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Rappel Backup Friction Knot


Original Post
Will Bland · · Halifax, NS · Joined Jun 2017 · Points: 315

What do you guys use? Be EXACT!

Looking to try out some different ones. I currently use 7ml accessory/static line but alternate between prussik and autoblock knots. Also, not sure if the length of my prussik is ideal.

Thanks in advance, I know this is a silly gumby thread. I'd just like to hear from someone who is stoked on their setup. 

Theodore Morrow · · Golden, Co · Joined Aug 2015 · Points: 20

I use a little prussik thing from sterling, I always use a prussik when I backup my raps. It's sewn together and maybe 10 inches diameter? It's a rectangle Kevlar cord, kind of like webbing, grabs onto the rope really nicely.
Edit note: I also, wrap the prussik three times, never more because it get's too tight.

Here's a pic: 

Squeak · · Perth West OZ · Joined Feb 2016 · Points: 21
Theodore Morrow wrote: I use a little prussik thing from sterling, I always use a prussik when I backup my raps. It's sewn together and maybe 10 inches diameter? It's a rectangle Kevlar cord, kind of like webbing, grabs onto the rope really nicely.
Edit note: I also, wrap the prussik three times, never more because it get's too tight.

Here's a pic: 

It's called a Stirling Hollow Block, I also use them, they are great. They come in 2 lengths. bear in mind, that they DO wear out so keep an eye on them

FosterK · · Edmonton, AB · Joined Nov 2012 · Points: 43

1. Short sterling hollow block, tied as an autoblock (90% of the time).
2. Remaining 10% a mix of grigri, 6.5 mm 30 cm prussik as autoblock or prussik.

FrankPS · · Atascadero, CA · Joined Nov 2009 · Points: 275
Will Bland wrote: What do you guys use? Be EXACT!

Looking to try out some different ones. I currently use 7ml accessory/static line but alternate between prussik and autoblock knots. Also, not sure if the length of my prussik is ideal.

Thanks in advance, I know this is a silly gumby thread. I'd just like to hear from someone who is stoked on their setup. 

Why do you alternate between knots? 

I use an autoblock on my leg loop (below the device).

Why are you not sure if the length of your prusik is correct? It should not be so long that when you are slumped over, the autoblock will hit your belay device.
Everett · · Nevada · Joined Jul 2016 · Points: 25
FrankPS wrote:

Why do you alternate between knots? 

(Not OP.)

When I have extra weight to deal with, I'll use the higher friction mode of the ATC -- but reduce the grabbiness of the knot to avoid a strugglerap.
FrankPS · · Atascadero, CA · Joined Nov 2009 · Points: 275
Everett wrote: (Not OP.)

When I have extra weight to deal with, I'll use the higher friction mode of the ATC -- but reduce the grabbiness of the knot to avoid a strugglerap.

What are you doing to reduce the "grabbiness"? Change knots? So you find that the friction knot makes it too difficult to feed/rap, sometimes? 

I have not noticed an autoblock below the device is difficult to operate, with or without a pack. Being below the device, it doesn't take much force to overcome the friction holding me in place.
Ryan Swanson · · Pepedidnothingwrong, freejg · Joined Jan 2018 · Points: 50

My hand

Ted Pinson · · Chicago, IL · Joined Jul 2014 · Points: 195

Yeah, you can just hold it down as you rap and let it go if you need to stop.  I like to use an autoblock with cord...never had any problems with it getting sucked into the device.

Everett · · Nevada · Joined Jul 2016 · Points: 25
FrankPS wrote:

What are you doing to reduce the "grabbiness"? Change knots? So you find that the friction knot makes it too difficult to feed/rap, sometimes? 

I have not noticed an autoblock below the device is difficult to operate, with or without a pack. Being below the device, it doesn't take much force to overcome the friction holding me in place.

It might be my rope + accessory cord autoblock combo, but sometimes I end up frustrated with a knot that keeps cinching down. Changing the autoblock wrap count or fucking with a prussik (which I hate) is how I've fiddled with it. This also happens with an extended rappel versus not extended. I've found the extension (which I prefer) causes more friction due to a tighter angle, so I don't use the exact same friction hitch.

Honestly, this discussion is just making me realize that I should stop doing anything other than Grigri rapping.
Jeremy R · · Unknown Hometown · Joined Apr 2016 · Points: 25

Nothing

Dylan B. · · Unknown Hometown · Joined Mar 2006 · Points: 521

Since I learned to rappel in the late 1980’s, I have been using a traditional prussik knot in 6mm cord, above the rappel device (originally an eight, then a sticht plate, and now a reverso). I know there are some theoretical problems—cinches too tight to undo, may not grab in a real fall—but it’s always been simple and functional for me. If I want to hang on the rope, I can tie a backup knot below the rap device, or just do a leg wrap. Sitting on the prussik has never been a problem.

Nonetheless, I’ve recently tried some alternatives to get with the times. For one, I’ve used an alpine smart for a couple of years, and generally have not bothered to back it up. A handful of garage fall tests seem to indicate it’s gonna lock up and catch if I somehow manage to fall on rappel. Perhaps this faith is misguided and will be the death of me.

I’ve also recently been goofing around with a prussik/kliemheist on the leg loop as a third-hand below the reverso. The problem with this, for me, is now I have to extend the rappel to avoid the knot getting sucked into the reverso. Suddenly, a very simple and intuitive system I have used for decades has become something elaborate with lots of extra parts that I have to stop and ponder at length every time I set it up. (FWIW, I use a Purcell as a tether in addition to the rope, not a PAS).

When I’m on the ledge, tired and hot and hungry, I want to default to simple systems I can set up by muscle memory, rather than more complicated ones that I have to stop and think about. Maybe this is just a problem of an old dog learning new tricks. But I’m having trouble really seeing the advantage of switching over.  

Cole T · · Cincinnati, OH · Joined May 2012 · Points: 386

I often use the Mammut Alpine Smart and don't back it up, if I happen to forget it then and autoblock on my leg loop with my atc

curt86iroc · · Lakewood, CO · Joined Dec 2014 · Points: 53

90% of the time, auto block or klemheist off my leg loop.

Buck Rio · · MN · Joined Jul 2015 · Points: 0

Girth hitched sling to belay loop with overhand knot to determine length and a tuber. French prussic clipped to belay strand locked to leg loop.

mbk · · Unknown Hometown · Joined Jul 2013 · Points: 0
Dylan B. wrote:  But I’m having trouble really seeing the advantage of switching over.  

https://outdoors.stackexchange.com/a/4595

Having trouble finding it right now but I remember reading at least one accident report where exactly this happened, so it is not theoretical.
Andy Eiter · · Madison, WI · Joined Jul 2014 · Points: 25

What are the downsides to a prussik below the belay device attached to the leg loop?

BigFeet · · Texas · Joined May 2014 · Points: 385

I use the Klemheist if a third hand is needed. Most ropes used will work very well with a 6mm cord loop. Once you start getting into the thin ropes you may want to make another wrap, or use thinner cord. You only need a loop long enough to make your connections, and for you to be comfortable. 

It is best if you try out some different methods, but having your third hand below the device is preferred. Make sure you have your method dialed in before launching.

It is also preferable to extend your rappel if connecting to the leg loop. Keep it on the inside where it does not interfere with the adjustment buckle. 

Andy Eiter · · Madison, WI · Joined Jul 2014 · Points: 25
BigFeet wrote: 
It is also preferable to extend your rappel if connecting to the leg loop. Keep it on the inside where it does not interfere with the adjustment buckle. 

Is that only to keep the knot away from the device without putting yourself on a pretty tight leash?

curt86iroc · · Lakewood, CO · Joined Dec 2014 · Points: 53
Andy Eiter wrote: What are the downsides to a prussik below the belay device attached to the leg loop?

The main downside is if your rap device is connected directly into your belay loop (meaning not extended), then it's possible for your back-up to get sucked into your device.  it's hard to actually do this in practice (as your control hand should be between your device and back-up knot), but it's possible. I've only seen this happen a few times in training scenarios.

Ways to avoid this:

1. Extend your rap device
2. Put your back-up above your device
3. check the length of your back-up knot before you take off and shorten if necessary
Brian Malone · · Olney, MD · Joined Jul 2014 · Points: 3,610

I buy 4 feet of 6 mm accessory cord and tie end together with double fisherman's knot.  I use a prusik knot only but autoknot is good too. You may need to extend the rappel divice so it doenst touch the prusik..
https://www.youtube.com/watch?v=0qgygg8pzGI

OR if you are rich, you can blow a bunch on this:
https://www.petzl.com/US/en/Sport/Packs-and-accessories/SHUNT

Guideline #1: Don't be a jerk.

Trad Climbing
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