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3:51:57 PM |
On 10/11/2010 jam wrote: > i'll have >a much better idea of how good my equipment and placements are (especially >with the data you've collected - thanks for that by the way :) ) Your judgement on whether placements will hold a fall or not will hardly be effected by the results of these tests, or the maths. There are three types of placements (in terms of quality). -A bomber placement is a bomber placement, it aint going anywhere. -A shit placement is a shit placement. Its most likely not going to hold a fall, hopefully you only use these when you are aiding but of course... -A marginal placement is where your might think the maths will come in handy, however, it wont. The reason the maths wont help you on a marginal placement is because the error in marginality is much greater than any guestimates you might make using the maths. Some marginal placements are actually quite good and some are complete rubbish. All the unknown factors such as unknown weakness in the rock, unexpected pull direction, etc etc will trump any uncertain maths you may do. Knowing the maths, although interesting from a physics point of view, doesnt do shit for your placement quality and judgement. You will always, in any situation that is half dodgy, place the best gear you can - thinking about the maths wont help. Most of the time you will probably go on anyway or search around for more gear if your doubtful. Logically knowing the maths wont make you any less doubtful/more confident. The only situation where I could see this benifitting is maybe when you are high up on a route above marginal gear and you decide to keep going because you know that impact forces are less. However for this you only need to know that you have heaps of rope out and wont fall too far; you really dont need to know any higher level maths than that. Where Claws and co's testing really come in handy is on the judgement of placements. A prime example would be the use of tricams in soft rock - I trust these more because I know marginal placements can be good. |
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4:15:47 PM |
On 10/11/2010 Olbert wrote: >Where Claws and co's testing really come in handy is on the judgement >of placements. A prime example would be the use of tricams in soft rock >- I trust these more because I know marginal placements can be good. > > Just because that manky looking tricam held doesn't mean that I would trust manky tricam placements generally! On 10/11/2010 jam wrote: > i'll have >a much better idea of how good my equipment and placements are (especially >with the data you've collected - thanks for that by the way :) ) This testing is in some ways scary because it could give people a sense that crappy placements are better than we think they are. Given that in the real world, gear seems to come out more often than the failure levels in these tests would suggest it should, I wouldn't be trusting manky placements any more because of it. Well, maybe I should as most of the gear that I think is less than fabulous, my seconds swear is bomber, but if I'm going to need it to keep me alive and kicking, I want something I know is good, not something that I know looks crap but Mikl's testing tells me probably isn't that crap. I expect that most of the reason that gear fails in the real world is people have misjudged the quality of their gear or rock or failed to managed their gear to minmise rope wobbles, outwards pulls etc etc. The rest of the time, people usually aren't surprised when the gear fails because they had made a realistic assessment of it. And this exercise as observed from the internet is not an extensive instruction in how good placements are, as pointed out by Stu and Mikls' comments about the limits of judging placement from photos. It's interesting, and it suggests that they survive static loads in the expected direction of pull better than expected most of the time, but i wouldn't call it a great tool to improve your judgement of placements. Getting out in the real world (with or without Mikl's testing kit), placing lots of gear and giving it a good hoik in some way is far more effective. I reckon there's a 4th type of placement too, - the sort you know intellectually is pretty good, but you really wish it was more perfect because you are still petrified. |
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5:00:02 PM |
On 10/11/2010 Wendy wrote: >This testing is in some ways scary because it could give people a sense >that crappy placements are better than we think they are. I was hoping to make the opposite point;- gear is stronger than I thought but always seems to come out - the real question is "why?" Seeing as the small number of testers we had were not great at assessing strength, maybe what we actually assess is security- whether a bit of rock movement or falling past it with a semi-tight rope will flick it out. |
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7:52:44 PM |
Ok, heres my take on it all, gleaned from climbing in the Blueies, and finalised on Doggie. It's called the 50/50 rule © and it goes like this - 50% of the gear you think is good is actually crap, 50% of what you think is crap is actually good. And 50% of the time you really can't tell the difference. Therefore ANY piece, (and I include all glue-in's and shite) has a 50/50 chance of holding you - it either holds or it fails, 50/50 is the best you get. Use your best judgement and back it up when necessary and if you feel like it . . . Re; Doggie free climbing. Classic example from Gigantor or Collossus; find a stance and plug a piece in as soon as you can, then put another piece in before readjusting your first piece, look at your second piece, and think I might just put a high piece in that looks good from here and fix that second piece, actually I might replace that second piece with something else, ko , is that actually better or worse?, damm it, better just keep climbing . . . Oh that high piece is not as good as I thought . . . well that looks like good gear up a bit further - OK Watch me, . . . Your wire just flicked out . . Damn! Amazing catches included Zac 's small fall onto the 15 year old abraided Hex cord that is missing it's sheath, Me having a seemingly perfect 3 or 4 hex slide down the crack for about a meter, Rohan blowing rock apart with cams and caught by a bolt or piton, Zac bending Yellow BD cams lobes in a fall. Great fun, you's all should try it . . . Cheers Macciza |
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9:38:07 PM |
On 10/11/2010 Olbert wrote: >On 10/11/2010 jam wrote: >> i'll have >>a much better idea of how good my equipment and placements are (especially >>with the data you've collected - thanks for that by the way :) ) > >Your judgement on whether placements will hold a fall or not will hardly >be effected by the results of these tests, or the maths. There are three >types of placements (in terms of quality). > >-A bomber placement is a bomber placement, it aint going anywhere. >-A shit placement is a shit placement. Its most likely not going to hold >a fall, hopefully you only use these when you are aiding but of course... >-A marginal placement is where your might think the maths will come in >handy, however, it wont. > >The reason the maths wont help you on a marginal placement is because >the error in marginality is much greater than any guestimates you might >make using the maths. Some marginal placements are actually quite good >and some are complete rubbish. All the unknown factors such as unknown >weakness in the rock, unexpected pull direction, etc etc will trump any >uncertain maths you may do. > >Knowing the maths, although interesting from a physics point of view, >doesnt do shit for your placement quality and judgement. You will always, >in any situation that is half dodgy, place the best gear you can - thinking >about the maths wont help. Most of the time you will probably go on anyway >or search around for more gear if your doubtful. Logically knowing the >maths wont make you any less doubtful/more confident. > >The only situation where I could see this benifitting is maybe when you >are high up on a route above marginal gear and you decide to keep going >because you know that impact forces are less. However for this you only >need to know that you have heaps of rope out and wont fall too far; you >really dont need to know any higher level maths than that. > >Where Claws and co's testing really come in handy is on the judgement >of placements. A prime example would be the use of tricams in soft rock >- I trust these more because I know marginal placements can be good. > > I think you've misunderstood me... I'm not worrying about marginal placements. I don't plan to be making any unless it's that or nothing. What bothers me is that all these numbers mean effectively nothing unless you have the corresponding numbers to match... They say the "average leader fall is about 4-7kN" - what is this based on? How much rope? How heavy is the faller? Are they wearing a bag? How far are they falling? This leads me on to ask - just how "bomber" is a really shit hot placement? For an extreme example, say I have a number 3 wire in the wall, it's real nice and snug and it's going no-where. But it's only rated 6kN... Will I be approaching a breaking load if I fall from 1m above to 1m below with not much rope out? Or is that well within the "average leader fall"... What about if I'm wearing a bag? Is that much much worse? What if it's 1.5m that I fall instead of 1m... Is that worse than having stuff on my back? It's all well and good having numbers on how good a wire or a cam or a hex really is in relation to its rating, but unless you can really quantify the difference several other factors make then you've not learned very much in that respect. I know that there's no substitute for experience, and that with time I'll know what different what makes, but until then, I'd much rather have a sound understanding of the maths so that I can make a calculation and say to myself for sure "ok if that's a bomber placement then I'm at about half the rated loading if I take a big old fall" rather than "well if that's a bomber placement then I guess if I fall on it then... it could well be between 4-7kN given an unknown amount of assumption and that would make it x amount of the rated strength.. but i don't really know how close I am to the limits because I haven't done this enough yet" Surely the more knowledge I can arm myself with the better? |
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7:35:25 AM |
On 10/11/2010 jam wrote: >What bothers me is that all these numbers mean effectively nothing unless >you have the corresponding numbers to match... They say the "average leader fall is about 4-7kN" - what is this based on? How much rope? How heavy is the faller? Are they wearing a bag? How far are they falling? Or 3 - 8 kN. The fall factor, rope, belay, and leader weight all make a difference, but you know if it will be hard or soft, few falls need to be hard. >This leads me on to ask - just how "bomber" is a really shit hot placement? Probably pretty good, unless it falls out, or unless you're wrong;- in either case doubling up is a good idea. >For an extreme example, say I have a number 3 wire in the wall, it's real >nice and snug and it's going no-where. But it's only rated 6kN... So it will take 99% of possible falls unless you have a weird belay (grigri, static rope...) >Surely the more knowledge I can arm myself with the better? yes. Or place more gear. Gear problems go away ( less flicking out, less drag, less than half the rope inmopact force) if you use double ropes, they were norm at Araps in the 80's and I'm always amazed that they are rarely used now. |
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8:05:43 AM |
>On 10/11/2010 jam wrote: >>What bothers me is that all these numbers mean effectively nothing unless >>you have the corresponding numbers to match... They say the "average >leader fall is about 4-7kN" - what is this based on? How much rope? How >heavy is the faller? Are they wearing a bag? How far are they falling? What if they are wearing a beanie? In all seriousness, very few placement failures are the wires breaking. I never think to worry about the wire's rating let alone do any calculation of whether a fall would be anywhere near their rated level. On very small gear where the rating is 2 kn or so, I might worry about it, but I'd be already worried about relying on a piece that small anyway, so it wouldn't change anything! I did hold several falls onto a 1 rp earlier this year though, I was quite impressed it worked. >>On 11/11/2010 mikllaw wrote: >So it will take 99% of possible falls unless you have a weird belay (grigri, >static rope...) Just to detour briefly, what do you reckon about use of a grigri with trad gear? Back when they first came out, it seemed generally accepted as a no no, but now I see more and more people using these or similar devices on trad gear. Do they increase impact forces? > >On 10/11/2010 mikllaw wrote: >On 10/11/2010 Wendy wrote: >>This testing is in some ways scary because it could give people a sense >>that crappy placements are better than we think they are. > >I was hoping to make the opposite point;- gear is stronger than I thought >but always seems to come out - the real question is "why?" It was just that the common comment seemed to be that everyone read into it that crappy looking gear was often stronger than it looked and they should toughen the fùck up. whilst many climbers have enough experience to be able to assess their gear realisticly, this could lead to some people thinking that crappy placements were actually quite good placements or people going for it more above marginal gear thinking that it probably would hold umpteen kilonewton. |
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8:35:13 AM |
On 11/11/2010 Wendy wrote: >what do you reckon about use of a grigri with trad gear? From the no good belay devices thread: On 13/10/2010 mikllaw wrote: >I don't think there are any good belay devices yet:- > >Autolockers encourage bad belaying, you still must use the anchor hand, and they can be fooled into dropping people. And they are definately not for trad. |
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10:06:44 AM |
When trad climbing - which admittedly isn't very often, as I prefer proper climbing these days - I always carry one quickdraw made from a Yates Screamer. I keep it for use on a marginal piece, which means I know the force will be limited to 3kN - the price being increasing the length of the fall as the Screamer unravels. It seems like a good idea to me but I've never seen anyone else do it. |
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10:32:33 AM |
The only places I have read of nutters using screamers are nutty alpinists and aid climbers. Thing I have started doing since hanging out with TooNuttyforMostM9 is when marginal pieces are necessary to make a MatrixODoom equalizing multiple scary pieces to make one decent. Even fell on one leading that WhatThef---WasIThinkingM6. Rotten incipient granite seam crumbling under my fingers, 3 micronuts, 2 peckers any one of which you could pull through its placement by hand. All together they held a factor 1ish fall. |
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3:34:43 PM |
On 11/11/2010 mikllaw wrote: >On 10/11/2010 jam wrote: >>What bothers me is that all these numbers mean effectively nothing unless >>you have the corresponding numbers to match... They say the "average >leader fall is about 4-7kN" - what is this based on? How much rope? How >heavy is the faller? Are they wearing a bag? How far are they falling? > >Or 3 - 8 kN. The fall factor, rope, belay, and leader weight all make >a difference, but you know if it will be hard or soft, few falls need to >be hard. > >>This leads me on to ask - just how "bomber" is a really shit hot placement? > >Probably pretty good, unless it falls out, or unless you're wrong;- in >either case doubling up is a good idea. > >>For an extreme example, say I have a number 3 wire in the wall, it's >real >>nice and snug and it's going no-where. But it's only rated 6kN... > >So it will take 99% of possible falls unless you have a weird belay (grigri, >static rope...) > >>Surely the more knowledge I can arm myself with the better? > >yes. Or place more gear. Gear problems go away ( less flicking out, less >drag, less than half the rope inmopact force) if you use double ropes, >they were norm at Araps in the 80's and I'm always amazed that they are >rarely used now. My point is that knowing how hard or soft a fall will be doesn't tell me how hard is a hard fall, how soft is a soft fall, etc. But it seems the general consensus is that I won't know until god forbid I end up tearing something out of the wall, or it fails. It's all very well saying "if in doubt double up" but I want to understand at least in theory where the doubt should start creeping into my mind.... Otherwise how will I know I'm not being reckless unless I stitch every climb up with a cluster of nuts at every placement.. Obviously that's an exagerration, but it does bug me that until I start testing this out in detail I just won't know even vaguely how safe I am. I guess maybe that's the correct approach... Go to the crag and find somewhere I can fall on a bunch of gear with a top-rope back up then test away. |
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5:03:05 PM |
On 11/11/2010 jam wrote: >My point is that knowing how hard or soft a fall will be doesn't tell >me how hard is a hard fall, how soft is a soft fall, etc. It's difficult to engineer a have a hard fall (> 6kN), if your gear is superbad,get your second to give you a soft catch >It's all very well saying "if in doubt double up" but I want to understand >at least in theory where the doubt should start creeping into my mind.... >Otherwise how will I know I'm not being reckless unless I stitch every >climb up with a cluster of nuts at every placement. If 1 nut in 10 that you think is good won't hold you (10%), the chances of 2 pulling in a row are 1%, of 3 pulling are 0.1%. So if three pieces pulling will land you on the ground, think about backing up (1/1000 adds up over a few climbs per weekend over a few years if you like to fall). If your gear likes to flick out (because you do something weird like climb on a single rope and don't use slings) and one nut in 3 is bad, the chances of 2 in a row pulling are now 11%, and 3 in row pulling are now 4%. Once again if 3 pieces pulling will land you on the ground, you absolutely need to back up, a few times. But you have a 96% chance of not hurting yourself. However, the odds start to stack up; if you fall on gear 10 times a year you now have a 33% chance of decking from this situation, over 2 years it rises to 56%, and over 5 years (if you've survived) you have an 88% chance of decking. if you don't want to carry a calculator to continually update the odds, place extra, good, pieces and sling them so they don't wander >Go to the crag and find somewhere I can fall on a bunch of gear with a top-rope back up then test away. I'd just throw yourself at hard cracky things at araps you can lace. If I'm any guide to the common method of getting up these things you're going to slump, whine, dog and have enough gear in (placed from arest) that you can take falls. |
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5:19:28 PM |
On 11/11/2010 Wendy wrote: >Just to detour briefly, what do you reckon about use of a grigri with >trad gear? Back when they first came out, it seemed generally accepted >as a no no, but now I see more and more people using these or similar devices >on trad gear. Do they increase impact forces? Just to split hairs for a moment, shouldn't the criticism levelled at the grigri in a trad situation not be that it increases impact forces but that it fails to decrease them (in the way that a slightly slipping plate-device might)? I make this distinction on the basis that the fast lock-off of the grigri isn't going to increase the rated impact-force of the rope (as dictated by rope elongation), whereas a softer-belay (either through slip, or better still dynamic belayer) will effectively reduce it. |
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5:27:22 PM |
Jam, to answer your question, all you need to know is the elasticity of the rope and you can work at the impact force. The force on the top piece of gear is generally considered to be 1.6x the impact force. (it would be 2x but for the effects of friction) The maths calculations are a fairly good approximation. Rope drag though can effectively INCREASE the fall factor. The formula is: F=mg+mg(1+2fEA/mg)^0.5 f-fall factor E-youngs modulus of rope A-area of rope cross-section m-mass g-gravity acceleration http://www.bealplanet.com/portail-2006/index.php?page=force_choc |
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6:46:45 PM |
On 11/11/2010 egosan wrote: >The only places I have read of nutters using screamers are nutty alpinists >and aid climbers. > > I have one of them on a route where the crux runout was big and the gear not totally bomber. Took one fall from about 1.5m above the piece with the screamer on it with about 20m of rope out (I down climbed a metre or two to that point out of fear). The gear held and the screamer pulled out. As to whether the piece would have pulled without the screamer I have no idea as I didn't want to test the concept and you tend to concentrate pretty hard when you get 5-6m out from gear like that. |
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8:35:09 PM |
Mikl law wrote; > It's difficult to engineer a have a hard fall (> 6kN), if your gear is superbad,get your second to give you a soft catch ... so you fall further and gravity helps load the pro piece? @ egosan wrote something about screamers... ~> Heh, heh, heh!! Post edit; ... ~> am going out to the shed now, to reorganise my aid-screamer onto its own set of krabs, instead of carrying it as a piece to deploy if needed! Note: my other 'industrial strength screamers' will remain as is, as I only use them for soloing and only set them at the belay... |
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8:19:45 AM |
On 11/11/2010 voodoo wrote: >Just to split hairs for a moment, shouldn't the criticism levelled at >the grigri in a trad situation not be that it increases impact forces >but that it fails to decrease them (in the way that a slightly slipping >plate-device might)? if you split enuff hairs you'll go bald yes, it makes the rope work more, at a higher force, so does tying down the belayer (unavoidable on multipitch). The nightmare is using a grigri clipped directly to a belay. |
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9:16:48 AM |
mikllaw, that said have you done testing on the force absorbed by a body in a harness. For example:bolt anchor, hanging belay on a 10mm rope with 1m between harness and anchor, grigri used as belay. What shock absorbtion does the body in a harness and a short bit of rope absorb? Quite a bit I reckon. Would it be better to have a light or heavier belayer for organic shock absorbtion? This would be a real acid test. | |||||
9:57:41 AM |
ok while we are still on grigri use and M9 might be nearby, what about impact forces when solo aiding? Seems like they might get up there a bit. Do you use the grigri and is that what the screamers at the belay are for? | |||||
9:59:40 AM |
The body absorbs (by moving its COG) down about 100mm gently (1kN), then the next 200mm is where all the damage is done. The rope is much more linear, to abouit 300mm and 9kN for this rope length. if the belayer is being lifted, lighter is better, so long as they don't let go. |
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