Continue with onX Maps
Sign in with Facebook
Ice Anchors
|
What is everyone’s go to screws for multipitch ice anchors? I’m upgrading to the Blue Ice Aeros (steel) but want to keep some of my BD Express’ for anchors because of the useful double hangers. How many and what sizes do you keep in your kit for anchors? I’m hearing some people say that 16’s are widely being accepted for anchors on most climbs with good ice, thoughts? |
|
My thought is delete the duplicate thread. |
Old lady H wrote: Thanks! |
|
I have Black Diamond and Petzl screws. I have never found a use for the two clip in points on the BD, stuff does not fit into both holes. I´m happy to clip a carabiner into a carabiner if I need to. |
|
IMO the only reason to have a few BD screws is because you already own them. If you're starting from scratch, there are better options. Again, IMO. |
Gunkiemike wrote: What you racking up with Mike? Also, what sizes are you using at the anchors? |
|
The easy and annoying answer is it depends on ice conditions and your risk tolerance. I’ve been perfectly happy with a pair of 13cm screws in fat blue ice and been terrified by a nest of 16cm to 22cm screws in shitty rotten aerated ice. In general, I try to keep at least one 16cm screw on my harness to pair with whatever else I have left at the top of a pitch for an anchor. Most often I’m building a two-screw anchor with that 16cm plus one. Sometimes that’s another 16, sometimes it’s a 13, occasionally its an 11. I rarely bring more than one 22cm screw per team and while I might use it in an anchor on the way up, I keep it free on the way down to drill threads. |
Jeff Barrett wrote: Two 16s is generally fine. In great ice I'm OK with a 16 and a 13. But every situation is different. Sometimes I can thread a pillar or curtain. My long screws are old Grivels. Shorter ones are CAMP and Blue Ice. Stubbies are BD. |
|
Since the breaking strength is almost exclusively determined by the thread length rather than the length of the full screw you can use any screw with 13 cm and above for building "full strength" anchors since they usually have identical thread lengths anyways. Ice quality always has to be considered but if the ice is just bad all the way and doesn't get substantially better on the inside, your safety margin with a longer screw is not greater than with a shorter one. Again, the thread / worm is what holds the screw in, the additional shaft length is just for reaching better ice if applicable. |
|
I almost climb exclusively with a fistful of Blue Ice and Petzl (3tooth) 13cm aluminums along with a Blue Ice 16cm steel just to feel good and for threads Haven’t had a screw bind in 3 years, and never had a 13cm bind period. Do not foresee ever climbing with a screw over 16 cm ever again and never with any steel other than a BI aero Edit caveat: I have and use some super stubbies that I had Gunkiemike make from some old BD Express. Those are nice to have and use to protect at thin, rocky, late season top outs. And Jeff, I looked at your climbs from Nipi and Northern MN. Using those as examples, All would do fine with either a 2x 13cm or a 13 and 16 cm screw anchor under 95% of their typical conditions. Those are as bomber as ice gets. |
Oliver Schmidt wrote: Exactly! Too many people don't understand this, and think of ice screws like framing screws or something - longer must equal more holding power, right? |
|
"Since the breaking strength is almost exclusively determined by the thread length rather than the length of the full screw..." Is there any reference or test results to support this? In this study, One the conclusions states; "the longer the ice screw is, the stronger the ice anchor will be". Youtube version; https://www.youtube.com/watch?v=j_xpQ7XkDas |
chris wrote: Unfortunately I only have a German source for this: https://tinyurl.com/DAV-Sicherheitsforschung By just skimming over it I don't draw the same conclusions as the authors of the study you linked. The drop tower tests (which are more significant than the slow pulls imo) don't show a strong correlation between length and breaking strength (fig. 7). Also this was not even part of the tested hypothesis, since the study was mostly about reusing holes and abalakovs. |
chris wrote: You read, but didn’t fully understand that 15 year old loosely applicable data. As far as it applies to you, the ice climber, placing on lead a fresh screw into decent ice, the length of screw makes no real statistical difference in whether that screw will hold your fall. It will. And don’t get confused on the density issue like Beverly and Attaway did. For example if you place a 13cm BI Aluminum screw in solid uniform lake ice (about as good ice as you’ll ever get) you will get about 24 ml of water. A gold std solid placement. If you screw into waterfall ice and your core comes out to be about 12 ml of water, your placement is roughly half as strong…as you hit about 50% air pockets/gaps in the ice during that placement. Now nobody is measuring their core volumes during a lead, but you CAN estimate it and note to self, roughly was that placement solid or maybe 75% or 50% marginal and factor that into your next planned placement |
|
Herr Schmidt. I believe paper states at one point, Long screws (22cm) bring no significant gain in strength compared to medium length ones. And, optimal lenght is 15 to 18 cm. (German classes a long time ago). They don't present much support for the statements. Mr. Pilate. I would like to think I understood it well enough. Like the German paper, there is not a lot of supporting data. The conclusion statement is quite clear (and in English). To your density concerns, the paper does propose ice testing as future research. |
|
Chris- fair enough, but your original post seemed a bit misleading as the very paper and data you cited showed no increased strength due to length for dynamic drop tests…which is what climbers care about. Regardless, the data is all over the map and was with a low sample size of all re-bores, not freshly placed screws so inferring any correlations from that data (slow pull or dynamic) would be a reach anyway. Edit: response to Jimmy Strange’s Grivel references above about threads: I would normally agree and thought that originally myself. In fact, if I would manufacture my own screws, they’d be basically Blue Ice aluminums with the Grivel thread….However, screws never fail by pure outward pull (unless you’re doing a glacier cave roof) the stress and fracture cone is immediately below the bottom surface of the screw. The ideal 13degree placement angle attempts to optimize this stress into the ice and upon the threads, but once that lower supporting cone fails, the screw tips or levers out regardless of thread style or length of screw. For sure if you were able to run enough tests, the data would begin to show that longer screws and reverse thread screws are a very small tad better overall on average, but at least I’m not convinced that slight edge is worth suffering the drawbacks 100% of the time for that 0.0001% of the time you may need it. |
|
2 16s is my gold standard for just about anything |
Mark Pilate wrote: Good info! Thanks Mark. We’ll seeya around Sandstone. I believe i’ve bumped into you a couple times already this year. |
|
The mention of the Grivel threads brought this paper to mind. https://www.cnsasa.it/storage/wcms_f/alleg/LPV_documenti/Articolo%20Viti%20Ghiaccio.pdf In Italian and they use the UIAA test medium (not water ice). Also, lacking support data. The axial pull tests seem to show 50 to 60% of radial tests for the short screws tested. Conclusion #6," in good ice even short screws can provide adequate sealing but, when the ice and climbing conditions allow it, it is always preferable a medium vine (15-18 cm); long screws may have their uses at belays or for the construction of Abalakov." #8 "straight or reverse threads, if they show no differences under radial loads, they certainly distribute the axial component of the load differently with better distribution with reverse thread." (translation by Google) |
