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Topic: alternative ice pro, or garbo? (Read 1366 times)
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alecapone
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Cleaning the garage and I found these pieces of fall protection from my construction days. debating if they have any use...
Same diameter as an ice screw. designed for a much heavier load, but with differant dynamics. weight is somewhere in between a real screw and the throw away bail out screws.
my thoughts of usefullness would be towards emergancy use as they would probably be hard to clean(remove)., but could posibly provide a more solid hold?
thoughts?
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scott
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Pete A
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interesting! seems like a puzzle for Mythbusters....
at least when those concrete anchors are new, they're pricey little suckers.... i wonder if you could craigslist them and pick up a few bail screws instead.
i could imagine the concrete anchor would dig into the ice under load enough that cleaning could be really tough... would be interesting to test one of those with a backup in place.... my worry would be that a screw distributes its load over a larger surface area if all the threads are engaged into the ice, while a concrete anchor would concentrate the load to a much smaller area (though it seems unlikely it could pull completely out if buried to the hilt in ice.
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T. Eastman
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Are you nuts? The comments are way to polite. Don't even think of using those things in ice.
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samthaman
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Are you nuts? The comments are way to polite. Don't even think of using those things in ice.
seriously, that seems so sketchy. You'd be putting a massive outward force on the ice from the inside. I'm picturing a "cam behind a flake" type effect.
If they made a smaller version, it seems like it would be a cool way to use old bolt holes for protection.
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blitz
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Posts: 314
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Lowell - regarding the V-threads:
I am not an ice climber - but I've built some rock anchors in my day. That "V-thread" looks REALLY scary to me.
Please explain why you trust that, do you make a few and then equalize them?
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alisa
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korup
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Posts: 320
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Well-built V-threads are completely bomber, assuming the ice is solid and there isn't too much bright sun (black nylon etc in the spring in direct sunlight, etc).
Always put two in, in different sections of ice if possible.
Here are some sweet pull tests, c/o Petzl:
http://www.dailymotion.com/video/x7z2t1_ice-anchor-workshop_sport
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Lowell_Skoog
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Hi Alisa,
Try this link:
http://www.theascendingpath.com/documents/Ice%20Climbing%20Anchor%20Strength%20-%20MRA%202009%20-%20Marc%20Beverly.pdf
I found it thru google. I think there are more studies out there. From the above study I learned that Abalakov anchors oriented vertically ("A-Thread," one hole above the other) are stronger than ones oriented horizontally ("V-Thread"). I didn't know that. The study debunks the notion that Abalakov anchors are stronger than ice screws (I didn't know that either), but says they are strong enough for rappels.
Like any ice anchor, you have to evaluate the quality of the ice and your placement when you build it. I've only used Abalakovs a few times, many years ago, but I think they're really useful. Much better than the older practice of pounding steel conduit into the ice as a back-off anchor. Talk about litter...
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blitz
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Posts: 314
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Scary - rappel gently or you die!
Thanks for the video and studies andy and lowell.
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alisa
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Scotsman
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Scary - rappel gently or you die!
Thanks for the video and studies andy and lowell.
Rapping from v-threads is fairly common and the preferred method for most of the modern day super alpinists.
See Colin Haley's' blog Skagit Alpinism.
http://www.colinhaley.blogspot.com/
Quote"
Yet more rappelling... The nice thing about rappelling the North Buttress is that there is enough ice to rappel on v-threads the entire way, and by threading the rope directly through the v-threads we were able to rappel a 1,500m buttress without leaving behind a single sling!" End Quote
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Chief Etiquette Officer of TAY and TAY's #1 Poster
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"Most Brilliant Move" of the 11/12 ski season
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Pete A
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by lacing the rope directly through a V-thread hole though, it seems like you'd be unable to have an equalized anchor spread over two V-threads... right? so you're just relying on a single V-thread...or is there some super-tricky method that I can't figure out? (like lacing the rope in and out of multiple holes...which would seem like a real rope drag mess when pulling ones ropes)
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Scotsman
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by lacing the rope directly through a V-thread hole though, it seems like you'd be unable to have an equalized anchor spread over two V-threads... right? so you're just relying on a single V-thread...or is there some super-tricky method that I can't figure out? (like lacing the rope in and out of multiple holes...which would seem like a real rope drag mess when pulling ones ropes)
You'd have to ask Colin but from his blog above I interpret that to mean single v-thread and pulling rope. Most of the guys at Colin's level... from what I read... have a risk tolerance ...and/or confidence in their anchors... way above what the recreational mountaineer is comfortable with. They are also probably using thin 7.6 mm weight ropes so pull drag but not be as much as you suspect.
Edit to add. Found this pic on the wed.....looks skookum!
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 vthread.jpg (92.2 KB, 375x500 - viewed 297 times.)
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« Last Edit: 07/21/11, 02:08 PM by Scotsman »
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Chief Etiquette Officer of TAY and TAY's #1 Poster
Poet Laureate of TAY.
Chairman and Founder of FOTAY( Friends of TAY)
Moderator of the moderators.
"Most Brilliant Move" of the 11/12 ski season
" Knows what he is talking about"
Expert Typist.
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ryanb
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You can back a v thread up with a screw in a separate part of the ice clipped to the rope with a sling and, send the heaviest dude down first and then the last (lightest) guy can pull the back up.
Equalization isn't as important as redundancy and minimizing extension in the event of partial failure for most anchor building...recent testing has shown that some of the most commonly used equalization techniques don't really do much (see the latest edition of john long's climbing anchors book).
They do sell removable bolt things like the ones pictured (in smaller size) for use on rock but they aren't very common and i wouldn't trust them in ice as i suspect their holding power is based on friction (rock climbing cams don't work on ice)...screws work because of the teeth which is why a slightly downward point screw is strongest.
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Lowell_Skoog
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The table on p. 13 of this document it says the mean strength for a V-thread was 11.3 kN and for an A-thread, 14.4 kN. The minimum for a V-thread was 5.2 kN and for an A-thread, 10.9 kN. For comparison, 10kN is equivalent to 2200 pounds.
On the same page it says: "The good news is that all of the configurations and materials used were strong enough to hold abseilers/rappellers with a significant safety margin from a single anchor point. Testing showed that anchors could fail at below expected climber fall (7.5 kN) forces and should be backed up if in any doubt."
From this I conclude that rappeling from a single Abalakov anchor in good ice is safe. During a typical rappeling sequence, climbers will place an ice screw for security before building a rappel anchor, so it's a simple matter to back up the Abalakov for every rappeller but the last. I think the fears about Abalakov anchors in this thread are unjustified if you know how to build the anchor properly.
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