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Dr.Sprock
Boulder climber
Sprocketville
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Apr 24, 2009 - 12:50am PT
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you can try and get into it from a rigorous approach, but it would be a model with many variables.
thats why i bet a lot of other people have not offered up a big scientific explanation, they know it is futile.
it would be like doing an analysis of a pile of wood blocks stacked in a pyramid.
you pull out a bottom piece, what exactly happens next?
too random to predict, although, believe it or not, some bored scientist on his lunch break developed a program that does just that.
but does it work in real life?
how would you know?
you would have to duplicate the exact model in real life to test it.
rope is sometimes woven, sometimes knot.
i imagine that the interaction of the core with the sheath would be a master thesis all by it self.
thermo, braiding action, core/ sheath, too much for my small brain.
thats why i head for the gym to try it out.
not only does the experiment win out over theory, it usually takes a hell of a lot less time to reach a conclusion.
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tradmanclimbs
Ice climber
Pomfert VT
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Apr 24, 2009 - 03:23am PT
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Osmo, Obviously you did not understand my posts, INMOP if the gear is sketch and the liklyhood of a fall is high you should place multiple pieces of gear and clip them SEPERATLY to alternating ropes if useing the double rope system. You aparently sugested that just clipping one strand of 1/2 rope to a sketch piece provided a soft enough catch that other percautions were not needed.
I contested that clipping a single strand of 1/2 rope to a sketch piece was little diferent than clipping that same piece to a standard single rated rope.
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tradmanclimbs
Ice climber
Pomfert VT
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Apr 24, 2009 - 03:29am PT
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I bet your hardest common climbing falls are the 10 to 15 footers on 20ft of rope blowing the 2nd clip.
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Dr.Sprock
Boulder climber
Sprocketville
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Apr 24, 2009 - 03:49am PT
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OK, GRAPHS you want, charts you get.
here is a simple experiment to show the difference between ropes.
maybe used stuffed animals instead of humans.
see which head gets snapped.
someone i can tell experienced more g's than the other three.
but ya never know.
in todays economy, you might find volenteers.
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healyje
Trad climber
Portland, Oregon
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Apr 24, 2009 - 05:39am PT
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Geez, talk about a bunch of knickers in a knott...
While I appreciate that our gear today are engineered products, I'm totally Edisonian in my approah to all this business. Thirty five years of climbing has taught me that 99.5% of climbing all happens well within the tolerance our gear and the very rare and deadly .5% are extreme edge cases. Now, that's not to say you shouldn't know about, be able to recognize, and avoid those edge cases, but I feel that today's climbing world is a pretty paranoid lot and heavily fixated on the 'rules' for this or that - i.e. 'always do this, never do that'. And I suppose in the context of the demographics involved with climbing today that's a reasonable deal - but it doesn't and never will reflect the reality of my climbing.
Over those years of climbing, I've climbed on a wide variety of ropes in doubles mode from 8.x to 11's to various mixed size combos. Typically when I depart from 'norms' or specs in my use of ropes (or screamers for that matter which I often pre-slice and label in a variety of ways), it generally means I'm on incredible sharp rock, really bad or technical pro, or both as in the case of a route I've been working the past two years. I'm usually operating in territory that's R-to-Xish, and often for more than one reason. The possibility of falling and somehow miraculously ending up with both ropes equally sharing the load is the very least of my concerns regardless of how or what I clip; but then I rarely if ever clip both ropes into a single piece as it's a pretty useless excercise. When I do, it's usually more about rope management and I use two biners end-to-end vs. side-by-side to avoid enabling that braking affect.
By and large if you're in territory where you absolutely better be on doubles - and sometimes one or both burly lines - then fall factors, loads on pieces, and body shock rank right up there with being hit by ligthning while I'm on a pitch. That said, you better really know the game well before you start bending and / or breaking the 'rules'. By 'know the game' I mean know your technologies of choice; have an intimate understanding of rock and pro; know how to perceive, rank and prioritize risk; and able to craft a consistently coherent and performant rope system as you go.
In the end though [for me] on rock, it's all way more a matter of constructive art than science and engineering, which again I appreciate, but personally never leave the ground because they have no sustaining relevance for me at that point - I'm almost exclusively operating on experience, instinct and intuition.
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hooblie
climber
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Apr 24, 2009 - 10:02am PT
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i'm exactly in agreement with healyje. i have an armchair appreciation for the scientific method. lab guys and theoreticians, and most especially, well spoken presenters of distilled results earn a special place in my heart.
jack dorn drove me crazy with technical safety specs, 50lb greater breaking strength kind of stuff. i argued that technicals only went so far, that the real safety factor had to do with intelligence, experience, judgement, intuition, tempered ambition, self knowledge as to limits, SOP's, etc. in a nutshell, not over pouring your cup has little to do with the cup. his death was a tragedy but i can't think of one technical value that could be applied to the particulars of his end story.
that being said the real value of this kind of thread is the contributions to the knowledge base which makes possible our intelligent application of the experience of others.
after you've weighed all the data and employed the human factors, the critical moment is when you hunch your shoulders and DECIDE, huh, i think i'll go for it.
for the record, leading on double lines satified me on many levels but i almost always succumbed to the less rigorous; huh, one will due.
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dirtineye
Trad climber
the south
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Apr 24, 2009 - 02:14pm PT
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Here's a spot where that index of Ander's would come in real handy.
Hey ANders, if you are looking at this, how about dredging up the relevant rgold/jim ewing ed H and a few others threads n posts on this topic, which has been more than adequately addressed over the years, and linking them to this?
It's a shame to dilute the good stuff with repeated attempts to create nonsense and drive away the guys who are doubtless by now TIRED of saying the same stuff over and over, and having it bounce off, only to rear it's ugly head yet again year after year.
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Osmo
Trad climber
Calgary, Alberta
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Apr 26, 2009 - 06:08pm PT
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I'm back, briefly I hope, as it's good to see a few other guys getting in again--they were likely afraid to get rolled up in the snowball that happened here over the last couple of weeks.
To Tradman, I understood your posts perfectly, unless they didn't say what you meant, but that would be YOUR problem: I never talked about diversity, multiple pieces, screamers, etc. because they were all off the topic of relative impact forces between thick and thin ropes. I'm also all FOR, and USE, all that stuff, BUT what we're talking about (and you're trying to wiggle out of it) is:
What IF?: you're leading on 2 ropes, and get in a sketchy piece, just before a tough section, and it's the only piece possible, and you have no screamer?! You said we should clip in both ropes to minimize the possible shock on that questionable piece, to give it the best chance of surviving if you fall off. I say clip in only one rope, because it's stretchier than two, and so will shock that piece LESS. And from what I've heard from several others over at least 3 of these forums, what THEY think is the same (as we've known since hemp ropes).
But I'm open to some real-world impact force tests as proof one way or the other. I think that's what most climbers (like healyje) would like to see, instead of speculation and technical explanations, and I haven't seen any yet--the UIAA test numbers are from fall factors 2-3 times higher than realistic. Maybe Jim Ewing is thinking about that right now. Let's hope.
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tradmanclimbs
Ice climber
Pomfert VT
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Apr 26, 2009 - 08:18pm PT
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Osmo. I NEVER said to clip 2 1/2 ropes to a single sketch piece. I DID say that you can use the doubbles as twins when the gear is bomber and the line of climbing is relativly straight.
You keep saying that a single strand of 1/2 rope is a softer catch than a normal single rope and Jims numbers CLEARLY prove that wrong.
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Jim E
climber
away
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Apr 26, 2009 - 08:20pm PT
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"Maybe Jim Ewing is thinking about that right now"
I can assure you... he is not.
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Osmo
Trad climber
Calgary, Alberta
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Apr 26, 2009 - 08:25pm PT
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OK Jim, I get it--it's a weekend; maybe during the week, you'll think about it; you should.
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Osmo
Trad climber
Calgary, Alberta
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Apr 27, 2009 - 02:24am PT
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Hi Tradman; we can all read in your many posts that you advocated clipping both ropes on sketchy gear because "Your ("skinny") rope is not extra soft and will yank that crap gear just as fast as your old fat single rope"--you said it yourself, as quoted.
Then in your last post you went on to compound your confusing opinion by contradicting yourself in two consecutive sentences:
"I DID say that you can use the doubbles as twins when the gear is bomber...". Ie., you're admitting what we all know already: that you should NOT clip both ropes when the gear is NOT bomber: why?: it can only be because a 'rope' of two ropes has a higher impact force (in a real climbing fall--do I really need to keep repeating that?) than only one of those ropes, alone, does.
But then you go on to try to have it both ways in the next sentence to the effect that 'Jim's numbers CLEARLY prove that a single strand of 1/2 rope is NOT a softer catch than a normal single rope'. Here it is:
"You keep saying that a single strand of 1/2 rope is a softer catch than a normal single rope and Jims numbers CLEARLY prove that wrong."
So which is it, Tradman? You were obviously unsure of what to believe, but it's either one or the other, so just admit it, pick one, and let's move on.
In fact, we can't be sure of what if anything, Jim's numbers--the ones I've seen--mean for real climbing falls, as his UIAA-type test results are from drops in the range of 2 to 3 times the fall factors of real climbing falls--a serious discrepancy. I believe they mean nothing to climbers in this regard.
No worry, guys, if we can't get any realistic data for rope impact forces in climbing falls, I may be prepared to do some tests myself and report the results here; we should be interested in the fall factor range from 0.5 to 0.75 as the Tradman suggests himself.
Osmo
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That Darn French Guy
Trad climber
Santa Clara, CA
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Apr 27, 2009 - 04:26am PT
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> why they would drop a lighter weight for the half ropes
Maybe because they technically would not pass at full load, until now? But it's OK because double climbers would not dream to factor-2 on 1 strand anyways? It's frequent to clip both on the 1st piece, then alternate.
*Twins: For some reason no-one seems to use twins, yet they're lighter, and less cluster-f*#ky since they both feed together. Are they that much worst than single ropes when angles change that you get horrible drag?
* Doubles have another drawback: you can twist them when clipping if you don't pay attention, and you loose all benefits of splitting them for drag reduction when wandering.
* Singles: With singles the real BS is you end up carrying 2 10.2mm ropes all the way to the top to rappel, after all, so no matter what singles become way heavier than having two doubles/twins. If you don't that other single will stay at the base, aka you brought it anyways. :\
* Caught: Are doubles less prone to get caught? I mean the weight/length is less so maybe they could coil over themselves less as they fall down?
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Jim E
climber
away
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Apr 27, 2009 - 08:55am PT
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"It's frequent to clip both on the 1st piece, then alternate."
I read and heard this said a few times over the past year. I would like to point out that from an impact force perspective clipping both on the first piece is probably the absolute worst time to do so. At no other time in a pitch is impact force likely to be higher, even on a single strand.
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Tomcat
Trad climber
Chatham N.H.
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Apr 27, 2009 - 09:10am PT
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So Jim,I have an unrelated,sort of,question that may beg an unscientific answer.Tradchick and I climb on doubles just about all the time,and one really noticable difference between them and our single is when I make a catch,the doubles obviously have more friction,thus catch easier.
Do you think the odds of success with a FF2 fall are better with doubles,just due to added friction in the system?
In my case it's when she is following,so the strands are pretty well equal.I've caught plenty of lead falls on doubles,and as Trad has mentioned I believe,often it's really just one rope doing the work,so maybe a little more effort then,but what is your opinion in the case of the dreaded FF2,and disregarding,for now,the orientation issue.
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Jim E
climber
away
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Apr 27, 2009 - 10:23am PT
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I think it's a fair assumption that catching a FF2 would be easier with double. More friction in the device and more rope surface area for the belayer to grip. Impact would likely be higher of course but would not really be a concern if the anchor is good.
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Tomcat
Trad climber
Chatham N.H.
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Apr 27, 2009 - 10:28am PT
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Thanks Jim.
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rhyang
climber
SJC
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Apr 27, 2009 - 11:31am PT
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It's frequent to clip both on the 1st piece, then alternate.
I've never seen anyone do this.
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That Darn French Guy
Trad climber
Santa Clara, CA
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Apr 27, 2009 - 01:18pm PT
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Well I have... Of course once clipped, technically you're only supposed to get 1x fall factor unless you run out to the 2nd piece.
However if the only reason they're rated at 55kg is because they take long to recover, it is dubious excuse, 'cuz they could've rated them 80kg, with less falls required to pass.
My take is at the time the standard was set, they were meant for teenagers, not burly trad climbers wearing too much gear.
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That Darn French Guy
Trad climber
Santa Clara, CA
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Apr 27, 2009 - 01:18pm PT
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BTW, why no-one uses twins then? Why does it suck more?
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