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Z-Man

ice screw placement in hollow ice

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This happened to me recently and was no big deal as the ice was easy but made me think. Say all you have on your rack are screws longer than the ice is thick, much longer. The ice is hollow underneath after some thickness so the screw easily punches through. What should the screw placement look like? I was thinking these are the three plausible placements:

 

screw1.JPG

 

The screw is put in only as far as the threads are all in the ice.

 

screw2.JPG

 

The screw is pushed back as far as possible so hanger is flush with ice surface.

 

screw3.JPG

 

Somewhere in between where screw is pushed in as much as possible while still keeping some threads in the ice.

 

I think that option 1 with a tie-off of the shaft would be preferable as the most threads are in the ice and would most approximate having a shorter screw available.

 

Option 2 eliminates leverage issues, but could conceivably shock-load if the screw has much wiggle room behind the ice.

 

Option 3 lowers the leverage issues and is my pick if you can get the hanger within 2" of the ice surface, as according to this data, web page , having the hanger that close eliminates the need for a tie-off, but this option reduces the amount of threads in the ice.

 

Any thoughts?

Edited by Z-Man

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in hypothetical fantasy world I would place #2 above and equalize it to the hanger of #1 directly below it and not use a tie off anywhere.

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dont place the screw in hollow ice! find a better placement.... honestly it is like placing a 1" nut in a 3" crack, you can, but why would you tongue.gif

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Why put 1 on the bottom and not 2? Or is this just arbitrary? Seems like the bottom placement you would want the least leverage problems.

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Hey Z-man,

 

My gumby $0.02:

 

If the ice is hollow, what about punching two holes separated by 12" or so, and threading webbing through them in a U shape? If one hole is above the other, hopefully the tail of the webbing will drop straight down and be reachable with your V-threader from the lower hole. I guess this presumes you can get a screw in to at least hang from, while you are monkeying around with cord and a V-threader.

 

Never really tried this on steep terrain, where the anchor had really better work. Maybe someone else has tried this?

 

Barring that, I'd go for option #1 with a tie-off and a screamer.

 

Option 2 seems like the worst possible idea, from the standpoint of shock-loading and also allowing more up-down play in the screw.

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Stephen, you ain't no gumby.

 

This is definitely not belay terrain, but a "v-thread" as it were seems like the strongest option.

 

Is there a way to directly tie off a screamer? Do they make them with extra material available to do this? I'm assuming you would otherwise just clip it in to the sling you tied off with? Seems like that puts a lot of room between the screw and the rope.

 

Again this is assuming you only have long screws, meaning that a shorter screw would work just fine if you had one.

Edited by Z-Man

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In my experience placing a screw as per diagram a) or c) above is completely unsafe. There is an enormous amount of force generated in even a short leader fall, and leaving part of a screw sticking out of the ice, even in good ice, creates an unwanted lever arm that just increases the load on the screw, especially around the bottom of the tube where the screw compresses the ice during a fall. Screws even in the best ice, fully in, rip out with regularity during leader falls.

 

I believe most climbers are willingly unaware of what their protection can actually do in the real world. Just as most trad rock climbers have never actually fallen, let alone fallen big on their own pro, even more ice climbers have never taken a lead fall, let alone on a screw, let alone on a screw in bad ice. (The same could be said about people's use of snow anchors.) Thats not a bad thing that ice climbers arent taking falls, but it doesnt lead to real awareness in inexperienced or even experienced climbers about what loads are generated or what the system can actually handle. In rock climbing the usual cure is to go aid climbing, where you bouce test and are forced to body-weight each piece you place, you get a very intimate awareness for what pro can do. Here you realize that most of the pro you've placed wouldnt probably hold a leader fall. But this type of education doesnt exist in ice climbing, so you are left with your own fall resume, what you've seen, and printed reports like that excellent study done some years ago on ice screw failure. For example, for me the only fall I've ever taken was a ground fall. The only other fall I've ever seen was a 10 foot fall onto a perfect screw in fat strong ice, which ripped easily and became a factor 2 fall directly onto the belay.

 

So the questions become "how comfortable are you soloing?" and "is your life worth leaving the ground unprepared?".

 

Because if you are placing screws in crappy ice in any of the above ways and actually believe in it, you are simply deluding yourself - you are soloing, your screws won't hold in a real fall situation, though if you are lucky they might hold you while you lower off. Even with screamers! ...screamers just get the load of a leader fall within the load limits of the ice screws themselves, around 10kN. If you use normal draws directly on ice screws you are hurting your chances for surviving a lead fall significantly. This is the reason you should use screamers...not to hold the falls when you place a screw in garbage (cause nothing other than God is propping you up there), but to hold the falls by well placed screws in the best ice.

 

Leaving the ground unprepared means leading ice without taking the tools you need to climb safely. This includes stubby 10cm screws, 13cm screws which have threads all the way to the hanger, pins, long slings to tie off bushes and large ice features, Vthread tat and a Vthreader. If you are not so armed, especially around here where the climbs are not so nearly frequented, fat, and well equipped as the Rockies or Lillooet or Hyalite, you are again deluding yourself about your safety.

 

<edit>So what to do? One option is the next time you go ice climbing, TR something. Take a pack and a 10-foot piece of rope. Load up the pack, place a screw, clip the pack to one end of the 10ft section of rope and clip the other end to the screw, and heave it off! See what happens. A day spent doing this will make you vastly more familiar with what ice and ice screws can actually do in even "light load" situations

 

As for being prepared, at a minimum always carry Vthread and a threader. 10 and 13cm screws are a very good investment, in fact 13s in good ice are going to be just as strong as the standard 16-17cm screws. As a bonus, the 13s have threading all the way up the shaft, making them the best option for tricky placements that might be partially hollow. Invest in screamers, one for each screw you own. Dont use them and blow them out during rock climbing season, as they trigger at really low loads, but every screw placement you make should have a screamer.

 

learn how to look for good ice and place screws effectively in it. Unfortunately, nothing substitutes for real experience and real mentoring here, and ever neophyte ice climber owes it to themselves to get real lessons in ice screw placement (and removal, I can't tell you how many times ive had a second get to the belay with cores still in screws, firmly frozen) from a very experienced climber friend

</edit>

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that's because if the screws fail, they brake. an ice screw is a tube, hence it has enough strength along the axis. most likely situation is you place a screw, you fall. the ice breaks under the hanger of the screw, creating shearing force and tube loses it's integrity. that's why it is important to place screws 10 degrees up.

one more note to alex's comment. yes 13 cm screws are as strong. as the matter of fact most of the guys in canmore use 1- 22cm for v-threads, have a couple 16cm and the rest is 13 and 10. much lighter rack. rock gear yes!. also be patient. one thing i have learned is that usually you can get decent gear if you are patient enough.

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comments:

 

a. if the ice really is as you describe, i.e., considerably thinner than the ice screw is long, i can't imagine ANY of the proposed placement options holding.

 

b. bob's comment is dead-on. if you look around lots, think about it, and work at it, you usually can get a decent placement, even in pretty poor ice. straight down often works for me when horizontal doesn't.

 

c. if you're on a "shell" of ice, you might well be able to knock a fist-sized hole thru the ice, girth-hitch the middle of the screw, insert the whole works, and "T-slot" the screw. any impact force will be spread over a FAR greater surface area this way than it would be with a "screwed" screw, and i suspect (as with crappy anchors in snow) the holding power might be surprisingly reasonable.

 

d. if you can't get pro, either just keep your shit together and climb the thing "solo", or come down - there's no dishonor in backing off, and there's a lasting stigma to dying!

 

cheers, don

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Even with screamers! ...screamers just get the load of a leader fall within the load limits of the ice screws themselves, around 10kN.

Hi Alex,

 

I'm sorry, but from a physics standpoint, I don't see how this statement is necesssarily true in all situations. A normal Yates screamer will activate at 2 kN. That leaves a big range of forces between the activation force of a screamer and the ideal 10 kN limit of a screw. Why is it not conceivable that a screamer could be useful even if your impact force without a screamer would be in the range 2 kN < X < 10 kN, for example, low fall factor, non-vertical terrain, and a nice dynamic belay?

 

Cheers,

Steve

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Why is it not conceivable that a screamer could be useful even if your impact force without a screamer would be in the range 2 kN < X < 10 kN, for example, low fall factor, non-vertical terrain, and a nice dynamic belay?

 

I believe strongly that screamers are not only useful in all situations, but necessary in all situations, which is why I suggested you put one on every ice screw placement you make. Sorry if this was not clear. The point I was trying to make is that screamers should not be reserved for or limited to junk placements in some mistaken belief that they will save your ass when the ice or the placement is crap, they should be used ubiquitously to get potential leader falls within acceptable load limits as much as possible.

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FWIW: I think Craig Luebben did a study a few years ago suggesting that one should NEVER tie-off and ice screw. In his tests, the sling ALWAYS cut on the hanger before the screw pulled out. Even with an inch of screw remaining out of the ice, it was better to clip the hanger.

 

I think this study was publishe in Rock and Ice or Climbing a few years ago.

 

Cheers

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Yeah, his results as I recall them were -

 

if less than 2" of screw is sticking out of the ice, clip it

 

if more than 2" of screw is sticking out, use a shorter screw instead.

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Not necessarily germaine to the discussion at hand but some might find interesting from the perspective of screamer use.

 

Anecdotal experience: when I fell last winter (~20-30ft) the screamer fully deployed and the screw held. No physical change to the screw whatsoever, at least not visible to the naked eye. The placement felt solid at the time and went in to the hanger but given the conditions of the ice where I fell, I am not so sure it was good ice.

 

Maybe its not terribly logical of me to feel this way, but I am convinced that the screamer saved my life. I'm with Alex, and will use screamers as much as possible.

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that's why it is important to place screws 10 degrees up.

 

Assuming solid ice, don't you mean place screws in an angle slanting down? I think that was the general conclusion of the Leuben/Harmsten study.

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Well if the hanger is down, you will have to screw it upwards into the ice......

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My 2 cents after spending time climbing with some very experienced ice climbers:

 

1. it was kind of mentioned, but if possible place screws at an upward angle - 10 degrees, not horizontal.

 

2. T-slotting a screw through a hole in the ice is a BAD idea. You'd be much better off putting two holes in and slinging it.

 

3. although i'll take some flak for this, other than for protecting the belay (first placement or two after the belay), screamers can be overrated. I've heard of good reasons why they can even be bad in some situations (specifcally for ice climbing), but i can't recall exactly why. But it made a lot of sense at the time and came from some very well respected climbers who now rarely use them. I'll see if i can find the info. The BD website also used to have a really good section on ice placements - they may still.

 

4. I also take some flak for this, but we did a number of test falls (using a dumby) on good to shitty ice and although it was anything but a controlled a scientific experiment, it was very surprising just how well screws held, even in what I would consider shitty ice. Not that this should encourage you to throw caution to the wind, but i was shocked at some of the falls that held.

 

5. but mostly, i'd stress what the other have, look around, be creative - find something decent, even if it means downclimbing a bit to find a better placement.

 

6. ps - for ice climbing buy the ropes with the lowest impact force. While you do open yourself up to longer falls, it can make a huge difference. Probably more so than any screamer would.

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