Prussick vs. autoblock
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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? |
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an autoblock will prove to be much faster once you practice with it |
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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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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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+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. |
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I prefer the autoblock over the prussic and have used it for years. |
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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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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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Thanks for all the feedback. I'll be playing around with the autoblock this weekend to see how I like it. |
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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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Unfortunately this threads gonna devolve into rappel extension bickering. |
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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. |
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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: mikebromberg.com/many-ways-… |
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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. |
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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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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. |
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Will, |
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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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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 harderIf 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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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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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. |