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Prussick vs. autoblock
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By Mark Lewis
From Salt Lake City, Utah
May 2, 2013

I wanted to get some people's opinions who have used both a prussik and an autoblock to set a rap backup below their rap device. What was your experience? Was either setup easier to deal with, especially managing the knot while on rappel?

I've used the prussik, but haven't tried the autoblock.


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By Stephen Ackley
From Richmond, Virginia
May 2, 2013

an autoblock will prove to be much faster once you practice with it


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By Jon H
From Boulder
May 2, 2013
At the matching crux

Stephen Ackley wrote:
an autoblock will prove to be much faster once you practice with it


+1

Just keep in mind that a prussic is more "grabby" than an autoblock, so confirm that the autoblock you tie with a given diameter cord will lock up nicely on your rope. As soon as you've confirmed that everything works as its supposed to, then you're in business. Autoblock is way faster to tie and untie - I haven't bothered with a prussic in years.


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By Matt Roberts
From Columbus, OH
May 2, 2013
Hittin' Miguel's with the new Chimps in tow

I've only experimented with a prusik--but I use an autoblock every time. To me, the primary advantage of an autoblock is that it is much quicker & easier to set up. Both seem to work about as well otherwise for a given number of loops.


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By Jake Jones
From Richmond, VA
May 2, 2013
Me and the offspring walking back to the car after a day of cragging.

I use a klemheist which is almost the same as an autoblock, except it goes back through the original bight like a girth hitch with multiple wraps and only one end goes into a biner. Like others have said, I prefer it because it's easy to set up and I always fumble a prussik and have to spend time dressing it, etc. I use three wraps for double ropes, and four or five for single. Works great.


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By RockinOut
From NY, NY
May 2, 2013
Gear

+1 on the Klemheist... Its much faster to set up and remove than the Prusik since you dont really have to dress it like a prusik and when you`re breaking it down just unclip it from the biner and pull the end of it to unwrap.

But dont forget the auto block is multi-directional where the klemheist is uni-directional, which isnt really a problem when rapping since youre only going down.


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By Marty C
May 2, 2013

I prefer the autoblock over the prussic and have used it for years.

I have recently started using a variation of the autoblock, Penberthy friction hitch, which I find even easier to set up and break down than the conventional autoblock (which uses a tied off sling of cordage).

The Penberthy uses a single strand of cord with a figure 8 on both ends.
One has a greater range of adjusting the amount of friction using the hitch (one can add a single additional wrap of cord vs. a tied sling which introduces two wraps every time).


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By CornCob
From Omaha, NE
May 2, 2013

I like using an autoblock because of how fast and easy it is to adjust the wraps. I also like that it can be tied around the rope without having to unclip the sling or cord from your harness/leg loop.


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By Rob Warden, Space Lizard
From Springdale Ut
May 2, 2013
blah

another +1 for the autoblock on the leg loop and an appropriately extended rap device. i have an aramid one form blue water


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By Mark Lewis
From Salt Lake City, Utah
May 2, 2013

Thanks for all the feedback. I'll be playing around with the autoblock this weekend to see how I like it.

What length have you all found best to extend your rap device when using the autoblock on a leg loop? About the same as when using a prussik?

And to clarify, when I refer to autoblock I'm thinking of the setup shown in Freedom of the Hills, where the cord is girth hitched to a leg loop, rapped around the rappel rope and then clipped back to the leg loop with a locker.


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By FrankPS
From Atascadero, CA
May 2, 2013

Mark Lewis wrote:
Thanks for all the feedback. I'll be playing around with the autoblock this weekend to see how I like it. What length have you all found best to extend your rap device when using the autoblock on a leg loop? About the same as when using a prussik? And to clarify, when I refer to autoblock I'm thinking of the setup shown in Freedom of the Hills, where the cord is girth hitched to a leg loop, rapped around the rappel rope and then clipped back to the leg loop with a locker.


You don't have to extend your rappel device to use an autoblock off of your leg loop, just make sure the autoblock can't get sucked in the rappel device because it's too long. A foot or a little less should do the trick.

Actually, if you choose to extend your rappel device with a runner, using the autoblock off of your belay loop works better than off of your leg loop.


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By Stephen Ackley
From Richmond, Virginia
May 2, 2013

Unfortunately this threads gonna devolve into rappel extension bickering.

But, ive got to say, you NEED to extend your belay device whether your autoblock is on your belay loop or your leg loop.

Its not too hard to imagine a rappelling climber becoming unconscious and crumpling and bringing the autoblock and belay device together causing literally a catastrophic failure.

I like basket hitching a double length sling through my tie in and throwing an overhand in it.

There are many ways to extend a device and its ultimately personal preference.

I'd recommend 'self rescue' by David Fasulo if you're interested in these techniques and much more.


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By randy88fj62
May 2, 2013
Thunderbolt Peak in the Palisades

I once asked the local SAR team practicing what they use most and their answer was the prusik because it bites down hard and locks. The way I understood their response was that they want the person to lock hard and immediately if they loose control or let go of the rope.

I personally switch every once in awhile based on what I'm practicing with most. I am back to the autoblock at the moment since it is easy to set up and remove as stated above.

I know I'm going to use the dreaded word but I carry a "PAS" on me when aid and trad climbing as my clip in point to an anchor when rappelling or any other time when not tied directly into the end of the rope.

I extend my rappel device to the first loop on my sterling chain reactor. This allows me to see my device better and leaves room between the rappel device and my back up.

A 60 cm standard length sling, ran through your harness and tied into a figure eight in the middle is a good length for an extension. It gives redundancy and everyone usually has a sling on them to use in this manner.


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By Jason Kim
From San Diego, CA
May 2, 2013
Descending Cox Col (Bear Creek Spire). Photo by Ryan Slaybaugh. <br />

Stephen Ackley wrote:
Unfortunately this threads gonna devolve into rappel extension bickering. But, ive got to say, you NEED to extend your belay device whether your autoblock is on your belay loop or your leg loop. Its not too hard to imagine a rappelling climber becoming unconscious and crumpling and bringing the autoblock and belay device together causing literally a catastrophic failure. I like basket hitching a double length sling through my tie in and throwing an overhand in it. There are many ways to extend a device and its ultimately personal preference. I'd recommend 'self rescue' by David Fasulo if you're interested in these techniques and much more.


+1 on this excellent advice.

If I'm rapping a multi-pitch route with bolted stations, I use this technique, which works really well:

www.mikebromberg.com/many-ways-to-skin-a-cat-rappelling/


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By Will S
From Joshua Tree
May 2, 2013

Another advantage to autoblock or klemheist over a prussik is that they work well with flat materials (i.e. slings/webbing), whereas the prussik does not.

I've used an autoblock with sewn runners plenty of times. These days I keep a small loop of 5mm cord on the harness, but tend to use a prussik above the device (despite the autoblock being faster and easier to dress).


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By Will S
From Joshua Tree
May 2, 2013

Stephen Ackley wrote:
ive got to say, you NEED to extend your belay device whether your autoblock is on your belay loop or your leg loop.


Disagree. Run the fricton knot above the rap device instead of below it, and you don't need to extend the device. Just don't be a dumb ass and have the friction knot so long that it can lock and be out of reach. Also be aware when rapping over roofs, and don't end up with the knot above the lip and your device and body below it.


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By Ryan Williams
Administrator
From London (sort of)
May 2, 2013
El Chorro

I like the auto-block because you can set it up and break it down w/o ever having to remove the cord from the biner. It means you can just leave the cord hanging on the biner on your leg loop when you are pulling the rope between raps, etc. I'm sure you can do similar w/ other friction hitches but I've always thought the a.b. made the most sense.

Like others have said, make sure to practice w/ the exact cord you plan to use, as it doesn't provide as much friction as a prusik and it's not hard to set one up that doesn't work that well.


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By randy88fj62
May 2, 2013
Thunderbolt Peak in the Palisades

Will,
Wouldn't there be more weight on the friction hitch above? Having the friction hitch below means most of the rappeller's weight is on the rappel device which makes it easier to unload the hitch should it be weighted.

I used to use a valdetan prusik (aka French wrap)above my device and switched to one below as my VT prusik would not bite on 8mm static ropes when canyoneering.


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By JeffL
From Salt Lake City
May 2, 2013

As far as extending your rap device and why to do it and why not to do it... What happens if you have to jug up the lines when your device is extended? Seems like it would be way harder


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By Will Gordon
From Boulder, CO
May 2, 2013

JeffL wrote:
As far as extending your rap device and why to do it and why not to do it... What happens if you have to jug up the lines when your device is extended? Seems like it would be way harder


If you are rappelling with an extension and a plaquette style device (ATCG, Reverso, GiGi, etc), you can easily clip it back into your belay loop and use it for ascending, without having to unclip the carabiner used for rappelling. This is, of course, much easier if you can get your weight off the rope.


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By Jared Garfield
May 2, 2013
Romancing the Stone

I use a prussick, it takes me 2 wraps around the rope and maybe 30 seconds to set up, I've used both but I don't really notice a difference. The reason I use a prussick is because my cord is pretty short and I cant get enough wraps for an auto block


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By Jon Nelson
Administrator
May 2, 2013
Me

One advantage from following Will S's advice above (autoblock above rap device) is the following. If you ever need to ascend the rope, you can clip another sling or two as an aider into your autoblock/friction hitch. Step up in the aider, take up slack and lock the rap device, unweigh the aider and slide it up. Repeat.

Also, it is a bit of a hassle to extend the rap device.


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By bearbreeder
May 2, 2013

alpine smart ;)


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By Ray Pinpillage
From West Egg
May 2, 2013
Cleo's Needle

bearbreeder wrote:
alpine smart ;)

Mega-Jul


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By bearbreeder
May 2, 2013

Ray Pinpillage wrote:
Mega-Jul


but but but ... my pristine shiny new yuppie megatron gridlocks will get scratched !!!


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By Zirkel
From Bishop, CA
May 2, 2013
Owens Gorge.  Mt Tom in background.

randy88fj62 wrote:
I extend my rappel device to the first loop on my sterling chain reactor. This allows me to see my device better and leaves room between the rappel device and my back up.

I too do this and really like the setup.

And I started using a Sterling Hollow Block this past year:

www.sterlingrope.com/product/155018/CHB/_/Hollow_Block


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