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Pulleys for crevasse rescue

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Re: Pulleys for crevasse rescue

Postby logsden » Mon Feb 18, 2013 7:18 am

A quick shoulder haul 2:1 with a micro-traxion is surprisingly easy.

A drop loop 6:1 is also quick to set up and will work with one hauler.

Rappelling into the crack to tend to an unconscious patient allows you to set them up with the drop loop while you're there anyway. Reascend to the surface and continue with a standard 6:1.

Additional pulleys have not been necessary in my experience.
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Re: Pulleys for crevasse rescue

Postby MoapaPk » Mon Feb 18, 2013 1:56 pm

Wastral wrote:
nartreb wrote:I've never done a crevasse rescue in the field, but with pulleys in general, a larger-diameter pulley is WAY more effective than a small one.


100% wrong!
Pulley diameter has little to nothing to do with efficiency as long as the rope/cable in question can bend the radius of the pulley. The larger pulley you used I am sure had a bearing at its center and for this reason was larger. It is the bearing that makes all the difference.


Terminology problem. Effective does not mean the same thing as mechanically efficient, in the classic way that the efficiency of pulley systems is calculated assuming ideal rope characteristics.

http://www.engineeringtoolbox.com/pulleys-d_1297.html

http://www.dynamicscience.com.au/tester ... lleys2.htm

Some people mix "mechanical advantage" with "efficiency." Ignoring friction, one typically does the same work, but perhaps with a smaller force through a longer distance. In real pulleys, a lot of energy can be lost in bending the rope on tight corners, friction, stretching, etc.
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Re: Pulleys for crevasse rescue

Postby WillP » Tue Feb 19, 2013 4:18 am

The Chief wrote:... neither the current AMGA nor the UIAGM/IFMGA Advanced Alpine Guide Certification process covers in-depth one to one (or as you suggest a 2 Man Rope Team) scenario. All CR instruction/Cert covers a "group" (min of 3) on a rope. They do this in order to promote the safety in numbers protocol when travelling in this type of enironment. Most Guide Services here in the US follow this protocol in general but do have rare exceptions to this"Safety" protocol.

Our policy at the service I am employed with for this type Alpine trip requires a min of 2 Clients to 1 Guide on any outting that may encounter crevasse fields. Again, in order to follow the Safety in numbers protocol. If the boss ok's a 1-1, he strictly requires a pre-req of the client to have previous Advanced Crevasse Rescue Training Cert and then he himself has the client demo their knowledge in their ability to set-up process properly and efficiently prior to considering the client for such a trip. In most cases, he himself will lead the trip.


Seriously? That's just nuts. Learning how to do something with someone else vs. learning how to do it by yourself is pretty freaken different. Given that, as stated by someone else, most climbing teams are a team of 2, what other rationale from the AMGA is given? And is it true that many AMGA guides make clients wear helmets on a glacier in case of a crevasse fall?
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Re: Pulleys for crevasse rescue

Postby WillP » Wed Feb 20, 2013 1:13 am

The Chief wrote:And may I ask, why are you wearing a helmet?


Ah, a fair question, but if you look very, very closely, you'll see that I'm not walking on a glacier.
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Re: Pulleys for crevasse rescue

Postby WillP » Wed Feb 20, 2013 3:28 am

With all due respect to your experience, IMO that's just ass-backwards. Wearing a helmet on a glacier on the slim chance of a crevasse fall (and the even less-likely headstrike occuring with that) because a governing body says you must, but not wearing one trad climbing where you're (sometimes / often) dealing with potentially loose rock, muppets above you dropping things, pendulum falls, etc. Hey, I know helmet use is individual choice, but at least make the decision based on risk factors.
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Re: Pulleys for crevasse rescue

Postby mrchad9 » Wed Feb 20, 2013 4:31 am

Well this argument reached a civil and reasonable conclusion.

Booooo....
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Re: Pulleys for crevasse rescue

Postby Wastral » Wed Feb 20, 2013 7:13 am

The Chief wrote:
Liability and Insurance.

It has absolutely nothing to do with walking on a glacier perse. Has to do with the entire evolution of the climb in a known hazardous Alpine environment.
I know helmet use is individual choice, but at least make the decision based on risk factors


It's a fad to wear a helmet these days. Up until some six or so years ago, you never saw anyone wearing a helmet on a sport or trad crag... never.

I have whipped hundreds of times on sport climbs in the past four decades and have never worn a helmet nor ever impacted my head in the process of doing so.


This is why I always listened to your posts till you went off the deep end and revealed your ignorance regarding 2 man crevasse rescue and crevasse rescue in general. When it comes to rock climbing you know your stuff, though only half true in this instance.

Any alpinist with even half of an air head density has worn a helmet for a very long time. Saved my bacon from falling rock once. Lets try a different subject. Regarding sport climbing, yup you are right. I have never seen someone wearing a helmet until the last few years. Though even that depended on where one was sport climbing. Here for instance, Index? Nope, but you would be very STUPID not to wear a helmet at mt. Erie where its a freaking park on top and kids go up there for the explicit purpose of throwing beer bottles, rocks, and whatever else they can get their hands on, OFF the cliff and to the poor SOB's below. Would I wear a helmet on a glacier? Not when crossing large glaciers when up in Waddington area or Alaska the few times I have gone as they are LONG treks and one needs to evaporate as much steam as possible. On the other hand, generally one is going steep ice, mixed, or rock climbing at the end of the glacier traverse anyways so may as well put the danged thing on your head as no idiot would even think of going mixed without a helmet or alpine climbing where falling rock is quite common. Though I have gone sans helmet every time I can on a ridge climb. At half a pound to three quarters of a pound depending on whose helmet you are wearing, its not a deal breaker for me.
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Re: Pulleys for crevasse rescue

Postby Brian C » Wed Feb 20, 2013 2:38 pm

I'm going to ignore all the arguing above and see if I can steer this back at least a little bit. This thread and an upcoming trip has inspired me to re-look through my old glacier setup and see what is "new out there". Here were a few unorganized thoughts I had (all this stuff was mentioned earlier in this post)...

1) Saw that DMM makes a carabiner with a built-in pulley that could replace the lower pulley in the z-haul setup (the one on the tibloc). This also would be awesome to put on as your "rescue" biner for rock stuff as it would be money if you actually had to haul somebody and didn't have a pulley.

2) Also, the new Petzl micro-traxion would be awesome to have on glacier stuff as it would replace the upper pulley and the prussic both and it weights about the same. Only problem is it is a bit spendy. It could also be used to ascend the rope.

I then did a bit of rough math on the weight differences and came up with this...

Potential "New Setup"
Micro traxion - 3.6oz
DMM Wiregate Revolver - 1.5oz
Tibloc - 1.4oz

Total weight - 6.5oz

VS...

My "Old Setup"
2 prussic loops - 2oz approx.
Petzl Oscillante Pulley - 1.94oz
Petzl Twin Prusik Pulley - 11oz (I didn't think it was that heavy but that's what the page says...)
Oval wiregate carbiner (to use with bottom pulley) - 1.6oz
Tibloc - 1.4 oz

Total weight - 17.94 oz

Thought this was pretty interesting is it was more weight difference than I expected.
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Re: Pulleys for crevasse rescue

Postby asmrz » Wed Feb 20, 2013 5:47 pm

Beg to differ with Chief on the helmet issue. Miguel Carmona and I wore helmets almost everywhere in the 80s and 90s. We did most of our First Ascents while wearing helmets and most of our era climbing buddies and friends did too. Just because some segment of the US climbing world thought helmets were not cool (even if all the climbing rags pleaded for their use) it does not mean the use was not accepted elsewhere (outside of Yosemite, for example). In Canadian Rockies as well as in the Big Hills of Asia, helmets were used quite a bit in my time. I wore and still do wear my helmet most of the time, the only ecceptions are scrambles on ridges, which we do a lot these days. Not because some GGMM AMCA, QURE or whatever tells me that I should do this or that, but wearing helmet makes common sense.

Still waiting for someone to chime in on the most important issue, two people in technical alpine and crevassed terrain... Anyone?
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Re: Pulleys for crevasse rescue

Postby asmrz » Wed Feb 20, 2013 6:05 pm

Brian C, since IMO, the issue is speed of set-up, weight of the gear and the ability to re-use the gear for other needs in technical alpine terrain, how does the above gear work for that? One could say that having prussiks or modern ascender equivalent is important on the climb as well as on the glaciated approach. Any comments?
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Re: Pulleys for crevasse rescue

Postby logsden » Wed Feb 20, 2013 6:26 pm

"Normal" kit in a standard two man team:
Micro-traxion, very short prusik, one length of 6mm cord-o-lette, one double length runner, two single runners, one picket. 3 wire gates, 3 lockers. Another locker and an ATC may get thrown in there depending...

I do not carry the DMM Revolver. I'm unconvinced of its benefit but admittedly don't really see a downside. Some of my partners carry one.

I generally do not knot the rope between me and my partner.

ymmv.
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Re: Pulleys for crevasse rescue

Postby logsden » Wed Feb 20, 2013 6:33 pm

asmrz, good question (to Brian C above). A standard "alpine" kit will already include everything you need to perform a crack rescue (as I'm sure you are aware). The micro-traxion would be my one addition to what most would consider a "standard" technical kit. The old "Mini-" was too heavy and bulky but the Micro- crossed the threshold of what I consider light enough to toss in, considering its benefits..."speed of setup" being one of those.
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Re: Pulleys for crevasse rescue

Postby asmrz » Wed Feb 20, 2013 7:06 pm

logsden

Appreciate the info. I will have to look at the different pieces of gear as I'm not familiar with most of it. I learned crevasse rescue ages ago and most of those around me for all these years since never changed our familiar set-up which was prussiks, 2-3 lockers, pulley,"V" loops for both boots, prussik for one's pack (to be able to tie off the pack) and the standard glacier gear of 3-4 ice screws each, short picket, deadman and some rock gear including short knifeblade or two (if needed). Thanks for the gear update.
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Re: Pulleys for crevasse rescue

Postby Brian C » Wed Feb 20, 2013 7:21 pm

logsden wrote:...The old "Mini-" was too heavy and bulky but the Micro- crossed the threshold of what I consider light enough to toss in, considering its benefits..."speed of setup" being one of those.


That's what I thought too. I have a mini but have always just used it for hauling on aid stuff, not alpine due to it's weight. Now that the micro is out and looking at the weights I posted above, I'm seriously considering getting one for alpine and glacier stuff.

asmrz. I was just talking about rescue-specific gear. I like having stuff that is multi-functional. Both setups I posted above would allow a competent person to utilize effective rescue techniques whether that be on glaciers on technical rock. The traxion functions as both a pulley and a traction knot (prussik) and the DMM Revolver functions as both a carabiner and a pulley. This allows to carry just a little bit less stuff. Was that your question?
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Re: Pulleys for crevasse rescue

Postby asmrz » Wed Feb 20, 2013 7:27 pm

Brian C
You answered it. Thanks.
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