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Tech Tip: Question Problem Solving

Discussion in 'Tech Tips and Gear' started by 2065toyota, Feb 7, 2018.

  1. Tom Collins

    Tom Collins

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    Serious question, if 50% strength is an acceptable safety margin to rappel on then why make ropes as strong as they are?
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  2. hank moon

    hank moon lovely ligatures

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    I think you just answered your own question...
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  3. ratagonia

    ratagonia

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    Fair question.

    Smaller ropes tear up faster. At the moment, the incidents of ropes tearing or cutting in use are extremely rare, and I suspect we all would like to keep it that way. In general, we are not all that concerned about the absolute strength of the ropes, even with knots in them. We are concerned about what happens when we scrape them across an edge and/or other things that result in a core shot.

    It would be unacceptable if, half the time we currently created core shots, the rope actually cut all the way through.

    This is what I worry about when people talk about using 6mm cord (of various types) for rappelling. YES, workable in an ideal situation. NO, not-workable in a general application.

    Tom
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  4. Tom Collins

    Tom Collins

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  5. Rapterman

    Rapterman

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    alpine butterfly is cool :cool:
    us old time mountaineers can tie em in our sleep..
    but the overhand Tom recommends (backed up by another overhand, nice)
    IS the EDK.
    Everyone should already know this, so keep it simple
    :D
  6. 2065toyota

    2065toyota

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    When person #2 went over the lip, the core wasn't noticed until it went through the device. He said there was no sheath attachment and approximately 6" of white core showing. That is an uneasy feeling when you are 200' off the deck on a freehang rap and are hanging below the coreshot. I'm good with keeping the strength of the ropes as they are.
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  7. Tom Collins

    Tom Collins

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    I was thinking more on the lines of making the core thinner (and thus reducing the strength), but making the sheath thicker and thus the rope is the same diameter, but more durable, but that was before your post about what happens once the core is exposed.
  8. Rapterman

    Rapterman

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    Good question, Mr Collins!
    more to Tom's point: knots in rope (and webbing) are a necessary 'evil' that we cannot
    do without, so the rope/web must have a robust 'absolute' strength to overcome the knot-loss.
    6mm cord should give everyone the heeby jeebies because of this....
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  9. ratagonia

    ratagonia

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    I hope the core without sheath was not in contact with the rock. Without the sheath, the core is not all that cut resistant.

    T
  10. ratagonia

    ratagonia

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    = Canyon Fire, though the formula there was to keep the core at its minimally acceptable strength, and put as much sheath on it as possible.

    Tom
    Last edited: Feb 9, 2018
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  11. Andrew J Farrow

    Andrew J Farrow

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    that is true - but its my opinion that you need 2 knots if you are going to " knot - pass " it

    my " step one " of any knot pass manouver = " clip cows tail into loop

    thre is zero point in clipping my saftey into a loop containing the daage

    so i NEED 2 knots to create a loop of undamaged rope
  12. Kuenn

    Kuenn

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    Brandon, not sure I'm following you here. Replaces catastrophe knot?

    I've never really considered clipping into the loop as a tether when it's being used to isolate a damaged section of rope (conditional, of course, on the degree of rope damage being isolated by the butterfly). I can see where that could be useful, though.

    Agree with not clipping into the damaged loop. Not sure why you would need/want to have a second knot loop though. Unless there's a shortage of "tools"/resources at hand.

    Just goes to show there are obvious difference in rope passing methods being considered in this thread.
    Last edited: Feb 10, 2018
  13. wsbpress

    wsbpress

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    Yeah, the damaged section can be isolated from the useable part of loop by throwing an overhand between the AB knot and the damage.

    The book variation of this is for passing a knot that is not being used to isolate damage. In this case you can join the ropes with a double fisherman's and leave the tail from the upper rope long enough to put a figure 8 OAB on the end.

    In both cases the benefit is getting a good backup connection to the rope prior to removing your rap device.







    Sent from my SM-G950U using Tapatalk
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  14. ratagonia

    ratagonia

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    There are a zillion ways to pass a knot. Some would make use of a clippable loop at the knot, and some would not. It is fairly easy to add a clippable loop by girth hitching a sling above the knot (for instance), therefore I would not consider making a clippable loop to isolate the knot critical.

    For many of my imagined knot passing methods, it helps if the "knot" section is as short as possible.

    Also easy enough to toss in a chicken loop before doing the maneuver.

    Tom
  15. Scott Patterson

    Scott Patterson

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    It's too bad all of them suck though. Even though I know how to pass a knot, I'd rather do Wild Wind Hollow ten times in a row without even doing Birch than pass a knot on a big rappel.

    ---------------------------------------------------------------------------------------------------------------------------

    Anyway, if this is Englestead, why not jut send the rest of the group back once the core shot was noticed? That's how I would solve it.

    If this isn't Englestead, and the rappel is located somewhere in the middle of the canyon, I'd send the experienced canyoneers through while the others are waiting and have them go get another rope if at all possible. This is certainly better than trying to teach the inexperienced people how to pass a knot on a big rappel if they have never done it before. Experienced or not, I hope I never have to pass a knot on a big rappel, though the skill of how to do so should still be learned.

    I know that these are boring answers, but the situation presented has a lot of factors that can easily lead to disaster. Trying to "solve" the problem on the computer after the fact is one thing, but trying to solve it in the field where people are likely scared and nervous is another. Even without passing a knot, a 280 foot rappel requires a lot of attention.
  16. gajslk

    gajslk

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    As first man down Heaps final, I'd much rather pass a knot than do the simul-rap/lower with someone who hasn't lowered a lot of people.
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  17. Scott Patterson

    Scott Patterson

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    I need to invite you when I do Heaps, because there is no way I'm passing a knot on that rappel. ;)
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  18. wsbpress

    wsbpress

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    Hey Tom. What is a chicken loop in this context? I'm not familiar.

    Sent from my SM-G950U using Tapatalk
  19. Kuenn

    Kuenn

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    What does that number look like? I could only come up with 47.... :rolleyes2:....48.

    [edit] ...49 if the granny knot is ok.
    Last edited: Feb 10, 2018
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  20. ratagonia

    ratagonia

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    A "chicken loop" is a wall-climber thing. When jugging up the rope and removing pieces, cleaning the pitch, every 30-40 feet, it is a good idea to tie a knot below you on the rope you are ascending and clip that to your harness.

    So, when passing the knot: rap down to close to the knot and tie your rap device off. Reach down about 10 feet below the knot and tie a figure8 on a bight, and clip it to your harness. Then do whatever else you wanna do. Once ready to go again, untie the chicken loop before it goes tight.

    Tom
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