/ NEW ARTICLE: Ice Climbing Anchor Strength - Analysis
Just how strong are abolokov threads and re-bored ice screws? Read on and find out!
Read more at http://www.ukclimbing.com/articles/page.php?id=4315
cheers there george mc.
easy to read, asked the right questions, realistic experiments.
can never be short of functional information in the department.
Another great article George, very informative on an interesting subject. I hope you don't mind if I post the link below? It is the Petzl test video, a wee bit older but interesting none the less.
Very useful, and well presented - thanks!
Regular pauchler of other folks screwholes so glad to see the stats.
The original article left out a fair bit of information regarding the method, for example the temperature at the time of each test and the time between the original hole and the re-bored screw being placed.
It's also worth noting that the tests were carried out on lake ice not waterfall ice. This is important and is shown by the difference in results for the few abolokovs they did do on waterfall ice.
The article also draws some quite strong conclusions from quite variable data, which is due to such a small sample size and often they should have stated it was inconclusive or done more tests to explain the anomalies.
My final point, which is seriously poor form for any work, is that the article states the best configuration is with the largest area enveloped then contradicts this saying you should drill a 60x60x60 anchor. This does not envelope as much ice as a 45x45x90 triangle, which is the configuration recommended in Allen Fyffe and Iain Peters book, 'The Handbook of Climbing'.
I was waiting for this post as I remember distincly a long UKC thread picking apart the original acrticle and dissmissing it in many ways. I couldn't find the thread, it would be great to link to it!
I seem to remember the study claimed that 60 60 60 anchor envelops the most area of ice, which is factually incorrect and IIRC would actually be the 45 45 90 config.
Very nice article, well done!
Is that likely to be serious though? Larger angles are harder to drill and the difference in area is about 13%. I thought the real key was maintaining good ice (take care chipping those start slots).
What a silly thing to say. My point is how carefully you make it is way more important than the exact angle.
I happen to mark on an S curve as do most academics. Even on a linear measure 13% can be the difference between a fail and a fail or a 1st and a 1st.
did you use area of a cone or area of a triangle
You remind me of the B ark occupants in hitchhikers guide: when questioned on why they hadn't invented the wheel yet they replied "if you're so clever you tell me what colour it should be".
Right, easy to dismiss my question but I believe you started using percentages. As in general a block of ice more akin to a cone is displaced than a triange the actual difference in volume of these cones is quite a lot, the 45 45 90 system produces a cone with 60 percent larger volume than the 60 60 60.
My thoughts too.
To those arguing over the volume of ice contained etc, it is all too academic, in reality you build the anchor (I don't carry a protractor on my rack) assess it and back it up if necessary
the article we are discussing is afterall academic, and really it's good to have an ideal to aim for isn't it.
In reality I'm always happy when the holes line up on an Abalakov, which seems uncannily often, maybe I am lucky?
While a 45 degree screw placement will give you a larger cone you won't be able to make practical use of this unless you excavate a large enough gap to spin the handle. A screw at 45 degrees to the surface will need a pretty big chunk chopped out if you want to use the whole length and disturbing the ice by a placement isn't the best practice.
Also a 45 degree hole will also put a higher load on the lip, which may make it more likely that the surface ice plates off.
I'd probably use 60 rather than 45 because it is easier to eye-ball it especially if you are using 1 screw.
You make a good argument, I think the main argument on the previous thread was that the paper was factually incorrect rather than the 45 45 45 arrangement was better, anyway it wasn't orginally my point to argue for.
however black diamond seem to have a different opinion and suggest 45 ;)
Best practice would be to aim for the strongest anchor possible. It's always hard to get the initial bite at an angle but it just takes practice and another benefit of aiming for 45 deg is that it's an easy angle to visually judge. Another thing to think about is you're never going to get the angle perfect - If you aim for 60 deg and are 5 deg out (so drill 65) then that is about 0.76 of the strength of the best, 45 deg case. 10 deg out and it's reduced 0.64 of the strength.
But for me the main issue with this is that, along with other poor parts of the article, it has made me questions their results and method to the point where I don't trust them. One of the questions which I think is important is regarding the time between re-bored screws. Do you get similar results if you place the screw straight after the initial hole was drilled as you would if you did it the next day? Unfortunately the article mentions the importance of this but then doesn't actually say what method was used in the tests.
Because of the lack of information about the method in the article it is impossible to know if the conclusions have been interpreted accurately from well thought out scientific experiments, or if they are complete non-sense.
All right then I'll bite on the angle point. Firstly the surface ice may be imperfect or not exactly flat and that little bit of extra depth in good ice will be handy. Secondly there is the full depth issue as the screw head will hit earlier at 45 than 60. You keep working with Curly on the colour for that wheel.
This is not really the main reason I brought it up though. The main point was that inconsistencies and mistakes reduce the credibility of the research.
Whilst this trigonometry discussion is fascinating, has anyone ever heard of the V thread related accident that occurred to a new thread, correctly tied and properly threaded with the rope of anchor? A cursory search reveals zero, so I might leave my protractor at home.
When drilling a thread you need to aim for an angle and this should be chosen for logical reasons.
These pointless arguments on safety trivia that often completely miss a wider perspective that I see as vital in climbing make me wonder why some people climb at all. I suppose protractors might distract the poor dears from the fact they might get hurt in their hobby. Sorry I missed your satire.
Now deadmen are a different story (a red one).
"I don't believe it's simply a question of area and you'd be daft to try and assert that it IS that simple - I know you're not doing that but some others are.."
Mike the original article asserted that the 60 60 60 enveloped the largest area of ice so was therefore the strongest, yet another potential oversight.
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