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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. Itīs 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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