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akclimber
Feb 18, 2005, 9:08 AM
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Anyone here done any testing with snow anchors? Any advice appreciated here...
We went out to a windblown snowslope today to test snow anchors. We used T shaped and V shaped pickets. Also with 1 fluke. The testing was done by placing the piece in, sitting on a sled, going on a ride, and taking a hit. I would call the slope 55 degrees. The lenth of rope out about 20 feet.
What we found:
The V pickets placed vertically, held 3 of 3 times they had wires already on them, so needed no slings. We tried attached to the top, and attached to the middle of the picket.They dug in deep and held strong.
The T pickets (MSR) held vertically pulled 3 of 3 times, we tried connecting the sling to the top and to the middle, did not work. We did fairly well in making a direct path for the slings. Perhaps horizontal is the best for them?
The fluke (deadman). It worked in the past with powder snow, but here it dug down and ripped right through.
After digging out a little, we made a snow bollard. (back up with an ice axe in the middle) I would say a 2 feet in diameter. Worked will for rappeling, however, givin solid bounce test, the rope pulled through. Perhaps the bigger the bollard the better?
We later set up a running belay, with several pieces in between. Worked well when jus sliding on our asses. Though once again, the V held, and one of the T ripped.
Horizontally placed pickets I have not done much testing with.
Any help appreciated, and why did the T pickets keep pulling?
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chugach001
Feb 18, 2005, 6:26 PM
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Ha Ha, I used to do that. I would set up the anchor, lay the rope down and jump off a big cornice. Yep, deadman anchors (buried horizontally) work best. Unlike an ice screw that is held in by threads, a picket has no resistance to being pulled in line. These work well in spring snow that is foot packed real strong in front or super-wind-pack. Deadmen work best in fluffy winter snow.
Have fun!
Jeff
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vashie
Feb 20, 2005, 9:34 PM
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Registered: May 12, 2004
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I am surprised the T pickets failed on you like that. Also, we kinked the cable on a fluke so bad while testing one last winter it had to be replaced!
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akclimber
Feb 21, 2005, 1:37 AM
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In reply to: I am surprised the T pickets failed on you like that. Also, we kinked the cable on a fluke so bad while testing one last winter it had to be replaced!
Haha. What did you find out? How did you mangle the fluke? What was the testing scenerio? details people details! :lol:
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adamtd
Feb 21, 2005, 8:38 PM
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having not done any "testing" but talking form experience, I've found that the firmer the pack, the better the t-stake holds, and vice versa, the more fluffy teh snow, teh better the fluke works. I like ot clip into teh middle of teh T-stake and drive it in. I then almost dig a trench for teh runner, so that it's not pulling on teh top. When it pulls on teh top, it's more likely to pull it in line. Also, a lot of peopel pack teh snow in front of teh Snow Stake, but forget about teh back. you need ot pack all the way around teh snow stake. If you don't pack behind it, teh back will blow through teh snow pack allowing you to pull in line. When it comes to teh Snow Bollard, I've found they work well, with or without the ice axe if you're gentle. If you bounce and swing you'll demolish it. i would never use it for a vertical rappell, only for a steep slope where I can still support a lot of my own weight with my feet. Bollard in alpine ice work really well and you don't need to be as gentle.
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akclimber
Feb 23, 2005, 7:10 AM
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Make sense, I am just relaying advice from another. But it was mentioned to me about puting in a picket and letting it freeze in overnight. Seems logical if you are going to go up it the next day.
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sandbag
Feb 23, 2005, 9:12 AM
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To make a good bollard it needs to be fairly large and you need to try to pack down the snow, similar to if youre making a quansit or a snow cave. Again, if you use a bollard, you should have a huge like 10 foot tear drop, and use cardboard too, helps to increase the surface area and reduce the pressure of the webbing giving more resistance.
As for dead man anchors, try your snow shovel. The Voile is designed for that use too.
good luck
:)
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tradklime
Feb 23, 2005, 9:31 PM
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Registered: Aug 2, 2002
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Interesting that the two different pickets performed so differently in the same conditions...
A horizontal picket in packed snow is bomber.
A friend of mine once buried a bick lighter horizontally and tied it off with webbing. The snow pack was firm, the anchor could not be pulled by a group of people playing tug-o-war with it down a slope.
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guanoboy
Feb 23, 2005, 9:42 PM
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Registered: Jan 2, 2004
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awesome to hear about the bic lighter. That is really going to cut down the size and weight of my pack on my next trip. :D
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tradman
Feb 24, 2005, 11:32 AM
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Registered: Jan 14, 2003
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My Hot Tips for snow belays:
GENERALLY:
Don't use them unless you have to. You should really be looking for threads and spikes, hexes nuts and cams, or screws and abalokovs before you think about using a snow belay. But assuming there's nothing else...
BOLLARDS:
Bigger is better, and deeper is better. We sent 6 people 2 at a time down a 100m vertical snow face on Saturday, off a bollard about 8 feet across and 10 inches deep in hard snow. Any smaller and we wouldn't have done it. Make sure the walls are at least vertical and make a groove along the bottom to hold your rope. Also, remember that if you build a bollard in a popular spot, someone else will come along and use it; it's every man for himself but try to be responsible and make it as good as you can.
T-BELAYS:
Only half the strength of a T-belay is in the T itself; the other half is in your stance. Get your T dug, make sure the walls are at least vertical, and pack it in. Now dig your stance, preferably a seated one. The bucket you sit in should be so deep that with your ass on the bottom, the backs of your knees are at the lip. If there is a fall, you will be pulled down and into the seat instead of onto your crampons. Tie into the anchor, and get ready to go. Remember, DON'T USE A BELAY PLATE WITH THIS SYSTEM: use a body belay, or your seat will be redundant. If you don't know how to do a body belay, LEARN!
Last of all, don't think that by reading this post you know how to build a good snow belay, they need loads of practice, so get someone who knows what they're doing to show you how.
Good luck!
:wink:
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