/ Ascending and descending ropes -- prusik alternatives
I teach crevasse rescue to a team that is in the position of only ever rescuing victims who are unequipped with ropes, harnesses etc. So one member of the rescue team always has to descend into the crevasse to take a harness, helmet etc.
At the moment I have them ascending and descending with prusiks as it's easy to transition back and forth between ascent and descent. The safety prusik for abseiling becomes the foot prusik, and an additional one is added above the belay plate. Then if they have to transition back to abseiling then they can lower themselves gently back onto the belay plate by loosening the prusik.
However, I've noticed a lot of people, especially heavy ones, struggle with the top prusik and I'd like to experiment with a mechanical alternative. Something like a Jumar is no good because it is toothed and they can't lower themselves down the rope again to weight the belay plate when transitioning back to descending.
Does anyone have experience of equipment that might be suitable? A mechanical ascender that can be slid back down the rope if required. I wondered about a Grigri or similar but haven't used one for 15 years and thought there is probably something new out there that may be better. I've done a search on some caving sites as I thought they'd be likely places, but haven't found anything right yet. Any advice appreciated!
Dare i Suggest you try a Shunt? With a bit of Practice rapping end rope Round foot a couple of Times you can ascend and descend Pretty effectively.
They Arent Made with this in mind Though, and Someone will Probably tell you why you shouldnt ;-)
What I use for bolting and cleaning routes is a GriGri on my belay loop. up the rope a shunt with a big crab and a pulley and a foot loop, take rope below you back up and over the pulley. Easy to go up and down. I use a shunt, others use a Jumar, I prefer the shunt because it is easy to rig a pull down cord making up and down adjustment easy. Lots about this on old threads.
Can I suggest you take a look at some caving SRT (single rope techniques)? The kit used for this is usually a hand held ascender and a petzl croll, with variations using the Basic and Pantin.
Lots of info on set-ups online.
Of course you can, how do you think cavers and roped access workers do it? Given the wet/icy ropes you're potentially dealing with for crevasse rescue I'd have thought a toothed device was exactly what you needed if you want to move away from cord.
Petzl Basic or the handled version.
The Petzl Rig is probably the best device for your needs.
I didn't realise the toothed cams could be slid down ropes while under load. I'm not sure if we're talking at cross purposes though, because I'm sure they're designed to make that impossible.
But anyway, thank you everyone for pointing me in the right direction; knowing to search for "single rope techniques" will be very helpful and I will take a good look at the Petzl Rig.
A grigri for the rap and as the waist prusik with a jumar for the leg will work fine.
The lightweight solution would be to use a reverso to rap and as the waist prusik with a normal prusik loop for the foot. A reverso can be switched from decent to ascent in about a second. See:
and scroll to the end of the section.
Lots of good advice about mechanical devices above.
My 2P. If you go down the mech device route practice on icy ropes, not all toothed devices are useable and from personal experience when it slides it is frightening... Petzl devices are as good as any IMHO.
For the knot option, try different knots and varying diameter cord. I have tried them all and have yet to be impressed by any other than a standard prussik with two or three wraps or the French prussik for abseil protection.
Moving a standard prussik up the rope is easy when one realises it has to be first unweighted and loosened slightly. A quick push with the thumb on the back loop should be second nature.
Again from personal experience, getting an unharnessed victim out of a crevasse is unlikely to be carried out by a heavy person. Crevasses often taper wickedly and the victim is likely to be crushed tight. If (when) I am ever daft enough to solo travel on a glacier I at least put on a harness and hope any rescue party has a long clip stick.
I'm sorry, I don't want to insult you or anything, but I can't help but think that you shouldn't be teaching people if you're having to ask these questions...
I'm under the impression that what you're doing is training a rescue team? If that's the case then surely the members of this team should already be well aware of the kit that's available to them and how to use it... let alone their instructor not knowing about it...
Your reply to jkarran on toothed devices also worries me. As an instructor you should know about the techniques involved in loading/unloading/releasing these and should be able to effortlessly impart the knowledge on how to perform these techniques upon your students.
Also, if you're actually performing a rescue as a rescue team then I'm pretty sure you should be employing IRT. I think it's a requirement to legally cover your back but don't quote me on that.
Agree with what has been said - and for the sake of completeness it would not be possible to bring a weighted prussik loop down a rope, anymore than a toothed device (or, at least, I hope not). Anyone moving into an arena as dangerous as you describe would do well to carry at least one ascendeur of some description (plus prussiks) as well as a means of getting down a rope along with some means of locking off said means (again, Petzl have the technology). In an ideal world the kit would include a chest harness linked to a sit harness, 2 ascendeurs, descendeur and slings the right length. Makes thing faster and safer, with the ability (if you know how to rig it and have a pulley or two) to lift bodies as well. These days I would always carry a device into places like sea cliff and glacier territory anyway - they weigh so little.
Why would you slide it under load, you have at least two points of contact on the rope, you use one to unload the others so as to slide them up or down. Switching from ascent to descent on SRT kit is easy when you're familiar with it as is shuffling down a rope without using a descender.
The downside to this SRT kit, if it's just for emergency rescue is it's heavy and not really multi-purpose in the same way cord or slings are. Perhaps though you're training a rescue team?
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