Autoblock or Prusik

As I get more into climbing, I find myself rappelling quite a bit, and not having my rap backed up scares the crap out of me. I just bought some accessory cord to use as a back up. Which method is best for backing up two rope rappels autoblocks or prusiks?

Thanks
Justin

Autoblock. Just wrap it around 3 times and clip to your belay loop. Also, I recommend extending the ATC away from you.

Check this out from the School of Rock section here on MP. I use 7mm cord instead of a sling and tie and overhand on a bight to create a loop for the ATC and locking carabiner to clip into instead.

mountainproject.com/v/a-saf…

I like the klemheist

It's super quick to tie, and I feel it's easier to keep it dressed nicely than any of the other friction hitches.

I agree with the autoblock using 6mm cord (typically 3mm smaller than the rope you are wrapping around.) I don't extend my ATC (I use an 8), I think it is too time consuming and clutter-y. I just attach my autoblock to my leg loop. It is a brake so it doesn't hold your entire weight, only a small fraction of it.

I can post photos if you want.

Joshua

+1 for the autoblock. Even easier to "tie" than the klemheist. Also, the klemheist tends to give a little too much friction for a rap backup, especially on double lines.

+1 for extending rappels as well. The extended rappel allows the rope to be in a position more conducive to a controlled rappel and allows the backup to be on a structural peice of your harness, namely the belay loop. If you are on a multi, then it also sets you up with a tie-in for each station. Obviously it's not something you have to do all the time, but it is certainly handy for most situations.

Here is an extended rappel using a Klemheist as a third hand backup. I set it up this way so I could go hands free due to the issue you can see in the picture of getting a rope unstuck. I don't always use one, but I find it advantageous in certain situations. The PAS (oh dear) is girth hitched through the tie in points and the 6mm acc. cord is attached to the belay loop by a carabiner and wrapped around both strands.

You will notice that by having the belay extended there is no interference of the third hand with the belay device, and ample room for me to have both hands below the belay device for rappeling. I also like an extended rappel if I'm slinging a pack under me from my belay loop.

If not extending the rappel I would advise attaching your third hand to the inside part of your leg loop to where it does not contact your adjustment buckle. I believe bearbreeder has a good illustration of this, as well as, a good heated discussion on some of this topic... mountainproject.com/v/placi…

Also, notice that I've oriented the belay carabiner gate to face away from the system so that I have less of a chance to contact and open the gate by accident.

The type of friction knot, diameter of the cord vs. rope, and the amount of twists around the rope by the cord will affect the friction generated. You may need to play around with a matchup to find what you like.

Think of the gear you are using as a complete system that will need to be checked before "jumping off". Rappelling seems to be the most likely time you will encounter accidents, injuries, and even death. This is due to rappelling usually happening at the end of a climb/day where you are tired, hungry, and ready to get back to camp for that beer. Your concentration is needed here and sometimes your thoughts can wander... be vigilant of what is going on.

I learned this from someone who knew what they where doing and I went home and practiced it. I practiced it some more with different setups until I found my preference. I prefer the Klemheist myself, but I also know how to use more than just one method to achieve the desired effect.

Never used one.

Keep it simple, and fast.

Are you going to be messing around with your auto-deal when we are racing a big T-storm that is quickly approaching?????

I also use a Klemheist. It's faster and easier to tie than a Prusik.

I don't like the Autoblock...it can become loose (and therefore ineffective) too easily.

Also, a Klemheist will work with webbing, where a Prusik will not.

I don't like extending my belay device and don't understand the advantage. If anything, I see a disadvantage in that there are more things to check and possibly go wrong.

I clip my belay device to my belay loop and use a short loop of cord to attach a Klemheist, below my device, to my leg loop (which is more than strong enough for this purpose) with a small locker. The short Klemheist prevents it from getting sucked into the belay device, and I've never had any issues with clothing, etc getting stuck in the device either. No problems going hands free with this setup.

Guy Keesee wrote:Never used one. Keep it simple, and fast. Are you going to be messing around with your auto-deal when we are racing a big T-storm that is quickly approaching?????

I like simple and fast. The piece of cord I use for my Klemheist is always on my harness, and probably takes 10 seconds to install. First guy down uses a backup, then firemans the next person.

Racing from a thunderstorm and possibly rapping on wet ropes and wet rock is EXACTLY the time when something can go wrong and you will want that backup.

I'm certainly not trying to talk you into using one, just like I don't try to talk people who don't like helmets into wearing one. Or people who think seatbelts are stupid. To each their own, but it certainly doesn't take much time to tie a potentially life-saving backup knot.

I recently started using two similar or same size carabiners to increase friction as well as an autoblock. Helps on thin ropes.

I use a mammut smart alpine. It autolocks with my body weight and is a great all around device once your used to it. It doesnt completely negate the use of a backup when rapping but i dont feel the need to use anything other than the device since i have never had it slip. Although, that might be due to me being over 200 pounds and the fact i havent used a rope smaller than 9.5 on it.

Safety aside, having a backup is great for when you need to untangle a poorly-throw coil, or try to free a stuck booty piece you run across, or stop mid-rappel and look around for your anchor. You can do the leg wrap instead, but the convenience of a third hand can't be beat. Yeah it takes a little longer, but if you're halfway competent it takes about 10 seconds to tie a prussik which is negligible compared to actually rappelling, pulling ropes, and getting the next one ready.

So, to the OP, Klemheist or autoblock, but not a prussik. Prussiks are a bit too much for the application. The difference between the remaining two is the Klemheist has the lower loop running through the top loop so you only have one loop to clip in to. The autoblock is just a piece of cordage wrapped around the rope with both ends clipped into the carabiner.

animatedknots.com/klemheist/
(Autoblock is in the details of the above link.)

Joshua

For all who don't get extending the rappel device:

As an ultimate failsafe for unconsciousness, if your body goes truly slack on rappel (difficult to simulate, but try it), your legs can tuck up high enough that the third hand (prussik, autobloc or klemheist) runs into the rap device and "self tends", i.e. the rap device continues to push the backup hitch down the rope and it does not stop you. Ultimately you need some distance between the backup hitch and the rap device. This is what the extension accomplishes.

I have tried various iterations with and without extensions. With my harness, my body and an ATC as rap device, even a klemheist tied in really closely to the leg loop (not even using a biner, but the cord tied into the leg loop), can contact the belay device if I completely crumple up. I view this third hand without extension as a backup that is helpful for cleaning pitches on rap, or for letting go if stung by a bee on the brake hand, when I might still have control of my legs, but not as an ultimate failsafe for getting hit on the head and going unconscious.

I could see how other people with different anatomical shape and different harnesses might still be able to use third hand effectively without extension and not have this problem, but doesn't work for me.

I generally use an extension on multi pitch raps or where loose rock is obvious. The extension is tied to use as an anchor tether as well. I generally don't use an extension cleaning one pitch sport routes, but do use a third hand for sure cleaning draws from overhanging routes

Guy Keesee wrote:Never used one. Keep it simple, and fast. Are you going to be messing around with your auto-deal when we are racing a big T-storm that is quickly approaching?????

Non issue. A third hand backup takes like 10 extra seconds to set up and you can use it to hold the rope with some slack while you feed the lines into the device, especially nice on double rope raps. Probably saves some of the time it takes to rig.

Prusik above device here - if I want to have a backup - because I periodically ascend with it and so know it works by experience.

Either way / type, I don't trust 'em to catch a surprise fall

I love the autoblock. doesn't take anytime once you know how to set it up. this is the best one;

gearexpress.com/sterling-au…

In order of better to worse, I think autoblock, kleimheist, prussik. The autoblock comes out first because it is the easiest to release under load. The ease of release becomes a dangerous liability if you don't extend the rappel, however.

An autoblock shouldn't be getting too loose if it is correctly-sized for the number of turns you intend to use. Play around in a safe situation to figure out how many turns you need.

I think the most intelligent rappel back-up strategy is for only the first person down to use an autoblock, with the rest of the party rappelling with a "fireman's belay" from below.

Thanks everyone. I was able to to test out the autoblock yesterday. worked like a charm. Now I feel way more comfortable on my raps.

Bill, while putting the prussic above your device might be easier for ascending it does work fundamentally different than putting it below your device. In the event of a fall your weight would be falling entirely on the prussic if it is above your device. Placing the prussic below your device it is acting as a "third hand," if you fall it simply holds the rope in a position to lock in your device and is only holding a small amount of weight. If you are using it for safety, rather than convenience, then you should put it below your device and extend your device. (You can fill in autoblock or klemheist in place of prussic if you prefer)

rgold wrote:I think the most intelligent rappel back-up strategy is for only the first person down to use an autoblock, with the rest of the party rappelling with a "fireman's belay" from below.

I do this either when my partner does not like to use a rappel backup or does not know how to use a rappel backup. However, there are two risks a fireman's belay cannot mitigate: 1. if my partner set up their rappel incorrectly, (for example: only clipping one strand of rope), I may or may not be able to hold on to both strands in a fireman’s belay; 2. If I get knocked unconscious by falling rock, my partner is without a backup. Worse still is if my partner gets knocked unconscious by falling rock, the same rock is likely to hit me as well (and knock me unconscious). The first risk can be somewhat mitigated if my partner extends his belay device, then I will have them set up their rappel before I rap so I can doubt check their set up. The second risk may be unlikely, but still a possible risk. Both can be better mitigated by an autoblock backup.