ATC in rope rescue?

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Re: ATC in rope rescue?

Postby NZcaver » May 7, 2010 2:21 pm

underdog wrote:hmm, my glancing didn't catch that. I use my guide in the climbing gym where the ropes are quite low stretch all the time, of course the fall factor is low, and it is not in high friction mode. Love it for multipitch climbing routes with a group of three, where two can follow at the same time. I wouldn't see an immediate issue with using them in auto block mode with low strech ropes as long as the fall factor is low. No lead climbs in the high friction/autobloc mode though. Good luck.

Related question - anybody know the parameters which define static vs. low stretch vs dynamic ropes? The old definitions of static vs dynamic were easy - static were fixed ropes for rappelling, caving etc, and dynamic was for climbers and mountaineers to catch a fall. Construction of each type is (usually) noticeably different, and the amount of stretch under body weight was generally 2-3% or less for static and anything greater for dynamic.

Now we have this "low stretch" category, which I'd been led to believe mostly applied to less-static "static-type" ropes rather than more-static "dynamic-type" ropes. But now folks are talking about using low stretch ropes in climbing gyms. I guess I'm a little confused.
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Re: ATC in rope rescue?

Postby underdog » May 7, 2010 4:01 pm

I can't answer your question but thought I'd add that the low strech ropes are used only for top rope climbing not lead climbing. I believe they are preferred over dynamic for top rope climbing in a gym setting because of durability.
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Re: ATC in rope rescue?

Postby gdstorrick » May 10, 2010 9:14 pm

Post deleted.
Last edited by gdstorrick on Jul 10, 2012 12:11 pm, edited 1 time in total.
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Re: ATC in rope rescue?

Postby sherppa » May 11, 2010 12:25 am

NZcaver wrote:
underdog wrote:Good luck.

Related question - anybody know the parameters which define static vs. low stretch vs dynamic ropes? The old definitions of static vs dynamic were easy - static were fixed ropes for rappelling, caving etc, and dynamic was for climbers and mountaineers to catch a fall.

As defined by Cordage Institute CI-1801-Low Stretch and Static Kernmantle Life Safety Rope:

Low stretch: A rope with an elongation greater than 6% and less than 10% at 10% of it´s minimum breaking strenght.
Static: A rope with a maximum elongation of 6% at 10% of it´s minimum breaking strenght.
http://www.scribd.com/doc/1603186/CI-18 ... afety-Rope
High stretch ropes (dynamic ropes): Present 40% to 60% elongation at forces equivalent to those required for breaking it, and 6% to 9% elongation under a load of 176lbf (this is the value that the UIAA set as the average weight of a climber).
CMC – Rope Rescue Manual, James A. Frank, Chapter 5 – Rope and Webbing, p. 20
:-)
Last edited by sherppa on May 11, 2010 7:52 am, edited 1 time in total.
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Re: ATC in rope rescue?

Postby NZcaver » May 11, 2010 3:09 am

Thanks for posting the link. :grin:

So according to the "Cordage Institute" standards, 0-6% elongation at 10% of the MBS would indicate a static rope, and 6-10% would indicate low stretch. Interesting. Perhaps my memory of 2-3% elongation under body weight wasn't too far off. I'm thinking a stationary adult body weight (i.e. 1kN force) could equate to approximately 3-5% of the MBS of your average 11mm rope (ignoring knots, bends, edges, devices, etc).

Also noticed at the top of the page it says "this standard does not apply to dynamic rope intended for lead climbing." I wouldn't have thought low-stretch rated rope would be appropriate for climbing gyms or other frequent fall-catching applications, but this seems to imply it may be OK as long as it doesn't take Fall Factor 2's? :shrug: And maybe an ATC would work OK on some low stretch rope, but I wouldn't personally want to use it on static.
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Re: ATC in rope rescue?

Postby Bob Thrun » May 11, 2010 5:39 am

sherppa wrote:Low stretch: A rope with an elongation greater than 10% and less than 10% at 10% of it´s minimum breaking strenght.

Huh? Both greater than and less than 10%? Please correct that.
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Re: ATC in rope rescue?

Postby sherppa » May 11, 2010 7:54 am

Bob Thrun wrote:
sherppa wrote:Low stretch: A rope with an elongation greater than 10% and less than 10% at 10% of it´s minimum breaking strenght.

Huh? Both greater than and less than 10%? Please correct that.

done!
:-)
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Re: ATC in rope rescue?

Postby underdog » May 12, 2010 12:20 pm

Wondering how folks feel about figure eights on static rope as opposed to atc on static rope? I have abseiled shortish distances with both. Found the eight to be scary fast, felt I had more control with the ATC. All in all though using them made me really appreciate my rack.
But if you are looking for a smaller peice of equipment to put in a resuce sack, that can handle two ropes, for a low fall factor rescue back up belay scenario - I am not sure what you would use other than an ATC type device, going with a guide or reverso can add the auto blocking high friction mode for increased safety. Sherppa, what is making you want to use this device? What other options exist that meet your needs?
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Re: ATC in rope rescue?

Postby NZcaver » May 12, 2010 2:43 pm

underdog wrote:Wondering how folks feel about figure eights on static rope as opposed to atc on static rope? I have abseiled shortish distances with both. Found the eight to be scary fast, felt I had more control with the ATC. All in all though using them made me really appreciate my rack.
But if you are looking for a smaller peice of equipment to put in a resuce sack, that can handle two ropes, for a low fall factor rescue back up belay scenario - I am not sure what you would use other than an ATC type device, going with a guide or reverso can add the auto blocking high friction mode for increased safety.

As I understand, figure 8 descenders were *originally* intended for use with a doubled rope - which makes a big difference in friction. Of course using it single is pretty common and considered normal by most people. Smaller (single) ropes, larger 8's, steel 8's... all mean reduced friction. I agree, it makes one appreciate the adjustability of a rack.

Not sure why you'd really need a small, double rope device like an ATC in a rescue kit. Double rope belay?
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Re: ATC in rope rescue?

Postby sherppa » May 13, 2010 12:01 am

underdog wrote:Sherppa, what is making you want to use this device? What other options exist that meet your needs?

I know there are many options to belay: münter hitch and figure eight (better aluminium than steel for this purpose) to belay a one person load; tandem prusik and the 540° for belaying two person load. I am just wondering, if the ATC could be just another option to belay one person load using low stretch ropes, knowing all its limitations. Why do I wonder?... well, just to know :)))

rgdstorrick wrote:OK, that quote from a former friend isn't really true, but ATCs (which is not what the picture showed) are lightweight devices that can get hot rather easily.

ok, ATC is a black diamond trademark, but the pic shows an item (trango belay device, btw) that works the same way :)
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Re: ATC in rope rescue?

Postby chh » May 22, 2010 1:03 pm

sherppa wrote:I know there are many options to belay: münter hitch and figure eight (better aluminium than steel for this purpose) to belay a one person load; tandem prusik and the 540° for belaying two person load. I am just wondering, if the ATC could be just another option to belay one person load using low stretch ropes, knowing all its limitations. Why do I wonder?... well, just to know :)))


It should work very well provided the rope is relatively clean, as has been stated. Climbers often rappel on fixed static lines after achieving a high point on bigger walls. I know it's not really "belay" but would feel similar depending on the anchor set up for your belay. Also, I"ve lowered a 2 person load on an atc during self rescue practice. With a doubled rope I don't need any additional friction. With a single line and two people I usually add some via a carabiner brake or munter on the brake line. similar to what you would do if lowering a two person load with a simple or stop, or even an 8 for that matter. Depending of course on the circumstances and whether you are lowering the 2 person load remotely or whether you are part of the 2 person load, if that makes sense. I don't really see why testing is necessary. You are using the ATC for it's intended purpose. Maybe you're just looking for hard numbers, which is something most rope nerds completely understand.......
Your words of caution are no match for my disaster style!
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Re: ATC in rope rescue?

Postby sherppa » May 27, 2010 8:53 pm

chh wrote:
sherppa wrote:
You are using the ATC for it's intended purpose. Maybe you're just looking for hard numbers, which is something most rope nerds completely understand.......

I could not find info about it (ATC´s in low stretch ropes), so I just wanted to know if I what I´m doing is correct. :-)
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