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High Spur Core Shot Supermoon Weekend

Discussion in 'Trip Reports' started by swampfox, Nov 26, 2016.

  1. swampfox

    swampfox

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    Tom asked me to put this in a trip report on the Collective after I sent him a note about the rope so I decided to have some fun with it.

    The combination of predicted warm weather , sun and no wind in the day coupled with just freezing temps. at night and the supermoon was too good to pass up. The High Spur area of the Roost is relatively isolated because of bad roads but is very beautiful. My son wanted to bring 5 of his fit, athletic 20 something friends along to do the Northeast Fork of High Spur Canyon. I chose a 60 something ex-NOLS instructor from the 70's with no technical canyoneering experience as my friend. And did I say wouldn't have to carry any ropes?

    NE ForK of High Spur is a relatively benign canyon described by some as just walking down a canyon with a rappel at the end. Its a bit more than that with 1 pothole (depending on recent weather) a couple of down-climbs that can be rappelled and the last drop is about 80 ft ending in 60 ft of free. It was a good choice for our group as I had done part of it before and 5 of our group were near noobs to total noobs with no technical rope experience. The corkscrew slot in the second half is very dramatic and compared by some who know to Antelope canyon as a photographers destination.

    The first half of the canyon if you gabislot. do the full thing, is a couple of miles through beautiful narrows that occasionally may get your pack off.

    Nothing very challenging but aesthetically pleasing and we went through very quickly. We rapped the one down-climb in the upper part and the two in the lower to get the beginners some experience dealing with ropes and devices and setting some best practices leading up to the last drop.

    We had fun working through the one pothole which was knee deep and not a problem but getting 8 people through is still a bit of fun logistics.

    We had decent light for the corkscrew slot. cork1.
    20161112_114917.

    SS2.

    Rapping the last drop before the free rappel. This can be down-climbed. noobrappractice.
    Last rap, view from the top. lastrapfromtop.

    The last rappel has at least two large blocks for anchors, one close to the edge and one 15 feet back and lots of room to safely work. Eddie, an expert climber and canyoneer had deployed my 200 ft Canyon Fire 8.3 mm as doubled on the mid-point and biner-blocked as most were rapping doubled on ATC's but a couple were going single on Critr2's.

    As rappels go this one is easy and a good first free rappel of some length. The first 20 ft are down a couple of ledges then a walk down a 60-70 degree slope followed by a very abrupt horizontal undercut leading to 60 feet of free. The rope had been carefully checked when bagged 2 weeks before and was looked at careful when deployed this day, the first usage since.

    First person rapped double on an ATC and began bottom belays. bottombelay.
    Second went single line on a Critr2. He spun slightly. No one went fast, bounced , etc. The third person went double on an ATC. As did the fourth. After the fourth Eddie called up that it looked like there was a nick in the rope so we pulled it up to 20161126_114806. (This picture taken later).
    We were somewhat taken aback as we now had one 120 and an 80 connected by a core shot and still four people to get down only one of whom was prepared to pass a knot. The most noob of the group was already unhappy with the situation and when she saw the rope her heart sank. gabiunhappy.
    Of course there was more than one way to skin this cat but since we also had a 100 ft 9.2 mm with us and a noob who wanted to either turn around or be lowered we re-rigged for a lower off of the other anchor block using a munter and as well a separate belay with an ATC off the original block. OK it was overkill but this was my first core shot.

    The lower went smoothly (mostly eyes closed) lowerinprogress.
    Lower in progress.

    I went last doubled on a Critr2 and observed that in many places the edge of the undercut was extremely sharp. Force per unit area tends to win in those situations.

    In this photo of the rappeller right after the single , we can barely see the core shot above the edge in this case as the rope is pulled up as he starts. (red arrow).
    PhillippeMarked2.

    In the next photo of the fourth rappeller we can see the core shot now below the edge as we had shifted the rope between rappels to distribute the wear. JoeMarked2.
    Both guys rappelled double right over it and didnt notice.

    The hike out was beautiful and long, with the short day we got back to camp at twilight.
    All happy but doing a bit of pondering. groupgrope.
    Next day the old people went off to attempt the NW Fork of Big Springs and the kids left.

    Fast forward 2 weeks and the football of either kind is over so i decide to turn this core shot over to the Seat of the Pants Institute for Cordage Testing, Back of the Envelope Lab. I have been thinking quite a bit about people rapping over the core shot and even though I found an old post from Tom Jones about no one wanting to go with him because his ropes had too many core shots, I was curious what it would take to break this thing.

    Even though there was a beautiful white tuft of core strands poufing out, it appeared that damage to the core was extremely limited. Probably less than 1 or 2 percent. The sheath had retained 8-9 mm of its originally 26 mm circumference. I had about 15 cm of rope left on one side and 10 on the other. I attached these to a Ropeman on the top and a Petzl Basic below. 20161126_102412.

    I attached 70 lbs below it, set up a Z-rig and hauled up the weight. I got up to 154 lbs and the weight was still all on the remaining now about 4 mm of sheath. The core was still puffed out.
    I lowered the weight then pulled back up until about two thirds of the weight was off the ground and almost immediately the core took the weight with about 2 very stretched strands of sheath remaining.
    20161126_125615.

    I added 7 gallons of water to now have 212 lbs (getting close to my weight).

    The last strands of stretched sheath broke and the sheath pulled off the core. Still no core damage. I knotted both ends of the now free core, reattached to the ascenders and loaded it up with 212 lbs. It has been sitting there for 3 hours now, no the worse for the wear.

    20161126_163927.

    Conclusions:
    While I wont be purposefully rappelling over core shots, these things do happen even when you are using high quality material that you have checked and deployed carefully in locations where many before you have ventured.
    It was not a random event. The very sharp edge while not everywhere on the lip is definitely present.
    In the case of the cutting of the sheath and the 2 who rappelled over the cut sheath, going double does appear to have defeated Force per unit area.
    These high quality ropes are really well made but not "overbuilt". Built right.
    The sheath is really strong.

    Addendum: The standard set of weights in th the Seat of the Pants Institute for Cordage Testing, Back of the Envelope Lab.
    20161126_163943.

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  2. Rapterman

    Rapterman

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    Nice report swamp fox!
  3. ratagonia

    ratagonia

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    Quote: "Conclusions:
    While I wont be purposefully rappelling over core shots, these things do happen even when you are using high quality material that you have checked and deployed carefully in locations where many before you have ventured.
    It was not a random event. The very sharp edge while not everywhere on the lip is definitely present.
    In the case of the cutting of the sheath and the 2 who rappelled over the cut sheath, going double does appear to have defeated Force per unit area.
    These high quality ropes are really well made but not "overbuilt". Built right.
    The sheath is really strong."

    Thanks for the thorough report.

    I have always claimed that ropes die when we make a mistake in rigging. Yes, some ropes are more resistant to sheath cutting (=coreshot) than others, but I would not put it as more than two to one... ie, I think there are ropes out there that cut twice as easily as my Canyon Fire; and I think there are fancy ropes out there that are perhaps twice as tough as my Canyon Fire. But it is mainly the operator, not really the rope. That said, sometimes the fierce edge in unavoidable, and has to be managed.

    Of course, the first problem is to identify the fierce edge, which is not always conspicuous. I coreshot 4 ropes on the first drop in Englestead (watercourse, off the left side 10 feet) before figuring out there was a fierce edge 10 feet down. I don't go that way anymore. In this case, and in many cases, it is up to the first rappeller to identify and call out sharp edges.

    Ideas for managing a sharp edge:
    1. Pad the edge: especially easy when the edge is at the top, more difficult when it is part way down (as in this example), but not impossible. Often easy to do for everyone but the last person, though Fiddlesticking the drop can allow for padding for the last person too. Can tie off a rope bag (or other pad) to the pull side, especially if the line of rappel traps the ropebag on the sharp edge well.
    2. Use a bigger rope: Swampfox indicated they had a Canyonero rope in the pack as backup - this might have been a better choice.
    3. Go double line: rapping on two strands seems to decrease the cutting force by more than half. Even better: Stone Knot the double strand, so the two are independent.
    4. Shift the rope after each rappel. Moving the point where the fierce edge contacts the rope.
    5. CREEP the rope. Lower the rope slowly from the top during the rappel, continuously shifting the rope.
    6. Choose a different line: There may be other anchor options, or not. But people can be sent down a kinder line via a meat anchor if another "real anchor" is not available.

    And???

    I get to be more lackadaisical on these issues, as ropes are less expensive for me. But I am trying to be better, and trying to shed the moniker "Coreshot Jones".

    :moses:
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  4. swampfox

    swampfox

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    Good list. Useful to see it all in one place. We could easily and quickly have done 4 or 3 for all. Intuitively for sheath wear I dont see the difference in size being that great for "knife-edge" sandstone, but certainly would be some and maybe a lot.

    Are there realistic comparison tests of technora, polyester and technora/polyester blended sheaths out there for cutting-type abrasion resistance? Could do a seat of the pants one relatively easily.

    George
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  5. ratagonia

    ratagonia

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    There are abrasion tests, and cutting tests. Plenty of them. What result would you like?

    There is really no lab test that accurately reflects what we do. Send me 20k and I will set up a lab to do real and realistic lab tests...

    Cutting and abrasion tend to be quite different in relation (especially) to Technora and Spectra type fibers. Technora being very cut resistant, but not all that abrasion resistant. Technora sheath rope manufacturers will tout the cut-resistance of Technora, which may be relevant, partly relevant, or not at all relevant. Hard to say.

    Tom
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  6. Rapterman

    Rapterman

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    Questions for Tom:
    Is there a method you prefer for rigging a knot or hitch for shifting a single rope after each rappel?
    Also for 'creeping' the rope?
    We do not often do this, but there ARE some rope eating canyons out there :facepalm:.
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  7. swampfox

    swampfox

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  8. swampfox

    swampfox

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    itrsonline.org/wordpress/wp-content/.../Mike-Forbes_The-Sharp-End-of-the-Edge.pdf
    There are lots of hi-tech tests. This one by a rescue group seems fairly realistic as a combination of cutting and likely abrasion. Technora first the Polyester/polyester. No dyneema cores for the technora. All diameters 11 mm.

    The 1999 Moyer tests were more realistic and polyester/polyester won out. No aramide bearing ropes tested.

    Seems possible that a skinny rope (8 mm) with technora sheath might be similar to a fatter (>= 9 mm) poly/poly).

    Core material for the technora sheaths is a difference in the latter test. Mixed technora/poly sheaths not in the tests.

    George
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  9. Bootboy

    Bootboy Atwood Gear

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    Canyoneering ropes never die, they just get shorter.
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  10. ratagonia

    ratagonia

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  11. Rapterman

    Rapterman

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    I enjoyed this study which attempts to shed light on rope damage over edges.
    It seemed well thought out until the test method for evaluating residual strength in the damaged samples:

    "A standard way to measure residual strength would be to statically pull the sample to failure and record the result. Many of the samples that did not fail would have required a slow-pull tester capable of generating >40 kN of force. The slow-pull device available was only capable of testing samples up to 22 kN (limitation set by the capability of the force measuring device). In order to address this deficiency the rope samples were deconstructed and the individual components were analyzed. The core strands were separated from the sheath and pulled to failure as well as the sheath as an entire unit. A sample size of 3-5 was conducted on all rope samples. The construction of the rope was evaluated and a calculated value based on the test results of the components was done. A calculated minimum breaking strength (MBS) was then compared to the manufacturer’s published MBS. A MBS of +/- 9% error was obtained and used for the residual strength calculations in this study"

    So they pulled the core out of the damaged ropes and broke the core and sheath separately?
    Maybe even seperated the core strands?
    Sorry folks, your 'scientific method' is poo :poop:.
    Go borrow a bigger load cell.
    Sheesh
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  12. Rapterman

    Rapterman

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    Stretch factors are very different for technora nylon and poly. You cannot test them separately and assume the result will be 'additive'
  13. Rapterman

    Rapterman

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    In the 'webbing world' where I live, when nylon fiber is blended with dyneema (as in the older climbing runners), the tensile usually ends up being only that of the dyneema alone. The nylon (even if it is 50% of the weave) does NOT add significant strength.
    You cannot crash test a car by throwing tires, the engine block, and the frame separately into a wall
    :D
    Last edited: Dec 1, 2016
  14. Kuenn

    Kuenn

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    Very good Trip Report and follow on discussion, especially @ratagonia valuable knowledge transfer.

    My 2 cents for what it's worth (admittedly 2 cents or less) on contingency rigs and rope creeping.

    History
    Black Friday our group has for many years tried to do something vertical - plus the lines are much shorter where we go. Living in a canyon deficient area it usually ends up underground, or open-air pit, or cliff/bluff (my apologies up front if this is acid to your eyes, not being canyon based).

    This past black Friday we went to a 225' open-air pit (fairly recent discovery, i.e. 90s). Tight and somewhat awkward start with some sharp edges for the first 20' that require padding - rope eaters. I realize that padding is rarely used in canyoning hence creeping methods, however with the introduction of fiddle stick anchoring it does open itself slightly more. IMO. But that's aside from my 2 cents.

    Contingency Anchor
    Point being, even though padded, we still used a munter mule for our anchor, adjusting periodically. Worked well, with no complaints. Was a new anchor method for a few in the group, they opted to NOT go first. In addition, given that the rope would also be ascended (tandem, most of the time) the adjustments/padding became even more desirable. (Another side note: When using padding, it is essential that each person ensures the pad is in-place after each pass. Can be especially challenging when awkward starts are involved.)

    Creep
    I can see where a creep contingency could be superior in some instances, especially when padding is not feasible or recommended. Never used a TRUE creep technique, but if I did, based on current knowledge, I would most likely use a f8/munter/etc. at the primary anchor and have the meat side monitor the creep through their rap device. Even tie a stopper a few feet down the feed side and reset after each use, just for added insurance/distracted meat determent.

    PB250011.JPG PB250071.JPG

    Feel free to critique/criticize.
    Last edited: Dec 1, 2016
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  15. ratagonia

    ratagonia

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    The core and the sheath are independent; therefore, we would expect that the "Lab Tech's" bi-section of the rope would not actually help with decreasing the load on their load cell, unless they broke half the core at a time. Perhaps they should learn how to set up a 2:1 and buy a good pulley or two.

    The core and the sheath are independent EVEN when they are made from the same material. You will notice that the fibers of the sheath are laid at a 45 degree angle to the line of the rope, while the core is at a zero degree angle. When you put the rope on the testing machine, one of two things might happen:
    A. Dynamic Rope: with a very stretchy core, a dynamic rope loads up the sheath first (stiffer fibers) and the sheath breaks as (say) 3500 lbs; then the core loads up and breaks at (say) 5000 lbs.
    B. Static Rope: without the engineered in stretch, the core loads up first to the breaking point (5000 lbs), then the sheath loads up...

    although my ACTUAL experience is in breaking dynamic ropes. Man, sure wish I had the Instron here so I could do this stuff for real... C'mon folks, buy more gear, Tommy wants a new lab toy!

    Tom
    Last edited: Dec 1, 2017
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  16. Bootboy

    Bootboy Atwood Gear

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    Wanna go halfsies? It would have to live in my garage though...Haha!



    Sent from my iPhone using Tapatalk
    Last edited: Dec 2, 2016
  17. ratagonia

    ratagonia

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