/ NEW ARTICLE: Rock Climbing Basics 9: Abseiling
Read more at http://www.ukclimbing.com/articles/page.php?id=5728
And I have to agree the American Jargon is utterly irritating.
Not sure how you'd generate a high fall factor abseiling or clipping to an anchor - assuming you're snug on it.
Perhaps you could explain to us all why that is such a problem.
What’s with the knott in the sling anyway? I appreciate you’re essentially backing up the sling but I would have thought if you’re putting enough stress in the system to snap dynema you’re pretty much f****d anyway.
I definitely never want to try it, and will hopefully arrange things so it is never a risk, but harnessed people are also a lot more squishy than the (standard) solid 80kg test weight DMM used, which will probably reduce the peak force considerably.
The extended ab works really well in a multipitch environment and yes you do of course have to know the effect of falling on slings when there's nothing dynamic involved, but knowing this info you can use it effectively.
If I'm tied to the rope I'll attach with that. If using a sling I'll attach to an anchor above me (and sit down if I need to). I'll keep the sling snug/tight (tying a second overhand knot and moving it up and down the sling the alter the length to suit). If that's not going to be possible I'll use another tool.
I use it regularly in multipitch situations but keep its limitations at the forefront of my mind. When I know I'm going to need a cowstail a lot for work I take a Petzl Dynaclip but a self tied rope lanyard (attached to me with a rethreaded figure of 8 and a barrel knot for the karabiner) would be even btter in terms of shock absorption. I still wouldn't like to take a factor 1 fall onto it though!
FWIW a friend took a fall (factor 1 or higher) on a cows tail like this last year. it didn't break. As op said test was conducted with an 80kg steel mass and we are a bit spongier than that. I wouldn't lke to rely on the shock absorbing properties of my body to keep me safe though so prevention is the key thing for me.
I usually extend my belay device during an ab just so that the prussic back up has a bit of space. But I usually just use a longish QD sling with a locking karabiner to the belay loop
Totally agree with you and jezb1, absolutely nothing wrong with using a sling like this. Like anything else they can fail if you don't use them properly - the key is to use them properly. I have a home made cowstail of 8.5mm dynamic rope that I use when I know/ expect to be clipping in to a lot of belays though.
Force of impact will also be reduced a bit by the fact the abseil device is attached to the rope rather than a fixed anchor so will have a little dynacism, and the abseil device is free to slip and further reduce the impact.
Plus a think at true free fall onto the anchor like the DMM video must be rare when setting up to abseil- as opposed to more of a slump/roll where the fall isn't so sudden / gradual.
One thought on the vid I did have is that we've always tied off so that the device is at sternum level, so that it can't smack us in the face/teeth! Just a personal preference thing that though...
You are right the climber is the one that breaks first in this scenario. Basically like being dropped onto a hard floor onto your groin from a few inches up - no possible damage possible there, eh ?
What's wrong with girth hitching through the waist and leg loops instead of the central loop?
The continentals often having the abseil device high up the rope. I have never fancied it, tricky to get at and a good opportunity for getting your hair caught in it.
I always use a belay plate (BRD) with a single screwgate on the belay loop and a short French prussik on my leg-loop clipped below the plate.
I know there have been some discussions about the safety of this 'trad' set-up, but can't say I can see anything wrong with it - and I am pretty neurotic about safety,
If the harness is a ziplock type one rather than a double back, it can under certain circumstances release the leg loop if it gets stuck in the buckle. This might cause the prussik to run up into the ab device then you're stuck.
I have however never seen this actually happen.
> If the harness is a ziplock type one rather than a double back, it can under certain circumstances release the leg loop if it gets stuck in the buckle. This might cause the prussik to run up into the ab device then you're stuck.
> I have however never seen this actually happen.
I have, quite recently as it happens.
It's not backing the sling up, it's so she can use the remainder of the sling as a cows tail to clip to anchors (at the next ledge for example).
> It's not backing the sling up, it's so she can use the remainder of the sling as a cows tail to clip to anchors (at the next ledge for example).
I have never considered doing this but it actually seems like a good idea.
> I have never considered doing this but it actually seems like a good idea.
It also makes it safer when checking/starting the abseil. Leave the cows tail clipped until you've test weighted and double checked your abseil.
Putting aside the possible implications of larks-threading a Dyneema sling, there's something I really don't get about the method shown in the video i.e. clipping the rappel device so far above the 'normal' (belay loop) attachment point.
In a typical rappel descent scenario (both single and multi-pitch) one or both climbers is/are usually clipped into the belay/rap anchors with slings and locking carabiners, at or slightly above head level.
With the method I'm used to employing — Rappel device clipped to the belay loop on my harness, and stopper-knot clipped to the right leg-loop — I can actually pull up a little and weight the rappel rope (and therefore check everything is properly set up) before I release my belay sling/krab.
The method shown in the video would seem to make this very difficult to do as the extending sling would introduce considerable slack into the system.
In the video demonstration I believe the climber is on the ground, not starting from a hanging belay or narrow ledge, both of which might have been more informative for the relative merits of using this particular setup.
Also (as mentioned elsewhere in this thread) the hair-trapping potential looks strong!
While I haven't been able to watch the video (crappy Internet connection away from home), it presumably reduces the Prussik-eating potential (which can now be attached to your belay loop instead of your leg loop)?
I larks foot through my belay loop, not top and bottom.
I tie my overhand about a third of the way up the sling so less entanglement potential.
So the spare end of sling is useful for clipping to anchors on multipitch stuff.
When rapping you can either clip the spare end back to your harness or clip it free running on the side of rope you need to pull, as a memory jog "which side do we pull on?!".
I use a similar method but just use a doubled over 60 cm sling with a screwgate to my belay loop. It's extended enough that everything runs smooth..but not so far that it's getting in the way.
Fair enough. If you tie the knot in the sling not more than a third of the way up then I guess you'll just about have enough room to weight the ropes before unclipping the krab on the higher loop.
However, it would seem the only possible reason for using this 'extended' system is to keep the prussik knot clear of the rap device, which is something that's never troubled me — I keep my right hand low, simultaneously regulating the tension on the doubled rappel ropes and stopping the knot from sliding higher.
Using your cow's tail sling and krab to clip into the rope you'll be pulling at the next stance/rap point is one of those simple yet essential techniques. It amazes me how many times (even after chanting "pulling blue, pulling blue" all the way down!) I've forgotten which rope to start pulling, with possibly serious consequences should the knot get jammed in the anchor.
But isn't the whole point of the prussik for when you let go (because a bit of rock hits you on the head and knocks you out of similar)? In which case, if the prussik hit the belay device, it could fail to lock up, and so fail to halt your abseil, with obvious unpleasant results...
Otherwise you might as well not bother using the prussik, and just lock off the device if you need to stop :P
Good point, but I was really responding to other folks' reasoning/concerns here, rather than my own.
I'm no super-Alpine guru, but on the various multi-pitch rock climbing trips I've been on in the last decade, using a rappel device on the harness loop and prussik clipped to the leg loop has always worked very well for me.
Maybe I use a tighter (shorter) prussik sling than others, but there's comfortably enough room in the system for the prussik knot to lock in the event of a disastrous event, or more commonly just to take both hands off to clear rope snarl-ups below.
I'll try the extended sling-thing next time out on the big stuff — interested to discover the pros and cons.
This is very similar to the way I do it.
This video shows almost exactly how I do it and teach it: http://www.youtube.com/watch?v=xddVyQUyJlE
It's important to consider the bigger picture, yes your hair is more likely to get caught if you haven't tied it away/kept it out of the way, but your prussik is much more likely to be effective, which is ultimately more important. Keeping my hair out of the abseil device is in my control, being knocked out by a random falling rock isn't.
As for using slings, keep them snug and you've nothing to worry about. it'd be nice to be able to use the rope, but hey, you'll be throwing down the cliff! So what else do you use, unles you're carrying spare lengths of rope around?
Finally, if you haven't already tried it, do so. Having the ab device above you puts your centre of gravity nicely low, the whole ab feels a lot more secure and comfortable in my opinion.
My ownly concern would be threading the wires on the nuts directly with the sling. I'm sure it's probably OK but "cheese cutter effect" springs to mind. I tend to carry an old karabiner or two specifically for this eventuality.
Could you swap them round so the prussik is extended above using a sling and the belay plate is attached directly to the belay loop?
With the protection above the plate, it has to hold 100% of the climbers weight when it locks off and it can be very hard to free it from there (I know, I've had to cut one off in my younger days). Furthermore, it needs two hands to work at all (one keeping the prusic 'free' and one as the brake hand) so you can't at any point easily pull yourself onto the rock, for instance.
I believe (but could be wrong) that the advantage of having the prussik below, rather than above, the belay plate is that the prussik only has to hold the braking force required for the belay plate to lock up, rather than the entire weight of the climber. It may then be easier to release/less likely to jam?
Like everything, there are pro's and con's. You have highlighted a con to the system demonstrated. The key is NOT to get the prussik stuck in the belay plate at any point. Another disadvantage comes when passing knots in the abseil line.
Neither method is perfect, but both are perfectly safe and workable.
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