UKC

Hi,
I might be about to make a compete idiot of myself, but is there a reason that in the loop haul in https://www.petzl.com/NL/en/Sport/Crevasse-rescue-no--3--haul-systems-for-c...
they set it up differently than one would on a rock climb?

On a rock climb the second would be hanging off the reverso in guide mode and you would toss him a loop and he would clip it to his harness on a locker and you would start pulling. Simple. The reverso would then be the safety clutch. You would not use the other end of the rope.

In the other two methods on that web page, they simply attach the trax to the anchor to escape the system. Why don't they do this in the loop haul? Why teach a different process for the loop haul? I would have thought one would want the same system as much as possible, especially during the first bit of escaping the system, when you are unsure of what you might do.

The method shown also leaves the hauler facing the wrong way and possibly walking backwards towards the hole.

Am I missing something?

Thanks

.....and isn't the pulley on the '7:1' in the wrong place? I thought the most efficient pulley (i.e. not the carabiner) needs to be closest to where one pulls to minimise losses.

In reply to David Coley:


I'd be surprised to be honest if a 7:1 system was of anything other than theoretical interest.

In reply to David Coley:

Maybe because it is easier hauling down slope than up, especially when 2:1 and 1:1.

In reply to David Coley: A few thoughts...

The original rope will probably have dug into the snow/ice, so using a new section of rope placed over padding may be a good option.

Being closer to the crevasse improves communication.

PS I agree about the pulley. Thin dyneema slings around karabiners have fairly low friction anyway so putting the one pulley there makes little sense.

In reply to The Ex-Engineer:



That seems sensible. However, they don't attempt to do this with the 3:1, so I wonder how much difference it makes.

In reply to David Coley:





With the caveat that a guide plate is an assisted (not automatic) belay plate (and could in theory slip)... you could indeed switch out the traxion for a reverso.

In reply to mmmhumous:


Thanks, but the guide plate vs. a trax was not my question. Rather it was why they use the other end of the rope?

In reply to David Coley:

In that case... good question. I can't see any benefits in terms of mechanical advantage or amount or rope needed. Only difference is the direction of pull for the the rescuer: As pictured, they're pulling towards the crevasse. If the Trax was where the clove hitch was on the central crab (and the hauling end loose), they'd be pulling away from the gap.

On which note.... what are people's views on the rescuer being past their anchor whilst hauling?

In reply to planetmarshall:


Not true. I recently set up a 9:1 system to haul my mate out of a crevasse in Alaska after he ended up free hanging after a fall of 5-6m. Might have been able to do it with 6:1 with great effort - there is a lot of resistance pulling a rope that has cut deep into the lip of a crevasse and the z pulley 3:1 system they often show in textbooks would be useless in most real life circumstances I would imagine.

In reply to David Coley:


I agree, however, I'd not carry that extra pulley, just the progress capture pulley (why haven't anyone found a better name?)

In reply to David Coley:

I'm not sure what you mean. In the Loop haul case, they don't use the other end of the rope, rather a unused loop of the same rope is sent down to the victim. Both climbers are still tied in to each end.

In reply to mmmhumous:

- and that's how I'd do a loop haul.

- depending on the scenario, I'd stay tied in and clove hitched to the anchor with an appropriate length of rope

In reply to Stefan Jacobsen:


Sorry, should have said another part, not end, of the rope.

If you look at the other two example on that web page the scenario is probably following what looks like a natural one of:
1. get dragged over onto your butt/face. Build anchor.
2. clip trax to anchor to escape system and catch one's breath.
3. figure out what to do next by visiting the edge
4. set up system and haul, with the trax still in place and not having been moved.

With the loop method - as shown - there is either the need to remove the trax and replace it further up the line (this is easy if you have done lots of stuff with prusiks before, but isn't obvious to a beginner), or start by tying the guy off with a clove hitch and hence know right from the start you will be doing a loop haul - before you have visited the edge.

The only logic I can see for not setting this up how one would in a rock climbing situation is that it means it will be easier to pad both moving lines, therefore less friction, and that the guy will find it easier to do the final exit as the ropes will be less cut into the side.

In reply to David Coley:

To keep all options open, you can do this:

1. get dragged over onto your butt/face. Build anchor.
2. attach a prusik/tibloc to the rope and fix it to the anchor using a munter mule. Then backup with a clove hitch
3. figure out what to do next by visiting the edge
4. set up system of choice, release munter mule and haul

In reply to David Coley:

The priority with a crevasse fall is setting up your system to maximise the chances of stopping the fall.

With a two person party that means you'll want to have knots in the rope between the climbers and that, together with the fact that it'll bite into the crevasse lip, mean that the rope between the party members is useless for hauling. The drop-loop system allows you to set up the loop before there's any load on it so you can place padding under it and dig away the lip. (If you don't prepare the lip you will not be able to haul the victim the last metre.) You can see in the diagram that the part of the rope which originally stopped the victim is slack & that strand is isolated by the clove hitch on the yellow krab on the anchor (the krab between the white one and the traxion.)

You're right that the hauler is facing uphill and it does feel weird pulling down on your anchor but it's ok. The rescuer is clipped to the anchor with some slack so they can move around but hopefully not enough to fall in the hole. They could also protect themselves with a long (or extended) prusik on the fall rope.

Both of the other systems shown on that page rely on there being no knots in the rope which is a scenario that would have made it harder to stop the original fall.

In reply to AdrianC:

Thanks Adrian, that was much my guessing. But seemed strange that the knots bit didn't get mentioned. Nor if using the other methods how to get past the knots - which is reasonably easy if practiced, and the opposite if not.

In reply to David Coley:

Yeah - you could argue that they're a little remiss in not mentioning knots but I think they're trying to produce clear and simple systems without too many ifs and buts to confuse us all.

Also, a couple of scenarios that come to mind where the rope to the victim would likely be free of knots are 1. With a party of three or four climbers on one rope in most conditions people may not bother with knots as you have much more stopping power and 2. When ski touring you're probably not roped up and if someone falls in you're going to drop them an un-knotted rope. (Incidentally, if for ski touring you're probably only carrying a 30 m rope which is very unlikely to be enough for a drop loop system. In that case the Mariner system (5:1) or double Mariner (7:1) as shown in your link are useful as they don't need much rope.)

In reply to David Coley:

I'm sure most of you will have seen this artical by Richard Delaney at Rope Test Lab, but if not then it makes interesting quick reading regarding Theorectical vs Practical Mechanical Advantage in a hauling situation. He has made the assumption that all the pulleys have an efficeincy of 95% which is the top of the range of efficiency.

Petzl Rescue: 95%
Petzl Partner Pulley: 91%
Petzl Micro Traxion: 91%
Petzl Rollclip: 85%
Petzl Fixe: 71%
Petzl Oscillante Swing Cheek: 71%

Climbing Tech Orbiter S: 96%
Climbing Tech Rollnlock: 85%
Climbing Tech Orbiter M: 80%

Kong Extra Roll: 96%

http://specopsblog.blogspot.co.uk/2014/01/theoretical-vs-practical-mechanic...

In reply to Jim Walton:
I'd not seen that, thanks for sharing. I'd normally have a micro traxion and a pulley so their placement seems like it'll make a difference.....

Edit: In my "normal" practiced method the best I could get would be 3.8 as I put the micro taxion straight on to the anchor (as per the Petzl guide).

In reply to galpinos:

If you've not used one before then I really would recomend the Climbing Technology Rollnlock.
Use with ropes EN 892 / EN 1891 Ø 8 > 13 mm;
Use with slings 10 > 16mm (if you really want to...)
Safe Working Load: 5kN
Breaking strength: 20kN
Weight: 80g
Efficiency: 85%

Compared to the Petzl Micro Traxion
Use with ropes EN 892 / EN 1891 Ø 8 > 11 mm
Safe Working Load: 5kN
Breaking strength: 15kN
Weight: 85g
Efficiency: 91%

I think it is slightly more useful than the Micro Traxion to the standard climber. The Rollnlock is a very good ascender and Hauling/progress capture device. The Micro Traxion is a very very good hauling/progress capture device and a decent enough ascender.

In reply to Jim Walton:

I've already got a micro traxion but, should it disappear down the mountain one day I'll bear the Rollnlock in mind. Thanks.