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Author Topic: Dyneema question?  (Read 1705 times)

DWT

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Re: Dyneema question?
« Reply #15 on: June 13, 2012, 05:15:57 PM »

  Do your homework outside of this website as some of this info isn't true. 

That's a grenade.  Could you be more specific? :)
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MJShove

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Re: Dyneema question?
« Reply #16 on: June 13, 2012, 09:07:56 PM »

Good stuff here.

http://www.geir.com/mythbuster.html

Pull tests on friction hitches for sling/webbing at Misty Mountain.  The highlight with the yellow smiley face is scary.  Also, a review of the test results indicate erratic and inconsistent behavior of the hitch/material interface.     


Full report here http://www.docstoc.com/docs/115249971/MMT-Testing         
                 
19   Pull test Kelmhiest       1/2" Nylon Runner   No   slippage at 650   6 wrap
   (10.5mm Dynamic Rope)      1/2" Nylon Runner   No   slippage at 460   6 wrap
         1/2" Nylon Runner   2020   slippage at 1850   6 wrap
         1/2" Nylon Runner   No   slippage at 1170   6 wrap
         1/2" Spectra Runner   No   slippage at 1330   6 wrap
         1/2" Spectra Runner   No   slippage at 610   6 wrap  :(
         1/2" Spectra Runner   No   slippage at 1180   6 wrap
         1/2" Spectra Runner   No   slippage at 750   6 wrap


A colleague on mine in NC pulled the nylon and dyneema slings after the friction hitch tests, and the dyneema failed at a substantially lower loads than the nylon.


The bottom line:  It might be better to have some nylon slings on your harness as well.  I always carry at least one.  It certainly can't hurt. 


More interesting info here.  http://www.mountainproject.com/v/105876750 It is around John Sherman's incident, but some of the comments revolving around testing are interesting. 


My intent is not to discredit DMAN (he's credible and we've even shared a rope at one point).  It's to be sure that you, as a climber make your own informed decisions that are not based on generalizations.  I find that DMM video to be eyeopening, and although the test is harsh, and would be difficult to recreate on the cliff, it's not impossible.  I try to stay objective and take the test data for the science it is.



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DMan

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Re: Dyneema question?
« Reply #17 on: June 13, 2012, 10:03:12 PM »

No worries Matt, I wasn’t feeling discredited. But here’s my revised official stance, and how I use dyneema.

1) Carry two prussik cords made from 7mm nylon tied at different lengths

2) Carry 1 cordelette (I use a 16 foot 5.5 mil tech cord)

3) I rack all my gear on a regular nylon sling for transport

4) Carry 1 or 2 double length nylon slings

Armed with the above there is almost no need for me to ever use one of my 8 or 10 alpine dyneema draws for anything but draws. However, if I needed to, I wouldn’t have a problem using it with due caution. But as is being pointed out, there are better materials to have on you for these contingencies...

And the ultra-light combination of Petzl Ange S carabiners and dyneema is really the coolest draw setup in my book. I hate having should length slings dangling over my head so this system works great for me. YMMV.

« Last Edit: June 13, 2012, 10:05:21 PM by DMan »
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DWT

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Re: Dyneema question?
« Reply #18 on: June 13, 2012, 10:12:17 PM »

good stuff indeed.  thank you.
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tradmanclimbz

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Re: Dyneema question?
« Reply #19 on: June 14, 2012, 07:02:05 AM »

I have seen folks with pre knotted skinny dynema equalet type setup for belays.  Also seen data that indicates that a slip onto the belay / rapell anchor with the anchor loose but at your waist may be enough force to break a knotted  dynema sling? 
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NY Climber

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Re: Dyneema question?
« Reply #20 on: March 12, 2013, 07:34:02 AM »

I think nylon is the way to go.  I was taught, about 6 or 8  years ago, that dyneema doesn't do well due to the friction and sliding.  As a result nylon is on most of my alpine draws (that and the fact it was cheap and I'm still not rolling in enough cash to upgrade).  That being said, materials have come a long way and I can't say compared to the stuff that's out there now.  I'm sure others have contradicting data with such and such.  But to keep it simple, I just use nylon rather than trying to keep up with all the new developments.

I agree. I persoanlly don't care for Dynemma much and use all nylon slings. Deeme is too stiff for me and way too expensive IMHO - esp if I ever have to LEAVE sling(s) behind on raps!
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Michael Urban, RN
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