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The Climbing Club • View topic - Glacier Travel

The Climbing Club

at the University of Washington
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 Post subject: Glacier Travel
PostPosted: Tue Aug 17, 2010 3:56 pm 
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UW Climber
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I was on the Emmons last week and for protection I carried two pickets and two screws. 99% of the surfaces seemed excellent for hammering pickets into, and occasionally there was some solid ice which sure looked like it would hold a screw. (I'm no expert).

My question is what distance do you want between two screws or two pickets when you set up equalized anchors?

Also, and its a long shot, does anyone have a glacier line or even half rope I could borrow for the weekend? Of course, if the rope sustains any damage, I'll replace it.


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 Post subject: Re: Glacier Travel
PostPosted: Tue Aug 17, 2010 7:03 pm 
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Tenacious Lee
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 Post subject: Re: Glacier Travel
PostPosted: Tue Aug 17, 2010 9:27 pm 
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Dr. Crevasse
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The answer here does not depend on sling length you carry. You should carry the correct length slings to construct an anchor as Lee states.

Ice screws should be placed a minimum of 12 in. apart, typical for good water ice (Ref: Ice & Mixed Climbing - Will Gadd). For glacier ice, I would probably spread them farther apart. This will depend on the quality of the ice you find. Don't forget to clear off the crappy surface ice dig for the good stuff.

Each picket should be pulling on different blocks of snow. I would say that they should be a minimum of 2 ft apart. I'm currently re-thinking my use of pickets so I'll get back to you on this one.

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 Post subject: Re: Glacier Travel
PostPosted: Tue Aug 17, 2010 11:26 pm 
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Mountain Rhombus
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I have a glacier rope you can borrow. Its actually a 60m half rope, but it has been primarily used for glacier travel.

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 Post subject: Re: Glacier Travel
PostPosted: Wed Aug 18, 2010 5:26 pm 
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UW Climber
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Thanks guys.

Related question. Is it fine to clip two separate runners (from the anchors, either pickets or screws) into a single carabiner. My concern is that they cross load the biner a little bit.

Thanks a lot Craig for offer; Brian D offered as well.


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 Post subject: Re: Glacier Travel
PostPosted: Thu Aug 19, 2010 11:45 am 
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experienced hiker of the climbing club
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Kurt - I agree that cross-loading does seem problematic. I find that bringing a cordalette along to equalize the two pieces is helpful and not much of a weight penalty. Others may have other approaches/thoughts.


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 Post subject: Re: Glacier Travel
PostPosted: Thu Oct 07, 2010 4:28 pm 
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Cap'n Wingspan
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I think that, given the fall factors in a glacier setting, any cross-loading of the biner is really a non-issue, since they are almost certainly rated for more than you can achieve. For ice climbing it might be a bigger issue, but you would probably have a cordelette with you as Brian suggested, or you can make a sliding x with a sling.

Maybe this is obvious, but it hasn't been directly addressed here. Look in freedom of the hills (I'm sure it's easily found online and in many other books) about the angle of the anchor when equalizing two pints. This applies for rock anchors as well, but as you get past a certain angle, I believe 90 degrees (someone will correct me if I'm wrong), you can end up applying more force on each anchor than if you had just one anchor loaded directly. This, along with the things Jim said should be considered when you're building your anchor. If you only have something short, they must necessarily be placed close together or you might as well use only one piece.


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 Post subject: Re: Glacier Travel
PostPosted: Thu Oct 07, 2010 7:21 pm 
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Dr. Crevasse
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 Post subject: Re: Glacier Travel
PostPosted: Fri Oct 08, 2010 12:16 am 
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Cap'n Wingspan
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Jim, you're correct. I should have been a little more clear - I was referring only to the type of cross-loading kurt was referring to, i.e., that achieved when you use one biner to join two slings coming from anchors situated 60 or fewer degrees apart. This to me doesn't seem to be the sort of cross-loading that the manufacturers rating is referring to, which in my understanding would be opposing forces at 180 degrees. It stands to reason that as you decrease that angle, the force is decreased, thereby limiting the 'cross-loading' effect to less than the 8kn limit. Yes?


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 Post subject: Re: Glacier Travel
PostPosted: Fri Oct 08, 2010 9:33 am 
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Dr. Crevasse
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Agreed.

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 Post subject: Re: Glacier Travel
PostPosted: Sat Oct 09, 2010 10:59 am 
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Longshanks
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I kind of knew, but I wanted to see exactly what the force multiplication curve actually looks like:
Image

The point at which equalization begins to hurt you is 120 degrees between the arms of the sling, but it seems that staying below 90 degrees is the best rule of thumb. Everyone knows what a 90 degree angle looks like, and at that point you are already applying ~70% of the total load to each anchor, so you haven't bought much by equalizing them; except of course the redundancy of having a backup.


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 Post subject: Re: Glacier Travel
PostPosted: Sat Oct 09, 2010 2:46 pm 
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UW Climber
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Probably the best way to place ice screws and pickets if you want to reduce force is to place one piece above the other (an appropriate distance above the other of course). That way the angle between the pieces is close to zero, and they are equally loaded.


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 Post subject: Re: Glacier Travel
PostPosted: Sat Oct 09, 2010 8:40 pm 
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One Armed Wonder
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