/ Snow Anchors - some recent strength results

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george mc - on 13 Feb 2013
Max Hunter MIC has done a great job describing our snow anchor testing at the AMI AGM http://maxhuntercouk.blogspot.co.uk/2013/01/cpd-at-ami-agm-snow-anchors.html

Also you can download the original article (which used a very similar snowpack to Max's account with results etc) at http://www.glenmorelodge.org.uk/cust_images/pdf/mountainsport%20articles/GMacDec06%20Snoe%20Anchors....

Or check out both links via stalkbo...err Facebook at:

https://www.facebook.com/MountainTraining?ref=hl


Ron Walker - on 13 Feb 2013
In reply to george mc:

Love the back up belay to stop the failed rocket propelled snow anchor taking out the test team...!
George_Surf - on 13 Feb 2013
In reply to george mc:

Thats interesting, it's always good to get a few real world figures on snow anchors and forces associated with winter climbing.
george mc - on 13 Feb 2013
In reply to george mc:

The snow pack was generally homogeneous and was on average allowed penetration by four fingers/fist i.e. was pretty soft and would be your amongst your worst case for building a snow anchor. The written test report records similar tests (as a similar aspect the other year)in a very similar snowpack.
george mc - on 13 Feb 2013
In reply to Ron Walker:
> (In reply to george mc)
>
> Love the back up belay to stop the failed rocket propelled snow anchor taking out the test team...!

Yup when these things pop out they do so at a fair rate!
IainMacG on 13 Feb 2013
In reply to george mc:
Really useful article and links George - thanks.
One question - photo of smaller snow bollard that failed was useful but how large was your large bollard?

cheers
Iain
Bruce Hooker - on 13 Feb 2013
In reply to george mc:

Just read that article - it doesn't really say much that isn't pretty obvious though, or is there a cmore complete version?
george mc - on 13 Feb 2013
In reply to IainMacG:

hi Iain
Glad you found it useful - the large bollard diameter was, if I recall, one arm span plus axe length i.e. stand at centre then, holding your axe by the end of the shaft reach up and scribe an arc - that's the diameter.

Cheery!
George
george mc - on 13 Feb 2013
In reply to Bruce Hooker:

Oh crap.... Linked to the wrong article.

This one should make more sense...

https://dl-web.dropbox.com/get/AMI%20Snow%20Anchors/GL%20Snow%20Anchor%20Testing%20December%202011_v...
george mc - on 13 Feb 2013
Ok I made a boo boo - wrong link to worng article (or correct link to wrong artcile...)

Take 2:

Max Hunter MIC has done a great job describing our snow anchor testing at the AMI AGM http://maxhuntercouk.blogspot.co.uk/2013/01/cpd-at-ami-agm-snow-anchors.html

Also you can download the original article (which used a very similar snowpack to Max's account with results etc) at https://dl-web.dropbox.com/get/AMI%20Snow%20Anchors/GL%20Snow%20Anchor%20Testing%20December%202011_v...

Or check out both links via stalkbo...err Facebook at:

https://www.facebook.com/MountainTraining?ref=hl
IainMacG on 13 Feb 2013
In reply to george mc:
Excellent - thanks George; a nice easy to remember approach to sizing!

cheers
Iain
jon on 13 Feb 2013
In reply to george mc:

The dropbox one doesn't work.
george mc - on 13 Feb 2013
In reply to george mc:

Not having much luck with my IT-fu...

https://www.dropbox.com/sh/jmj5qot769f9nng/GD5AC5bqgw
MG - on 13 Feb 2013
In reply to george mc: Thanks for that. Curious about the table showing comfortable and max loads sustainable using a braced sitting position. Large people apparently have a lower comfort force than medium people. Is there a reason for this (or are we just wimps)?

Also all the axe anchors seem pretty flimsy and not much if any stronger than a braced sitting position. Presumably a bucket seat is stronger than this. If so is digging a deeper bucket a better use of effort than trying to set up (weak) axe anchors?
george mc - on 13 Feb 2013
In reply to MG:

Before answering the context is that all these anchors were done in a poor quality snow pack i.e. it was not very strong. So you would expect most anchors to fail at some point. If the snow was very hard i.e. like cutting a pavement then you would expect non of the anchors to fail.

What we found was a bucket seat (and belayer sitting inside it) does a good job of sustaining a load - the limiting factor is the rope hurting as it's loaded around your waist (mind these were all static loads).

The key thing is the bucket seat should not be too deep (most folk though did them not deep enough). You'd want your bucket to have the front face perpendicular to the slope and deep enough so that the rope running around your waist comes out level with the top of the bucket. You don't want it either so deep your legs stick straight up (you could be pinged out) or b/ not deep enough or the front face sloping (most common error) such you are shot out of the bucket.

Bottom line as stated in the report - you want a bomber snow belay use an anchor, dig a bucket and attach yourself to both and use a waist belay to dynamically arrest a fall. Simples!
Lukeva - on 13 Feb 2013
In reply to george mc: Is a reinforced axe belay a T axe belay?
george mc - on 13 Feb 2013
In reply to Lukeva:
No it's a reinforced horizontal axe belay - a T Axe belay is a different beast and we did not test them.
Lukeva - on 13 Feb 2013
In reply to george mc: Thanks
Bruce Hooker - on 13 Feb 2013
In reply to george mc:

Thanks, I got it in the end. Now I am a member of "drop out" too which might be useful.

No mention of the old fashioned ice axe belay though, I suppose they are really out these days? Can't help feeling that the double buried axe of mammoth snow bollards would be a bit slow for anything except short climbs though.
nz Cragrat on 14 Feb 2013
In reply to george mc:

This might be of interest to people

www.mountainsafety.org.nz/assets/images/Snow%20Anchors0705.pdf
Kelcat - on 14 Feb 2013
In reply to george mc: hi George, couldn't make the link work (me I think, not you) but is it the recent article from the AMI magazine? If so it made very useful well informative reading.
george mc - on 15 Feb 2013
In reply to Kelcat:

Aye it is - in the Septemberish issue if I recall.
george mc - on 15 Feb 2013
In reply to Bruce Hooker:
> (In reply to george mc)
>
> Thanks, I got it in the end. Now I am a member of "drop out" too which might be useful.
>
> No mention of the old fashioned ice axe belay though, I suppose they are really out these days? Can't help feeling that the double buried axe of mammoth snow bollards would be a bit slow for anything except short climbs though.

Hi Bruce
The old style ice axe belay has been out of general use for a long time now. Even going back to the early eighties and beyond (according to my 'experienced' sources) because - it as very unreliable. Bit like snowstakes placed vertically. In saying that if the snow is very hard (and assuming you could get the thing in) then it might work but trying to insert a vertical axe into a pavement like snow pack is no mean feat...

Double buried axe? You mean the cattlehorn arrangement? Nope not that slow - quick to do and if working in a shite snowpack gives a reasonable increase in strength that's worth the time and effort.

Giant bollards - well you'd really only use a bollard for descending eh? In which case abbing off the thing I'd be taking the time to dig a massive one (and have done so on several occasions - bailing of Centre post direct and an ice route in the Rockies - both done using huge bollards in shite snow).
steveshaking - on 16 Feb 2013
In reply to george mc: Still not sure what you mean by the reinforced T axe belay, is the reinforcement a vertically buried axe behind the horizontal one with the load coming off the vertically buried one?
steveshaking - on 18 Feb 2013
In reply to steveshaking: Still hoping for an answer to this question. I can't see an explaination of the type of reinforcement in the articals.I am now presuming that following a previous answer on this thread the reinforcement is not from a vertical axe due to the difficulties of achieving this?
george mc - on 18 Feb 2013
In reply to steveshaking:
It's not a reinforced T axe - it's a reinforced horizontal axe. A T axe belay is a different beast and we did not test them. I think your confusing the two very different axe belay set-ups.

In the reinforced horizontal axe the sling comes of the buried horizontal axe, the vertical axe is inserted between the sling strands in front of the horizontal axe.

A T axe is a different belay. If you have access to the MTUK publication Winter Skills it'll show the difference.

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