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cintune
Mar 20, 2007, 12:41 AM
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So have at it. Ingenious suicide device or useful multi-purpose tether?  Cabin fever is an insidious force to reckon with.
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anykineclimb
Mar 20, 2007, 12:48 AM
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haveyou tried it yet?
the prussiks on Spectra and the girth hitches don't inspire much confidence.
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cintune
Mar 20, 2007, 1:07 AM
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Only played around with it on a bolt ladder at the gym when no one was looking, but I didn't feel like jumping off to test it. That would be the next step, obviously. Thought about using 6 or 7 mm cord instead, too.
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j_ung
Mar 20, 2007, 1:38 AM
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Girth hitches on skinny Dyneema = bad. Other than that, very interesting. I won't use it, 'cause I don't like extraneous gear, but interesting, none the less.
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tradrenn
Mar 23, 2007, 1:18 AM
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Few problems that I see:
1. No Girth Hitch, juts use 2 locking biners.
Maybe you could have a look on some of new and light DMM biners like Zodiac or Sentinel, just to save you from some extra weight.
2. 2 biners in your pic should be a locking one.
( I had to say it, I have a feeling that you already know that )
About PP
I'm under impression that PP is suppose to be made of nylon cord which is a bit dynamic in comparison to dynema slings which is totally static.
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cintune
Mar 23, 2007, 3:02 PM
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Good points all, but now it's too bulky to be convenient. But then, convenience is overrated anyway.
(This post was edited by cintune on Mar 23, 2007, 3:03 PM)
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cintune
Mar 23, 2007, 4:49 PM
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Cabin fever, like I said.
"The term possibly originated in the United States at the time when settlers would be snowed in to their log cabins and had to wait for the spring thaw in order to travel to town. Another possible source for this phrase could be that during an outbreak of some disease, people who had a fever were confined to a cabin as a quarantine. Most likely, the phrase may be associated with ocean-crossing sailing ships in which passengers had to endure weeks and months of slow travel while living in cramped cabins below deck."
So, instead of lashing out at my loved ones, which would be wrong, I lock myself in my room and fidget with gear for no really good reason. Look. I made a tether. 
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knudenoggin
Mar 23, 2007, 7:22 PM
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In reply to: girth hitches in skinny HMPE = bad
Prusiks of HMPE on itself I see as a dubious venture--low friction, low
grip, and a question of heat generation, which HMPE doesn't like.
As for Girth hitches at all, just flip your cordage around such that the 'biners
clip into the end you've tied to the Yates, and run the adjustablEye's legs
through the Yates eye--one knot fewer. (Similarly with the rope, you could
use a Grapevine bend vs. the <?> hitch. --yeah, not so readily removed
from the Yates, but then is that likely anyway?
Why double up? --what they said about nylon vs. static material, and if
you double the nylon, even, then you've halved its shock-cushioning effect.
As it stands, your shock behavior depends upon the initial extentsion of this
Purcell P.--longer it is, the more 2-strand vs. 4-strand it is.
You could get consistency in this regard by making the full loop/sling of
doubled cord running through a Prusik (or other) at the end, with ends
joined in some stopper knot just as a safety, and maybe the end-side
normally half-hitched to back up the friction hitch. Release from other
attachments by untying the stopper and drawing out the cord ends from
through the friction hitch.
*kN*
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brent_e
Mar 23, 2007, 7:36 PM
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cintune wrote: Cabin fever, like I said. "The term possibly originated in the United States at the time when settlers would be snowed in to their log cabins and had to wait for the spring thaw in order to travel to town. Another possible source for this phrase could be that during an outbreak of some disease, people who had a fever were confined to a cabin as a quarantine. Most likely, the phrase may be associated with ocean-crossing sailing ships in which passengers had to endure weeks and months of slow travel while living in cramped cabins below deck." So, instead of lashing out at my loved ones, which would be wrong, I lock myself in my room and fidget with gear for no really good reason. Look. I made a tether.
sorry cintune,
i missed that. Thanks for the definition, though. I'll probably whip that out at an inopportune time and look like a geek, as per usual.
Brent
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stymingersfink
Mar 25, 2007, 1:24 AM
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cintune wrote: Good points all, but now it's too bulky to be convenient. But then, convenience is overrated anyway.
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majid_sabet
Mar 25, 2007, 3:04 AM
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cintune wrote: [image]http://www.oldnewspublishing.com/tether2.jpg[/image] Good points all, but now it's too bulky to be convenient. But then, convenience is overrated anyway.
You got AAA+ on this cause it seen it survie during fall test.very nice
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unreleasedenergy
Mar 25, 2007, 3:07 AM
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i've used a pair of these in 5mm prussic cord girth hitched to my harness as adjustable anchors when i didn't have my adjustable daisies.
they work ok, big thing is that the prussic needs at least 3 wraps due to the diameters being equal.
one question, why the screamer?
are you planning on using these instead of daisies on aid? or is this just for anchoring?
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coolcat83
Mar 25, 2007, 4:44 AM
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any thoughts on if this setup might be safe for a via ferrata if you used suitable cord and biners?
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elnero
Mar 25, 2007, 5:02 AM
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somewhat related question: would a purcell prusik be safe to use as a substitute for a daisy? clipping into bolts to clean anchors etc. what size cord should be used?
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elnero
Mar 25, 2007, 5:47 AM
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Don't mean to hijack, but im gonna...
First, why can you not girth hitch the prussic setup to your tie-ins. just tie a bigger loop in the figure 8, and girth hitch it.
Second, I've never really understood the logic in using two biners on a daisy chain. won't you still load the short-clipped pocket? I read somewhere on this site (so it must be true) that when the bar tacks blow, the material is pretty much shot, so if you threw a big load on the daisy, and the tacks blew, even if you were still clipped into the end loop, wouldn't you still be pretty screwed?
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coolcat83
Mar 25, 2007, 10:48 AM
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elnero wrote: Don't mean to hijack, but im gonna... First, why can you not girth hitch the prussic setup to your tie-ins. just tie a bigger loop in the figure 8, and girth hitch it. Second, I've never really understood the logic in using two biners on a daisy chain. won't you still load the short-clipped pocket? I read somewhere on this site (so it must be true) that when the bar tacks blow, the material is pretty much shot, so if you threw a big load on the daisy, and the tacks blew, even if you were still clipped into the end loop, wouldn't you still be pretty screwed?
you could girth the prussics to the tie-ins but i think the op's point was to have the screamer reduce the shock to the system (the prissic slip would reduce the impulse too) although with the screamer it extends the system but as long as the screamer doesn't fully deploy you'll theoretically reduce the shock load. (i generally feel uneasy girthing most anything to my tie ins or belay loop, try taking some webbing and rubbing against some other webbing for a while, it get's scary surprisingly fast) as for the second biner thing, basically depending on how your daisy is twisted you clipping in short while being clipped to the end is like clipping in between two pockets, i saw a video on BD's website of it but i can't find it atm. if i used a daisy (which i wouldn't unless i had to for some reason) i'd rather have the chance that a damaged daisy will hold me rather than coming totally out of the system for sure. those really thin spectra daisys i see at gyms and stuff for belay anchors scare me, if i used a daisy i want it nice and thick.
in my other reply i was wondering about using the op's original design for via ferrata and now that i think about it perhapy using something like a petzl zyper but one legged like they make for indistrial uses might be an option for substituting for a daisy... but tradition dies hard. i'm gonna goto my yard later and try to break some things 
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coolcat83
Mar 25, 2007, 2:02 PM
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http://www.kong.it/doc408.htm
http://www.kong.it/doc407.htm
first one seems to be basically a resettable screamer as they suggest it for rock and ice pro, i like that you can sort of set the activation force yourself, but i'm not sure how much i'd trust myself without some testing.
the second one is available using either a sling or a rope...
i found these made by kong, anyone have any experience with either? perhaps it might be safe to link the plate to either a prussic or use the plate then daisy so that if you shock load the daisy hopefully the device will save the daisy, it seems like the extra few oz. would be worth it imo, since thses are made for via ferrata they are designed to take a high static shock load of falling to the end of the cable segment. kong site says "impact shock on the body of a climber that weights 85kg, when he falls 5m along a fixed line.
The sliding of the rope through the friction plate reduces the impact shock from 20kN to 4-5kN" seems pretty darn good imo
anyone have any data on shock loading a prussic? i know there's lots of when it slips, but in this case slipping is ok and even a little desired, but a prussic is basically a bunch of girth hitches...so what's the breaking point?
(This post was edited by coolcat83 on Mar 25, 2007, 2:13 PM)
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cintune
Mar 25, 2007, 4:07 PM
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Okay, same thing only different. The prusiks are backed up with single fisherman's knots, which keep them in place. Reducing the legs to single strands is a little spooky, but the screamer should activate before the cord would ever come close to snapping... I think.
The idea was definitely inspired by different via ferrata and ropes course and industrial shock lanyard setups. But I'm also wondering about dual-purposing it as a quick 2-point belay anchor. I should probably ask Yates gear if that would be a good idea or not. No point reinventing a wheel that gets you killled, but hey, it's supposed to rain for the next week anyway, so there's still time to scrap the whole thing if it's a really really bad idea.
Edit: Also thought of putting cloves on the biners to keep them at the end of each loop, yet still adjustable.
(This post was edited by cintune on Mar 25, 2007, 4:10 PM)
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coolcat83
Mar 25, 2007, 5:16 PM
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damn you beat me to it:P the only problem i see is that over time the screamer stitching would come loose from repeated sub-activation force falls and weighting an unweighting ofi might be inclined to use something like a petzl nitro or other screamer like device that you can cheach the condition of the screamer with from time to time. other than that the only problem is that if you fully deploy the screamer you will still encounter a shock load when the runner fully extends.
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microbarn
Mar 25, 2007, 11:50 PM
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personally, I dislike the idea of the cloves. The prussiks already give you the adjustability. You would have to adjust two things if you also used a clove hitch on the end.
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stymingersfink
Mar 26, 2007, 5:43 AM
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exactly on the cloves... that would reduce the utility of the prussik's inherent adjustability.
if one were to clove anywhere in that setup, replace the g-hitch with one.
when i was rigging for the local theatre union i made my own Y-tethers from 11/16th tubular hitched to a screamer in a similar manner. I had strung some bungee cord through the core of the webbing to keep them at a reasonable length. Worked o.k., but I had no real plans to ever fall on them.
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cintune
Mar 26, 2007, 6:59 PM
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Tried it out again on the bolt ladder at the gym, with the hangers spaced about every 3' it worked nicely using cloves to set the length and keep the biners taut, without having to wonder if the prusiks would slip. Pretty limited application obviously, and again I didn't take any falls, just bounce-tested it a few times. So, the cloves seem to be a good option under those circumstances, when they only need to be adjusted once. With unevenly spaced anchors I suppose it would be best to go with just the prusiks.
I like the idea of running bungee cord through webbing. This gear fetish is getting out of hand.
Also got a PM with the pics below of related setups on steel cable from Delrio, who knows a thing or two about these things. Definitely saving that one.
(This post was edited by cintune on Mar 26, 2007, 7:02 PM)
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Picture 12.jpg
1
