petzl rack on a loaded rope

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petzl rack on a loaded rope

Postby brrrdog » Apr 9, 2007 4:42 pm

I just got a petzl rack. As far as I'm concerned it's a perfect rack for a beginner like me. The 1st and 3rd bar are permanently installed and the second is the non-locking type that keeps you from putting it on in "suicide" mode. However it's occurred to me that because the rope has to be pulled thru the 1st and 3rd to allow enough room to swing in the 2nd bar, that it could not be installed on a loaded rope. Is this correct?

I'm way off from doing deep pits with a lot of rope weight and even farther off from some mid rope rescue ;), so this is mostly for my own info for now. However is there some other situation that this might be a concern? Any tricks to get around it? I thought about maybe using a carabiner or a piece of webbing as a pull handle to pull it thru.
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Postby Scott McCrea » Apr 9, 2007 4:59 pm

The first bar never needs to swing open so that's not a big deal. The suicide bar is a good safety feature but a PITA when it's not on rope, IMO, cause it flops around. It would be very difficult to install on a loaded rope. Some improvising, like you suggest, is great. That kind of thinking will take you far underground. Can't say if it would work or not. Give it a try and let us know what happens.
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Postby volica » Apr 9, 2007 5:58 pm

It is sweet rack, I have one, however I prefer bobbin to take underground with me.
To load Petzl's rack or bobbing with heavy rope, use your upper ascender, put in on the rope underneath your waist upside down, so between your ascender and mounting point is slack, and rope weight is on your harness, not in your hand
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Postby ian mckenzie » Apr 9, 2007 6:20 pm

A rope that's too heavy to lift by hand will be undescendable with a rack, no?

To use a bobbin on a loaded rope, e.g. with a disabled caver on rope below you, just hold the bobbin at right angles to your body, open it, put it on the tight rope straight thru the middle, and close it. It looks unlikely, but it works... when you put your weight on it, the end of the bobbin tips up and you go nowhere. To proceed, place the palm of your hand on the end of the bobbin and carefully push down. Should only be used with a prussik, shunt or other brake, because if the rope below suddenly becomes unloaded, it's bad news for you. Useful to know in emergency situations.

I wonder if there's a way that a rack can be similarly rigged?
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Postby volica » Apr 9, 2007 6:26 pm

Hmm. Interesting way of use bobin. gotta give it a try, when I will be older.
A rope that's too heavy to lift by hand will be undescendable with a rack, no?

I weight about 170 lb, I am not able to lift it with one hand, yet my body weight can make rack to slide down on rope.
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Postby ian mckenzie » Apr 9, 2007 6:33 pm

Yup, agree; I was thinking of a rope weighted by a body, which cannot be lifted by hand by a normal mortal.
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Postby Scott McCrea » Apr 9, 2007 7:13 pm

Rappelling on loaded ropes with racks is done quite a bit. It happens at super long drops like El Cap (2650') and Mt. Thor (3000'+ (?)). They have around 200# or more rope weight. Tandem rappels are done at long drops too. One person gets on rope goes down a few feet, then another gets on above and they ride down together. The upper person usually has a long rack tho.

When I have practiced rappelling down a rope loaded by another caver. I down climbed past the lip, rigged my rack, 3 bars, to the rope before attaching it to my harness so it can be pushed and pulled to get the rope in. Don't try this at home unless you take the necessary safety precautions.
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Postby bperkins » Apr 10, 2007 8:15 am

I would advise against using this on longer drops (600+). I saw somebody have to get picked off the NRG bridge rappell (800+) because he couldn't adjust the spacing between his bars and was going nowhere. He eventually got tired of feeding rope and had to be assisted.
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Postby brrrdog » Apr 10, 2007 9:31 am

rigged my rack, 3 bars, to the rope before attaching it to my harness so it can be pushed and pulled to get the rope in. Don't try this at home unless you take the necessary safety precautions.
.

Yeah that's what I figured for a regular rack - put on an angle to install bar #2, pull back (levering the rack against the rope), and install bar #3. However, that's not possible on a petzl. Bars 1 and 3 don't swing so a bight has to be pulled thru enough to swing in bar 2.

I would advise against using this on longer drops (600+). I saw somebody have to get picked off the NRG bridge rappell (800+) because he couldn't adjust the spacing between his bars and was going nowhere. He eventually got tired of feeding rope and had to be assisted.


I'm a long way off from doing 600+, but I'm curious what you think the issue was here. A petzl is a little shorter than some racks, but I wouldn't think it would be so much that you couldn't space three bars to move on such a drop just as you would any other rack. Maybe my 200 lbs is a better match for the petzl :tonguecheek: Maybe next time we practice I'll put 50 lbs on the end of the rope and see what happens.
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Postby Scott McCrea » Apr 10, 2007 11:22 am

Just as a reminder, no one should ever rappel on a rack with less than 4 bars. Never. If you find that 4 bars is too much friction, that is Karma/Mother Nature/God telling you to go home. Or you need a longer rack, so you can spread those 4 bars more. The only time a rack user can get away with using less than 4 bars is in dire emergencies (someone will die if you don't) or in practice situations where added safety measures are taken.
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Postby NZcaver » Apr 10, 2007 7:18 pm

Scott McCrea wrote:Just as a reminder, no one should ever rappel on a rack with less than 4 bars. Never.

Generally good advice, but never say never (well, almost never). :wink:

I've seen the old first bar/second bar/hyper-bar combo (on a micro-rack) used before, and it was very effective. Of course this was a lightweight guy doing a short sloping drop on thick (11mm) gypsum-encrusted rope, and he's experienced. I wouldn't say this situation was a dire emergency - maybe just another rare exception to the rule?

Anyway, back to this 5-bar Petzl rack. Correct me if I'm wrong here, I haven't used one personally. By having that third bar fixed, Petzl has added a certain degree of idiot-resistance to the rack. Those last 2 swinging bars give you more friction options than a standard U-rack, but the downside with that fixed third bar is this whole "what if I have to use a loaded rope" thing. Right?

Here's a thought - you can get replacement bars for the Petzl. If you don't mind sacrificing the idiot-resisting factor, just swap out that third bar (part number D11300) for a swinging one that latches (D11250). In fact, if you don't like that second bar (D11200) not latching, you can swap that for a latching one too. Problem solved? :cool:

I hope Hank doesn't shoot me for suggesting this... :devil:
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Postby brrrdog » Apr 10, 2007 9:05 pm

Just as a reminder, no one should ever rappel on a rack with less than 4 bars.


Thanks for mentioning that Scott. I knew I heard that somewhere before so I went and looked it up.

On rope says:
"There should never be fewer than four bars engaged on a rack. If using a rack with three bars and the angle of the rope below the rack changes only slightly, the number three bar loses contact with the rope and can fall to the lock nut. If it becomes unclipped, the rappeller is on a two bar rack that rotates out of contact with the rope and the result is an unstoppable fall to the bottom."

Unfortunately, all you're going to get out of all this is another question from me :doh:. Because the third bar is permanently installed and cannot come unclipped on a petzl, does that mean that this rule does not apply to it? Sorry man, I had to ask (plus it's in the spirit of NZ's "never say never" argument).
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Postby brrrdog » Apr 10, 2007 9:47 pm

Here's a thought - you can get replacement bars for the Petzl. If you don't mind sacrificing the idiot-resisting factor, just swap out that third bar (part number D11300) for a swinging one that latches (D11250). In fact, if you don't like that second bar (D11200) not latching, you can swap that for a latching one too. Problem solved?


Worth considering for somebody with more experience, but I should probably keep "idiot-resisting" factor for now as "new guy" might as well equal "idiot". My overactive brain is just making sure it understands my equipment - and thanks to Scott I'll never forget the "4" rule again. I suppose if this was really an issue for the situations mentioned I'd go out and and get a full size rack ;).
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Postby Scott McCrea » Apr 10, 2007 9:52 pm

brrrdog wrote:On rope says:
"There should never be fewer than four bars engaged on a rack. If using a rack with three bars and the angle of the rope below the rack changes only slightly, the number three bar loses contact with the rope and can fall to the lock nut. If it becomes unclipped, the rappeller is on a two bar rack that rotates out of contact with the rope and the result is an unstoppable fall to the bottom."

Unfortunately, all you're going to get out of all this is another question from me :doh:. Because the third bar is permanently installed and cannot come unclipped on a petzl, does that mean that this rule does not apply to it?

I would say the rule still applies. An accidentally unclipped bar or not, 3 bars makes the margin for error extremely small. If you truly anticipate the need to rappel on 3 bars, you should get a longer rack. 3 bars is just too risky.

BTW, hyperbars may allow one to cheat the rules a bit, but the same risks still apply. It's probably easier to accidentally flip the rope off the hyperbar than it is to accidentally unclip a bar.
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Postby hank moon » Apr 10, 2007 11:41 pm

NZcaver wrote:I hope Hank doesn't shoot me for suggesting this... :devil:


Blam! Seriously, I don't know if a latch bar would work there w/o modification or a bit of hassle. Not much room for the frame to flex due to the fixed bars above and below.

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