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jt512
Nov 11, 2009, 11:54 PM
Post #126 of 159
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The overarching point is not whether the denominator of the probability is days or falls or whatever, but that thinking of anchor failure as a random event is contrived. Events have probabilities because they are produced by processes that are random, or contain uncertainty. A flipped coin has a probability of landing head up because the process of flipping it randomizes the outcome. An individual piece of gear has a probability of failing at its rated strength because there is random error in the manufacturing process. But what is the source of randomness in determining whether a top rope anchor will fail? In practice, there essentially isn't any. The anchor is either good enough or it isn't.
Jay
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jt512
Nov 11, 2009, 11:55 PM
Post #127 of 159
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sittingduck wrote: jt512 wrote: sittingduck wrote: jt512 wrote: sittingduck wrote: jt512 wrote: My point is that until someone carefully defines what they mean by the probability of an individual anchor failing, there is nothing to talk about. The way "probability" is being used in this thread is meaningless. Jay If the probability of failure is undefinable, maybe the climber should consider rigging the anchor in a way that changes said probability closer to zero? Huh? Jay The definition of the probability of failure in the anchor you captured, is that it is most likely not 0 (zero). If the climber rigged that anchor with opposed and opposite carabiners at the masterpoint, he would change the probability of failure closer to zero. You are confusing definition of probability with estimate of probability. My point was that no one has come up with what "probability" means in this context; therefore, it is meaningless to attempt to estimate a value of that probability. Jay So what? The value of probability of that anchor failing was high enough to catch your attention and post pictures of it here, right?
That's a tough question to answer with a straight face.
Jay
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dugl33
Nov 12, 2009, 12:59 AM
Post #128 of 159
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So when do we get to see the pic with you standing on the ground, next to the anchor?
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jt512
Nov 12, 2009, 2:10 AM
Post #129 of 159
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dugl33 wrote: So when do we get to see the pic with you standing on the ground, next to the anchor?
I've already stated twice that it was a real anchor being used for real. Whether I thought it was dangerous or not is an entirely different question.
Jay
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Couloirman
Nov 12, 2009, 2:52 AM
Post #130 of 159
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jt512 wrote: Either way, if there is a failure to jettison the first chute, then failure of the reserve, due to entanglement with the main parachute, is almost guaranteed. Jay
Nope, look up canopy transfer and it will shed some light on why its not a death sentence.
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LamontagnedeGatineau
Nov 12, 2009, 4:27 AM
Post #132 of 159
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Looks to me like a sloppy job , but not a dangerous one because there's enough redundancy. Also looks like the dude only climbs with quickdraws. Best recommendation could be to stock up on a couple of trad slings next time he hits the climbing store!
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moose_droppings
Nov 12, 2009, 5:34 AM
Post #133 of 159
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^^^
I agree, to many links in the chain so to speak. I'd use it with out worry though.
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airscape
Nov 12, 2009, 8:50 AM
Post #134 of 159
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I love the way that if someone compares anything to a situation in another sport (in this case skydiving) then all of a sudden that sport also becomes a topic for discussion.
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king_rat
Nov 12, 2009, 9:05 AM
Post #135 of 159
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I haven’t read through he rest of the thread so most of this has already been mentioned.
1. The pieces placed look Ok but can’t really see them.
2. The two biners clipped to the rope are not opposite or opposed.
3. The use of quick draws means that the anchor is not equalised particularly the top two.
4. use of quickdraws means that any change of direction of the load will load different legs of the anchor.
5. The top biner looks like it could push against the rock and the gate could be forced open.
6. The second quickdraw on the chain clipped to the top peace of gear is not directly clipped in to the quickdraw leading to the rope, but is clipped to the other leg of the anchor.
7. I don’t like metal on metal(possibility of the biners twisting open.
I wouldn't want to climb on it, adn if i did I certanly would not want to be swinging round while working a route. I certainly would not belay my kids on it.
(This post was edited by king_rat on Nov 12, 2009, 10:47 AM)
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dingus
Nov 12, 2009, 12:46 PM
Post #136 of 159
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airscape wrote: I love the way that if someone compares anything to a situation in another sport (in this case skydiving) then all of a sudden that sport also becomes a topic for discussion.
The anchor reminds me of tiddlywinks.
DMT
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LostinMaine
Nov 12, 2009, 2:17 PM
Post #137 of 159
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jt512 wrote: The overarching point is not whether the denominator of the probability is days or falls or whatever, but that thinking of anchor failure as a random event is contrived. Events have probabilities because they are produced by processes that are random, or contain uncertainty. A flipped coin has a probability of landing head up because the process of flipping it randomizes the outcome. An individual piece of gear has a probability of failing at its rated strength because there is random error in the manufacturing process. But what is the source of randomness in determining whether a top rope anchor will fail? In practice, there essentially isn't any. The anchor is either good enough or it isn't. Jay
The manufacturing process might not have random error affecting holding strength. Many manufacturing processes have strong biases where they may be very precise, but highly inaccurate of hitting their end product goals.
I agree that the use of probability estimates is kind of funny here (it's a threshold). You could take 13 billion FF 0.2 falls on a shoddy, unequalized, non redundant, anchor that can withstand a FF 0.4 fall and it will not fail. Now, take this same anchor and use it where there is the potential for a fall greater than 0.4, and the story changes.It is still not a probability, but there is a threshold at which the anchor will fail.
The problem with the anchor pictured is that it takes perfectly good gear, decent individual placements, and combines them in such a way as to lower the threshold of failure. This makes it a shoddy anchor. Though it could hold a TR fall for an indefinite number of falls, if someone rope solos on the same line to clean it afterward and takes a fall approaching FF 1 near the top, the anchor could be compromised.
In an odd way, it reminds me of the duel between Huygens and Newton... is light a wave or a particle?
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reno
Nov 12, 2009, 11:14 PM
Post #138 of 159
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jt512 wrote: reno wrote: seatbeltpants wrote: screw climbing on an anchor that has a 1% chance of blowing - but i'm terrified that some posters seem to have no worries climbing on an anchor that has a 1 in 5 chance of blowing?! russian roulette, anyone? It must be comforting to do all your climbing on rock that is 100% solid, with all the gear you could possibly need to construct an anchor that is 100% safe from any possible chance of failure. That sort of climbing has nothing in common with the kind of rock/ice/alpine/mountain climbing I've ever seen and done. Maybe it's just me, but every anchor I've ever seen has potential to fail. Some have more potential than others. I can count on my fingers the number of times I've climbed on an anchor that at least a 1% chance of failing, and still have 10 fingers left over. I have a feeling you could, too.
Not really. Let's put aside, for the moment, Dingus' (correct and wise) comment that placing a numerical value on an anchor is an exercise in mental masturbation.
I've had situations where the "anchor" was, to be charitable, "less than optimal." While not trad, I've had a couple stubby screws in shitty ice and a nut slotted in a rotten crack constitute an "anchor." I've had partners on the sharp end call down to me "You're on belay, but please don't fall" and arrived at the belay to find one piton pushed by hand into the soft kitty-litter rock that is the Fisher Towers. I've rapped off a single piton.
Did I like any of these? Hell to the no. At the time, that was what we had, and other options -- down climbing, a different rap path, etc. -- weren't as safe (for a variety of reasons.) Some times, "as good as you're going to get" is the best you can hope for. Most times, sure, we can build an anchor that will hold any fall we can create.
If this area you mention in the OP is a popular area, I'd expect that would be the case... the anchor you posted could have been done better. Hell, a couple different slings, switch around a couple 'biners, and badda boom, you've got a more solid anchor.
I'd say that I could count on both hands the number of times I've had an anchor with at least a 10% chance of failure and have 6 fingers left. That's still enough fingers to hold a beer and hitch a ride to the crag, though.
(This post was edited by reno on Nov 12, 2009, 11:16 PM)
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wanderlustmd
Nov 15, 2009, 4:33 PM
Post #139 of 159
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epoch wrote: west_by_god_virginia wrote: GO DARWIN!  I've made worse...
yes, you have.
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king_rat
Nov 16, 2009, 1:15 PM
Post #140 of 159
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reno wrote: kylekienitz wrote: reno wrote: "What percentage of risk am I, personally, willing to accept?" Personally I don't see much reason to risk it for TR. That's the rub, though... Risk WHAT? Would you accept a TR anchor with a 1% chance of total failure? A 2% chance? 3? Where is your line? That's the question. There is no answer that fits all.
I think when talking about the acceptability of risk, we need to consider what the alternatives are. Given that the anchor is for a toprope, for the climbers kids, and that the climber has the time and luxury to spend carefully setting it up, many of problems with the anchor could easily be rectified. I therefore cannot see how this could be seen as an acceptable risk.
a 1% risk of failure(over a day??) for a top rope anchor set up for my kids seems remarkably high risk to expose my kids to. So lets say I take my kids climbing every weekend, a 1% failure rate means on average I’m going to kill 1 of my kids every two years? I can really see me selling that one to my wife.
We are not talking about a sketchy anchor set up on a long alpine route.
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dingus
Nov 16, 2009, 1:47 PM
Post #141 of 159
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We are not talking about an anchor with a mythical chance of failure of 1% either.
But whatever.
DMT
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billcoe_
Nov 24, 2009, 5:12 PM
Post #142 of 159
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dugl33 wrote: Not textbook, but adequate... pros: 1.) individual placements look solid. (Parallel cracks and cams at mid expansion range or better, in direction of pull) 2.) rock looks solid 3.) not really equalized, but not major shock-loading if a piece fails cons: 1.) equalization could obviously be better 2.) no opposed biners or locker at rope 3.) nose of black draw pushing into the rock 4.) gear is old -- old style .75 camalot, rigid stem friend. 5.) biner on biner chains, not ideal, but not the end of the world. easy minor improvement would be to clip the draw from the chain of draws connecting to the nut straight into the draw with the green gate. I'd be happier with a cordellete (despite its imperfect equalization) with opposed biners, but this anchor wouldn't freak me out upon arrival. I've seen much worse....
This said it for me. The addition of an opposed and reversed biner or even a locker replacing a regular biner would greatly improve it imo. I've seen one old timer tie a single 1" tubular webbing sling to another via waterknot in the middle and consider the bush it terminated at plenty good as an anchor. I couldn't bring myself to tie in just thinking of the lower off though....
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knudenoggin
Nov 25, 2009, 3:20 PM
Post #143 of 159
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dugl33 wrote: To no one in particular, I know I'm new here, but what's up with the massive quote within a quote text strings? Is it so hard to pick out the specific text you are responding to? Maybe I'll feel differently when I've broken the 10,000 posts threshold. 
-- usually of one-liners. 
Amen!
(Sometimes it feels like you're getting much of the 10,000
all in one of these multi-nested-quotes posts!)
At least on DPR, you get different colors: then, it's lovely!
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dingus
Nov 25, 2009, 3:26 PM
Post #144 of 159
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knudenoggin wrote: dugl33 wrote: To no one in particular, I know I'm new here, but what's up with the massive quote within a quote text strings? Is it so hard to pick out the specific text you are responding to? Maybe I'll feel differently when I've broken the 10,000 posts threshold. -- usually of one-liners. Amen! (Sometimes it feels like you're getting much of the 10,000 all in one of these multi-nested-quotes posts!) At least on DPR, you get different colors: then, it's lovely!
Build-a-quote.
DMT
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knudenoggin
Nov 25, 2009, 3:52 PM
Post #145 of 159
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In reply to: 6. The second quickdraw on the chain clipped to the top peace of gear is not directly clipped in to the quickdraw leading to the rope, but is clipped to the other leg of the anchor.
This is I think the first critique of that 2nd draw,
which is slack, and which caught my eye, too.
It sh/could be clipped at the top through both upper draws' 'biners,
and through the load-transmitting next-draw-in-chain 'biner at
the bottom: as there seems no chance that this draw can be
loaded against two 'biners (one of which would be away from
its axis), being unequalized. It also makes for a lesser extension
should the shorter draw-chain fail.
Currently, it looks as though should the lower two placements
fail, the lower 'biner of this slack draw would be hit right on the
wire gate by the failing adjacent chain.
And the lower 'biner of the red draw should be turned 180deg or so
around clockwise to untwist the draw and put its gate facing away
from the rock.
*kN*
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acorneau
Nov 26, 2009, 7:05 PM
Post #146 of 159
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[Edit: Oops! Not a trad anchor, so if mods want to move this it's fine by me.]
Here's another one I found on MP:
At first glance it appears that they have 4 quickdraws on one bolt! A closer inspection reveals that it's just the camera angle makes it hard to see the second bolt behind the gear. The QD's look to be opposite and opposing, but still, 4 QD's on a top-rope?
(This post was edited by acorneau on Nov 26, 2009, 7:06 PM)
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dingus
Nov 27, 2009, 1:35 PM
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acorneau wrote: [Edit: Oops! Not a trad anchor, so if mods want to move this it's fine by me.] Here's another one I found on MP: [image]http://www.mountainproject.com/images/89/18/106608918_large_e81112.jpg[/image] At first glance it appears that they have 4 quickdraws on one bolt! A closer inspection reveals that it's just the camera angle makes it hard to see the second bolt behind the gear. The QD's look to be opposite and opposing, but still, 4 QD's on a top-rope?
Clearly they drank the 'a locker or two biners, opposite and opposed' koolaid a little too swiftly.
DMT
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Adk
Nov 30, 2009, 11:48 PM
Post #148 of 159
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acorneau wrote: [Edit: Oops! Not a trad anchor, so if mods want to move this it's fine by me.] Here's another one I found on MP: At first glance it appears that they have 4 quickdraws on one bolt! A closer inspection reveals that it's just the camera angle makes it hard to see the second bolt behind the gear. The QD's look to be opposite and opposing, but still, 4 QD's on a top-rope?
Sport climbers.........
(This post was edited by Adk on Nov 30, 2009, 11:49 PM)
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jakedatc
Dec 1, 2009, 11:26 PM
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Adk wrote: acorneau wrote: [Edit: Oops! Not a trad anchor, so if mods want to move this it's fine by me.] Here's another one I found on MP: [image]www.mountainproject.com/images/89/18/106608918_large_e81112.jpg[/image] At first glance it appears that they have 4 quickdraws on one bolt! A closer inspection reveals that it's just the camera angle makes it hard to see the second bolt behind the gear. The QD's look to be opposite and opposing, but still, 4 QD's on a top-rope? Sport climbers.........
unlikely.. probably trad climbers that don't know what to do with a set of bolts :P looks like Jtree
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