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spikeddem
Oct 13, 2007, 1:08 AM
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So today I was practicing rappelling and I found that my back-up knot kept jamming.
I tried both a prusik and a kleimheist hoping that one would work better.
Perhaps I went around too many times on the kleimheist, I don't know. The prusik worked better, but I found that when I got towards the bottom, I let go of the knot to stop since I was on the ground, and when it got loaded I couldn't push down on it to come down further.
Am I just supposed to be more controlled about loading it or what? By the way, I was using prusik cord.
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rockguide
Oct 13, 2007, 1:50 AM
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spikeddem wrote: So today I was practicing rappelling and I found that my back-up knot kept jamming. I tried both a prusik and a kleimheist hoping that one would work better. Perhaps I went around too many times on the kleimheist, I don't know. The prusik worked better, but I found that when I got towards the bottom, I let go of the knot to stop since I was on the ground, and when it got loaded I couldn't push down on it to come down further. Am I just supposed to be more controlled about loading it or what? By the way, I was using prusik cord.
First question - was the back up knot above or below the device?
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spikeddem
Oct 13, 2007, 2:49 AM
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http://www.muirvalley.com/pdf/CleaningBook_v1.pdf
I followed that to a T. Except when I was setting it up this afternoon, I went with the prusik above the ATC.
While I was searching on rock climbing for an answer to my question, I found that it seems that the above/below thing is kind of debated. I probably should have gone below, eh?
That's what it says in "The Climbing Handbook" by Steve Long, and that's also what the tutorial I am looking at (above) says.
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wiki
Oct 13, 2007, 2:58 AM
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A prussic won't unlock if it has weight on it - they aren't supposed to.
To unlock it, get your weight off the prussic (doing a one-armed pull up whilst taking in through your belay device is the simplest way), flick the loop on the prussic with your thumb and pull the prussic down the rope. If you are a light-weight like me, you may get away with just flicking the loop with your weight still on the prussic (unlikely). This works for both the classic prussic and the klemheist.
Alternatively, if you put your prussic below your belay device, it will unlock very easily.
Sounds like you need to find yourself an instructor. Kudos on practicing rappelling but books are for reference not for learning from.
Good luck! 
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jakedatc
Oct 13, 2007, 3:03 AM
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do a search for Autoblock goes below the device and works really well.
-Locker to your brake side leg loop, clip cord loop to that
-wrap cord down the rope 3-ish(test what works for your weight/cord size etc on the ground) times, clip loop back into locker. lock shut.
**Test before undoing your anchor.
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rockguide
Oct 13, 2007, 3:53 AM
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spikeddem wrote: http://www.muirvalley.com/pdf/CleaningBook_v1.pdf I followed that to a T. Except when I was setting it up this afternoon, I went with the prusik above the ATC. While I was searching on rock climbing for an answer to my question, I found that it seems that the above/below thing is kind of debated. I probably should have gone below, eh? That's what it says in "The Climbing Handbook" by Steve Long, and that's also what the tutorial I am looking at (above) says.
Yup ... you should have gone below, especially if you attached the prussik to your legloop.
A beginner learning from a book (no matter how well w written) without the advice of an experienced climber or instructor is sketchy enough - If that beginner starts improvising on a whim ... not good.
(This post was edited by rockguide on Oct 13, 2007, 3:56 AM)
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spikeddem
Oct 13, 2007, 5:16 AM
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Thanks for the suggested readings everyone.
Just so you guys know, I was practicing indoor with an auto-belay back-up.
I'm not so foolish as to try this stuff without an experienced climber :p (Unless I have an auto-belay back up, like I did).
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skiclimb
Oct 13, 2007, 6:41 AM
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prusiks take some playing around with to get right. different diameter and weave cords create more or less friction. skill and technique play a part also..
just keep working with it till you find stuff that works well for you.
these are some of the most useful knots there are and will save your arse if needed. Get familiar with em
you should find the kleimheist more useful in time.. tends to be easier to unlock..usually can be done under load.
(This post was edited by skiclimb on Oct 13, 2007, 6:44 AM)
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rockguide
Oct 13, 2007, 12:21 PM
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spikeddem wrote: Thanks for the suggested readings everyone. Just so you guys know, I was practicing indoor with an auto-belay back-up. I'm not so foolish as to try this stuff without an experienced climber :p (Unless I have an auto-belay back up, like I did).
Cool
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microbarn
Oct 13, 2007, 1:06 PM
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wiki wrote: A prussic won't unlock if it has weight on it - they aren't supposed to. To unlock it, get your weight off the prussic (doing a one-armed pull up whilst taking in through your belay device is the simplest way), flick the loop on the prussic with your thumb and pull the prussic down the rope. If you are a light-weight like me, you may get away with just flicking the loop with your weight still on the prussic (unlikely). This works for both the classic prussic and the klemheist. Alternatively, if you put your prussic below your belay device, it will unlock very easily. Sounds like you need to find yourself an instructor. Kudos on practicing rappelling but books are for reference not for learning from. Good luck!
One hand pull ups on a small diameter rope are not easy. An easier and more reliable way to get your weight off the prussic is to stand on the rope.
Pull up the loose rope that is below your feet. Hold the loose end of the rope with the weighted rope. Stand in the loop that is formed. This gets your weight off the prussic, and it also acts as your brake hand below your ATC while you release the prussic. After you release the prussic, move your brake hand back below the ATCv Drop the free end of the rope. Rap as normal.
(This post was edited by microbarn on Oct 13, 2007, 1:07 PM)
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microbarn
Oct 13, 2007, 1:08 PM
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I forgot to mention that I still think the backup is better below the device.
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rudolphluciani
Oct 13, 2007, 7:03 PM
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microbarn wrote: wiki wrote: A prussic won't unlock if it has weight on it - they aren't supposed to. To unlock it, get your weight off the prussic (doing a one-armed pull up whilst taking in through your belay device is the simplest way), flick the loop on the prussic with your thumb and pull the prussic down the rope. If you are a light-weight like me, you may get away with just flicking the loop with your weight still on the prussic (unlikely). This works for both the classic prussic and the klemheist. Alternatively, if you put your prussic below your belay device, it will unlock very easily. Sounds like you need to find yourself an instructor. Kudos on practicing rappelling but books are for reference not for learning from. Good luck! One hand pull ups on a small diameter rope are not easy. An easier and more reliable way to get your weight off the prussic is to stand on the rope. [image]http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=1495;[/image] Pull up the loose rope that is below your feet. Hold the loose end of the rope with the weighted rope. Stand in the loop that is formed. This gets your weight off the prussic, and it also acts as your brake hand below your ATC while you release the prussic. After you release the prussic, move your brake hand back below the ATCv Drop the free end of the rope. Rap as normal.
Or...you could just put the prussic below the device like you're supposed to
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rgold
Oct 13, 2007, 7:27 PM
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There is a little-appreciated danger associated with the autoblock knot on a leg loop if the rappel device is not extended up from the belay loop.
It is possible, when in a locked postion, that stepping up with or otherwise raising the leg whose loop has the autoblock attached will enable the rappel rope to pull the autoblock into contact with the belay device and release the autoblock.
This possibility may have caused a rappel fatality a year or so ago.
The rappel device should be mounted on a short sling so as to extend the distance between the autoblock knot and the rappel device. This distance may appear to be adequate but may not be if the autoblock leg is raised.
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skiclimb
Oct 13, 2007, 8:21 PM
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i've seen the leg loop idea used once by a buddy and really don't like it...
the brake end of the rope runs a risk of loss of control during transition from unlocked prusik to having conrtrol with your hand.
Suggest becoming more practiced and refined with the kleimheist.. you can make them unlock without a full pullup if done right. You should be able to pull up on the brake end and down on the line above to transfer enough weight to the repel device to loosen the prusik with your non braking hand.
This allows you to keep the brake end of the rope always in tight control. Once proficent you can get loose and going in seconds after a hang.
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jakedatc
Oct 13, 2007, 8:50 PM
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skiclimb wrote: i've seen the leg loop idea used once by a buddy and really don't like it... the brake end of the rope runs a risk of loss of control during transition from unlocked prusik to having conrtrol with your hand. Suggest becoming more practiced and refined with the kleimheist.. you can make them unlock without a full pullup if done right. You should be able to pull up on the brake end and down on the line above to transfer enough weight to the repel device to loosen the prusik with your non braking hand. This allows you to keep the brake end of the rope always in tight control. Once proficent you can get loose and going in seconds after a hang.
Not sure how that is an issue.. i control my Autoblock with my Left hand and control the rope below that with my right hand.. brake hand never leaves the rope.. left hand manages the autoblock and keeps things moving smoothly.
Rich that's good to know.. at least to know that if you're not extended to not lift your leg when you're hanging on the autoblock
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drjghl
Oct 13, 2007, 10:10 PM
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Of all the locking knots out, I think only the Autoblock can be released when under full tension. Ergo, my knot of choice to back up my rappel.
As for setups to back up a rappel, there are lots of configurations that work. But there are two things you should note. Ideally you want your back up knot below your belay device so when it catches, it's not holding your full body weight. And you don't want your knot too close to your belay device for obvious reasons.
And one specific scenario where using a back up knot is very useful is when rappelling off thin ropes. I lead with a 9.5 and trail a 8 mm static line and you can go pretty fast with this setup. The autoblock allows me to rappel with less stress. Not only will it stop you, it will also add friction; kind of acting like your own "fireman's belay".
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rgold
Oct 14, 2007, 4:02 AM
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In reply to: the brake end of the rope runs a risk of loss of control during transition from unlocked prusik to having conrtrol with your hand.
This is not true if you use an autoblock, which can be unlocked with the brake hand in braking position even when the knot is loaded.
In reply to: i control my Autoblock with my Left hand and control the rope below that with my right hand
A number of authorities recommend this method and depict it in diagrams. I think it has the potential to undermine one of the purposes of the back-up, which is to stop you if you let go with your brake hand.
With the left hand on the knot and the right hand braking, the knot won't engage unless you let go with the left hand. If something causes you to release the brake hand, you also have to let go with the other hand to engage the back-up knot. Tests have shown this will not happen unless the rappeller is unconscious. If a rock hits the right shoulder and causes the brake hand to release the rope, there is no way a rappeller will let go with the left hand, and so the back-up will never engage.
It may not be particularly likely that something will happen that keeps the rappeller conscious but forces a release of the brake hand, but why use a method that will probably fail in this case when there is an alternative that won't?
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desertwanderer81
Oct 17, 2007, 7:24 PM
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this is the exact reason why I don't recommend people using prusics who don't know what they're doing.
Anouther method to getting the prusic loose is to wrap the rope around your foot, clamp down with your other foot, and stand up on it just like if you were climbing a rope.
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