UKC

Preferred ice screw length - Scottish winter

New Topic
This topic has been archived, and won't accept reply postings.
 Stevie989 06 Dec 2015
What's is your preferred length for nice screws for Scottish winter?

I'd be tempted to get 2 or 3 shorter screws (logic being that the ice will often not be 'that' thick) a couple of medium lengths and one (or two?) large screw.

 CurlyStevo 06 Dec 2015
In reply to Stevie989:
I dunno about that. I've seem a lot of fat ice in Scotland. Certainly for N Wales stubby screws are the norm. For mixed routes I often don't bother with screws, it depends on the venue, conditons and route choice obviously.

For pure ice routes with ice screw belays suitable for uk and euro ice I'd go for something like:
2 22cm, 2 19cm, 4 16cm 2 13 cm 2 10cm

I guess if I was buying only for Scotland I'd loose a 22 and maybe a 10 and get more 13/16
Post edited at 20:16
 Mountain Llama 06 Dec 2015
In reply to Stevie989:
shared gear as follows;

16cm BD turbo express are my preferred ice protection (6 max)

also carry DMM 13cm (2 off)

maybe 1 or 2 19cm BD turbo express depending on conditions


 Jamie B 06 Dec 2015
In reply to Stevie989:

16cm screws are the backbone of my rack, I find that a range of different sizes plays havoc with my racking system. As long as I've got one bigger and one smaller stashed somewhere off to the side.
 planetmarshall 07 Dec 2015
In reply to Stevie989:

16cm is typical from personal experience and observations of others. Short screws are useful when in "panic mode". Have rarely used anything longer except for drilling threads.
1
 CurlyStevo 07 Dec 2015
In reply to planetmarshall:
For true ice routes with ice screw belays I'd really want something longer than 16cm for atleast one of the belay screws per belay. Results from BD do show the 22cm screws generally seem to fail at a higher load, http://www.needlesports.com/content/ice-screw-placement.aspx

What's especially interesting and important are the lowest fail kn figures are quite a bit higher than for smaller screws they tested.


Post edited at 10:54
 CMcBain 07 Dec 2015
In reply to Stevie989:

Most of mine are 16cm, with a couple longer ones for belays(19/22cm) and a couple shorter ones for thin ice (13cm). You can always tie off 16cm ones if they don't screw all the way in, not ideal but you probably shouldn't be contemplating falling in that sort of situation anyway!

I'd echo Jamie B's comment above about too many sizes being a faff, especially if you just have 2 ice clipper things. I usually put all the 16's on my right side, and the rest on the left side.
 planetmarshall 07 Dec 2015
In reply to CurlyStevo:

> For true ice routes with ice screw belays I'd really want something longer than 16cm for atleast one of the belay screws per belay. Results from BD do show the 22cm screws generally seem to fail at a higher load, http://www.needlesports.com/content/ice-screw-placement.aspx

Higher, sure, but if the average breaking strength of a 17cm screw ( in good ice ) is 21.6kN, it's probably not the screws I'd be concerned about.
 Mr. Lee 07 Dec 2015
In reply to Stevie989:

Not climbed Scottish ice for a few years now but generally speaking I'd say 16cm screws are my stock. Longer is definately better for belays, or when there's a good resting position for placing a longer screw. A longer screw can be good for the head beneath cruxes as well but once into the difficulties 16cm screws are quicker to place and easier to handle. If carrying 9 screws I would around one 13cm screw for when thinner ice or when urgently in need of a quick placement. Generally I don't bother with short screws otherwise. If I can't sink a decent length screw then I just larks hitch the shaft with a short sling. Also, Scottish ice is often not as hard as pure water ice, which makes it easier to climb but probably weaker to protect. Therefore I'm not convinced 10cm screws are going to hold much of a fall in many cases. Incidentally I like the look and idea of the Eclimb Icepider for thin/desparate ice placements, although don't own one yet (Santa). I'd go for 5 16cm, 2 19cm and 1 13cm if BD? 22cm best for abalakovs but I can't recall ever doing an abalakov in Scotland.
 NottsRich 07 Dec 2015
In reply to Stevie989:

Agree with everyone else. Mainly 16cm for Scottish ice, with a longer 22cm for making threads.
 SteveJC94 07 Dec 2015
In reply to Stevie989:

I mostly go for 13cm and 16cm but its worth having a few stubbies in case you fancy doing some thin face climbing
 CurlyStevo 07 Dec 2015
In reply to planetmarshall:

> Higher, sure, but if the average breaking strength of a 17cm screw ( in good ice ) is 21.6kN, it's probably not the screws I'd be concerned about.

That wasn't really the point I was making. Screws are far less predictable than rock gear. They can fail at much lower loads even when there is no obvious visual clues. I was pointing out that the lower end of the failure, the force a screw can hold is greater for the longer screws and its at a level that could cause belay failure (especially for a factor 2 fall) at a around 8 - 10 kn.
 CurlyStevo 07 Dec 2015
In reply to planetmarshall:

Plus you've also got to consider those tests were done in solid dense ice. Sometimes you may be relying on ice which isn't as good as that.
 planetmarshall 07 Dec 2015
In reply to CurlyStevo:

> I was pointing out that the lower end of the failure, the force a screw can hold is greater for the longer screws and its at a level that could cause belay failure (especially for a factor 2 fall) at a around 8 - 10 kn.

Possibly, but that's not what their data shows. A single screw out of 113 17cm screws failed at a lower threshold than a single screw out of 86 22cm screws, is what their data shows. They also show that a 13cm screw failed at 10.6 kN - but I'm not about to start replacing all my 16cm screws with 13cm ones - I'm not going to draw conclusions from a single sample.

In the absence of more useful data - say the 10th percentile values - I maintain that the difference in average performance between the 17cm and 22cm screws is negligible enough to not be a cause of concern.

As for screws in cruddy ice - well then all bets are off. Maybe someone should do an experiment in ice that more accurately reflects Scottish conditions, but for an experiment to be useful we do need to eliminate some of the variables - the obvious one being the condition of the ice.

I did find the observation about horizontal vs vertical placements interesting, though.



 CurlyStevo 07 Dec 2015
In reply to planetmarshall:
You are completely correct that the difference in average performance is negligible (when you consider the kn that the average are failing at in the bd test) however I think the data is pointing towards 22cm screws having a lower frequency of screws pulling out at levels that could be experienced when ice climbing. Some other studies have also found longer screws are stronger http://hmga.gr/storehouse/word-acrobat/Ice%20Climbing%20Anchor%20Strength%2... "The longer the ice screw is the stronger the ice anchor will be" and you can clearly see failure rates at fairly low peak forces in their study.

I wasn't suggesting testing screws in cruddy ice, however ice does vary and can be hard to completely assess. I'm just saying the figures they found may suggest trends but I wouldn't take the strength of the ice screws in the BD test too literally when you are applying them to Scottish ice, AFAIK they created the ice in a lab in smallish cells .

In the real world you also need to account for the deeper ice being often more homogenous, having a more stable temperature and being less brittle, longer screws give better access to this ice.
Post edited at 17:10
 alasdair19 07 Dec 2015
In reply to Stevie989:

1 or 2 max shorties mostly mediums one long. but borroe b your mates as much as possible or get the petzl sharpening tool
OP Stevie989 07 Dec 2015
In reply to Stevie989:

Cheers guys - all noted.

New Topic
This topic has been archived, and won't accept reply postings.
Loading Notifications...