Mark O'Neal Posted February 10, 2008 Share Posted February 10, 2008 If you were only going to carry one ice screw on a mixed alpine climb (as oh sh*t pro, it's icey here) What length would it be? Quote Link to comment Share on other sites More sharing options...
TrogdortheBurninator Posted February 10, 2008 Share Posted February 10, 2008 13 cm if you dont think youll need v threads 19 or 22 if you do Quote Link to comment Share on other sites More sharing options...
mike1 Posted February 10, 2008 Share Posted February 10, 2008 The more screw/ice surface contact the stronger the anchor. So it makes sense to take the longer screw if you have no idea what condition you may be faced with. You cover all your bases and you could always sling the screw if placing it in a shallow spot. Quote Link to comment Share on other sites More sharing options...
Mark O'Neal Posted February 11, 2008 Author Share Posted February 11, 2008 you could always sling the screw if placing it in a shallow spot. Â Am I understanding you right? If the screw is too long and can't go all the way in to the hilt, you can sling it? Sling it where? At the ice line around the screw? I think I'm missing something because it would seem like the threads on the screw would be kinda sharp. Quote Link to comment Share on other sites More sharing options...
crmlla2007 Posted February 11, 2008 Share Posted February 11, 2008 The threads don't go all the way to the end. Plenty of room to girth hitch a sling - check out some books and articles for pics and details. Quote Link to comment Share on other sites More sharing options...
catbirdseat Posted February 11, 2008 Share Posted February 11, 2008 Some tests were done by Leubben involving slung screws and unslung screws that were partially driven. What he found was that in a big fall, the unsupported part of the screw bends, the sling slides to the head and the hanger cuts the sling. If the screw is not slung, the screw bends, and it either fails or doesn't fail, but at least you don't have to worry about the sling getting cut. Quote Link to comment Share on other sites More sharing options...
luvshaker Posted February 11, 2008 Share Posted February 11, 2008 Bury you screw all the way. Bring two if need be. I'm fumbling to remember where I saw one of the best articles in a while on this stuff recently. Â "How to Ice climb" by Chris Luebben, was pretty sweet on describing different fall senerios (pp. 144-148) Just looking again, I'm remembering that a long screw is not always your friend (insert joke here). Lots of cool pics of 22cm screws bent to heck, and the poundage of falls listed below the pics. Good news is that often the carabiners broke first, which means that there where some pretty big fall factors going on. Â Â Quote Link to comment Share on other sites More sharing options...
Dane Posted February 11, 2008 Share Posted February 11, 2008 For that scenario, no question in my mind....10 to 13cm. Tying off screws is pretty much left to the unprepared or desperate these days. Although I thought it a resonable idea twice in one pitch this week  Only reason I still own a couple of 22s is to cut V threads. The threads give the holding power not the length of the screw.  But you can forget the V threads with a 13cm screw if you weigh more than 100#..btdt as well. Didn't work well. The newest generation of screws also preserve the ice (and its strength) during placement much better than the old days. Small blobs of good ice that will take a 13cm screw might well do the trick.  If you disagree read these links and goggle Craig Lubben...not *Chris*.  http://www.terragalleria.com/mountain/info/ice/bd-test.html  http://www.grivelnorthamerica.com/headlines.php?id=1&GrivelSess=b5803cb72430edd7ed2423fe3e973fdd  http://www.mra.org/services/grants/documents/DynamicShockLoadEvaluationofIceScrews_Final.pdf Quote Link to comment Share on other sites More sharing options...
TrogdortheBurninator Posted February 11, 2008 Share Posted February 11, 2008 The more screw/ice surface contact the stronger the anchor. So it makes sense to take the longer screw if you have no idea what condition you may be faced with. Almost all the holding power of a good screw comes from the outer threads of the screw (closer to the hanger). Moreso, the actual thread length on 13 cm and 22 cm is pretty similar (or identical i think). Your statement is only true if the surface ice is bad, but the underlying ice is decent. Even then, you could clear the surface ice. On a mixed alpine climb where the choice was between one screw and zero, you are far more likely to find thin ice <13 cm vs >22cm. In that situation, the completely driven 13cm screw is much stronger than a half driven 22cm screw. Â You cover all your bases and you could always sling the screw if placing it in a shallow spot. Quote Link to comment Share on other sites More sharing options...
Mark O'Neal Posted February 11, 2008 Author Share Posted February 11, 2008 Ah, see I knew I was missing something. You gotta love Google. They have the Luebben book online and I jumped right to the pages of interest.  I'm not anticipating a big leader fall. I'm thinking I could be on a 45-50° slope and want to put a screw in, either as piece of mind fall protection or to rap down. I suck at making V-threads btw.  So would the consensus be a 13cm? Quote Link to comment Share on other sites More sharing options...
Chudio Posted February 11, 2008 Share Posted February 11, 2008 I haven't tried this myself, but I read that it's better to use a wire nut to sling the partially driven screw. Push the wires up past the plastic thing that holds both wires together, sling it around the screw and choke it down. Has anyone tried this method? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.