UKC

... for backing up an abseil. Any thoughts?

I'm heading off for some long sport routes in France and so I'm pondering my abseil technique. I'm currently erring towards the autoblock but would welcome any suggestions / thoughts.

In reply to MttSnr:

French Prusik / Autoblock, same thing.

They release under load, the others don't.

In reply to jezb1:

Prusik, simpler and faster. I use the other knots for crevasse rescue, where you know the system will be under load, which most of the times does not happen while abseiling.

CB

In reply to MttSnr:

I've been using a French for about 15 years for my abseil back up. Last night, while on a free hanging ab off the top of Stoney Middleton, for first time ever it jammed at a most unpropitious time, leaving me dangling in space, unable to move. I felt like a total wally. I had to set up a quick ascending foot and harness prusik system to take the load off, remove it, and continue with the ab. Glad that has never happened in the Alps or somewhere more time-pressured!

With that being said, I'd totally recommend the French, but take time to experiment with the length of it, how many wraps you need with your rope(s) to get the right amount of friction for it to bite but not lock!

In reply to MttSnr:

Autoblock / French Prusik. Less faff than the standard prusik to tie / dress correctly. Much easier to release if you need to stop and sort ropes etc, though conversely doesn't bite as well and slips at a lower load (still much higher than anything you should see on abseil!).

Cheers!

Stu

In reply to MttSnr:

Prusik though probably not a greasey one.

In reply to MttSnr:

French/Autoblock from my belay loop with my device extended with a sling as per the "Petzl Method".

Klemheist for ascending......

In reply to ChrisBrooke:

Out of interest, why couldn't you just release it as normal?

In reply to David Coley:

It looked like one of the coils had got rucked up and overlapped another, so that the rope was being bent and pinched through an angle. It would not yield to any amount of pulling, squeezing, jiggling etc. Completely locked. Never happened to me before, so I assume I must just have been careless in setting it up. An old dog can still learn new lessons!

In reply to MttSnr:

french prussic is what you want. Bare in mind if you have quick release leg loops current advice is to run it all off your belay loop and extend your belay device with a sling (about 30 cm is ok). Personally I just run it off my leg loops but make sure the biner is in a position that it can't open the leg loop.

In reply to MttSnr:

another issue with running it off your leg loops is if you were to pass out then you leg may rise, if the prussic reaches the belay plate it will release and you'll fall.

In reply to Greasy Prusiks:

I use one of my prusiks to extend the belay plate then the other as a French Prusik off the belay loop. Anyone see an issue with this?

In reply to Greasy Prusiks:

Only if you need your second prusik to escape a jam like ChrisBrooke above

In reply to ChrisBrooke:


I've never seen this happen, but it seems to me that it could be a result of winding the sling up from bottom to top so far that only a very short loop is left at the top, so short that when clipped and weighted, it causes the bending and pinching mentioned.

In reply to rgold:

It was certainly strange. Unfortunately I was so preoccupied with getting out of the predicament (setting up the system to get the weight off the locked prusik) that I didn't make much of a mental note of what seemed to have gone wrong...

In reply to humptydumpty:

OK thanks.

In reply to Greasy Prusiks:


Your prussik loops (particularly if they are 5mm) are likely to be significantly weaker than a sling (Mammut 5mm cord is 'only' 5.5kN, although you will get more than this in a loop). Whether this matters to you is up to you.