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sittingduck
Dec 1, 2009, 6:46 PM
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From the other day on an alpine ice-climb, anchor rigged by me wearing big mittens. - 2 screw-gate carabiners - 2 fig 8's on a bight - 2 clove-hitches We used a 50m 1/1 rope and a 60m 1/2 rope, so it made sense rigging with the 60m rope.
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altelis
Dec 1, 2009, 7:22 PM
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only thing i would change is putting a knot in the section of rope in b/w the two screws. without the knot, the gear pulls or the rope gets cut (however unlikely) the anchor is poop. with a knot its redundant. other than that, assuming the ice is good and there's more than a single thread in the ice, gtg.
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sittingduck
Dec 1, 2009, 7:29 PM
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altelis wrote: only thing i would change is putting a knot in the section of rope in b/w the two screws. without the knot, the gear pulls or the rope gets cut (however unlikely) the anchor is poop. with a knot its redundant. other than that, assuming the ice is good and there's more than a single thread in the ice, gtg. The ropes coming down from the screws are connected to the powerpoint. One by a screw-gate carabiner and the other going into the fig-8 knot that makes the powerpoint. If the rope you mention gets cut the powerpoint will still be connected to both icescrews. Sorry that the picture is a bit obscured by my sloppy rigging.
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altelis
Dec 1, 2009, 7:37 PM
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sittingduck wrote: altelis wrote: only thing i would change is putting a knot in the section of rope in b/w the two screws. without the knot, the gear pulls or the rope gets cut (however unlikely) the anchor is poop. with a knot its redundant. other than that, assuming the ice is good and there's more than a single thread in the ice, gtg. The ropes coming down from the screws are connected to the powerpoint. One by a screw-gate carabiner and the other going into the fig-8 knot that makes the powerpoint. If the rope you mention gets cut the powerpoint will still be connected to both icescrews. Sorry that the picture is a bit obscured by my sloppy rigging. No, I get that. I see that. But WHY make it that complicated with that much slack in the red rope's knots? If it were me? I would only have incorporated ONE rope into the anchor. Just like you did with red rope. But put a knot in b/w the screws and clip myself with a clove in the rope going to me into that knot. Leave the second rope out of the anchor completely (including as a connection to the anchor). Gives more versatility. LIke I said though- as long as you put that knot in I would climb on it even with the 2 ropes being included....
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sittingduck
Dec 1, 2009, 8:01 PM
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If you put a knot in the rope between the ice-screws you do not get dynamic equalization. The slack I think you have in mind, is there to allow dynamic equalization. Incorporating both ropes in my self belay gives me a redundant powerpoint. Maybe it looks complicated, fact is that I rig this in a minute wearing mittens. Knitting a pair of mittens is complicated rope management, rigging this anchor isn't.
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altelis
Dec 1, 2009, 8:19 PM
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the slack i'm looking at is b/w the cloves and the knot in the red rope. this does NOT provide for dynamic equalization. i guess that i'm just not sold on the importance of dynamic equalization (at least most of the time). i know the anchor isn't going to take a while to construct, and its not over the top complicated. but what is complicated is how you expect it to function. you have, in essence two anchors. one you expect to dynamically equalize and a second as a backup in case a piece blows and the dynamically equalizes anchor fails. why? just throw that knot in and don't obsess about the dynamically equalizes bit.
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majid_sabet
Dec 1, 2009, 8:23 PM
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sittingduck wrote: If you put a knot in the rope between the ice-screws you do not get dynamic equalization. The slack I think you have in mind, is there to allow dynamic equalization. Incorporating both ropes in my self belay gives me a redundant powerpoint. Maybe it looks complicated, fact is that I rig this in a minute wearing mittens. Knitting a pair of mittens is complicated rope management, rigging this anchor isn't. you used a dynamic line to build that anchor and like or not, you have a semi dynamic anchor to start with which subject to 30% elongation is SOL fall factors. the several inches of slack that you got in between the two points will rip that ice screw out so put a fig 8 in the master point and do not worry about micro equalization.
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sittingduck
Dec 1, 2009, 8:38 PM
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Sure the slack could have been tighter, I'll tune it in next time. You are not sold on dynamic equalization, why do that make me obsessive about it? You chose a method that likely will put all the force on one piece, while I use a method that likely will put 50% of the force on each piece. I consider this an important factor for my anchor to withstand a FF2 fall, that is WHY I use it.
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majid_sabet
Dec 1, 2009, 8:49 PM
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alright let me ask you this if I get puller and start pulling those ice screws out (one by one), How many KN do you think it requires to pull them out ?
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sittingduck
Dec 1, 2009, 8:56 PM
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majid_sabet wrote: alright let me ask you this if I get puller and start pulling those ice screws out (one by one), How many KN do you think it requires to pull them out ? Try the search function or start your own thread about ice-screw properties. Whatever you do, please stop spamming this thread.
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rockforlife
Dec 1, 2009, 9:02 PM
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majid_sabet wrote: alright let me ask you this if I get puller and start pulling those ice screws out (one by one), How many KN do you think it requires to pull them out ? if they were put in right, in good ice... more than you think
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altelis
Dec 1, 2009, 9:26 PM
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sorry, you aren't obsessed by it. like i said, its prob fine. but my way won't put all the force on one piece, either- fairs fair.
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hafilax
Dec 1, 2009, 9:39 PM
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I probably would have lowered the power point. Looks like the angle is close to 90*. The question of equalization vs. shock loading may never get answered. It seems to be an even more convoluted question with ice screws as far as I can tell. I just did a quick search and came up with a paper I hadn't read before. http://www.mra.org/..._IceScrews_Final.pdf They did some drop tests at Ouray. Seems that screws can fail anywhere between 4 and 15kN in 'good' ice. Experience in placing screws is perhaps more important than for placing rock gear. With FF2 drops they never got above 9kN which is probably due to the maximum impact force properties of the ropes. The data points over 9kN and up to 14kN were FF1+ and the highest were FF1.4+ in simulated lead falls. Given that seemingly well placed screws can fail at surprisingly low loads means that answering the equalization vs. shock loading question could be of great value. It also shows that the pulley effect must also be taken into account when planning for the worst case scenario.
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sittingduck
Dec 1, 2009, 9:48 PM
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altelis wrote: sorry, you aren't obsessed by it. like i said, its prob fine. but my way won't put all the force on one piece, either- fairs fair. How much equalization do you get in the case of a pendulum? You advised me to belay myself with only one of my ropes to the anchor. If I did that, the powerpoint would be a single strand fig 8 loop. In the case of a FF2 fall, this loop would be the only component connecting me and my partner to the mountain. The ropes get pretty badly abused in the mountains, with crampons and ice axes, hence the 1/1 rope and the double loop at the powerpoint.
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altelis
Dec 1, 2009, 9:59 PM
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when i tie anchors like this i use a double loop knot (usually an 8, though a bowline on a bight works too). i also try and incorporate as much "stance" into alpine anchors as possible, which helps the most with a pendulum. though, for the second the fall will pull from the last piece of pro (a known place), and the pull for the leader will be from the first piece of pro (a piece one can take a good guess about). and a ff2? well, that will pull straight down. again, i want to stress that i would prob climb on it, and have climbed on similar anchors before. i was just saying what i would have done differently in a similar situation. not saying yours is wrong, just saying i apparently have different priorities (apparently).
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sungam
Dec 1, 2009, 10:34 PM
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hafilax wrote: I probably would have lowered the power point. Looks like the angle is close to 90*. That' my only real comment, though I would have clove-hitched the screws.
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sittingduck
Dec 1, 2009, 10:51 PM
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hafilax wrote: I probably would have lowered the power point. Looks like the angle is close to 90*. That scared me to when looking at the picture. I think it is the point of view that makes it look that way. Imagine leaning towards and below the anchor, the angle would look more and more like 180*. I know I am aware of that angle when I rig my anchors. Thanks for noticing.
hafilax wrote: The question of equalization vs. shock loading may never get answered. It seems to be an even more convoluted question with ice screws as far as I can tell. I just did a quick search and came up with a paper I hadn't read before. http://www.mra.org/..._IceScrews_Final.pdf They did some drop tests at Ouray. Seems that screws can fail anywhere between 4 and 15kN in 'good' ice. Experience in placing screws is perhaps more important than for placing rock gear. With FF2 drops they never got above 9kN which is probably due to the maximum impact force properties of the ropes. The data points over 9kN and up to 14kN were FF1+ and the highest were FF1.4+ in simulated lead falls. Given that seemingly well placed screws can fail at surprisingly low loads means that answering the equalization vs. shock loading question could be of great value. It also shows that the pulley effect must also be taken into account when planning for the worst case scenario. Shockloading seems to be right up there with the microfractures, when it comes to adding enormous peak loads to the anchor. It will be great when someone bust that myth. Strange that it takes so long? Interesting article. Ice quality and experience seems to be key, and anything else than ice-screws is worthless as protection on ice. For instance, using the axes as part of the anchor has little to no value. I still use snargs on slush and warthogs on top outs, even if I doubt they will hold a fall. Appreciate your comments hafilax.
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sittingduck
Dec 1, 2009, 10:56 PM
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sungam wrote: hafilax wrote: I probably would have lowered the power point. Looks like the angle is close to 90*. That' my only real comment, though I would have clove-hitched the screws. The screws are clove hitched. It says so in the first post: "two clove hitches".
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sungam
Dec 1, 2009, 11:05 PM
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sittingduck wrote: sungam wrote: hafilax wrote: I probably would have lowered the power point. Looks like the angle is close to 90*. That' my only real comment, though I would have clove-hitched the screws. The screws are clove hitched. It says so in the first post: "two clove hitches". So they are. Cool beans, it seems. Although, tbh, if I'm reading the situation right you are leading on twins or doubles, right? I would have cloved one to each screw, then just sat back and belayed off myself. Though having said that, this will be my first season with an autoblocker so my tactics will probably be changing.
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hafilax
Dec 1, 2009, 11:13 PM
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I wouldn't call shockloading a myth*. It's a question of knowing in what situations shock loading is dangerous. Rigging an anchor with dyneema and clipping to it with a dyneema sling would make shock loading a worry whereas using dynamic materials may reduce the effect. It's understanding the transition between the two regimes that needs to be explored. Ice is another issue because with 2 screws there is a relatively high probability that one could fail at a modest load and maybe even both of them. The properties of ice in responding to a dynamic load are far more complicated than with rock and metal. So what is the best strategy for creating an anchor system that is least likely to fail? I don't know the answer and it would be nice to have something more concrete than people's gut feeling as to how much equalization and shock loading play a role in that equation. *nor microfractures for that matter since they are important outside of climbing
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sittingduck
Dec 1, 2009, 11:14 PM
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altelis wrote: when i tie anchors like this i use a double loop knot (usually an 8, though a bowline on a bight works too). If you use a bunny ear fig 8 on your powerpoint, and one of your loops blows, your knot is compromised since the bunny ear fig 8 is not redundant. Meaning the other loop will blow to.
altelis wrote: i also try and incorporate as much "stance" into alpine anchors as possible, which helps the most with a pendulum. though, for the second the fall will pull from the last piece of pro (a known place), and the pull for the leader will be from the first piece of pro (a piece one can take a good guess about). and a ff2? well, that will pull straight down. again, i want to stress that i would prob climb on it, and have climbed on similar anchors before. i was just saying what i would have done differently in a similar situation. not saying yours is wrong, just saying i apparently have different priorities (apparently). Could you post a picture or a drawing of a simular anchor? I'd be very interested! We have different priorities, no problem.
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sittingduck
Dec 2, 2009, 12:01 AM
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In reply to: I wouldn't call shockloading a myth*. It's a question of knowing in what situations shock loading is dangerous. Rigging an anchor with dyneema and clipping to it with a dyneema sling would make shock loading a worry whereas using dynamic materials may reduce the effect. It's understanding the transition between the two regimes that needs to be explored. The way shockloading has been hyped here at this forum is worthy of mythology imho. The anchor has no static components, myth or not, there is not much more I can do to take the myth into consideration. Maximum equalization between two good placements is the method I chose to avoid shock loading. The question is, do I know what constitutes a good ice-screw placement? Edited to add quote tags
(This post was edited by sittingduck on Dec 2, 2009, 12:07 AM)
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sittingduck
Dec 2, 2009, 12:29 AM
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In reply to: Although, tbh, if I'm reading the situation right you are leading on twins or doubles, right? I would have cloved one to each screw, then just sat back and belayed off myself. Though having said that, this will be my first season with an autoblocker so my tactics will probably be changing. Yes and no, it is a 1/1 rope and a 1/2 rope. Used as doubles. What if you collected the ropes between you and the screws and tied a fig 8 on a bight on it? Then you could have one rope run through a carabiner in this powerpoint. If the leader where to fall on the anchor you would not have him hanging only from your belayloop and belay carabiner. One rope would go directly to the leader and one rope upward, through the powerpoint, and then to the leader.
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hafilax
Dec 2, 2009, 12:39 AM
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sittingduck wrote: In reply to: I wouldn't call shockloading a myth*. It's a question of knowing in what situations shock loading is dangerous. Rigging an anchor with dyneema and clipping to it with a dyneema sling would make shock loading a worry whereas using dynamic materials may reduce the effect. It's understanding the transition between the two regimes that needs to be explored. The way shockloading has been hyped here at this forum is worthy of mythology imho. The anchor has no static components, myth or not, there is not much more I can do to take the myth into consideration. Maximum equalization between two good placements is the method I chose to avoid shock loading. The question is, do I know what constitutes a good ice-screw placement? Edited to add quote tags You miitigate shock loading by using your ropes in the anchor and limiting extension. You equalize the anchor in the hopes that by sharing the load between the screws you may not have to test whether or not shock loading is a myth.
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sungam
Dec 2, 2009, 8:46 AM
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sittingduck wrote: In reply to: Although, tbh, if I'm reading the situation right you are leading on twins or doubles, right? I would have cloved one to each screw, then just sat back and belayed off myself. Though having said that, this will be my first season with an autoblocker so my tactics will probably be changing. Yes and no, it is a 1/1 rope and a 1/2 rope. Used as doubles. What if you collected the ropes between you and the screws and tied a fig 8 on a bight on it? Then you could have one rope run through a carabiner in this powerpoint. If the leader where to fall on the anchor you would not have him hanging only from your belayloop and belay carabiner. One rope would go directly to the leader and one rope upward, through the powerpoint, and then to the leader. That would magnify the forces exherted on the anchor by the pully effect. Also, I generally get some kind of stanceness going on (even if it's just a very small chopped ledge) I can take some of the weight on me, using the anchor as little as possible. If need be I can escape the system fairly rapidly.
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patto
Dec 2, 2009, 1:44 PM
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sittingduck wrote: hafilax wrote: I probably would have lowered the power point. Looks like the angle is close to 90*. That scared me to when looking at the picture. The perspective of the photo if anything decreases the angle and so flatters you anchor. At 90* you have already increased the force on your anchor by 41% so well done!
sittingduck wrote: You chose a method that likely will put all the force on one piece, while I use a method that likely will put 50% of the force on each piece. On what basis do you make this claim? Basic triginometry says otherwise. Basic trigonometry has already pointed to the fact that you are now loading each piece with 71% of the total force on the anchor.
sittingduck wrote: Shockloading seems to be right up there with the microfractures, when it comes to adding enormous peak loads to the anchor. It will be great when someone bust that myth. Strange that it takes so long? Shock load IS NOT A MYTH Shock loading is extremely real. In fact a Factor 2 fall is a shock load otherwise you wouldn't need to build anchors 10x the weight of a person. As I have said 100x already on this site, in the case where there is negligable weight attached to the anchor then shock loading becomes a non issue. But in cases where there is a load involved, ie the belayer or equipment then shock loading is VERY real.
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shoo
Dec 2, 2009, 2:23 PM
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patto wrote: sittingduck wrote: hafilax wrote: I probably would have lowered the power point. Looks like the angle is close to 90*. That scared me to when looking at the picture. The perspective of the photo if anything decreases the angle and so flatters you anchor. At 90* you have already increased the force on your anchor by 41% so well done! That number is more or less meaningless. The sum of the forces on all points of an anchor doesn't have any direct bearing whatsoever on the safety of the anchor. What does matter is the force experienced by each individual piece. By your logic, one piece loaded directly would be the ideal, since any additional piece would increase the total force experienced by all pieces in the system as long as there was any angle between them and the master point. However, 90 degrees is quite a bit more than you want in general. I agree that the master point should probably have been lower to reduce this angle.
(This post was edited by shoo on Dec 2, 2009, 2:43 PM)
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patto
Dec 2, 2009, 3:01 PM
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shoo wrote: By your logic, one piece loaded directly would be the ideal, since any additional piece would increase the total force experienced by all pieces in the system as long as there was any angle between them and the master point. Most certainly not. I have not suggested anything of the sort. Please do not assume things I haven't said. By my logic less time should be spent worrying about 'micro equalisation' as majid put it and more time worrying about getting a good redundant anchor that is equalised for a downwards pull. An anchor that isn't going to shockload and extend in the rare chance of a piece blowing.
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sittingduck
Dec 2, 2009, 9:05 PM
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sungam wrote: That would magnify the forces exherted on the anchor by the pully effect. Also, I generally get some kind of stanceness going on (even if it's just a very small chopped ledge) I can take some of the weight on me, using the anchor as little as possible. If need be I can escape the system fairly rapidly. Maybe until the second rope tightens up? By all means, go ahead and take all the force you manage off your anchor from your chopped ledge. Why do you suddenly bring escaping the system into the discussion? Do you think it is relevant?
patto wrote: - T1 text removed -
shoo wrote: However, 90 degrees is quite a bit more than you want in general. I agree that the master point should probably have been lower to reduce this angle. Dont feed the troll. Of course the angle should be 60* or less, you are correct. The anchor is not there anymore so I can not take any more photos of it. I know the angle is less than what it appears in the picture. It is easy for you to have a look at a sling rigged correctly, from different angles to see for yourself.
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rangerrob
Dec 2, 2009, 9:07 PM
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I'm not sure I understand why this anchor needs to be so complicated. Two piece anchor using the rope as anchor material right? Use enough slack to clove hitch each pitch and have slack in between. then fix the tie in point with afigure eight on a bight. Pretty simple. The more complex you make it the easier you will f*** it up! RR
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sittingduck
Dec 2, 2009, 9:16 PM
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rangerrob wrote: I'm not sure I understand why this anchor needs to be so complicated. Two piece anchor using the rope as anchor material right? Use enough slack to clove hitch each pitch and have slack in between. then fix the tie in point with afigure eight on a bight. Pretty simple. The more complex you make it the easier you will f*** it up! RR I think I said it earlier in this thread: to have dynamic equalization between my two ice-screws. If I could make it any less complex, and keep the properties, I would.
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sungam
Dec 2, 2009, 9:39 PM
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sittingduck wrote: sungam wrote: That would magnify the forces exherted on the anchor by the pully effect. Also, I generally get some kind of stanceness going on (even if it's just a very small chopped ledge) I can take some of the weight on me, using the anchor as little as possible. If need be I can escape the system fairly rapidly. Maybe until the second rope tightens up? By all means, go ahead and take all the force you manage off your anchor from your chopped ledge. Why do you suddenly bring escaping the system into the discussion? Do you think it is relevant? Is it relevant? yes - it's the main downside to belaying directly off your harness. What do you mean by "until the second rope tightens up"?
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patto
Dec 2, 2009, 11:18 PM
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sittingduck wrote: Dont feed the troll. You posted 'An alpine anchor to analyze' yet you call me a troll because I analyze it? Poor form sittingduck. Did you only want to hear positive comments? Is you head in the sand so much you don't want to believe shockloading exists?
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sittingduck
Dec 2, 2009, 11:43 PM
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sungam wrote: Is it relevant? yes - it's the main downside to belaying directly off your harness. What do you mean by "until the second rope tightens up"? Are you trying to say that belaying the way I do makes self rescue difficult or more difficult than the way you belay? I mean that there are two ropes and maybe both will become tight in a FF2 fall because of the stretch in the ropes. The stretch in the rope through the powerpoint, in addition to the slip in the brake, might be enough to engage the second rope. If so, the carabiner in the powerpoint would take downward force, almost the same way the carabiner in the belay loop would, if you where belaying directly from the harness without a redirect.
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dingus
Dec 3, 2009, 12:22 AM
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sittingduck wrote: Shockloading seems to be right up there with the microfractures, when it comes to adding enormous peak loads to the anchor. Shock loading myth HAS BEEN BUST but members of this site for some reason are very slow to hear the news. Oh well. DMT
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sittingduck
Dec 3, 2009, 12:39 AM
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dingus wrote: sittingduck wrote: Shockloading seems to be right up there with the microfractures, when it comes to adding enormous peak loads to the anchor. Shock loading myth HAS BEEN BUST but members of this site for some reason are very slow to hear the news. Oh well. DMT well, that's well. Lets move on.
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majid_sabet
Dec 3, 2009, 12:43 AM
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patto wrote: sittingduck wrote: Dont feed the troll. You posted 'An alpine anchor to analyze' yet you call me a troll because I analyze it? Poor form sittingduck. Did you only want to hear positive comments? Is you head in the sand so much you don't want to believe shockloading exists? he is a troll
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sittingduck
Dec 3, 2009, 1:21 AM
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How many accounts do you have?
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hafilax
Dec 3, 2009, 1:29 AM
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dingus wrote: sittingduck wrote: Shockloading seems to be right up there with the microfractures, when it comes to adding enormous peak loads to the anchor. Shock loading myth HAS BEEN BUST but members of this site for some reason are very slow to hear the news. Oh well. DMT I wouldn't call it a myth and it hasn't been busted. Ask rgold why he doesn't use a PAS. It's a major consideration with static materials. It's less of a consideration if there is a length of dynamic rope in there but the transition between the two regimes isn't fully understood.
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patto
Dec 3, 2009, 1:41 AM
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dingus wrote: sittingduck wrote: Shockloading seems to be right up there with the microfractures, when it comes to adding enormous peak loads to the anchor. Shock loading myth HAS BEEN BUST but members of this site for some reason are very slow to hear the news. Oh well. DMT Dingus it most certainly hasn't. And it doesn't become anymore of a myth the more you assert it. Basic physics and hard evidence has shown that shockloading exists. You arguing it doesn't is denying basic physics. JL's testing has shown that that shock loading is negligable in circumstances where there is negligable weight on the anchor. This is as theory predicts. It deeply disturbs me the way so many people have gotten this wrong. Significantly higher forces will result if a weighted anchor is allowed to extend and shockload. THAT IS FACT.
hafilax wrote: ]I wouldn't call it a myth and it hasn't been busted. Ask rgold why he doesn't use a PAS. It's a major consideration with static materials. It's less of a consideration if there is a length of dynamic rope in there but the transition between the two regimes isn't fully understood. You are correct. In fact more of my anchors I make are with dynamic rope. With a dynamic rope as part of your anchor you are essentially created a 2nd fall scenario. With hardness/body stretch and the rest of the rope in system this 2nd fall would be have a <0.5 FF equivalent. Still this is unecessary extra load being put on an already compromised anchor. Where the hell is everyone getting this notion that it is only a myth!? Is it only JL's work? If so you need to understand the limitted context in which that applies.
(This post was edited by patto on Dec 3, 2009, 1:48 AM)
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patto
Dec 3, 2009, 2:10 AM
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But some of you don't seem to have faith in my appeal to maths and physics. Do you have faith in Rgold? (Bolding is my emphasis)
rgold wrote: I agree with Jim that shock loading is an undefined term. Although defining it as exceeding some particular threshold value of df/dt (sometimes called the jerk---I don't think, as claimed above, that impulse is the appropriate quantity) would be essential for mathematical modeling and certain types of testing, it won't be of any direct use to climbers to have such a distinction. Nonetheless, it is clear what shock loading has always meant when used in climbing contexts: a shock load has always been the load imposed on an anchor by the arresting a free fall of some sort, and in this sense, there is nothing remotely mythical about the concept. According to this reasonable working definition, any time something drops and is stopped, there is a shock load to the arresting system. Of course, once you have an actual definition like this, you have to give up the mythical uniform condemnation of all shock loads as "bad." A shock load is only "bad" if it breaks some part of the system or is the direct cause of an injury to a climber, and in this sense is neither better nor worse than any other kind of load. However, system performance under shock loads (i.e. free-fall impacts) may not be the same as if the system is loaded slowly to the same maximum level. For example, there is some preliminary evidence that shock-loaded dynamic ropes behave like ideal Hooke's law springs (during the loading phase), but the same ropes, if slow-pulled to the same maximum tension, exhibit a load-elongation curve that is better modeled with a quadratic equation. In the sliding-X testing, opposite results on equalization have been obtained (by different testers) from slow-loading and shock loading tests. One reason for the discrepancies that have emerged to date may be differences in the role of friction, both within the rope itself and in the system, for the two types of loading (and it is here that the threshold value of the jerk might actually become definitive). I think it is fair to say that the current characterization of shock loading as a "myth" traces its ancestry to Sterlingjim's tests about the effect of the failure of an anchor leg in a two-point anchor rigged with a sliding X. In these tests, after the simulated failure of an anchor point, the elongation in the anchor rigging extended the fall of the weight, resulting in what I think should be called a potentially higher shock load to the remaining anchor point (whether or not an anchor point fails, the system was shock loaded). The tests revealed no major increase in the expected load to the second anchor point after the first anchor point had failed, and it is this result that has been interpreted as busting the "myth" of shock loading. Personally, and with all due respect to and gratitude for the amount of thought and work that went into the testing, work done by Sterlingjim and others on a pro bono basis with the expectation of nothing but hassles in the discussions to come, I think the tests themselves may have been misleading, because the amount of rope in the system was relatively large compared to the anchor extension. The result of that configuration is that the anchor point failure resulted in a very small increase in fall factor, which therefore should not be expected to produce much beyond the expected effect in the remaining anchor. In a climbing situation in which gear failure produces anchor extension, the belayer takes a short fall whose energy must be absorbed by the tie-in. Even forgetting entirely about the load imposed by the falling leader, the ratio of anchor extension to tie-in length determines a fall factor for the belayer that could be high and so could result in a significant load increase on the remaining anchors. Until it is possible to do anchor extenstion tests involving a belay weight tied in realistically close to the anchor as well as a falling weight, I'd be cautious about assuming anchor extension has a negligible effect on the load on the remaining pieces. This means that equalette users would be wise to minimize the potential effects of anchor extensions by making their tie-in to the power point as long as is feasible. (This is usually easy to do. For example, a three-foot tie-in to an anchor that has a potential three-inch extension gives rise to a tie-in fall factor less than 0.1.) The most important single thing to do to keep potential small anchor extensions from being a problem is to use the climbing rope to tie in to the power point. Using nylon or, even worse, spectra slings or cords would significantly magnify the effects of the tie-in fall factor and could, in principle, result in extremely high loads if the anchor extends. But sittingduck YOU should know all this because YOU started the thread http://www.rockclimbing.com/...um.cgi?post=1637886;. It seems ducks don't learn quickly.
(This post was edited by patto on Dec 3, 2009, 2:17 AM)
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sungam
Dec 3, 2009, 12:33 PM
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sittingduck wrote: sungam wrote: Is it relevant? yes - it's the main downside to belaying directly off your harness. What do you mean by "until the second rope tightens up"? Are you trying to say that belaying the way I do makes self rescue difficult or more difficult than the way you belay? I mean that there are two ropes and maybe both will become tight in a FF2 fall because of the stretch in the ropes. The stretch in the rope through the powerpoint, in addition to the slip in the brake, might be enough to engage the second rope. If so, the carabiner in the powerpoint would take downward force, almost the same way the carabiner in the belay loop would, if you where belaying directly from the harness without a redirect. Look, I'm not sure if you are trying to act stupid or not, but I'm going to answer. The inability to easily and quickly escape the system, as I said before, is the main downside (a long with the fact autoblockers are just less hassle) in my eyes of belaying off your harness directly to the second. If the rope goes from the belay plate on your harness up to a caribiner attached to the anchor then down to the second, the forces on the anchor are more then doubled. This is the main downside of belaying from your harness with a redirect through an anchor. Belaying directly off the anchor with an autoblocking plate does not cause this effect.
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dingus
Dec 3, 2009, 2:24 PM
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patto wrote: If so you need to understand the limitted context in which that applies. Right the 'limited' context is a multi-piece anchor where one piece pulls and the rig extends and this extension 'causes' a shockload on the remaining pieces increasing the risk that they will fail too. THAT is the limited context we are talking. Which just so happens to be the context of this thread. PAS has nothing to do with it. Cheers DMT
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dingus
Dec 3, 2009, 2:27 PM
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patto wrote: Significantly higher forces will result if a weighted anchor is allowed to extend and shockload. THAT IS FACT. Prove it. Real world, not chalk board. Prove your math is correct. No PAS, no FF2s on static bullshit... real world belays, real world measurements... prove it. No one ever had done this. Its theory, nothing more. DMT
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shoo
Dec 3, 2009, 2:37 PM
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sungam wrote: If the rope goes from the belay plate on your harness up to a caribiner attached to the anchor then down to the second, the forces on the anchor are more then doubled. Close, but not quite. A redirected belay will increase the forces on the anchor by a maximum factor of 2 compared with belaying directly off the anchor. Any friction or angles in the system will reduce this force multiplier.
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sungam
Dec 3, 2009, 2:43 PM
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shoo wrote: sungam wrote: If the rope goes from the belay plate on your harness up to a caribiner attached to the anchor then down to the second, the forces on the anchor are more then doubled. Close, but not quite. A redirected belay will increase the forces on the anchor by a maximum factor of 2 compared with belaying directly off the anchor. Any friction or angles in the system will reduce this force multiplier. What I was referring to was the fact the belayer takes some of the force when belaying directly off themselves. Sorry for my terrible grammar/writing.
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Rudmin
Dec 3, 2009, 2:47 PM
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Kind of a tangent here, but Remember the tests that a sliding x didn't equalize perfectly because of friction. That means it also won't shock load perfectly because of the same friction. A 2 arm anchor equalizing anchor is somewhat analogous to a differential on a car. It works until one of your wheels loses traction and spins out (like an anchor blowing and the master point sliding). The solution of course is a limited slip differential that locks up to some degree when you let one of the arms go free. This is basically what the friction in a sliding X is doing to some degree. You could increase that friction by putting another wrap around the biner in, giving you something between a sliding X and knot on a bight. Not perfect in either situation, but the ideal case is probably somewhere in between.
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sittingduck
Dec 3, 2009, 8:49 PM
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sungam wrote: The inability to easily and quickly escape the system, as I said before, is the main downside (a long with the fact autoblockers are just less hassle) in my eyes of belaying off your harness directly to the second. If the rope goes from the belay plate on your harness up to a caribiner attached to the anchor then down to the second, the forces on the anchor are more then doubled. This is the main downside of belaying from your harness with a redirect through an anchor. Belaying directly off the anchor with an autoblocking plate does not cause this effect. You are talking about bringing up a second while I'm talking about belaying a leader that falls into the anchor. I belay from the anchor when belaying a second. When belaying a leader I belay from the harness and clip one of the ropes to the powerpoint. Do you now understand what I said about the second rope?
Rudmin wrote: Kind of a tangent here, but Remember the tests that a sliding x didn't equalize perfectly because of friction. That means it also won't shock load perfectly because of the same friction. That makes sense, to bad it equalizes so poorly.
Rudmin wrote: A 2 arm anchor equalizing anchor is somewhat analogous to a differential on a car. It works until one of your wheels loses traction and spins out (like an anchor blowing and the master point sliding). The solution of course is a limited slip differential that locks up to some degree when you let one of the arms go free. This is basically what the friction in a sliding X is doing to some degree. You could increase that friction by putting another wrap around the biner in, giving you something between a sliding X and knot on a bight. Not perfect in either situation, but the ideal case is probably somewhere in between. Clipping the leaders rope to a screamer in the powerpoint?
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adnix
Dec 3, 2009, 9:54 PM
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[image]http://www.home.no/sittingduck/sd_anchor.jpg[/image] 1. Use only one rope with a fig 8 power knot for anchor and ditch the backup rope. 2. 20cm Longer ropes would help with angle. By alpine standards your stand is quite ok, though. I've belayed on a single ice hook with my partner falling while seconding. Alpine superstars like Marko Prezelj sometimes belay on ice tools. Imagine two ice tools in stead of your screws. If the ice is thin screws don't work. I wouldn't advise belaying on tools regularly but in some cases improvisation is better than nothing.
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sittingduck
Dec 3, 2009, 11:49 PM
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adnix wrote: 1. Use only one rope with a fig 8 power knot for anchor and ditch the backup rope. 2. 20cm Longer ropes would help with angle. By alpine standards your stand is quite ok, though. I've belayed on a single ice hook with my partner falling while seconding. Alpine superstars like Marko Prezelj sometimes belay on ice tools. Imagine two ice tools in stead of your screws. If the ice is thin screws don't work. I wouldn't advise belaying on tools regularly but in some cases improvisation is better than nothing. 1. As long as no one falls, any rig works fine. If those where ice-tools, instead of good ice-screws, any rig would probably be useless if tested with a FF2 fall. Improvising with marginal placements, I will use the rig in the picture because I believe it increases our chances of avoiding a ground-fall. 2. The angle of the photo makes the anchor look worse than it is. My axes holds my body weight all the time, I am not surprised that your ice hook held, even if the force where somewhat larger. I where lucky enough to attend a presentation held by Marko Prezelj a while ago. He didn't seem to need an anchor at all. I don't think he believes an ice-axe anchor will catch a FF2 fall, it is like you say, improvising.
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patto
Dec 4, 2009, 12:07 AM
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dingus wrote: patto wrote: If so you need to understand the limitted context in which that applies. Right the 'limited' context is a multi-piece anchor where one piece pulls and the rig extends and this extension 'causes' a shockload on the remaining pieces increasing the risk that they will fail too. THAT is the limited context we are talking. Which just so happens to be the context of this thread. PAS has nothing to do with it. Cheers DMT As I have explained that is not the limited context in which JL's test applies. If you want to assert otherwise without any explanation fine. But you are quite incorrect.
dingus wrote: patto wrote: Significantly higher forces will result if a weighted anchor is allowed to extend and shockload. THAT IS FACT. Prove it. Real world, not chalk board. Prove your math is correct. No PAS, no FF2s on static bullshit... real world belays, real world measurements... prove it. No one ever had done this. Its theory, nothing more. DMT I never said anything about a PAS. I'm not sure why I need to prove that a falling mass stopping in a short distance exerts more force than a static mass under the influence of gravity. To most climbers this should be common sense. It seems increasingly clear common sense is something you lack.
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dingus
Dec 4, 2009, 12:28 AM
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patto wrote: To most climbers this should be common sense. It seems increasingly clear common sense is something you lack. Oh MY! "You are correct Dingus I have absolutely NO real world data to back up my chalk board." Thank you for your candor. DMT
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hafilax
Dec 4, 2009, 12:58 AM
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dingus wrote: patto wrote: To most climbers this should be common sense. It seems increasingly clear common sense is something you lack. Oh MY! "You are correct Dingus I have absolutely NO real world data to back up my chalk board." Thank you for your candor. DMT And how many anchors have you seen fallen on where a piece pulled? AFAIK there is little empirical evidence either way. Shock loading is a real phenomenon but nobody really understands how it applies to anchors ITRW.
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dingus
Dec 4, 2009, 1:16 AM
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hafilax wrote: dingus wrote: patto wrote: To most climbers this should be common sense. It seems increasingly clear common sense is something you lack. Oh MY! "You are correct Dingus I have absolutely NO real world data to back up my chalk board." Thank you for your candor. DMT And how many anchors have you seen fallen on where a piece pulled? AFAIK there is little empirical evidence either way. Shock loading is a real phenomenon but nobody really understands how it applies to anchors ITRW. Oi vey! No one understands and yet many pretend to and actually make recommendations on how to protect against they know not what! IN THIS VERY THREAD no less. To the extent that if someone some how fails to protect against this phenom, you know the one that no one understands, then their anchor is faulted as inadequate by the very same people who have never tested the theory. Bwahahahahaha! Right. DMT
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hafilax
Dec 4, 2009, 1:28 AM
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That's the second Oy Vey I've gotten today. Is it international Yiddish day or something?
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patto
Dec 4, 2009, 1:42 AM
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dingus wrote: No one understands and yet many pretend to and actually make recommendations on how to protect against they know not what! IN THIS VERY THREAD no less. Just because you don't understand it doesn't mean 'no one' understands it. The physics is quite basic and simple.
dingus wrote: very same people who have never tested the theory. If you place doubt in this 'theory' as you call it you are placing doubt in the foundations of Engineering and Physics. Conservation of energy, and behaviour of forces have been tested 100s of times. Much of our modern world of cunstruction and machines would not exist if 'theory' needed to be tested for each individual item. Engineering is about accumulation of knowledge and then being able to apply that knowledge and understanding behaviour WITHOUT needing to test. I haven't got empiracal evidence to show that kitchen twine is not a useful climbing rope. Should I therefore assume that in fact it is? How about you go out and test it by climbing on it for a day and report back your results. I don't need tests to show that shockloading increases the force applied to anchors. In the same way I don't need a test whether a hammer dropped and shockloaded on a glass will break the glass.
hafilax wrote: AFAIK there is little empirical evidence either way. Shock loading is a real phenomenon but nobody really understands how it applies to anchors ITRW. I would not agree with this statement halifax. How it applies to anchors is really quite simple. As Rgold stated it effectively becomes a second fall on the anchor as it extends. The increase in load is dependent on the mass, the extension and the stretch of the components involved. If the rope is dyamic and the extension is minimal then the increase in load would likely around the weight of the mass attached. So we are really only talking about ~1kN for your typical belayer mass. If you are dealing with a large extension onto a static anchor then we could be looking at a FF1 onto static material. We all know about these. 10kN is not unrealistic.
(This post was edited by patto on Dec 4, 2009, 1:51 AM)
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altelis
Dec 4, 2009, 1:54 AM
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patto wrote: ...snip... I'm not sure why I need to prove that a falling mass stopping in a short distance exerts more force than a static mass under the influence of gravity. I may be wrong. In fact its quite possible. I think there is potentially a miscommunication problem here. I will say, too, that there is probably also a deeper disagreement, but I think there is also some miscommunication. As I read it, Dingus is saying that SHOCKLOADING is a myth. And by SHOCKLOADING he means that the extra force exerted on an anchor caused by a piece failing and the subsequent extension of the rest of the anchor is enough force to be catastrophic to even a well placed anchor. Right? Patto, you seem to be saying that shockloading isn't a myth because basic physics shows that the forces put on an anchor if a piece of the anchor where to fail and there were extension the forces on that anchor will be higher than if there were no extension at all. Right? It seems (and again, I've certainly been wrong on more than one occasion) that Dingus is saying "sure, the forces will be higher, but not high enough to matter in the real world and so we shouldn't worry about it). Patto, you seem to be saying that its indisputable the forces will be higher and until further proof comes along to show that those forces don't matter you will assume they do. Or, you two totally understand each other and I've totally misunderstood JL' testing. Because, to be honest, I understood it showing what Dingus was saying (ie an increase in force occurs with extension but it isn't on a magnitude to make it troubling for us out in the world).
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sittingduck
Dec 4, 2009, 2:09 AM
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Altelis, I believe you nailed it perfectly.
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patto
Dec 4, 2009, 3:05 AM
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altelis wrote: Or, you two totally understand each other and I've totally misunderstood JL' testing. Because, to be honest, I understood it showing what Dingus was saying (ie an increase in force occurs with extension but it isn't on a magnitude to make it troubling for us out in the world). The key point that I have highlighted on numerous occasions is that on JL's testing he did NOT have a mass attached to the anchor. It is this mass that is attached to the anchor that is the source of the shock loading. JLs results where there is no mass attached to the anchor is exactly what the math predicts. If the belayer is belaying off his harness OR is a semi-hanging or hanging belay then this belayer is a signifacant mass on the anchor and will shockload the anchor if there is extension.
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glahhg
Dec 4, 2009, 6:16 AM
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Whatever, it's got two screws and some rope tied to them. It's probably fine.
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patto
Dec 4, 2009, 6:52 AM
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glahhg wrote: Whatever, it's got two screws and some rope tied to them. It's probably fine. I would agree with that statement.
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sungam
Dec 4, 2009, 12:38 PM
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sittingduck wrote: sungam wrote: The inability to easily and quickly escape the system, as I said before, is the main downside (a long with the fact autoblockers are just less hassle) in my eyes of belaying off your harness directly to the second. If the rope goes from the belay plate on your harness up to a caribiner attached to the anchor then down to the second, the forces on the anchor are more then doubled. This is the main downside of belaying from your harness with a redirect through an anchor. Belaying directly off the anchor with an autoblocking plate does not cause this effect. You are talking about bringing up a second while I'm talking about belaying a leader that falls into the anchor. I belay from the anchor when belaying a second. When belaying a leader I belay from the harness and clip one of the ropes to the powerpoint. Do you now understand what I said about the second rope? I got my writing all f*cked up, it happens alot (more and more recently, it seems). Second or leader, either way my point stands on both accounts. The second rope would only come tight if the stretch in the first rope was twice the distance from you to the powerpoint. I guess this could happen depending on the situation. I guess this is also where it get's funky. What has the larger effect? The pully effect of increasing the load on the anchor, or the added dynamicy of having more rope out? I guess it once again depends on how close your belay plate is to the powerpoint biner.
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dharold
Dec 4, 2009, 1:24 PM
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the red lines to each screw should be taught. if you weight the lines, and your powerpoint is equalized, then it is still a dynamic system, although the dynamic property of the rope with such a short distance is negligible. best to always weight your anchor, ie "no slack", and belay off your harness, this puts less stress on the anchor in the event of a fall for shock loading. THAT is how to make it dynamic, no?
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rangerrob
Dec 4, 2009, 5:06 PM
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Do you people have any idea how fucking annoying these triple and quadruple nested quoted posts are to follow??? What a bunch of computer dorks
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dingus
Dec 4, 2009, 5:20 PM
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rangerrob wrote: Do you people have any idea how fucking annoying these triple and quadruple nested quoted posts are to follow??? What a bunch of computer dorks I have no idea what you're referring to. Can you elaborate? DMT
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dingus
Dec 4, 2009, 5:20 PM
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dingus wrote: rangerrob wrote: Do you people have any idea how fucking annoying these triple and quadruple nested quoted posts are to follow??? What a bunch of computer dorks I have no idea what you're referring to. Can you elaborate? DMT Please? DMT
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dingus
Dec 4, 2009, 5:25 PM
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dingus wrote: dingus wrote: rangerrob wrote: Do you people have any idea how fucking annoying these triple and quadruple nested quoted posts are to follow??? What a bunch of computer dorks I have no idea what you're referring to. Can you elaborate? DMT Please? DMT I wish there was a 'scribble in the margins' formatting option too. DMT
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rgold
Dec 4, 2009, 10:40 PM
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Folks often get backed into extreme positions by the nature of internet debate. The idea that theoretical "chalk board" calculations are of little practical relevance is just as wrong as the idea that these theoretical calculations model reality perfectly. Testing is subject to all kinds of design errors and confounding influences, to the extent that it may be impossible to decide on best practice without a good mathematical model to sort out the effects of various variables. On the other hand, basic mathematical models that have not been reworked in the light of test results may oversimplify so much that their results are only vaguely related to what one experiences in the field. I think Atelis has already neatly summarized the current debate while avoiding the distracting irrelevancies. The fact of the matter is that we do not have good test data on the effects of extension in anchors. Moreover, it isn't even clear whether the participants in any discussion either have or agree on a clear definition of what is meant by an "effect." This problem is compounded by the fact that people continue to use the undefined term "shockload," sometimes in ways suggesting that there is something unusual and avoidable about it in the context of anchor loads. If a load supported by three pieces is suddenly supported by only two, there will obviously be a sudden increase in the load experienced by the remaining anchors. Given that nobody knows what "shockload" means anyway, it would be perfectly reasonable to call this a shockload, in which case the failure of a piece will shockload an anchor whether or not there is any extension. So the effect of extension, if there is any, would have to be an increase in load beyond the shockload that is guaranteed by the failure of a piece in an analogous fixed-arm set-up. Our inability to standardize the "analogous fixed-arm set-up" makes for all kinds of issues with respect to testing. It isn't going out on a limb at all to say that there are circumstances and configurations in which the effects of extension will be critical---really, this is beyond question. Although the confounding variables in real anchor situations are daunting, I believe that the crux of the matter boils down to the ratio of anchor extension to tie-in length, a fall factor for anchors. This is because, if the belayer is pulled off his or her stance, the only part of the system absorbing the belayer's fall energy is the tie-in, and the measure of the tie-in's ability to absorb fall energy is the same old H/L ratio, but now H is the amount of extension and L is the tie-in length. (A secondary but potentially serious problem occurs if the tie-in is made of low-stretch material.) Definitive results may be a long time in coming. We have a little information about two-anchor equalizing systems, but almost nothing about three-anchor systems. In the meantime, climbers have to make anchor decisions, which are really carried out in a state of almost complete ignorance by people whose experience is acquired by building anchors that are never tested to evaluate the builder's judgments. By far the best approach is to make sure that there won't be a fall directly onto the anchor, in which case most discussions like these become moot. But, at least in my experience, the potential for such a fall is present, if unlikely, most of the time, and so the building of very strong redundant anchors remains a consideration. What to do in practice is still pretty much witchcraft. Or put another way, it's psychology, not physics. The thing that makes people feel best is what they do, in the absence of really effective guidelines. Like it or not, theoretical calculations are pretty much all we have to go on in this situation, and if they are not to be taken too literally, they at least provide an ingredient or two for the witch's brew. It seems to me that if anchors are made of reasonably good pieces (remembering our fallibility in judging), then they should be viewed as distributed systems, not equalizing systems, and the speed and simplicity of fixed-arm rigging as opposed to dynamic equalizing systems makes the most sense for climbers doing climbs of any length. One of the many theoretical predictions that has been confirmed by experiments for fixed-arm rigging is that the piece on the shortest fixed strand gets the highest load, and so it makes sense to try to keep the anchor strands approximately the same effective length. The "effective" modifier here has a purpose. The idea is that, first of all, the anchor rigging itself should be constructed from dynamic material, either 7mm cordelette or, as good if not better, the climbing rope itself. If a piece has a rigging arm that is significantly longer than the shortest arm, it should be extended with a low-stretch sling of some sort, thereby yielding an "effective dynamic arm" of shorter length. Such decisions can be made instantly, are easy to implement, do not involve the fiddling ultimately required by more complex systems, and seem as likely, given what we actually know, to distribute loads in a three-anchor system as well as can be expected, as long as the direction of loading agrees with the way the anchor was constructed. If the anchor pieces are suspect, then equalization methods, in spite of our lack of knowledge about their behavior, may be a better option. The obvious solution to the three-anchor conundrum is to use four pieces equalized with a cascade of three sliding X's or, preferably, one of their modern lower-friction improvements. Then, having signed on for possible extension, one wants to tie in with as long a tie-in section of the climbing rope as is possible for the given stance. This will minimize the anchor fall-factor described above in case of a factor-2 fall, and so hopefully relegate the extension effect to the mythical status it now fallaciously enjoys for all configurations. The trouble with all this is that "alpine" anchors are often suspect and building a four-piece monstrosity is mostly not an option for various reasons. So you live with more uncertainty, and do whatever makes you feel best. If an extending anchor is what is chosen, then the long tie-in for the belayer seems to me to be a sensible adaptation to the potential for extension. Although this is pretty speculative, I think the best solution for alpine conditions, given our current ignorance, may be to build a two-piece anchor and with a third piece very close above, independent from the anchor, and used as protection for the leader. Equalette-type equalization for two pieces seems to be fairly effective, and three-piece systems may still deliver half the load to one of the pieces, making them perhaps no less resistant to some kind of failure, although of course more redundant. The extra redundance in an alpine setting might well be trumped by the fact that the two-piece protected anchor is less likely---one would hope much less likely---to be subjected to a factor-2 load at all.
(This post was edited by rgold on Dec 5, 2009, 1:10 AM)
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sittingduck
Dec 5, 2009, 12:07 AM
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glahhg wrote: Whatever, it's got two screws and some rope tied to them. It's probably fine. Exactly, it was fine until the coach-potatoes decided it was time to throw a beaten to death horse on it.
sungam wrote: I got my writing all f*cked up, it happens alot (more and more recently, it seems). Second or leader, either way my point stands on both accounts. Look at your experience to post-count ratio and tell me if you expect all of your 20000 posts to be correct?
dharold wrote: the red lines to each screw should be taught. if you weight the lines, and your powerpoint is equalized, then it is still a dynamic system, although the dynamic property of the rope with such a short distance is negligible. best to always weight your anchor, ie "no slack", and belay off your harness, this puts less stress on the anchor in the event of a fall for shock loading. THAT is how to make it dynamic, no? The ropes to the screws are not separate ropes, it is a red rope going from the powerpoint fig 8 and clove hitched to the first screw. Then it goes down through the upper carabiner in the powerpoint and back up to the second screw where it is tied with another ch. Finally, the rope goes back to the powerpoint where it is connected to the powerpoint with a fig8 and a screw-gate carabiner. There are two rope-strands per screw, made by the same rope. I wish I could explain it better. The powerpoint is hanging on the rope between the screws. There is no slack between the pp and the screws. Making "it" dynamic consist of several factors so I am not sure I understand what you mean by "THAT"?
rangerrob wrote: Do you people have any idea how fucking annoying these triple and quadruple nested quoted posts are to follow??? What a bunch of computer dorks I did not notice the problem until ppl started complaining about it. No offense, I thought it was the dorks that complained, since clicking "quote" takes no computer skills at all.
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sungam
Dec 5, 2009, 12:28 AM
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sittingduck wrote: sungam wrote: I got my writing all f*cked up, it happens alot (more and more recently, it seems). Second or leader, either way my point stands on both accounts. Look at your experience to post-count ratio and tell me if you expect all of your 20000 posts to be correct? the majority of my posts (I'd say around 18k) are chat posts, me talking to people about climbing or non-climbing related shit that isn't right or wrong. I'd say another 1k was me making an ass of myself. I'm not sure what you're getting at with some of your comments. They seemed kind of hostile (what's with the implications that I have little experiance? I certainly don't have a huge amount but I wouldn't consider myself inexperienced) - you posted the picture and asked for feedback, then go into "two screws with ropes attached to them - it's good enough" mode. If you're the type of person that looks at a set-up that could easily be made even slightly better and says "meh, good enough", then a slight change in your attitude could be for the better. Not saying I wouldn't tie in with you, just that the ideal situation would be trying to optimise the time/complexity/safety thing. A side note - the reason I posted the kind of vague half question posts was in the hope that someone who knew more on the topic would be able to come in and fully explain it.
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altelis
Dec 5, 2009, 12:47 AM
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Bolding emphasis mine...rgold wrote: ...snip... By far the best approach is to make sure that there won't be a fall directly onto the anchor, in which case most discussions like these become moot. But, at least in my experience, the potential for such a fall is present, if unlikely, most of the time, and so the building of very strong redundant anchors remains a consideration. .... It seems to me that if anchors are made of reasonably good pieces (remembering our fallibility in judging), then they should be viewed as distributed systems, not equalizing systems, and the speed and simplicity of fixed-arm rigging as opposed to dynamic equalizing systems makes the most sense for climbers doing climbs of any length. One of the many theoretical predictions that has been confirmed by experiments for fixed-arm rigging is that the piece on the shortest fixed strand gets the highest load, and so it makes sense to try to keep the anchor strands approximately the same effective length. .... The trouble with all this is that "alpine" anchors are often suspect and building a four-piece monstrosity is mostly not an option for various reasons. So you live with more uncertainty, and do whatever makes you feel best. If an extending anchor is what is chosen, then the long tie-in for the belayer seems to me to be a sensible adaptation to the potential for extension. Although this is pretty speculative, I think the best solution for alpine conditions, given our current ignorance, may be to build a two-piece anchor and with a third piece very close above, independent from the anchor, and used as protection for the leader. Equalette-type equalization for two pieces seems to be fairly effective, and three-piece systems may still deliver half the load to one of the pieces, making them perhaps no less resistant to some kind of failure, althogh of course more redundant. The extra redundance in an alpine setting might well be trumped by the fact that the two-piece protected anchor is less likely---one would hope much less likely---to be subjected to a factor-2 load at all. First of all, Rich, thanks so much for that post. It really helped distill down some ridiculously useless and long threads into real world applicability. Secondly, given the bolded statements, how do you feel about clipping the leader's line into the masterpoint as the first piece of gear? It seems to me that your post would suggest this is a poor practice. And I know this has been hashed to death- I think I am asking specifically about the world of alpine anchors here, where less-than-ideal placements are the norm.
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sittingduck
Dec 5, 2009, 12:57 AM
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rgold, thanks for posting! This is embarrassing, if I knew you would be looking at my anchor I would have rigged it more neatly!
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sittingduck
Dec 5, 2009, 1:16 AM
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sungam wrote: A side note - the reason I posted the kind of vague half question posts was in the hope that someone who knew more on the topic would be able to come in and fully explain it. I could not know that and I tried to respond seriously to you. I understand that you find me hostile. No hard feelings here.
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sungam
Dec 5, 2009, 1:22 AM
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sittingduck wrote: sungam wrote: A side note - the reason I posted the kind of vague half question posts was in the hope that someone who knew more on the topic would be able to come in and fully explain it. I could not know that and I tried to respond seriously to you. I understand that you find me hostile. No hard feelings here. Cool. Well, that's that, then. Although I am curious about the pully effect/fall factor thing - perhaps that's for a different thread, though.
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sittingduck
Dec 5, 2009, 1:49 AM
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sungam wrote: Although I am curious about the pully effect/fall factor thing - perhaps that's for a different thread, though. It is relevant, and now that rgold is here we might get a comment ... Fwiw, I always clip one of the two ropes to the powerpoint when belaying the leader from the harness. I hope that both ropes will eventually engage in the event of a ff2 fall, and by that neutralize the pully effect to some degree. If you belay directly from the harness, the redundancy for the leader becomes very far stretched. If the belay loop or the belay carabiner fails, the leader will fall until the rope catches him again, since he still is tied in. edited to add sungams quote
(This post was edited by sittingduck on Dec 5, 2009, 2:09 AM)
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altelis
Dec 5, 2009, 4:25 AM
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sittingduck wrote: sungam wrote: Although I am curious about the pully effect/fall factor thing - perhaps that's for a different thread, though. It is relevant, and now that rgold is here we might get a comment ... Fwiw, I always clip one of the two ropes to the powerpoint when belaying the leader from the harness. I hope that both ropes will eventually engage in the event of a ff2 fall, and by that neutralize the pully effect to some degree. If you belay directly from the harness, the redundancy for the leader becomes very far stretched. If the belay loop or the belay carabiner fails, the leader will fall until the rope catches him again, since he still is tied in. edited to add sungams quote SD, my personal preference on alpine type anchors is to NOT clip the leader through onto the powerpoint because of the pulley effect. 9 times out of 10 I've been able to integrate some sort of stance into my alpine anchors, and my thinking is i'd rather use that in the case of a FF2 than 2 screws in ice whose quality i'm not always totally stoked on. That is just me, and like I said that 9/10 has been MY experience. Yours may differ and lead to different decisions.
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sittingduck
Dec 5, 2009, 11:17 AM
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altelis wrote: SD, my personal preference on alpine type anchors is to NOT clip the leader through onto the powerpoint because of the pulley effect. 9 times out of 10 I've been able to integrate some sort of stance into my alpine anchors, and my thinking is i'd rather use that in the case of a FF2 than 2 screws in ice whose quality i'm not always totally stoked on. That is just me, and like I said that 9/10 has been MY experience. Yours may differ and lead to different decisions. A ff2 fall is roughly 12kN. In the picture you see a guy holding 4,5kN. I am no mathematician or phycisist, and that is probably why I think that he would not be able to hold a ff2 fall. I have taken a long ff2 fall on multipitch trad, nobody could have stopped that fall with a stance in MY experience. So yes, my experience leads to different solutions. Belaying a second from a stance is perfect with a marginal anchor. We are normally strong enough to hold that weight.
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altelis
Dec 5, 2009, 3:15 PM
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I think you misunderstood my intentions for including a stance. I (I think) clearly said that I am not planning on catching a FF2 from the stance alone. But rather by integrating myself into the anchor I will be able to at least take some force away from the anchor...
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adnix
Dec 5, 2009, 3:45 PM
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sittingduck wrote: adnix wrote: 1. Use only one rope with a fig 8 power knot for anchor and ditch the backup rope. 1. As long as no one falls, any rig works fine. If you use dynamic cord for anchoring (like you did) it's better to use knots. The dynamic cord is doing load distribution quite ok already - dynamic rope stretches 40% before it snaps. There is no need for sliding x. And if one piece fails the drop and "shockload" are less if you use static knots. Plus its faster and more simple to rig.
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sittingduck
Dec 5, 2009, 5:50 PM
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altelis wrote: I think you misunderstood my intentions for including a stance. I (I think) clearly said that I am not planning on catching a FF2 from the stance alone. But rather by integrating myself into the anchor I will be able to at least take some force away from the anchor... Off course it will be a good thing if you manage to take any weight of the anchor. On that note: I often stand facing the wall, weighing my extension to the anchor, with my front-points dug into the ice. I am worried that I may hurt my knees and ankles if my hips where suddenly twisted by the pull of a ff2 fall. This might also prevent me from taking any weight of the anchor. With a redirect I will be pulled upwards.
adnix wrote: If you use dynamic cord for anchoring (like you did) it's better to use knots. The dynamic cord is doing load distribution quite ok already - dynamic rope stretches 40% before it snaps. There is no need for sliding x. And if one piece fails the drop and "shockload" are less if you use static knots. Plus its faster and more simple to rig. You might be able to anticipate where the direction of pull will come and have good distribution, or you might not. I have rigged many rap anchors with a knot, and thought I placed the knot perfectly, only to see one arm getting all the weight once we rapped off. I use different methods now because of that. About the speed and simplicity issue; how many knots do you have in your anchors? edit to get the names right. sorry guys
(This post was edited by sittingduck on Dec 5, 2009, 7:41 PM)
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altelis
Dec 5, 2009, 6:12 PM
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Yo, that last quote about the knots wasn't me, it was from adnix. if you don't mind fixing that i would appreciate it, or i'll have to ask for the BANZING@>!>!>!@#>#>#(*$
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adnix
Dec 5, 2009, 7:04 PM
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sittingduck wrote: About the speed and simplicity issue; how many knots do you have in your anchors? If the pieces are solid, my anchors have two pieces and no knots. I'll "equalize" the anchor close enough with slings and carabiners. The resulting anchor is resting on one piece (preferably cam) and the second piece is a backup with very short or none slack in case the main piece rips (which it has never done so far). The system is kinda like a modern parachute with a pilot and a backup. The backup is easy to clean once the leader has his main piece in. The main piece is removed the same second the leader yells "belaying!" This saves a great deal time. A cam is easier to clean than anything else. If the pieces are not too solid I'll add a third and fourth piece the same backup style. If it's really bad I might consider adding cord loop with fig 8 knot for distributing the load. I usually carry one 120cm cord loop knotted with fishermans to be left behind while abseiling. I usually use this cord loop in stead of climbing rope since block leading doesn't allow using climbing rope. In case I'm climbing with less experienced partner I'll usully rig a main powerpoint which he/she feels comfortable (usually a loop of cord with carabiners clipped in pieces and a fiig 8 knot in the middle). The carabiners can be removed easily even by complete amateurs. I've learnt opening knots causes problems for less experienced people.
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sittingduck
Dec 5, 2009, 7:50 PM
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altelis wrote: Yo, that last quote about the knots wasn't me, it was from adnix. if you don't mind fixing that i would appreciate it, or i'll have to ask for the BANZING@>!>!>!@#>#>#(*$ My apology to you! I have edited it.
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altelis
Dec 5, 2009, 7:53 PM
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no worries- cheers!
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sittingduck
Dec 5, 2009, 8:58 PM
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adnix wrote: sittingduck wrote: About the speed and simplicity issue; how many knots do you have in your anchors? If the pieces are solid, my anchors have two pieces and no knots. I'll "equalize" the anchor close enough with slings and carabiners. The resulting anchor is resting on one piece (preferably cam) and the second piece is a backup with very short or none slack in case the main piece rips (which it has never done so far). The system is kinda like a modern parachute with a pilot and a backup. The backup is easy to clean once the leader has his main piece in. The main piece is removed the same second the leader yells "belaying!" This saves a great deal time. A cam is easier to clean than anything else. Is it something like this: You are right, that is faster. Yeah, taking down parts of the anchor is the right ting to do when it is not needed anymore.
adnix wrote: If the pieces are not too solid I'll add a third and fourth piece the same backup style. If it's really bad I might consider adding cord loop with fig 8 knot for distributing the load. I usually carry one 120cm cord loop knotted with fishermans to be left behind while abseiling. I usually use this cord loop in stead of climbing rope since block leading doesn't allow using climbing rope. In case I'm climbing with less experienced partner I'll usully rig a main powerpoint which he/she feels comfortable (usually a loop of cord with carabiners clipped in pieces and a fiig 8 knot in the middle). The carabiners can be removed easily even by complete amateurs. I've learnt opening knots causes problems for less experienced people. Sounds like you guide, adnix? Judging from your experience with climbing partners.
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adnix
Dec 5, 2009, 9:18 PM
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The harness is not directly clipped in as in your picture. I use a cow tail with a carabiner for clipping in the anchor (ie. a carabiner clipped into the carabiner of the cam). Otherwise you have it perfect there. The best belay device is Reverso or Atc xp or similar. The second is belayed directly off the stand in autoblocking mode. The leader is belayed of the harness like in your picture. I'm no guide but I've taken loads of friends for their first multipith. And I've passed plenty of guides with their clients in Chamonix. This gives me perverse pleasure in most cases.
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sungam
Dec 5, 2009, 9:24 PM
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adnix wrote: The best belay device is Reverso or Atc xp or similar. The second is belayed directly off the stand in autoblocking mode. The leader is belayed of the harness like in your picture. Yeah - I've only had one season with a reverso, and it was mostly ice cragging in ouray, but I was pretty chuffed at how east it was to belay a second, and how much warmer my hands felt. I was also pleasantly surprised at how easy it is to switch to belaying off the harness. Before using or seeing one I had the idea in my head that stuff would have to get unclipped.
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sittingduck
Dec 5, 2009, 9:48 PM
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adnix wrote: The harness is not directly clipped in as in your picture. I use a cow tail with a carabiner for clipping in the anchor (ie. a carabiner clipped into the carabiner of the cam). Otherwise you have it perfect there. The best belay device is Reverso or Atc xp or similar. The second is belayed directly off the stand in autoblocking mode. The leader is belayed of the harness like in your picture. I'm no guide but I've taken loads of friends for their first multipith. And I've passed plenty of guides with their clients in Chamonix. This gives me perverse pleasure in most cases. Ok, I see. I do not fancy the cow tail myself and use the climbing rope. Especially after some horrible accidents recent years. I found a picture of one of my anchors where I could have used your method: I am happy for you that you are not a guide. I most often meet the guides and their clients while ski-mountaineering, it actually is a pleasure watching them!
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adnix
Dec 6, 2009, 8:46 AM
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sittingduck wrote: I do not fancy the cow tail myself and use the climbing rope. Especially after some horrible accidents recent years. Climbing rope is more elastic and harder to unclip, it has its advantages. In my experience it's slower but on the other hand, everyone has to find his own comfort systems. There's no right or wrong here.
sittingduck wrote: I found a picture of one of my anchors where I could have used your method: [image]http://www.home.no/sittingduck/anchor321.jpg[/image] With those two pieces I would have clipped full weight on the cam and used the hex extended with a quickdraw as backup clipped to the biner of the cam. The biner of the cam would have been "the master point". It basicly has the exact same qualities as your current config. The sling isn't too equalized or is it? Your stand has the full weight on the hex and the cam is the backup.
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hafilax
Dec 6, 2009, 10:02 PM
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sittingduck wrote: altelis wrote: SD, my personal preference on alpine type anchors is to NOT clip the leader through onto the powerpoint because of the pulley effect. 9 times out of 10 I've been able to integrate some sort of stance into my alpine anchors, and my thinking is i'd rather use that in the case of a FF2 than 2 screws in ice whose quality i'm not always totally stoked on. That is just me, and like I said that 9/10 has been MY experience. Yours may differ and lead to different decisions. [image]http://redlinegym.com/images/andy-bolton-01.jpg[/image] A ff2 fall is roughly 12kN. In the picture you see a guy holding 4,5kN. I am no mathematician or phycisist, and that is probably why I think that he would not be able to hold a ff2 fall. I have taken a long ff2 fall on multipitch trad, nobody could have stopped that fall with a stance in MY experience. So yes, my experience leads to different solutions. Belaying a second from a stance is perfect with a marginal anchor. We are normally strong enough to hold that weight. Falls don't have an intrinsic force, they have a certain amount of energy that must be dissipated through friction, damping in the rope and other mechanisms. The most force one can exert with a tube device is around 4-5 kN. To slow a falling body this means that some rope has to slip through the device until the body comes to rest. Catching a fall on the anchor directly on the harness minimizes the force on the anchor at the expense of letting rope slip through the device. This could be disastrous with bare hands but should be manageable with gloves. By redirecting through the power point the force on the belayer is minimized by using the friction over the biner to increase the arresting force but his puts a much larger force on the anchor. Choose wisely.
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adnix
Dec 7, 2009, 7:25 PM
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hafilax wrote: [Catching a fall on the anchor directly on the harness minimizes the force on the anchor at the expense of letting rope slip through the device. This could be disastrous with bare hands but should be manageable with gloves. There should be two or three more points here. 1. Belaying the second directly from the anchor is usually the most effective way. Use an autoblocking device. 2. Belaying the leader is to be done off the harness if the achor is on traditional gear. Setting up a truly multidirectional anchor is quite rare. In my experience I could say 90% of my anchors aren't such. Remember to have enough slack between the belayer and the first point of protection. 3. On fixed gear the UIAA advice is on belaying the leader directly off the anchor. If you use munter hitch or similar method the extra slippage is no problem. There isn't such. Zanantoni of UIAA calculates that loosing the grip is more likely on belaying off the harness than belaying off the anchors. http://theuiaa.org/...aying_Techniques.pdf In addition, the best belay method depends on the weight of the belayer. If the belayer is much lighter than the leader, you should favor belaying off the anchor.
(This post was edited by adnix on Dec 7, 2009, 8:01 PM)
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