Self-locking descender for rappelling

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Re: Self-locking descender for rappelling

Postby Scott McCrea » Jul 11, 2008 12:18 pm

Used properly, all of the discussed device are very safe. Proper use is key, though.

To sum up many cavers thoughts on rappel safeties, read Gary Storrick's article.
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Re: Self-locking descender for rappelling

Postby ek » Jul 11, 2008 12:45 pm

Chads93GT wrote:With all this talk about autostops and racks letting you fall out of control if you let go of the rope...........do none of you use a Prusik or autoblock backup when rapelling, no matter what device you use???

A double-stop, which brakes when the handle is either not pressed or pressed too hard, will stop when you let go. If you let go of the handle, it stops, and if you panic and grab it, it stops. These devices are heavier than single-stop devices and tend to have problems with stiff, swollen, muddy rope, and they cost more, but if you're using one of these (and in the double-stop configuration) then I think there would be no sense in also having a friction hitch safety.

In addition, as we have discussed in this thread, a friction hitch safety may also not save you, if it is not set up just right.
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Re: Self-locking descender for rappelling

Postby Chads93GT » Jul 11, 2008 1:02 pm

I read the article and I understand what you mean. However wouldn't a friction back up be better than no back up if you are rapelling with a figure 8, or something else down a hole? I understand you are screwed if it fails, however..........you are REALLY dead if you don't have any backup at all. right?
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Re: Self-locking descender for rappelling

Postby ek » Jul 11, 2008 1:24 pm

Well first of all, I would argue that when using a double-stop device, a friction hitch backup is not better than no backup. The probability that the device will itself fail or come off the rope is exceedingly low (it better be or you have no business using that device). And if it did come off, an autobloc/French prusik would not be guaranteed to hold you to the rope. If you use a Prusik as your backup, it would hold you to the rope, but it might not be releasable if it were accidentally weighted while rappelling, so you could get stuck on the rope. Harness hang syndrome is not a real issue with a Stop descender[*] unless you are rappelling with a huge weight hanging off you--for single person use, it is easy to make it go again at will if your are conscious. If you're rappelling with a friction hitch that might not be releasable, harness hang syndrome is a problem, getting stuck in a waterfall is a problem, having to change over (which, in trying conditions, may be very difficult even for the very experienced) is a problem. The friction hitch only makes rappelling with a double-stop descender more dangerous--every time.

Looking now at cases where you use a non-optimal configuration for your friction hitch, putting it somewhere or holding it in some way such that you could grab it in panic and make it slide, or where it can slide into and jam in or be minded by the descender, these all make rappelling more dangerous as well. There is precious little evidence that anybody has ever been saved by a friction hitch that they had to willfully release. There have been studies where people have been blindfolded and sent off the end of ropes. Then they took off the blindfolds and people still rappelled off the end of ropes, minding their friction hitches all the way. I say using a friction hitch in this kind of setup makes things more dangerous because (1) you have a false sense of security when doing so, and (2) additional complexity is added to your system, which makes it more dangerous.

Addressing (1), I would argue that absolutely everybody who uses a friction hitch while rappelling in a non-optimal configuration is deluding themselves and has a false sense of security. If you have a piece of cord and a way to tie it so that it will stop you from falling, then you have to be irrational to tie it in a way that probably won't. Either you believe that it won't, or you cling to your technique because it makes you feel safer. In each case, you feel that what you are doing is safer than it really is. And that's dangerous.

Addressing (2), to change over you have to take off or put on your friction hitch, to pass rebelays...well, I won't even go there, to pass a knot you have to take it off and put it on, to switch ropes you have to take it off and put it on, it takes longer to get on or off rappel....all these things increase the complexity and time of maneuvers and make it more likely something will go wrong.

So I have thus far argued (as many have, as Storrick has but he more dogmatically) that a friction hitch rappel backup makes rappelling more dangerous if it is used with a double-stop device (which is already way safer than a friction hitch), or when used in a non-optimal way. Now suppose it is used in an optimal way. Here we have the advantage that it makes every rappel device about as safe as a double-stop descender (let go to stop, or grab hard to stop). This is very compelling. But still, issue (2) pertains, even in the case where everything is set up correctly and the hitch is guaranteed to save you if you are injured or panic.

So you have to weigh the benefit of the "double-stop" function of the hitch against the complexity it produces. There is no general agreement regarding which is safer. I suspect that for less technical rappels of greater length (or where loose rock at the pitch head or elsewhere, or pitch geometry, prevents an effective bottom belay of the less experienced members of the group), the autobloc/French prusik tied correctly below the descender and operated by being clutched by the brake hand provides significant safety benefit, and that in any other situation the benefit is minimal or even negative.

*Well actually, in a case where you are bottom belayed and the drop is really short enough that the bottom belay will be effective, even the autostop feature probably makes things more dangerous for you, because if you were to be knocked unconscious while rappelling with a normal device, the bottom belayer could easily and in a controlled manner lower you to the ground by letting up carefully in their tug on the rope. But usually, a bottom belay is not guaranteed to be effective, so in cases where there is the potential for rockfall--which often makes safe bottom belays impractical anyway--autostop function probably does make you safer.
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Re: Self-locking descender for rappelling

Postby Tim White » Jul 11, 2008 1:39 pm

:thanks: WOW! Well said and well presented ek! :yeah that: :bow:
Be safe,
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Re: Self-locking descender for rappelling

Postby Scott McCrea » Jul 11, 2008 2:47 pm

Tim White wrote::thanks: WOW! Well said and well presented ek! :yeah that: :bow:

x2

Complexity decreases safety. :kewl:
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Re: Self-locking descender for rappelling

Postby shibumi » Jul 11, 2008 4:18 pm

There is no substitute for proper training and practice.

And there's no excuse for sloppy training.

Considering the number of complete incompetents I've seen in vertical caving, and
the number of scared witless newbies being talked down a multi-hundreds of feet
pit on ther first ever rappel, I've always marveled that we don't have more people
cratering.

Good post EK.
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Re: Self-locking descender for rappelling

Postby NZcaver » Jul 12, 2008 1:13 am

:agree: Kudos to you, Eliah... but don't let this go straight to your head. :wink:
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Re: Self-locking descender for rappelling

Postby Therrin » Jun 30, 2012 6:48 am

Howdy,

Ken here, an associate member of the UndergroundExplorers.

Just came across this post. Knew it had to be several years old upon reading it even before seeing the date.

Thought I'd throw in mention of my current setup here. After upgrading from an ATC, I used a BMS 6-bar rack for long descents (200 to 300ft) while doing mineshaft exploration, as well as in work with trees. I like it, but it's heavy and bulky. The bulk doesn't matter so much in all the verticals I've been down with it, but the two combined lends it to being something you don't really want to lug around with you all day.

Having seen some of the "creep" issues with the stop, and the difficulty some of the crew guys had in getting it to feed smoothly; I never ended up picking one up. While at a wind turbine technician trade show I stopped by Petzl's booth and saw their new RIG descender. I'd been looking at the I'D for a while, but due to the price I never picked one up either. The RIG I was pretty instantly impressed with. Relatively light, included features I was wanted, not amazingly affordable, but getting to actually see/feel/test one made me want to try it out. So I bought one on sale for $120 USD.

The RIG weighs 380g (0.83lb) vs. the Stop at 326g (0.72lb), the I'D at 530g (1.17lb), the BMS 6bar Rack at 886g (2lbs), or an ATC at ~20g (0.04lb)
Not even gonna mention my collection of Figure 8's, cuz twisted rope just sucks.

The pictured device is the RIG, not to be confused with the I'D which looks similar.
Image
http://www.petzl.com/us/pro/self-brakin ... ders-0/rig

I *really* like it. I've used it on about a dozen 150 to 200ft descents, a 300ft descent, and dozens of shorter ones.
It is marketed as a device "for expert users only", being as how it doesn't have all the overbuilt safety features of the I'D. As with anything else, you have to learn to use it THE RIGHT WAY, or you can risk serious injury or death; pretty much like everything else in high-angle hobbies.
So far I've used it on ropes from 3/8" to my KM-III 7/16". It feeds nice and smooth, the handle is larger than on the Stop or Grigri, and is easy to feel fine manipulation of even with gloves on. When in soft-lock (not pulling on the lever) I've never had it creep on me, even on the 3/8" line (a tad smaller than what it's actually rated for), and I weigh right around 220lbs with full gear on. In the hard-lock position (handle flipped around and locked facing down) not only can nothing hit it and unlock it due to the position, but I've found that I fully trust it not to budge at all on the line.

This came in handy during the 300ft rappel down a vertical mine shaft one night. On the way between the surface and the first drift level at 295ft down, I had to stop about 10 times to clear beams and debris from the vertical haulage-way I was descending down. When approaching a plugged/blocked section, I simply flipped the handle over into the hard-lock position and then could easily work with both hands to free timbers and move them over into the (totally unusable and deteriorated) manway side of the shaft. While moving a beam weighing maybe 60lbs I was keeping a close eye on the device (and with rope still held in my brake hand just-in-case) and it stayed locked down hard; with almost 300lbs on it.
It allowed fast and simple switching back and forth to switch between rappel and lock-off for debris removal.
Couldn't have been happier with it that night. The range of descent speed is widely variable.

In the instance of being struck by debris from above, upon releasing the handle the device will soft-lock and STOP you in place. There is a bit of learning that goes along with using it, if you let up too fast while rappelling at a normal speed its return spring will stop you fast enough to bounce a little on the line, and I try to avoid that by being light-handed on it.

Not really sure how much you cavers would like it, or if it would fit with your needs. I love it though, a big two thumbs up to Petzl for this product. :clap:

Haven't got the other guys on the crew to get any yet, but spending $120 to $150 on another descender when you've already got a Stop or a Grigri isn't everyone's idea of fun I suppose :tonguecheek:


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Re: Self-locking descender for rappelling

Postby driggs » Jul 2, 2012 10:54 pm

Therrin wrote:While at a wind turbine technician trade show I stopped by Petzl's booth and saw their new RIG descender. I'd been looking at the I'D for a while, but due to the price I never picked one up either. The RIG I was pretty instantly impressed with. Relatively light, included features I was wanted, not amazingly affordable, but getting to actually see/feel/test one made me want to try it out. So I bought one on sale for $120 USD.
...
I *really* like it. I've used it on about a dozen 150 to 200ft descents, a 300ft descent, and dozens of shorter ones.
...
Not really sure how much you cavers would like it, or if it would fit with your needs.


The Petzl RIG was briefly discussed on CaveChat before, and vertical guru Tim White said (emphasis mine):


Tim White wrote:The Rig is NOT designed to replace the STOP for cavers, but for “difficult-access professions” i.e. industrial rope access technicians.

The big difference between the Rig and the I’d is that Petzl has removed what they refer to as the “anti- error catch”. This catch along with the anti-error design of the cam on the I’d is an idiot-proof design. If you rig the I’d backwards the anti- error catch lock into the rope and keeps you from falling.

Problem with this catch/cam combo is it is difficult to take up slack when doing a changeover and difficult to use the I’d in the ascending mode (R.A.D.) Petzl listened to rope access professional and produced a device in the Rig that meets their needs.

Neither the I’d nor the Rig are good in a cave environment! I suspect that exposure to dirt, dust, etc. might not allow the eternal workings of these devices to work as designed. For an example...at the 2009 International Technical Rescue Symposium (ITRS) we were shown an I’d that had failed due to a very small of paint that got between the cam that housing.

I would caution anyone using these two devices in a cave setting. Although the I’d has gone through the strenuous testing to be NFPA and CE EN certified, IMHO it is not cave proof. Unlike most cavers, the users of the Rig and I’d are required to have an equipment inspection and replace plan.

My suggestion, as a caver, stick with the devices that were designed by cavers for cavers.

FYI I have a Rig that I use for rope access and have used the I’d a lot in rope access and technical rescue settings (BUT not in a cave!)


It does look like a nice device for single-rope rappel aboveground, though the manual specifies 10.5 - 11.5mm rope only.
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Re: Self-locking descender for rappelling

Postby Therrin » Jul 3, 2012 4:41 pm

An interesting read. Thanks for sharing the info.

Some things came to mind while reading it.

Unlike most cavers, the users of the Rig and I’d are required to have an equipment inspection and replace plan.


Having come into mineshaft exploring through running my own tree service business for several years and learning how "the ropes" are different, and how they are the same; (in my mind at least, and others) ALL equipment you use should have an inspection and replace plan. Camming devices wear out over time, no matter who makes them. Petzl and other companies sell replacement parts for their camming devices, and have guidelines on when they should be replaced. Petzl even has a computer program for logging all of your gear data, and for logging inspection records so you know when items should be replaced.
What I'm getting at, I suppose I don't see why something would be suggested as unsafe if it's routine inspection and maintenance is being ignored in the first place. Is he saying that cavers just aren't required to inspect and replace their gear? Or that most of them don't inspect it very often?


Neither the I’d nor the Rig are good in a cave environment! I suspect that exposure to dirt, dust, etc. might not allow the eternal workings of these devices to work as designed.


Anything with a mechanical camming action in it can become jammed up, but what I find interesting about the quoted statement is that it is not being suggested for use underground, yet does not appear to have been tested by any of the underground crowd; instead, 2 similar but very different devices (the RIG and the I'D) are being thrown out as though they are the same device, for a malfunction in one of the devices due not to dirt or dust (or tree sap!) but to a piece of "paint". Nor does it specify if the RIG would have similarly failed, just that the I'D failed.

The argument about threading it the wrong way is (not be be rude) sort of irrelevant. It's like suggesting against using something because if you don't use it properly it doesn't work right, instead of saying that the hobby itself is dangerous and you learn to do something the RIGHT way, you don't rely on "idiot proof" devices to keep you safe.
For example: Years ago when I was applying for the insurance for my tree business I was informed that I would have to follow OSHA specs to qualify. Around that time someone in OSHA decided that because a guy fell out of a tree after not screwing down his screw-locking biner, they would mandate that all tree workers must use auto-locking biners and that would just fix the problem.
The problem with that is that some guy who never actually used the devices made the decision. Trees have sap, and sap will jam an auto locking biner so fast that the locking mechanism won't work AT ALL and revert it to a simple non-locking biner. But the decision was made, and that's how it stands; instead of trying to ensure that people pay attention to the equipment they're using, and use it properly (check your biner before use to verify it's screwed shut).


After rereading the article you posted several times over, it seems not so much that the RIG is a poor device, but that there is not sufficient data on its actual use underground for anyone to make a truly informed decision. And not purely to be argumentative because it's the device I use either. It almost seems to have a "it wasn't designed by a caver so it CANT be any good" vibe going on.

I'm not a caver though, and have been using the device regularly underground for some time. I suppose if someone had specific examples of the RIG failing due to specific instances then I would feel differently. But if no one is opposed to it, I will keep you all updated as to how it functions, when it wears out, and if I have any problems with it.
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Re: Self-locking descender for rappelling

Postby Therrin » Jul 3, 2012 4:58 pm

After rereading some of the pages here I thought I might also point out, that you do not rely ONLY on the brake handle on the RIG (or the I'D) for your descent braking. The directions emphasize that you should always use your brake hand as well, just as you would with any other normal descender.

I *always* use my brake hand as I normally would, and my other hand controls the lever. The negative thing that I *can* point out about this is that you don't have a free hand to help you navigate the walls or to assist in balancing, you have to either let go of the handle and use your lever hand, or just use your brake hand with the rope in it while you're descending.

That was a little awkward at first, and took some getting used to.

Just wanted to allay any possible misunderstandings that the lever is the ONLY thing braking you, or thoughts that you aren't still using your brake hand on the rope with the RIG device. :grin:
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Re: Self-locking descender for rappelling

Postby gdstorrick » Jul 4, 2012 6:23 pm

Post deleted.
Last edited by gdstorrick on Jul 7, 2012 8:26 pm, edited 2 times in total.
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Re: Self-locking descender for rappelling

Postby NZcaver » Jul 5, 2012 4:29 am

Hi Ken. Welcome to the forum. :waving:

You bring up some interesting points and counter-points. I have an I'D (never used underground) but not a Rig. I too have been told by several experienced caver sources that it would be foolish to use these sealed-clutch type descent devices in the underground environment for fear of the mechanism failing due to saturation by mud or grit etc. This is well-intended advice which as far as I know seems to be based more on conventional wisdom and anticipated performance rather than real-world experience and failures. Personally I'd like to know if anybody can provide evidence to the contrary, or tell us more about the "chip of paint" failure. The Petzl guide for the Rig and I'D do not appear to warn specifically against use in adverse dirty environments.

Carry on.
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Re: Self-locking descender for rappelling

Postby Therrin » Jul 7, 2012 6:40 am

gdstorrick wrote:
Therrin wrote:Petzl even has a computer program for logging all of your gear data, and for logging inspection records so you know when items should be replaced.


:rofl:

Great idea for the corporate world and its lawyers. I prefer to look at my gear myself.


It's possible you misunderstood, but you're SUPPOSED to look at your gear yourself. Then you log the results on the program. Though some people are still archaically connected to things like, using paper. :big grin:
I suppose if you only have a small bit of personal gear, then tracking the dates when things should be retired or replaced, or assessing wear, or maintenance needs is fairly simple.

Some of us have a LOT of gear, used both in our personal professional lives, in rock climbing activities, and in the underground world. I couldn't tell you off the top of my head the stats on most of my gear, but having it logged by purchase date, any dynamic loading sustained, end-of-life and replacement dates seems JUST A DARN GOOD IDEA to me. I tend to think that most people who operate in a professional manner (whether underground or above it) are interested in these kinds of things. It's possible that many people just don't give a damn though.
Or were you suggesting that negligence with your life-supporting gear is fine as long as there's no lawyers looking over your shoulder? :rofl:

Wait... Storrick... I've seen you on other forums. You really get around don't you? I've heard good things about you. Nice to see you here.

@NZCaver, Thanks for the reply. And yes, I tend to see a lot of warnings against devices for certain reasons which sound like they'd be great reasons not to use most other devices. Sometimes I wonder if there is a little bit of gear-favoritism at play. :shrug: But there still seems to be a lack of hard data to back up a lot of it.
I can't say I've encountered many paint cans laying around in mines, or paint chips, or anything else that would get paint in my gear. It also makes me wonder what other devices we could get to fail with carefully applied chips/pieces of paint. Interesting idea.
I would imagine even if I purchased a brand new device, dunked it in water and ran it through silty dirt and glommed it with mud, then tested it in a controlled manner without a life hanging on it, and it DIDNT fail, someone would still point out that it COULD still fail, at anytime, and without notice!

There's just got to be better data available, or testable, than tossing out "untested" devices as a whole because they weren't designed by a caver.
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