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jkornelis
Dec 29, 2004, 2:53 PM
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Was told Rock and Ice did a test and that dynema/spectra was breaking at less loads/falls than nylon. the guy said that Dynema is super strong if you put a constant weight on it, but if you put the load on it suddenlly, IE a fall, it has a chance of breaking before nylon. Can anyone confirm this? I was not able to find the test or article.
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trenchdigger
Dec 29, 2004, 3:04 PM
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Without seeing the actual test, it's hard to make any conclusions, but one fact is widely known. Spectra/Dyneema stretches very little and will be subject to much larger forces in a fall situation where only material of these fibers are catching the fall. For example, a direct fall onto your spectra daisy chain while clipped into a spectra cordelette anchor. Because of the dynamic nature of climbing ropes, a fall onto a rope connected to a spectra equalized anchor is not very different in terms of forces than the same on a nylon or webbing equalized anchor.
~Adam~
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jkornelis
Dec 29, 2004, 3:09 PM
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So you think switching all your quickdraws to Spectra should be just as safe as your old webbing/nylons?
I was looking at doing this until I heard the rumor, just want to confirm or deny it before I spend my $$.
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dynosore
Dec 29, 2004, 3:23 PM
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If you're not sure, why are you doing it? Ever hear of a nylon quickdraw breaking? Neither have I. A glance at my sprectra quickdraw sling shows a strength of 22kn. It's basically as strong as the biners. Your rope probably has a max impact force of around 10kn, if you somehow fall in a manner that genrates 22kn of force :shock: you are in serious trouble no matter what. If spectra wasn't an improvement over nylon (cut resistance), why would they have started making slings out of it?
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elwood86
Dec 29, 2004, 3:50 PM
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The article said that a direct fall from a relativly short distance, I cant remember the exact distance, resulted in spectra breaking. When they tested nylon it held. They compared the strength/ rigidity of spectra to steel it is very strong but a sudden direct force can snap it. The moral to the story was if you are above your anchor dont clip in directly with spectra. As far as draws go, you will be falling on a dynamic rope and this eliminates the direct shock load on the Spectra. I will try to find the back issue and post it.
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euroford
Dec 29, 2004, 4:34 PM
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they were talking about static falls if i remeber correctly. of course, i highly recomend that you don't take statics falls on any material and in an appropriote application spectra/dynema is perfectly safe.
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buckyllama
Dec 29, 2004, 4:47 PM
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If you are regurlarly taking static falls hard enough to break spectra, you have more problems than mere equiptment failure.
I should point out here that as a bag of water, which is more or less what humans are when dealing with forces that high, it's impossible to generate a static load high enough to cause this failure mode. In a static fall onto a sling, your body will deform and flex enough to reduce the shock load on the spectra sling. Your harness will quite probably tear you in half long before the sling breaks.
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paulraphael
Dec 29, 2004, 6:29 PM
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The moral of the story is don't take a static fall.
It's very possible that nylon webbing will take a static fall better than spectra, simply because it's less static. It's for the same reason that a fall could snap a steel cable, even if the cable was many times stronger than a climbing rope.
If a nylon sling stretches 2% under X load, and spectra stretches 1%, then with a given fall directly onto the sling you're going to generate double the force on the spectra. And as you know, the spectra sling is not double the strength ... it's probably the same strength but lighter.
But this should never happen, because climbers are supposed to know better. If you're clipped to an anchor with only a webbing sling, don't climb above the anchor or let a lot of slack build up. Period. The forces you could generate if you fell, even if they didn't snap the webbing, could put way more force on the anchor than you ever would with a rope. Your back probably wouldn't like it, either.
Spectra is better sling material than nylon for a lot of reasons. The static fall issue shouldn't be a consideration. All it means is that nylon is slightly less deadly than spectra when grossly misused in a specific way.
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euroford
Dec 29, 2004, 7:47 PM
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another good reason to:
A: not be an idiot. no reasonably conciencious climber should take a static fall onto an anchor, runner or daisy.
B: keep a dynamic tie in. clip to the anchor with a clove hitch on the rope rather than a daisy or runner.
C: build anchors with dynamic rope. using the climbing rope to build your anchor is one of the quickest, safest and most versatile methods available. sure it has its downsides as well, and i myself also use cordolets and runners some of the time, but you need to be versatile.
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chriss
Dec 31, 2004, 6:30 PM
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In reply to: Was told Rock and Ice did a test and that dynema/spectra was breaking at less loads/falls than nylon. the guy said that Dynema is super strong if you put a constant weight on it, but if you put the load on it suddenlly, IE a fall, it has a chance of breaking before nylon. Can anyone confirm this? I was not able to find the test or article.
Someone told about an article in a magazine; can't find the article yourself; his version of article questions the safety of material used in most climbing slings and some cords.
Does that some up your statement?
I have seen articles on some of the new fibers used in slings that state they are very strong but brittle. Meaning low stretch characteristics and suffer high bending fatigue issues. This does not mean the use of these materials in slings and cords is unsafe.
Most all climbing related slings and cords are blends of nylon and other materials to improve the overall performance. All are safe if used correctly. As stated before, try to avoid the potential of falling onto a system with no dymanic elements.
And don't repeat unvarifiable rumors about safety.
chris
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gunksgoer
Dec 31, 2004, 8:05 PM
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yeah, this only matters in static falls, like if u were anchored with a daisy chain. in this case spectra will break more easily, but other then that its fine. this is why it sucks to fifi flop and take a static fall on a spectra daisy while aiding.
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euroford
Dec 31, 2004, 8:45 PM
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it sucks to take a daisy fall reguardless of material.
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petsfed
Dec 31, 2004, 9:06 PM
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In reply to: If you're not sure, why are you doing it? Ever hear of a nylon quickdraw breaking? Neither have I.
I've seen nylon slings break before. I was lucky it was in a low slack line rig.
The point however is that if you find yourself in a situation where your slings are breaking, you've done something very wrong. Those situations are not unheard of however. Quickdraws rarely break, but longer slings do break (perhaps a greater workload?) and there is fundamentally no difference between an 8" sling and a 48" sling.
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cyanamid
Dec 31, 2004, 10:55 PM
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In reply to: And don't repeat unvarifiable rumors about safety. chris
In reply to: I have seen articles on some of the new fibers used in slings that state they are very strong but brittle. Meaning low stretch characteristics and suffer high bending fatigue issues. This does not mean the use of these materials in slings and cords is unsafe. Most all climbing related slings and cords are blends of nylon and other materials to improve the overall performance. All are safe if used correctly. As stated before, try to avoid the potential of falling onto a system with no dymanic elements. |
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chriss
Jan 1, 2005, 5:51 PM
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I'm sorry if I offended anyone with my tone. BUT, posts (and rumors) like these have a way of gaining credibility as they gain momentum. Everyone remembers the post but no one remembers the responce.
I overheard a climbing class while in the gym (chain climbing gym in big city) a few months back. Instructor explaining how to belay. Went through all the motions and explained that "belay" is a french word for rope handling. "Belay" is an English word. Take a moment and look in a dictionary for word origins. How many people where taught or heard this? Not a safety issue though.
Same climbing class. Instructor informs class to leave some slack in the belay "to lower the fall factor". Seems he believes that more rope out will give a "softer" catch. Not true. More rope also adds to the fall distance as well as the "active" rope distance. This INCREASES the fall factor for fall factors less than 1 (or any fall where the climber doesn't fall past the belayer). I think this is major misinformation. Who has heard this repeated?
Don't believe everything you hear, or read on the internet for that matter. Me included.
chris
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overlord
Jan 4, 2005, 6:22 PM
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if you take such a fall you will break your back if you use spectra OR nylon.
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mince
Aug 3, 2006, 2:56 AM
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is there any substantial evidence to prove that placeing a knot in a dynema sling will decrease the strength of the material?
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