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David p
Trad climber
Mountain View, CA
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Topic Author's Original Post - Sep 12, 2014 - 12:37pm PT
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I've been climbing a good many years, but have been on hiatus the last few. I recently took a trip with a friend and he questioned an anchor I did and I wanted to see what the general wisdom on the matter is.
We had a simple enough 2 bolt anchor above 3 climbs we were going to be top roping (left, right, and center). I did an anchor with 2 extra long double length slings (each attached to both bolts the same), twisting one strand of each for the sliding X (two lockers on the end and all that).
My friend pointed out the that there would be a slings length worth of extension if one bolt failed, putting a shock loading on the other and called that risky. I countered the debate by pointing out that a cordelette or the like (no extension) would provide poor equalization across the 3 routes we were doing.
The last time I put much time into analyzing these kinds of things this was a tradeoff, but I vaguely recall there being some talk of an alternative to cordelettes that provided equalization and no extension, I also vaguely recall there being some talk of shock loading being a lesser evil than was previously thought.
I'd love to hear what others have to say here. Is there a better option for anchoring 2 bolts for the 3 climbs? Is the tradeoff of one over the other preferable, no extension vs. equalization?
An alternate arrangement we discussed might have been individual slings on each bolt joined to a couple half slings with a "sliding X" for equalization. This way the extension would have been only as much as a half sling allows for rather than the double sling.
David
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G_Gnome
Trad climber
Cali
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Sep 12, 2014 - 12:48pm PT
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Clip one runner into each bolt and the rope into the other end of each.
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Tvash
climber
Seattle
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Sep 12, 2014 - 01:34pm PT
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If one anchor point is notably mankier than the other - a non-dynamically equalized (figure 8) tied sling(s) - slightly favoring the better of the two anchors, might be better, but with two decent bolts? You're fine. You can always backup the 'mankier' anchor point with an extra sling if you've got one, too.
Cordelletes are not full strength as compared to slings or a rabbolet - not even close. Plus, they're more time consuming. I never use them.
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David p
Trad climber
Mountain View, CA
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Topic Author's Reply - Sep 12, 2014 - 01:35pm PT
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My partner is fantastic, I trust him with my life, in large part because he asks questions like this, and certainly appreciate that he does. I would have it no other way.
I haven't heard of a rabbolet (nor has google it seems). Do you mean equalette? They were both solid bolts, I wouldn't anchor to anything less to be sure.
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Aaron Johnson
climber
Bear Valley, CA
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Sep 12, 2014 - 01:40pm PT
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don't get hung up on the webbing anchor points
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the Fet
climber
Tu-Tok-A-Nu-La
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Sep 12, 2014 - 01:47pm PT
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Yeah the good news is with 2 good bolts any decent setup will work fine.
For 3 climbs on 1 set of bolts I would use something that equalizes if only for the fact that the anchor point will move and the climber will be looking at less swing if they fall near the top.
You won't get equalizing and non extending. But you can minimize the extension but 1. using sliding Xs with limiter knots (I carry two, pre-tied with unequal length arms that work on 90%+ of all two placement anchors, they are tied so little binding occurs on the powerpoint biners which limits how much they equalize, I use 1 on trad anchors where I can see them or two on top ropes where I can't see them) or 2. using an equallette, something developed for John Long's latest anchor book, perhaps this is what you were thinking of. For sport anchors it's really slick.
Both of those options will limit extension to maybe 6". With all the rope in the system during a top rope that's minimal. Hell even the extension of a full length runner extending with all the rope out in a TR situation I bet the shock forces would be low.
Edit; haha as I posted this Aaron posted some great photos of those two options. Sliding X with limiter knots above and quad (which if I remember correctly is a variant of the equallette) below.
Edit 2: there's how you tie it and there's material used. Cordelletes usually use cord and Runners webbing but you could go either way. However it is best IMO to use Nylon not spectra because Nylon holds up better over time and has a tiny bit more stretch.
Rabbit runners perhaps that what was meant are a single strand runner with loops on the end, I never saw the point in them.
The sliding X photo above it extra long IMO, I use 48" sewn runners and just leave them tied all the time.
On the sliding X you can see the strand of runner that has the X in it that goes around the biners, I tie it so that's a little longer than the other strand that goes straight thru the biners to reduce binding so it equalizes better.
BTW that's what I like for biners for top ropes too. Two reversed and opposed ovals. Low friction, very unlikely to get unclipped or hung up in any way, no gates to bang against the rock.
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David p
Trad climber
Mountain View, CA
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Topic Author's Reply - Sep 12, 2014 - 01:52pm PT
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Yeah, both of those look like the options I should be thinking of, thanks for the pictures and good discussion both Aaron and Fet!
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Big Mike
Trad climber
BC
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Sep 12, 2014 - 03:09pm PT
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Shouldn't the real question be: will you ever generate enough force in a toprope situation to worry about it?
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neversummer
climber
30 mins. from suicide USA
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Sep 12, 2014 - 03:35pm PT
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couchmaster
climber
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Sep 12, 2014 - 03:41pm PT
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Time to embrace the Clusterf*#kolette™ ™ ™ ™ or the sucko-lette™ ™ ™ ™ I guess.
I'd climb on your rig all day long. 2 slings -one from each bolt wou;d be much better than Neversummers abortion-o-lette™ up there but that wouldn't fail either.
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skcreidc
Social climber
SD, CA
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Sep 12, 2014 - 03:44pm PT
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I like the quad too. As long as you have 2 bolts it works great for lead or following. Have it pre-rigged and its very fast and flexible; becomes an equalette with no problem. But there are endless solutions.
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neversummer
climber
30 mins. from suicide USA
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Sep 12, 2014 - 03:46pm PT
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Better yet...explain what the issue is again with my abortionlette??
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JonA
Trad climber
Flagstaff, AZ
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Sep 12, 2014 - 04:29pm PT
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You guys are seriously arguing about how to rig a TR anchor off two bolts that were installed for that purpose? God the Internet has made us dumb.
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Vegasclimber
Trad climber
Las Vegas, NV.
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Sep 12, 2014 - 04:43pm PT
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No, people are actually having a discussion about climbing content so take the trolling to the political stuff.
First off, welcome back to climbing!
Like a few of the posters here, I have no issue with the sliding X and unless the bolts are manky as hell the chance of shock loading the other bolt to failure on TR is minimal with that setup. Maybe one of our residents experts that have done some actual testing on that could chime in here. When I use a sliding X I usually back up with a second sling and run the biner(s) through both.
I have been using the quad almost exclusively for the last 4 years or so. Limiting knots, equalizing, bomber and usable in many ways.
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ruppell
climber
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Sep 12, 2014 - 04:46pm PT
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Didn't John Long do some tests for the last climbing anchors book that prove shock loading does not exist? SO that debate is way last year. As long as the anchor is redundant rig it however you want. I just clip a couple runners or draws to each bolt and call it good. For multi-pitch I use the sliding X without limiters. To each their own.
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BG
Trad climber
JTree & Idyllwild
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Sep 12, 2014 - 08:57pm PT
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Here are a couple of self-equalizing rigging methods I often use when I know the anchor will be loaded in different directions.
Just finished a new anchoring book (with John Long): Climbing Anchors Field Guide, 2nd edition. Publication date set for Nov. 6. This is the latest in the Climbing Anchors series, featuring all-color photos and detailed analysis of state-of-the-art rigging methods including: magic X's, stacked X's, the QUAD, the equallette, the double equallette, the Joshua Tree System for rigging TRs with an extension rope, and much more.
Available right now for a pre-publication discount at amazon.com
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ms55401
Trad climber
minneapolis, mn
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Sep 12, 2014 - 10:00pm PT
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how many climbers are going to die driving to and from the crag? I'd worry about that more than worrying whether something is five- or six-sigma, because five and six sigma isn't going to be tested in the field
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ryankelly
Trad climber
el portal
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Sep 12, 2014 - 10:09pm PT
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is that Bill Murray of CaddyShack fame tossing his club up thread?
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rgold
Trad climber
Poughkeepsie, NY
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Sep 12, 2014 - 11:49pm PT
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Lots and lots of testing as well as theorizing has been done on sliding X's by now. I think it fair to say that the results suggest that you cannot, in general, count on any equalization advantage from a sliding X over some fixed system, and when you get to three-anchor situations the sliding systems can be far worse than fixed ones. This means that the only advantage of a sliding X might be convenience of installation.
Shock loading. The first problem is that people use this term without having any plausible definition for it. There is in fact no reasonable definition that would not classify all climbing falls as shock loads, except perhaps for certain tightly-belayed top rope falls. So the idea that you will or will not avoid shock loads with this or that rigging is fundamentally nonsensical.
So if we can manage to forget that term, there is a question whether the extension in a sliding anchor that occurs when a piece fails will produce a bigger load on the remaining piece(s) than they would have felt had some sort of fixed rigging been used and the same piece failed. The answer is, it depends, and significantly elevated loads are most definitely possible.
The tests on "shock loading" done, I think, by Jim Ewing of Sterling Ropes for Long's anchor book only considered one of several scenarios of importance to climbers, essentially a leader fall onto a two-piece sliding X anchor. It would have been easy to predict from strictly theoretical considerations that the scenario tested would show only a neglible extension effect, because in the situation tested, the anchor extension only made a tiny change in the fall factor.
The DAV in 2009 found a 40% increase over what would have happened with fixed rigging when a sliding X failed, for example. The reason their results are so different from the ones reported in Long is, I think, because of varying relations between the actual extension and the fall height. The bigger the extension relative to fall height, the bigger the increase in fall factor due to extension and so the more effect on the remaining pieces.
A scenario of some interest to climbers that Long/Ewing did not consider is what happens in a factor 2 fall onto the belayer if the impact pulls the belayer off. In that case, the fall energy of combined leader and belayer has to be absorbed by the belayer's tie-in, and for this the anchor extension could be relatively quite large and so lead to a very high fall factor with a load of not one but two body-weights. In this case the effect of anchor extension will be enormous.
The upshot of all these considerations is that there doesn't seem to be any simple mantra to be uttered about the performance of a sliding X. Extension could matter---in some cases a lot---and the variation in performance in any one situation makes it impossible to count on a level of equalization better than one gets from fixed rigging. Although there is some room for debate when there are two anchor pieces, the performance of sliding systems for three pieces is in general bad enough that there is no reason to prefer them over fixed rigging, imperfect as it is in equalizing.
Perhaps it is worth concluding with the fact that equalization has been oversold. It is based on an assumption that the pieces themselves are more or less of the same strength. When this is not the case, equalization makes little sense, and one can even describe hypothetical situations in which equalization causes the failure of two pieces which would, however, survive sequential loading.
When two good bolts are involved, there is virtually no good case for equalization, most especially for top-roping. It makes perfectly good sense to rig so that all the load goes to one bolt with the other one as a backup in case the first one fails. Rigged this way, you get a multi-directional anchor as well.
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bhilden
Trad climber
Mountain View, CA/Boulder, CO
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Sep 12, 2014 - 11:55pm PT
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When two good bolts are involved, there is virtually no good case for equalization, most especially for top-roping. It makes perfectly good sense to rig so that all the load goes to one bolt with the other one as a backup in case the first one fails. Rigged this way, you get a multi-directional anchor as well.
^^^^^^^^^^^^^
What he said!
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JimT
climber
Munich
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Sep 13, 2014 - 05:12am PT
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There are other reasons why some of the extension/impact force testing isn´t as revealing as it should be. Generally the set-ups are as shown in all the photo´s in this thread with the central karabiner nicely in the middle of the two limiting knots. Logically however if you require that amount of movement in the anchor to cope with load shift then you need to test when the load has moved, i.e at one end or the other where the extension is potentially worst.
Top-roping what you do is irrelevant but this doesn´t make dynamically equalising anchors desirable for multi-pitch.
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Tvash
climber
Seattle
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Sep 13, 2014 - 08:38am PT
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a rabbolet's just a long rabbit (metolius...)
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BG
Trad climber
JTree & Idyllwild
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Sep 13, 2014 - 09:48am PT
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Tvash
climber
Seattle
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Sep 13, 2014 - 09:52am PT
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Not full strength. Not dynamically equalized.
One side takes nearly all the load in a fall.
Just sayin.
I'm gonna try the quad (with a full strength runner, not a clothesline o let). That seems to provide the best of all worlds.
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Tvash
climber
Seattle
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Sep 13, 2014 - 10:03am PT
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Not if you're awesome.
Are you...awesome?
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Tvash
climber
Seattle
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Sep 13, 2014 - 10:07am PT
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I mean truly...AWESOME
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Tvash
climber
Seattle
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Sep 13, 2014 - 10:08am PT
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If not, then...
...BEHOLD, THE LOCKER THAT BLEEDS!
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Tork
climber
Yosemite
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Sep 13, 2014 - 10:15am PT
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Not full strength????
I can not think of a single top rope situation that this isn't 100%.
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Tvash
climber
Seattle
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Sep 13, 2014 - 10:34am PT
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"Not full strength????
I can not think of a single top rope situation that this isn't 100%."
The strength of an anchor is independent of how it's used if it's built to be omni-directional and dynamically equalized.
7mm accessory cord (typical cordelet) has a rated strength of 11 kN - as compared to 22 - 25 kN for a dyneema runner - which is also lighter weight. This can make a difference when the anchor is shock loaded (one pro point fails - not unheard of with a trad anchor when catching a lead fall). It's pretty much free extra safety, anyway.
That's all I'm sayin'.
Not a huge deal for top roping, obviously. For hanging belays on walls with haul bags? I go for all the strength I can get.
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the Fet
climber
Tu-Tok-A-Nu-La
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Sep 13, 2014 - 10:43am PT
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An advantage of the quad/X over the cordolette in the photo above is no messy knot to undo after a bunch of falls.
The only thing I don't like for two bolts on TR is a quick draw clipped to each one separately. You don't have two reversed opposed biners on the rope connection which is a red flag to me. I could see someone climbing above the anchor or the biners clashing together and unclipping a biner, then you are only on one biner which isn't enough safety factor.
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OR
Trad climber
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Sep 13, 2014 - 10:47am PT
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Just checking in on this soon to be 100 page dork a thon thread of tech weenies going berserk. NTTIAWWT ;)
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Tvash
climber
Seattle
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Sep 13, 2014 - 10:48am PT
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For TRing just use all lockers. Problem solved.
It's a dork a thon - but if you've ever known anyone who was almost kilt by an anchor failure (I have), sometimes being a dork is just OK.
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Josh Nash
Social climber
riverbank ca
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Sep 13, 2014 - 10:55am PT
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Why am I seeing three ovals on a lot of pics? I thought two opposed lockers or two opposed out facing gates at the least is ok.
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j-tree
Big Wall climber
Typewriters and Ledges
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Sep 13, 2014 - 11:38am PT
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"Hmmmm a thread about TR anchors?, This would be a great place to post my opinions and relevant experience about multi-pitch anchors for belaying a lead climber."
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Josh Nash
Social climber
riverbank ca
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Sep 13, 2014 - 11:53am PT
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3 is standard for TR'ing...
for only a couple of years...so yeah not long at all.
Why three? is it for redundancy or rope handling?
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JimT
climber
Munich
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Sep 13, 2014 - 12:04pm PT
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They sit on the rock better to stop any twisting in the NooB-a-Lette forcing the rope to rub.
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adam d
climber
CA
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Sep 13, 2014 - 12:08pm PT
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3 ovals makes a great TR masterpoint. Wide radius for the rope to run over for less friction and wear, opposite and opposed for security, symmetrical and the carabiners play nice with each other and don't pinch or load funny like some other combinations.
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rockgymnast
Trad climber
Virginia
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Sep 13, 2014 - 01:03pm PT
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I was led to believe that adding additional biners increased the friction, not decreased it.
That is why when rappelling, if one needs more control/friction, you would use 2 biners on your belay loop/rappel device.
Am I mistaken?
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Tvash
climber
Seattle
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Sep 13, 2014 - 01:37pm PT
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When you add more biners rapping - it tightens the radius of the bend in the rope as it passes through your device, increasing friction.
Adding more biners to a TR anchor increases the radius of the power point - and therefore increases the area upon which the force of the rope is applied. More area = less force/area = less pressure = less friction.
Wide ski versus skinny ski, etc.
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rgold
Trad climber
Poughkeepsie, NY
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Sep 13, 2014 - 01:48pm PT
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That would be a nice explanation if friction depended on pressure, which it does not, at least not the classical version.
Since you get the same 180 degree bend in the rope (split into two 90 degree bends) and then friction along the top surface, my guess is the three carabiners provide more friction than one in a top-rope setup.
There may be other reasons to use them, but decreasing friction isn't one.
Adding a biner to the rappel can either increase or decrease friction, depending on whether or not the added biner is clipped to the belay loop. So there isn't any fundamental principle that equates more biners with more friction independent of the configuration involved.
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Ksolem
Trad climber
Monrovia, California
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Sep 13, 2014 - 02:30pm PT
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such as the masterpoint flipping during a lower
By masterpoint I assume you mean the 'biners the top rope is passing through? That point can flip while loaded up in a lower? I'd have to see that.
Personally if the anchor is two modern bolts in good rock, any setup which is attached to both bolts, is approximately equalized and can't un-clip is bomber. An anchor built with gear for top roping should be 100% bomber as well. If it's not then someone is not competent or your TRing the wrong route.
Belay anchors on routes should be bomber as well, unless the climbers go into that terrain knowingly. In such a case every trick in the book comes into play. First is real expertise in placing gear, never settle for second best.
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apogee
climber
Technically expert, safe belayer, can lead if easy
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Sep 13, 2014 - 05:41pm PT
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"In which case the added security and reduced wear become more important."
Nah...it's really not about the security factor....doubled/opposed would be plenty secure.
As mentioned, it's the larger radius the rope moves across, which tends to run smoother and is less hard on the rope. Seems like a minor detail, but the ease of rope management over the course of the day really makes a difference.
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rgold
Trad climber
Poughkeepsie, NY
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Sep 13, 2014 - 07:30pm PT
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"A scenario of some interest to climbers that Long/Ewing did not consider is what happens in a factor 2 fall onto the belayer if the impact pulls the belayer off."
Maybe they didn't consider what happens in this scenario because...it is obvious...the whole team takes the dirt nap.
There are plenty of "obvious" things that are just plain wrong. I've had to catch a factor 2 fall and one very close to that with the so-called "shock load" horizontal without the party taking even a dirt coffee break. Fortunately, my anchors and the way they were rigged were up to the task.
Long, Gaines, and Ewing were well aware of situations in which factor-2 falls were held and other situations in which the anchor blew and the party was killed, so it is beyond question that this scenario was of "some interest" to them as contributors to a treatise on how not to take that dirt nap. But the test protocol used didn't address this situation and others as well (recall the DAV result mentioned above), and the results were widely misunderstood as saying, universally, that extension doesn't matter.
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Ksolem
Trad climber
Monrovia, California
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Sep 13, 2014 - 07:55pm PT
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So you will be psyched to TR on my sliding x made of dental floss, right? It's self equalizing!
Pardon me. I made the assumption this chat involves people who are discussing the use of climbing gear. ;-0
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Bill Mc Kirgan
Trad climber
Cedar Rapids, Iowa
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Sep 13, 2014 - 08:33pm PT
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Three ovals for the master point is good, but I think 5 might be even better. Has any one tried 5?
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JimT
climber
Munich
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Sep 13, 2014 - 11:43pm PT
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Since you get the same 180 degree bend in the rope (split into two 90 degree bends) and then friction along the top surface, my guess is the three carabiners provide more friction than one in a top-rope setup.
This is so.
Three ovals for the master point is good, but I think 5 might be even better. Has any one tried 5
Sure, I´ve tested up to 7 to see at what point the friction from adding karabiners stops increasing, after 7 it´s not detectable.
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the Fet
climber
Tu-Tok-A-Nu-La
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Sep 14, 2014 - 11:26pm PT
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^^ you've tested this? My guess would be 2 or 3 biners have close to identical friction.
Adding surface area doesn't increase friction. Friction is a function of pressure and the coefficient of friction of the two materials. At least that's what the experiments in physics class taught me. We tested a wide tire vs a skinny tire, exact same friction if the same weight is applied to both.
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Big Mike
Trad climber
BC
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Sep 14, 2014 - 11:50pm PT
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I could see adding a biner dissipating heat a bit better possibly causing less wear!
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bhilden
Trad climber
Mountain View, CA/Boulder, CO
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Sep 15, 2014 - 12:01am PT
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The key factor in choosing the number of carabiners for a TR anchor is not the number but making sure you use ones that are from different manufacturing lots. That's why I only use carabiners with individual serial numbers.
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clinker
Trad climber
Santa Cruz, California
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Sep 15, 2014 - 08:23am PT
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Four bolt anchors at all belays would allow more options.
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RyanD
climber
Squamish
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Sep 15, 2014 - 10:50am PT
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Can't believe nobody has mentioned making revolver quickdraws for Lowering off bolted anchors & TRs. Low friction & makes your rope last forever. You can't oppose 2 of them though because the wheels won't line up properly, causing the bearing to wear out quickly, so most ppl will probably want at least 5 of them on the rope side just to be safe, unless they are reckless n00bs.
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JimT
climber
Munich
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Sep 15, 2014 - 10:54am PT
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Can't believe nobody has mentioned making revolver quickdraws for Lowering off bolted anchors & TRs. Low friction & makes your rope last forever. You can't oppose 2 of them though because the wheels won't line up properly, causing the bearing to wear out quickly, so most ppl will probably want at least 5 of them on the rope side just to be safe, unless they are reckless n00bs.
If you reduce the friction at the top you´ll have to increase it at the bottom when you lower someone and wear the rope even faster on your belay plate.
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RyanD
climber
Squamish
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Sep 15, 2014 - 10:55am PT
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Grigri Jim T, but that's for another thread.
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donini
Trad climber
Ouray, Colorado
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Sep 15, 2014 - 10:57am PT
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Overkill is fine and dandy with short climbs and TRs but don't being doing that if you multi pitch with me!
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RyanD
climber
Squamish
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Sep 15, 2014 - 10:58am PT
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Hahah!!
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JimT
climber
Munich
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Sep 15, 2014 - 11:03am PT
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^^ you've tested this? My guess would be 2 or 3 biners have close to identical friction.
Adding surface area doesn't increase friction. Friction is a function of pressure and the coefficient of friction of the two materials. At least that's what the experiments in physics class taught me. We tested a wide tire vs a skinny tire, exact same friction if the same weight is applied to both.
The classic model of friction is really virtually worthless anyway but don´t worry about that. The reason there´s more resistance over more karabiners is the resistance over a karabiner or whatever is the sum of the force required to bend the rope around the object and the surface friction. Round a biner rope bending is the major resistance and bending, straightening the rope and bending it again takes more force than doing it once. The further apart the bending takes place the straighter the rope is inbetween and so more force is required to bend it again.
Sure I´ve tested it, here´s the results;-
The caption is a bit confusing as it´s part of something else, basically the lower the force on the left scale the less effort was required to move an 80kg load.
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Moof
Big Wall climber
Orygun
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Sep 15, 2014 - 11:55am PT
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What the heck is your X axis? I am really confused as to what that graph is trying to convey.
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Barbarian
climber
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Sep 15, 2014 - 01:25pm PT
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I looked at the chart and discovered my problem - I keep using blue carabiners. I don't worry about friction. The one's I use are oval ones marked Eiger USA. I've been using them since 1972, and they're really smooth.
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JimT
climber
Munich
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Sep 16, 2014 - 12:08am PT
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What the heck is your X axis? I am really confused as to what that graph is trying to convey.
Like I said, it´s a bit confusing because the captions were related to something else really.
Basically the X axis is the force required to lift an 80kg load using a 2:1 hoist (Z haul) with varying numbers of karabiners at the turning point. Add karabiners and the force required increases i.e the friction increases. There are a number of ways of testing this experimentally and I´ve done most of them, the end result is always the same.
As part of testing lower-offs we´ve also tested how what happens if you move two rings apart, the resistance stops measurably increasing at about the equivalent of 7 karabiners.
The Y axis is the pull time in the test rig but it´s left off since its a)irrelevant b)offset for each test otherwise you wouldn´t be able to see anything.
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climbski2
Mountain climber
Anchorage AK, Reno NV
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Sep 16, 2014 - 12:11am PT
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OH jezzus freaking christ..I didnt even read a single post on this thread..
84 posts??
cmon..have we become rcnoob on noob dot com?
here is my advice..not having read a damn thing other than the title
don't fall
oh
YER GUNNA DIE
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neversummer
climber
30 mins. from suicide USA
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Sep 16, 2014 - 07:18am PT
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murcy
Gym climber
sanfrancisco
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Sep 16, 2014 - 07:44am PT
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Basically the X axis is the force required to lift an 80kg load using a 2:1 hoist (Z haul) with varying numbers of karabiners at the turning point. Add karabiners and the force required increases i.e the friction increases.
That doesn't make sense. The force required to lift 80KG goes to infinity as the "load" approaches 60kg? What then is the "load" (y-axis)? Maybe instead of telling us what your graph "basically" is, tell us what it is?
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the Fet
climber
Tu-Tok-A-Nu-La
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Sep 16, 2014 - 08:26am PT
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JimT, thanks for your posts. Your sharing of test results gives us some actual hard data to settle years of speculation. It is much appreciated.
P.S. I wish I could get an Augustiner in America.
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donini
Trad climber
Ouray, Colorado
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Sep 16, 2014 - 09:31am PT
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For information germaine to the saftey of TR anchors perhaps we should drift away from the two bolt anchor discussion and have a horticulturalist talk about tree root strength.
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Tvash
climber
Seattle
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Sep 16, 2014 - 09:43am PT
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Think you won't sling blueberry bushes? Trust me - you will.
Back to the fail-o-let discussion - knots reduce the strength of your tat by as much as 50%. Now your cordelet is down to 5-7 kN - way below your internal injury threshold.
Hence - 22 kN tat. It's nice to have a safety factor considering wear and tear, UV damage, and knot factor (for tied power points, etc).
Plus, an 8mm dyneema runner is lighter, less bulky, and quicker to set up than anything else out there. Free speed and safety.
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JimT
climber
Munich
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Sep 16, 2014 - 10:53am PT
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That doesn't make sense. The force required to lift 80KG goes to infinity as the "load" approaches 60kg? What then is the "load" (y-axis)? Maybe instead of telling us what your graph "basically" is, tell us what it is?
You are right. The force required to lift the load of 80kg is the Y axis, the X axis is simply time. It´s confusing because in the context I originally did the graph the force actually was a "load" and so got described as such. Too early in the morning I guess!
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murcy
Gym climber
sanfrancisco
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Sep 16, 2014 - 10:55am PT
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Thanks, Jim! Makes sense now.
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skcreidc
Social climber
SD, CA
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Sep 16, 2014 - 11:09am PT
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A woman climbing a route I had top ropped for all got the the top and exclaimed, "Do you know what this rope is anchored too? A bush!!". To which I replied, "That is not just any bush madam, but a 4" diameter Manzanita. I dare you to pull that thing out." SHe was not particularly thrilled with my response, but Manzanita have DEEP roots, and are drought tolerant. Still have to test it out first though.
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OR
Trad climber
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Sep 16, 2014 - 11:17am PT
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OH jezzus freaking christ..I didnt even read a single post on this thread..
84 posts??
cmon..have we become rcnoob on noob dot com?
This thread is just getting warmed up.
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Branscomb
Trad climber
Lander, WY
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Sep 16, 2014 - 12:57pm PT
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I found rappelling from tied-off alder bushes on Valdez ice climbs to be most stimulating. Ablakov anchors are a near second, though a little more secure. The thrill on the latter can be maximized by submitting to late day exhaustion, cold and darkness and ignoring any cracks that develop between the holes and/or using <5mm diameter strings.
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snarky
climber
vantuna
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Sep 16, 2014 - 01:36pm PT
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Wank, wank, wank.
Skeet, skeet, skeet.
(Howz about a climbing topic?)
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Tvash
climber
Seattle
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Sep 16, 2014 - 01:45pm PT
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BG
Trad climber
JTree & Idyllwild
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Sep 16, 2014 - 03:08pm PT
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Bomber! or not?
Would you rappell or TR off this anchor? The trunks of the "tree" are roughly 2 inches in diameter.
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Tvash
climber
Seattle
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Sep 16, 2014 - 03:15pm PT
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We'd hang a school bus off that in the Cascades.
But we might plug our ears from all the screaming children.
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Pie
Trad climber
So-Cal
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Sep 16, 2014 - 03:51pm PT
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Gains... That from anchor at p1 of El whampo?
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skcreidc
Social climber
SD, CA
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Sep 16, 2014 - 04:17pm PT
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^^^^ IT does look like El Whampo P1. Holy sh#t, I've used that.
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the Fet
climber
Tu-Tok-A-Nu-La
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Sep 16, 2014 - 04:24pm PT
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Plus, an 8mm dyneema runner is lighter, less bulky, and quicker to set up than anything else out there. Free speed and safety.
There was a test a few years ago that showed dyneema/spectra loses a lot of strength after repeated bending. The fibers break. Which happens in a few years of clmibing use. So I use nylon or combo nylon/dyneema runners for anchors.
I think the quad or slidingX is the quickest. The PowerPoint biners stay on it, so it's just taking one thing off your harness and clipping two biners to the bolts, done.
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BG
Trad climber
JTree & Idyllwild
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Sep 16, 2014 - 04:26pm PT
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Gains... That from anchor at p1 of El whampo?
Yep
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BG
Trad climber
JTree & Idyllwild
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Sep 16, 2014 - 04:45pm PT
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There was a test a few years ago that showed dyneema/spectra loses a lot of strength after repeated bending. The fibers break. Which happens in a few years of clmibing use. So I use nylon or combo nylon/dyneema runners for anchors.
I've addressed this topic in some detail in my book Toproping (2012), and in Rockclimbing; The AMGA Single Pitch Manual (published May 2014) , which I co-authored with James Martin.
Spectra/Dynemma loses an appreciable amount of strength when tied with a knot. Some manufacturers warn of a 50% strength loss when tied with an overhand knot (a property that nylon does not possess).
From the Bluewater Company, referring to their 5.5 mm Titan Cord, which consists of a Dyneema core and Nylon sheath: "Dyneema does not lose significant strength with repetitive flexing and offers a huge increase in abrasion and cut resistance over other materials."
Aramid fibers (eg. Technora, sold as Sterling Power Cord, which has a technora core and nylon sheath, or Maxim/New England Tech Cord) used in cordellettes DO suffer from strength loss with repeated use and flexing, much more so than Dyneema or Nylon.
In fact, one study showed that when Technora cord was loaded with a 40 lb. weight and flexed 1,000 cycles over a 180 degree radious, the material lost 50% of its strength, while nylon cord, in the same test, lost virtually no strength.
More research is warranted, but the bottom line is that with Technora cord, you'll want to replace it more often with heavy duty use.
A question for the engineers out there, that I've often pondered: If Dyneema is static material, by adding nylon to it (like a Dyneema/nylon blend sling, or a Dyneema core/nylon sheath cord) isn't the combination still essentially static? Like a rubber-coated wire cable?
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climbski2
Mountain climber
Anchorage AK, Reno NV
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Sep 16, 2014 - 06:23pm PT
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Now that BG has chimed in I guess I'll read some of the thread. His stuff. It's not that I dislike great anchors.. it's that I dislike the endless conversations with questionably qualified people about them.
There is always more to learn when BG starts talking.
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rgold
Trad climber
Poughkeepsie, NY
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Sep 16, 2014 - 07:56pm PT
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If BG thought like you, he wouldn't be responding to those questionably qualified people, whose stupid questions and never-endingly ignorant statements provide fodder for his responses. The effect, as you say, is that you learn something, which wouldn't have happened if all us idiots hadn't weighed in to give BG the chance to set everything straight.
So maybe you need to rethink some of your scorn, or failing that, refrain from posting just to say you aren't reading any of the thread you just posted to.
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climbski2
Mountain climber
Anchorage AK, Reno NV
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Sep 16, 2014 - 08:19pm PT
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Is ok.. I deserved that comment. rgold you are no idiot either..lol.. but you knew that.
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donini
Trad climber
Ouray, Colorado
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Sep 16, 2014 - 08:19pm PT
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I'm somewhere in between. I believe that there have been excellent responses from well qualified people. I also believe that we are beating a dead horse. Yo dudes.....setting up safe anchors from two bolt anchors is not something that requires diagrams, formulas, force vectors and the like.....it's easy and pretty f*#king hard to screw up.
I am forever mystyfied at why it takes people today so f*#king long to set up belay anchors on multi pitch climbs. Speed and efficiency on long climbs is a saftey factor that seems to be ignored.
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donini
Trad climber
Ouray, Colorado
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Sep 16, 2014 - 08:22pm PT
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Yikes!
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Scrubber
climber
Straight outta Squampton
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Sep 16, 2014 - 09:09pm PT
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As ridiculous as this thread is getting, I feel I need to speak to one recurring myth/ error. Repeatedly, 7mm cord for a cordalette is stated to only have a strength of 10-13kN, versus a sewn sling of around 22kN. This lower strength is the cord's tensile strength. As in, single strand. Once it's tied into a loop, the strength is double, as it is shared by two stands, then take away about 1/3 for the knot. (13x2)x.67= 17.3kN
When you use cord in an equalized and tied off at the focal point two bolt anchor with a single loop going to each bolt your strength would be (13x4)x.67= 34.6kN
If you rigged something like the one shown several posts ago with two loops of cord going to each bolt you get a whopping (13x8)x.67=69.3kN
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BG
Trad climber
JTree & Idyllwild
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Sep 16, 2014 - 09:37pm PT
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I am forever mystyfied at why it takes people today so f*#king long to set up belay anchors on multi pitch climbs. Speed and efficiency on long climbs is a saftey factor that seems to be ignored.
My experience is that people take so long because they haven't learned how, when, and where they can trim the fat with anchor building.
I concur. There is usually no need to get fancy. In 30 years of guiding multi-pitch routes at Tahquitz, 90% of the time it's as easy as place 3 bomber pieces, pre-equalize with a cordellette, and I'm done. I shoot for a master point at waist to chest level and use a direct belay.
In guides' courses I teach the same thing when it comes to anchors: keep it simple, especially with TR anchors. If the vector is one direction, there isn't much to gain with complicated self-equalizing systems. AS JL always said, the key is sound primary placements.
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JimT
climber
Munich
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Sep 17, 2014 - 12:32am PT
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A question for the engineers out there, that I've often pondered: If Dyneema is static material, by adding nylon to it (like a Dyneema/nylon blend sling, or a Dyneema core/nylon sheath cord) isn't the combination still essentially static? Like a rubber-coated wire cable?
A problem is there are various ways slings are woven, in a lot of the very thin slings the nylon is merely there to hold the Dyneema together. The ones with coloured edges and basically white in the middles are like this. The more normally woven hybrid slings you can actually see the Dyneema cut through the nylon threads when you tensile test them which I guess why they got rid of them.
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GDavis
Social climber
SOL CAL
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Sep 17, 2014 - 12:38am PT
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Sliding X with 1 single sling - Not Ideal (IMO) and should tie limiter knots (again IMO).
Sliding X with 2 slings - Ideal in most situations.
Call it old-fashioned, but I have a weird rule I try to follow: I should be able to slice any single strand of my anchor at any point without failure. The single sling fails that, however a second one is the best of both worlds.
The cool cordalette style is great but a bit bulky - I prefer 12-15' of 6 mil and rely on extra shoulder slings/etc in the odd event I'm equalizing gear not nearby (or even the rope).
Am I gonna die?
Thanks to Gaines for his input, I took his How To Rock Climb (3rd) out to Dixon Lake with my brother when we were in high school and I was WELL equipped to learn and explore anchoring - a great tool and one I've sold to dozens and dozens of climbers at Nomad!
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Tvash
climber
Seattle
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Sep 17, 2014 - 12:59am PT
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good stuff. thanks for all the testing etc.
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Delhi Dog
climber
Good Question...
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Sep 17, 2014 - 03:40am PT
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climbski2 writes:
Now that BG has chimed in I guess I'll read some of the thread. His stuff. It's not that I dislike great anchors.. it's that I dislike the endless conversations with questionably qualified people about them.
There is always more to learn when BG starts talking. rgold write:
If BG thought like you, he wouldn't be responding to those questionably qualified people, whose stupid questions and never-endingly ignorant statements provide fodder for his responses. The effect, as you say, is that you learn something, which wouldn't have happened if all us idiots hadn't weighed in to give BG the chance to set everything straight.
So maybe you need to rethink some of your scorn, or failing that, refrain from posting just to say you aren't reading any of the thread you just posted to.
climbski2 responds:
Is ok.. I deserved that comment. rgold you are no idiot either..lol.. but you knew that.
I just want to say that it is refreshing to hear a bit of smack talk and no one really getting their panties in a twist like so many do around here. It ain't that hard now is it?
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BG
Trad climber
JTree & Idyllwild
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Sep 17, 2014 - 10:44am PT
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A problem is there are various ways slings are woven, in a lot of the very thin slings the nylon is merely there to hold the Dyneema together. The ones with coloured edges and basically white in the middles are like this. The more normally woven hybrid slings you can actually see the Dyneema cut through the nylon threads when you tensile test them which I guess why they got rid of them.
JimT;
So when you tensile test a Dyneema/nylon hybrid sling does the nylon add any elasticity? Or is the elasticity of the Dyneema based soley on the weave pattern, adding a modicum of stretch to an essentially static material? Does pure Dynemma (in a short sling or cord length) have ANY elasticity at all (say 1-2%) at mbs?
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j-tree
Big Wall climber
Typewriters and Ledges
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Sep 17, 2014 - 10:48am PT
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climbski2
Sep 16, 2014 - 08:19pm PT
Is ok.. I deserved that comment. rgold you are no idiot either..lol.. but you knew that.
Very classy.
Delhi Dog
Sep 17, 2014 - 03:40am PT
I just want to say that it is refreshing to hear a bit of smack talk and no one really getting their panties in a twist like so many do around here. It ain't that hard now is it?
+1
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Tvash
climber
Seattle
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Sep 17, 2014 - 02:14pm PT
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"Repeatedly, 7mm cord for a cordalette is stated to only have a strength of 10-13kN, versus a sewn sling of around 22kN. This lower strength is the cord's tensile strength. As in, single strand. Once it's tied into a loop, the strength is double, as it is shared by two stands, then take away about 1/3 for the knot. (13x2)x.67= 17.3kN"
Mammut tested a 13kN 7mm cordelet and found that it broke at the anchor point (biner) at about 17 kN. Knot factor didn't figure in - in that it didn't break at the knot (double fishermens). Empirically, therefore, they found the strength of the doubled 7mm cord to be 1.35x, not 2x. Compound this ratio accordingly.
Comparatively, a 22 kN sling doubled should yield a breaking strength of at least 29 kN, using the same ratio.
http://www.highinfatuation.com/blog/cordelette-for-climbing-what-are-the-issues/
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Tvash
climber
Seattle
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Sep 17, 2014 - 02:30pm PT
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Regarding nylon versus dyneema runners - the problem isn't really a difference in melting point (unless you're pulling a rap rope directly through a dyneema sling - don't do that), but elasticity.
DMM tested 120 cm x 11mm (22 kN) dyneema versus 16 mm (12 kN) nylon sewn runners with F1 and F2 falls, knotted (overhand - a figure 8 is slightly gentler though) and not knotted.
The dyneema's strength remained nearly double that of nylon when not knotted but was about equal to nylon when knotted.
http://dmmclimbing.com/knowledge/how-to-break-nylon-dyneema-slings/
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JimT
climber
Munich
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Sep 17, 2014 - 02:43pm PT
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Cord (and tape) are tested using a large diameter drum and clamp system to get the actual strength of the material. Tested using karabiners you´d expect to see around 75% of the stated strength. Sewn slings are tested over 10mm pins and so their rating reflects normal usage (they are made from ca. 16kN material).
Slings doubled over a karabiner are generally weaker, the outer strand cuts the inner strand.
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Tvash
climber
Seattle
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Sep 17, 2014 - 02:52pm PT
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Does the % loss of strength from being wrapped around a biner differ between cord (6 to 7mm being the most commonly used) and runner material?
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JimT
climber
Munich
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Sep 18, 2014 - 12:09am PT
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There are so many different makes of cord, tape and karabiners that it would be impossible to test (or possible but waste of time). You just have to take a rough estimate of around 75% which covers most of the stuff that´s ever been tested. Some of the thinner Spectra cord has a reputation of being worse affected (Blue Water saw a reduction of 60% in some tests they did and I´ve seen similar from others) but since the stuff is strong anyway whether this is a problem is debatable.
Normally with appropriate knots the point of failure is at the karabiner so discussing the relative knot strength is a bit of a waste of time. Where it is relevant is if you tie into pieces with a clove hitch where things get marginal quickly.
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greyghost
Trad climber
Las Vegas, NV
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Sep 23, 2014 - 09:49am PT
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+1 for BG!
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Rosamond
Trad climber
Truckee, CA
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Sep 23, 2014 - 11:29am PT
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Good gawd, are people still arguing about this kind of shite? Here's a hint: there is no one single way to do most things safely in climbing. Personally, I always use a fully load equalized pair of dental floss runners on all my anchors. They're good to at least 8 pounds.
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donini
Trad climber
Ouray, Colorado
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Sep 23, 2014 - 11:34am PT
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+1 Rosamond!
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phile
Trad climber
SF, CA
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Sep 23, 2014 - 12:12pm PT
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I am forever mystified at why it takes people today so f*#king long to set up belay anchors on multi pitch climbs...
HA! It would slow you down too if you had to figure out how to hang a quadolette and 3 lockers off your single #3 Camelot.
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oldnutz
Trad climber
OAKLAND
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Sep 23, 2014 - 12:41pm PT
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Normally with appropriate knots the point of failure is at the karabiner so discussing the relative knot strength is a bit of a waste of time. Where it is relevant is if you tie into pieces with a clove hitch where things get marginal quickly.
uh oh...I'm sorry but I have to ask Jim T...define "marginal" within the context of this sentence?
I had been led to believe, in regard to a multi-pitch anchor (not TR anchor), that clove hitches could help reduce max forces.
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Tvash
climber
Seattle
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Sep 23, 2014 - 12:59pm PT
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Clove hitches are fine for anchoring a belayer with a climbing rope. I haven't seen anyone use them with cordelets.
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dubhouse
Trad climber
Los Angeles, CA
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Sep 23, 2014 - 01:01pm PT
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The most important finding from John Longs experiments for the recent anchors book is the value of using dynamic cord for over static cord. What he found was that using a more dynamic cord in anchors will always reduce forces significantly even to the point where a weaker, more dynamic cord(eg. nylon) will not fail and a stronger, static cord(eg. dyneema) will fail.
So, even with mild extension, as long as you are using somewhat dynamic material, shock loading forces will be reduced dramatically and are not likely to cause any issues.
-tavis
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Largo
Sport climber
The Big Wide Open Face
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Sep 23, 2014 - 01:07pm PT
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Most of the elaborate rigging systems are on little use on the vast majority of anchor arrays. They only come into play when the primary anchors are sh#t, and you need to spread the load or risk anchor failure fi the leader pings straight onto the anchor. This happens so infrequently on the routes most people climb that a cordellette will usualy suffice. But when the primary placements are piss poor, knowing a few tricks can be a life saver.
No-extension is a better objective than equalization since the later is rarely achieved save for the "quad" clipped to side by side bolts and rigged with anodized krabs.
JL
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Tvash
climber
Seattle
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Sep 23, 2014 - 01:14pm PT
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What effect does anodizing have? It wears off a biner almost immediately. It's just for color coding, I think, no?
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Largo
Sport climber
The Big Wide Open Face
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Sep 23, 2014 - 02:00pm PT
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We did a lot of testing with Sterling and found that binding was a bigger factor than first suspected, especially with sliding X, where a sling is basically hitched around the biner, less so on somethng like a quad, where anchor point biners are clipped though a comparatively wide loop. In both cases, the rope ran apreciably better and bound far less when wide-mouth anodized biners were used. Basically, the cord sticks on non-polished aluminium when an attached sling is cinched or sitting fairly snug around the shank of the biner. In short, the combination of the wide mouth and the anodize polish reduced the binding and when an anchor had to self adjust, the results were worth the trouble of using the special gear - but only in those situations when the primary anchors were crap.
JL
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Tvash
climber
Seattle
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Sep 23, 2014 - 02:11pm PT
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A used biner's rope surfaces get polished pretty quickly - I assume that's as good as anodizing at reducing friction (a good thing - given that anodizing doesn't last long on such a surface).
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Largo
Sport climber
The Big Wide Open Face
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Sep 23, 2014 - 02:35pm PT
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It's the combo of the the wide mouth and the anodizing that inhibits the binding. Any polished surface will probably achieve the same results given the wide mouth. Fact is, the times you really need this are almost nill. We did the testing mostly to find if true equalization was EVER possible. Turns out it is, but only with the quad - wide mouth - anodized medly. And with two side-by-side bolts in good shape, it hardly matters how you tie them off. They so rarely fail in good rock.
JL
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Tvash
climber
Seattle
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Sep 23, 2014 - 02:36pm PT
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You might consider using a more conventional cordelet anchor setup.
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Tvash
climber
Seattle
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Sep 23, 2014 - 02:46pm PT
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I use a quad with a fatty nylon/dyneema sewn runner and a wide mouthed anodized locker. The teen program I'm involved it standardizes on a tied power point cordelet - but some of them are as thin as 5 mm, so I'm going to inject a little alternative anchor love into the program with some specific breaking strength numbers (these kids ask about everything).
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Tvash
climber
Seattle
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Sep 23, 2014 - 03:38pm PT
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The knots reduce the strength of your single 7 mm considerably because you're not using a double fishermanned loop and you're using clove hitches.
I put in a lot of trad anchors, so I like a system that's optimized for whatever comes along. For a 3 point anchor the system (3 Nanos, a locker, and the runner) weighs 147 g or thereabouts.
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Tvash
climber
Seattle
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Sep 23, 2014 - 03:54pm PT
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I always go for the free safety for that 1/1000 chain of events that might lead up to a factor 2 fall directly onto the anchor - even if I can't think up a scenario when that might happen beforehand. As has been said, with two bolt anchors - lots of stuff works fine.
Just my philosophy. I know that speed (weight) is safety. My stuff's all pretty light. If I can prevent one of my students from biting in during their climbing life with a little bit of extra robustness here and there, it's worth it to me to be a bit of a nerd in some areas.
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Tvash
climber
Seattle
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Sep 23, 2014 - 04:06pm PT
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You just gotta know when to say "Yer off belay" and when to say "Sorry about this" (nodding to the anchor)
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oldnutz
Trad climber
OAKLAND
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Sep 24, 2014 - 09:17am PT
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I believe in the JL/BG climbing anchors book it was recommended to use clove hitches with the equalette (in some scenarios), in order to both easily adjust the arm length and also provide a reduction in max forces on each piece, since the clove hitch will gradually slip well below the breaking strength of the rest of the anchor components.
Not sure if JimT's "marginal" statement refers to this aspect of the clove hitch, which could be a good thing by lessening force on marginal placements.
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JimT
climber
Munich
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Sep 24, 2014 - 10:58am PT
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uh oh...I'm sorry but I have to ask Jim T...define "marginal" within the context of this sentence?
I had been led to believe, in regard to a multi-pitch anchor (not TR anchor), that clove hitches could help reduce max forces.
Like in the picture below from prrdylady. The tests done for the DAV show that with dynamic loads on thinner cord clove hitches fail at lower levels than previously thought. The DAV have a criteria of requiring (or expecting) a single point on a belay to hold 6kN (in case it is taking the full load) and with most cord and tape the clove fails below this. From memory 8mm was the only one that held from the ones they tested.
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JimT
climber
Munich
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Sep 24, 2014 - 11:07am PT
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A used biner's rope surfaces get polished pretty quickly - I assume that's as good as anodizing at reducing friction (a good thing - given that anodizing doesn't last long on such a surface).
We´ve done an enormous amount of testing of friction of nylon rope, cord and various tapes over the years and never detected any difference in anodised, worn anodised, non-anodised aluminium or ground or polished stainless at normal climbing loads. We even had some karabiners specially treated with various types of low-friction anodising to test and there is no noticaeble benefit. The variation of the friction between various makes of tape and cord is vastly greater.
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BG
Trad climber
JTree & Idyllwild
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Sep 24, 2014 - 11:09am PT
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which could be a good thing by lessening force on marginal placements.
In nylon, knots can have a shock absorbing and force lessoning impact. With Dyneema, a knot may be an achilles' heel.
As a stunt coordinator, I've rigged falls with a series of loosely tied knots as shock absorbers back in the day when we used wire cable attached to nylon rope.
If you analyze the DMM factor 1 and 2 dynamic drop tests with nylon vs. Dyneema slings, the impact force with a nylon sling (that did not break) actually decreased slightly when tied with an overhand knot.
The Dyneema sling broke (both knotted and unknotted) in nearly every fall factor 1 and 2 test with 120 cm and 60 cm length slings at impact force of roughly 10 to 11 kN when knotted with an overhand and 22 to 25 kN when unknotted.
In every FF1 and FF2 test where the unknotted sling did not break, the impact force was less with the nylon sling vs. Dyneema sling.
Because of Dyneema's low melting point, high lubricity (slipperiness), and lack of elasticity, knots create a weak point in Dyneema. Maybe not the best material when used with knots for multi-pitch anchors?
I'd like to see more testing with Dyneema slings and clove hitches, often used when rigging 2 pieces in opposition vs. the same rigging with nylon slings.
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Largo
Sport climber
The Big Wide Open Face
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Sep 24, 2014 - 12:18pm PT
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In all the testing we've seen/done over the years, it seems that problems arise in proportion to the elasticity of a given piece in the roped safety system. The more stretch, the less the poroblems. Tech webbing and cordage is "stronger than steel," but it gives so little that this often compromises a system built to produce "soft" falls by way of the inherent stretch of the components.
Long story short, the old nylon is heavier and bulkier but in many regards is still the go-to stuff in rock climbing.
JL
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SammO
Social climber
Ohio
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Sep 24, 2014 - 12:53pm PT
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Props to Largo, BG, and JimT for up-to-date info that appears to meld bench data and real-world data. My humble summary offering:
Multiple anchor systems vary; OP scenario appears as a typical fixed one, where each piece appears trustworthy, as opposed to a marginal rap system where one or more is suspect. Equalization is paramount in the latter, as no single piece may hold. This is not true in fixed cases, I would hope! There, the redundancy principle is for backup, should any portion of a system fail, including a carabiner, bolt/piece, single sling unit, and so on. Locking biners reduce risk of something rotating, which has resulted in slings or ropes unclipping themselves.
Most of the reputable solutions here seem fine, and the basic cordelette which isolates each leg after initially equalizing the directionality is the fastest, simplest compromise. Directional forces might apply the load mostly to one or the other bolt during use, but that's minor loading; if that bolt OR that half of the sling failed, the load would suddenly swing onto the other bolt, but that is more like a pendulum swing, compared to a one or two foot drop, statically, onto it if an X system were used.
Keep in mind, also, that while the basic systems here all may serve adequately for the stated purpose, funny things happen in the real world, ie climber reaches anchors, clips directly into system to do something, then slips off stance - shock load, where choice of sling materials etc. suddenly matter.
I'm pretty sure far more have died from failed anchors, than from failed protection pieces. These are not "arguments" but valuable discussions where newbies et al may read how/what those with 50 years experience have settled on, and why.
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oldnutz
Trad climber
OAKLAND
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Sep 24, 2014 - 12:55pm PT
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Like in the picture below from prrdylady. The tests done for the DAV show that with dynamic loads on thinner cord clove hitches fail at lower levels than previously thought. The DAV have a criteria of requiring (or expecting) a single point on a belay to hold 6kN (in case it is taking the full load) and with most cord and tape the clove fails below this. From memory 8mm was the only one that held from the ones they tested. JimT: when you say "fail" does that mean the hitch slips with no friction, or that it slips with some friction?
I'm using 7mm nylon or 6mm tech cord for my equalette, and I'm using cloves on all 4 strands. Typically I would have no more than a foot of slack rope between the cloves on each side.
Since it's impossible to exactly equalize the two strands, one hitch is going to take most of the force until it starts to slip, at which point the other hitch will start to absorb some force as well (and of course the other side of the equalette is going to be similarly loaded and absorbing some of the force).
Unless you're asserting that when a clove hitch slips it goes from static to zero friction, this is not analogous to a typical "extension" scenario where a piece blows and the load freefalls onto the next piece. So even if there's quite a bit of slack in the equalette, it doesn't seem that the knot slipping would be the same situation as a piece blowing. In fact there is little to no extension even if an entire side blows out with this rig.
While this scenario is very specific, it does represent the majority of trad anchors I build, and I've been very fortunate to never catch a leader fall directly on the anchor to see what happens. All kidding aside, if this is a dangerous rig then I'll stop doing it, but my back-of-the-napkin noodlings leave me hopeful this is a safe rigging method.
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RyanD
climber
Squamish
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Sep 24, 2014 - 01:38pm PT
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Bump spam
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BG
Trad climber
JTree & Idyllwild
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Sep 24, 2014 - 03:13pm PT
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In all the testing we've seen/done over the years, it seems that problems arise in proportion to the elasticity of a given piece in the roped safety system. The more stretch, the less the poroblems. Tech webbing and cordage is "stronger than steel," but it gives so little that this often compromises a system built to produce "soft" falls by way of the inherent stretch of the components.
Long story short, the old nylon is heavier and bulkier but in many regards is still the go-to stuff in rock climbing.
JL
Well said. Ten years ago when I was training to become an AMGA Instructor/Examiner, all my mentors had skinny Dyneema double runners for critical applications like building a redundant extended masterpoint or extending a rappel device. Now the same dudes (and myself) all carry big, fat, old school nylon slings.
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maldaly
Trad climber
Boulder, CO
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Sep 24, 2014 - 04:11pm PT
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Okay, I'll pitch in here.
First of all, let's geek out on fixing problems in climbing that actually kill and maim people. If you look at the accident stats published in ANAM you have to go pretty deep to find a single accident in which belay anchor failure ever hurt or killed people. I think there have been three, none of which would have been prevented by any of the discussion in this thread. Two of them were cordalletted and master-knotted SRENE anchors which were loaded in a direction that was not anticipated for by the anchor builder. The third was from broken tat at the Red.
Second, I tell people in my clinics about the three rules of anchor building. Bomber, Bomber, Bomber and Multi-directional. Some bright young attendee always points out that I had, in fact, listed four. Thanks for paying attention, now back to BBBM. That's right, if you want to be uber-safe, place three bomber anchors, two of them should be for a downward pull and the third, tensioned to the other two in the opposite direction so the whole sh#t pile won't pull out when the belayer gets pulled up or to the side when the next leader falls. Imagine that...
Third, getting back to ANAM, looks at what causes the majority of accidents. It's getting stuck, benighted, stormed or slow, setting up a cascade of events that you can no longer control. All that sh#t happens because you weren't moving fast enough (re: Donini) because you were bogged down trying to construct, then arguing about, a SRENE anchor.
Climb safe,
Mal
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BG
Trad climber
JTree & Idyllwild
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Sep 24, 2014 - 04:45pm PT
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If you look at the accident stats published in ANAM you have to go pretty deep to find a single accident in which belay anchor failure ever hurt or killed people.
Good point. In pure rock climbing the number one accident is leader falls. Entire books are written on the subject of anchors (JL and I just finished another one- Climbing Anchors Field Guide, 2nd edition) but the bottom line is that anchors rarely have to absorb much force at all- it's that single piece that the leader falls on that must withstand a big impact force.
When it comes to anchors, people like to go right to worst case scenarios and work back from there. But there are instances, albeit rare, where crafty rigging might have saved the day.
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Mark Force
Trad climber
Cave Creek, AZ
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Sep 24, 2014 - 05:23pm PT
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Beautiful discussion. Thank you everyone!
;-)
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BG
Trad climber
JTree & Idyllwild
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Sep 24, 2014 - 07:24pm PT
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BG
Trad climber
JTree & Idyllwild
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Sep 24, 2014 - 07:33pm PT
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Nope, it's the real deal. Fixed lines (a couple sets) at the Sickle Ledge anchor, Nose Route, El Cap, 1983, before anyone ever heard of SRENE or a cordelette!
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JimT
climber
Munich
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Sep 24, 2014 - 11:59pm PT
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JimT: when you say "fail" does that mean the hitch slips with no friction, or that it slips with some friction?
I meant fail as in the material breaks at that point.
I´ve had to cut enough clove hitches off gear to know that expecting them to slip is optimistic, expecting the slip to provide a dynamic element in a system is wild optimism.
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oldnutz
Trad climber
OAKLAND
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Sep 26, 2014 - 10:28am PT
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I meant fail as in the material breaks at that point.
Thanks JimT...I just want to understand the mode of failure...so in my example of using 6mm tech cord in the equalette, the cord breaks at the clove hitch under much lower force than would be expected?
If so, in my 4-point anchor with "somewhat" equalized strands, the equalette itself could fail well before an individual piece? That would be disheartening :(
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oldnutz
Trad climber
OAKLAND
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Sep 27, 2014 - 01:09pm PT
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Thanks Locker...
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Allen Agopsowicz
Trad climber
BC
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Sep 27, 2014 - 03:48pm PT
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I've had a parachure company sew me some two-point dynamically equalizing slings with extension limiters. They are expensive to make so they might not ever get to the market. A few guides and industry insiders have seen them and the next batch will include their recommendations. Destructive testing revealed a 3200 lb. breaking strength per arm so I'm guessing the theortical limit of 6400 lbs break is probably true for the system. The construction method is under industrial patent pending and the equalization range is nearly 90 degrees. There are limitations of course, three point systems require a brain to set up, and the placement of the anchors has a measured effect on the equalization range. Otherwise, perfect for TRs and newbies who haven't a clue how to build an anchor.
The holy grail remains the dynamic, dynamically equalizing anchor system.
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JimT
climber
Munich
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Sep 28, 2014 - 12:32am PT
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The holy grail remains the dynamic, dynamically equalizing anchor system.
Depends on your religious bent I guess, for me it´s two or three bombproof anchors you can use any way you like.
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overwatch
climber
Arizona
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Mar 20, 2016 - 09:55am PT
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Not really an article but a great primer, especially for kids
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healyje
Trad climber
Portland, Oregon
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Mar 20, 2016 - 10:15am PT
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Two bolts? TR? Two draws, clip the rope, climb.
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healyje
Trad climber
Portland, Oregon
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Mar 20, 2016 - 10:26am PT
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15 hours of which is deciding which end of the draws goes on the bolts...
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Prod
Trad climber
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Mar 20, 2016 - 10:44am PT
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"Two bolts? TR? Two draws, clip the rope, climb."...
Mostly overkill but if we're running sport climbing laps. I sometimes use a locker draw for one of the anchors.
Prod.
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jeff constine
Trad climber
Ao Namao
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Mar 20, 2016 - 12:25pm PT
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Slings.
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rgold
Trad climber
Poughkeepsie, NY
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Mar 20, 2016 - 01:33pm PT
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Some people seem to equate the ability and interest in having a nuanced technical discussion with an inability to construct an anchor in the field in a timely fashion.
It may be that relative beginners with limited practical field experience get bogged down in considerations of little practical value after reading too many of these technical discussions. And I suppose that some climbers get trapped in an arrested state of development and never emerge from the thrall of theoretical exhortations about equalization and redundancy.
But there isn't necessarily any link between the two activities, one primarily an intellectual exercise conducted indoors at one's leisure, and the other an active application of ingrained knowledge under conditions imposed by the environment. It is possible to both know trigonometry and build anchors with speed and efficiency. Just sayin...
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jstan
climber
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Mar 20, 2016 - 01:49pm PT
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It's possible different people get into climbing for different reasons. This thread threatens to persuade me some people are interested in climbing because, there, it is possible to construct very complicated anchors. Recent events provide evidence failures, as often as not, occur because we don't predict in sufficient detail the subtle behavior of materials and systems. Both dynamic and static. Building more complicated systems that layer additional uncertainty on top of this, seems a mistake. A mistake someone else will pay for,
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rgold
Trad climber
Poughkeepsie, NY
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Mar 20, 2016 - 02:11pm PT
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Recent events provide evidence failures, as often as not, occur because we don't predict in sufficient detail the subtle behavior of materials and systems.
I'd go further and say that we don't even understand those subtle behaviors. And I fully agree that even though K.I.S.S. is sometimes used as a cover for ignorance, by and large adding complication is also going to add unaticipated side effects, some of which could be fatal.
The real question, and one not at all easily answered, is where to draw the line. John and I and others on this site who started out with swamis, goldline, and hip belays have seen the level of complication explode. Surely some of this is a good thing?
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