my friend's choice. Anyway, I guess my point is that from my perspective, niceties such as multiple ascenders on rope get tossed out when trying to do something as extreme as an unconscious patient, single rope pick-off.

Derek, be advised that the only thing more non-advisable than debating Stan is the sacrilege of questioning The Book. ACT will not tolerate dissent.

Both you and Derek will probably spend eternity in ACT hell for your acts of sacrilige. This will involve mopping up nasty leads for eternity on one of my cartography projects. Thus speaketh the Stan, head of the Church of ACT.

[Extremeophile]

I would also recommend if you are going to use an ascender, which I don't recommend, place it on the upper rope where you are less likely to create a serious FF. placing the ascender just below the anchor as Derek does creates more of an opportunity for shockloading the ascender. With very little rope between the anchor and the ascender that possibility exists.

Since I'm generally hanging from my short cowstail clipped to the anchor, the slack in my long cowstail attached to an ascender on the down rope is the difference in length of the two cowstails plus the length of the knot. This is generally only about a foot. Keeping the ascender on the up rope is more likely to result in unintentionally weighting the long cowstail when unclipping the short cowstail.

I disagree with Derek's statement that it would be possible to generate up to a FF2 impact on the long cowstail if it failed. If the long cowstail was attached to the bolt and the caver was the length of the cowstail above the bolt it would be possible to create a FF2 impact. However the long cowstail is connected to the loop in the rope which is probably going to be at least 10 feet long even for two tightly placed rebelay. My long cowstail is 2 feet long. Even in the worst situation, I can't see where I would even drop as many as 6 feet onto my long cowstail. Assuming that this extreme 6 foot drop occurred onto a total of 12 feet of rope including the long cowstail and the rope this would only be a FF0.5 even in this extreme example of only ten feet of rope between rebelays. Most rebelays have much more rope between them.

It's a good point that the up rope will absorb some of the impact of a fall. I was calculating FF with the assumption that the up rope is static, i.e. a 4 foot fall might be possible onto a 2 foot cowstail, but this of course ignores the real-world shock absorption of the up rope, harness, knot tightening, body compression, etc.

Derek, be advised that the only thing more non-advisable than debating Stan is the sacrilege of questioning The Book. ACT will not tolerate dissent.

I'll consult The Book to see what the one true rebelay crossing technique is. I may have to do some resto as a penance.