Rappel Backup Friction Knot

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. 

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: 

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

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.

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? 

FrankPS wrote:

Why do you alternate between knots? 

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? 

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.

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.

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

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

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.

Dylan B. wrote:  But I’m having trouble really seeing the advantage of switching over.  

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

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. 

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?

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.

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

curt86iroc wrote:

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

Righto! I always check the length to make sure it can't get sucked up.

Ryan Swanson wrote:

You'd still have your rappel device hooked up, so that's not the issue.  The issue is getting the knot to slide while fully weighted.  Not impossible, but it sucks.

there are some devices that you should generally use a back up above, not below:

I like to sit on my hands for a few minutes before I rap so that it feels like a fireman's belay.

30cm 5mm cord tied as autoblock, on a locker at the belay loop(rappel is extended w girth hitched 30cm runner)