UKC

positive and negative ice screw angle...

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Hornster 28 Oct 2004
Just read a really interesting article on the different loading strengths of an ice screw. From all the tests it was found that by placing the screw at a positive angle i.e. in the direction of the loading force (downwards) as opposed to the conventional 10' over perpendicular, the screw was in most cases twice as strong. This is because the strength of an ice screw comes from the thread and not from the "piton" effect as is commonly believed. However, this therefore means that in poor ice, the ice screw will need to rely more it's leverage ability than the thread.

Makes sense I thought.
Dave Hunter, Rock + Run 28 Oct 2004
In reply to Hornster:

Yes but only applies to good quality screws with good threads in decent ice.
Mind you, cheap screws tend to be unpredictable in breaking strength, have weak hangers and be difficult to insert into dense ice.
Hornster 28 Oct 2004
In reply to Dave Hunter, Rock + Run: That would also be true. That's why I don't climb with cheap screws. BD tubular screws for me.
SeanMcc 28 Oct 2004
In reply to Hornster:
Where did you read this? I would be interested in having a look at the article.
Hornster 28 Oct 2004
Dave Hunter, Rock + Run 28 Oct 2004
In reply to SeanMcc:

Craig Luebben's book 'How to Climb Ice' has a big section at the back on this. The Black Diamond website used to (and may still) have basically the same article (the testing was done mainly by BD)
Removed User 28 Oct 2004
In reply to Dave Hunter, Rock + Run: Worth a look at Will Gadd's book which uses the same credited information...but you already know that...
 Mike Pescod 30 Oct 2004
In reply to Hornster: I've known about this for a few years and have tried to place my ice screws accordingly but, to be honest, practicalities make it very difficult to do anything other than welly it in perpendicular to the surface. This also allows it to go in all the way which I'm sure is a major advantage!
Shaun@home 30 Oct 2004
In reply to SeanMcc: Here are a whole lot of Andy Kirkpatrick articles, lots of excellent reading if you haven't seen them already, he also comments on this topic of placing ice screws with a negative angle in one of the articles...
http://www.planetfear.net/climbing/highmountainmag/equipmentnotes/index.htm...
Hornster 01 Nov 2004
In reply to Mike Pescod: I was thinking the same thing with regards to the practicalities of placing a screw at such an angle. Especially when on steep ice. In situations where you are able to get both hands free I would think it possible but otherwise not.
 TobyA 01 Nov 2004
In reply to Hornster:
> In situations where you are able to get both hands free I would think it possible but otherwise not.

I climbed on pure ice probably averaging one day a week from december to early april last winter, so lets say around 20 days - I don't really know how many screws I placed but we tend to use quite a few here as the routes are short so you don't have to worry so much about getting completely pumped but you do have to think more about hitting the ground, but lets say it averages 10 placements a day. So from a guess of at least 200 screw placements last winter, I can tell you that you are wrong. It is perfectly possible to place a scew at, say, 10 degrees up even on vertical ice.

If you can't you are doing something very wrong, or need to buy some decent screws.
Hornster 01 Nov 2004
In reply to TobyA: We are talking about 1o degrees down i.e. negative angle not positive as is the traditional method.
Hornster 01 Nov 2004
In reply to TobyA: I will be exceedingly impressed if you managed to place the 200 screws you talk about in a negative angle to the ice. positive angle is easy and the norm. but negative is an all together different proposition.
 TobyA 02 Nov 2004
In reply to Hornster:
> (In reply to TobyA) I will be exceedingly impressed if you managed to place the 200 screws you talk about in a negative angle to the ice. positive angle is easy and the norm. but negative is an all together different proposition.

I mean with the hanger lower than the teeth, i.e. you point it up as you place it. I think what you describe as "the norm" hasn't been the norm amongst experienced ice climbers for about 8 years since BD and Climbing first did their research.

I'm not sure what you think is so impressive - it is not like you are trying to put them in at 45 o angle, I think BD's recommendation is only for 10 degrees or so.

Putting screws in on vertical ice is always a battle in my experience, getting the weight right between your arm and feet is important - sometimes you need to bend the legs a bit which can feel weird but having a straight arm is better: http://www.ukclimbing.com/images/dbpage.php?id=13576 some times you can use features in the ice to make it easier: http://www.ukclimbing.com/images/dbpage.php?id=10611 Adding a pit of angle to it is no big deal.

Anyways, how and where you place your screw all depends on the ice.

Have you actually tried it?
Alii 02 Nov 2004
In reply to TobyA:
>
> I'm not sure what you think is so impressive

I agree. If you're putting a modern screw in, at say waist level, not much difference putting it slightly upwards to putting it in perpendicular. Totally different with an old drive-in type obviously.
 TobyA 02 Nov 2004
In reply to Alii:
> Totally different with an old drive-in type obviously.

Yep. That would be 'fun'.

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