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Tech Tip: Question Winter - time to practice and learn knots

Discussion in 'Tech Tips and Gear' started by ratagonia, Dec 1, 2016.

  1. ratagonia

    ratagonia

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    Bored? It's winter. Could work on knots.

    I have a couple of Tech Tips on knots, that people might want to cruise through. Who knows you might learn something... or even better, if you feel like commenting, we might all (or at least me) learn something.

    TT1: Basic Building Blocks of Knots

    TT2: Tying two ropes together


    TT3: The Stone Knot (Hitch)


    TT4: Figure 8 on a bight and variations

    TT5: The Water Knot and how to use it

    TT6: Knots for Webbing and Anchors


    Also suggestions for more I could or should add to this.

    Thanks. Tom
  2. John Styrnol

    John Styrnol

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    Tom,

    I always put a few inches between the two knots. Good/No good?

    John
  3. ratagonia

    ratagonia

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    A gap between the knots serves no purpose, and gives the rope-sticking gods (Kinesava around here) an opportunity to have mischief with you.

    (No good).

    Tom
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  4. Kuenn

    Kuenn

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    During my October excusrion to southern Utah, @Sonny Lawrence introduced me to a new knot for tying two ropes together. Don't recall if it even has a name, but it's basically an overhand with an added twist. Basic overhand then one strand doubling back around and thru. Seemed like an improvement... (maybe just because it spoke to my inner psyche which thinks a lifesaving knot should be more complex than the knot used to tie a shoe.)

    Any opinion/experience with this one? Does it have a name?

    IMG_0483.JPG IMG_0484.JPG
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  5. dakotabelliston

    dakotabelliston Living life to it's fullest

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    @ratagonia is there a variation of the stone knot that you prefer?

    Sent from my SM-G930V using Tapatalk
  6. ratagonia

    ratagonia

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    There are many variations on the Offset Overhand Bend that (probably) prevent the knot from rolling. None has come out as the 'new standard', though I think the backup overhand knot is the closest to doing so. I WANT something to become the standard, so that lots of people can easily visually inspect it. I KNOW tying a backup overhand PREVENTS the knot from rolling because I have had it on the test machine, oh so many years ago. So - how about we standardize on that one, as shown on my Tech Tip?

    Tom
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  7. ratagonia

    ratagonia

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    I use the upward overhand Stone, as the easiest and the one that works best with the Fiddle Stick.

    T
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  8. Brian in SLC

    Brian in SLC Brian in SLC

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    I think that's it...people balk at the simplicity of the EDK. Which is too bad. 'Cause it works.

    I like the looks of the extra pass through, but, what does it really buy you? Does it test stronger? Rappel knots really don't need to be "that" strong. Or, shouldn't need to be at least. Maybe it makes the knot even easier to untie after use? Wet ropes easier to untie?

    My tie in knot for climbing is the time tested figure eight retraced. But, I've gone to tucking the tail back around and through the knot. Much easier to untie and I don't have a loose end flapping around (or in need of a finish). Seems to work well.

    For the EDK, especially on thin cords, or, where I'm matching to very different rope diameters and rope types (6mm static kevlar to 10.5mm dynamic), I'll sometimes add another EDK snugged against the first one. Although a friend in Australia, who used to train SAR guys and has plenty of time in the technical rope work business says, if you trust it you trust it and there's no need for a back up.

    I've seen folks tie a "flat" double fisherman's to tie two ropes together too. Kinda crazy but it works and would seem bomber.

    Maybe when Sonny takes a break from the emerald isle and the kissing of the blarney stone he can chime in here and respond to this EDK variation and its advantages...
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  9. ratagonia

    ratagonia

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    I disagree.

    In pretty good conditions, no backup knot required. But when something is a little off, I like having some kind of backup that blocks the roll out. A single EDK is NOT self-locking. I like self-locking; it is a good quality in a life-safety knot. With backup knot = self-locking.

    Much easier to explain once we have it on the test machine and video, and test 20 kinds of rope, wet, dry, icy...

    "Although a friend in Australia, who used to train SAR guys and has plenty of time in the technical rope work business says, if you trust it you trust it and there's no need for a back up." = close to equivalent to "I saw it on the Interwebs, so it must be true."

    Tom
  10. John Styrnol

    John Styrnol

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    Faith and canyoneering do not mix well.:cautious:
  11. gajslk

    gajslk

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    That is very, very cool. I've never liked that second knot and don't tend to use it unless the rope is new, stiff, and wet.

    Gordon
  12. ratagonia

    ratagonia

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    It is the "1-1/2 Offset Overhand Bend."
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  13. Brian in SLC

    Brian in SLC Brian in SLC

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    That wasn't the point. The point is, if its good enough to use, then it doesn't need to be backed up. Not something seen on the iterwebs, but, from someone who's done a bunch of technical rope training.

    That said, I think most of us tend to use a back up, especially with skinny ropes and especially on multiple rappels (16 in a row for me on a route in Switzerland) where you don't break down the knot and retie.

    The beauty of the EDK is that its simple. Which, is also its downfall. It just isn't complicated enough for most folks to get their head around.

    Its also pretty easy to break down if it hasn't been shock loaded (especially). Which, is also its downfall (could be untied in repeated cycling, although I think that's been tested as well, at least water knots have been).

    The oft cited reference for EDK and figure eight testing:

    https://user.xmission.com/~tmoyer/testing/EDK.html

    Yeah, it can roll. At loads that no rope should be seeing whilst a person is on rappel. A backup knot mitigates that roll.

    I don't know that it'll be in the short term that anything becomes standard in the US.
  14. hank moon

    hank moon lovely ligatures

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    Brian, I don't understand how this point is valid. In some situations, a knot is good enough to use ONLY with a backup. For example, the bowline is arguably "good enough to use" but requires a backup to be solid for life-safety application. Would you explain further as to your understanding of your SAR friend's statement?
    Last edited: Dec 5, 2016
  15. hank moon

    hank moon lovely ligatures

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    re: @ratagonia's quest to make the backup overhand knot* a standard joining knot for USA canyoneering. A noble goal, and perhaps an uphill battle in our individualistic culture? Nevertheless, I use and teach this knot because of its performance advantages and ease of tying / inspection. I have seen a lot of time wasted on field debates about the proper amount of tail on an EDK. Best thing to do with all that extra tail is tie another (backup) knot with it! Generally speaking, of course.

    re: Overhand 1.5 (the knot @Kuenn references above). The attached test report suggests that it might be “safe” enough, but should it become the standard? I find it substantially less easy to tie and inspect (and by inference, teach) than the Stacked Overhand* (Tom’s standard knot by another name), which disqualifies it for consideration as the standard.

    Thanks to Tom for the forum Winter Fuel.

    References on rappel rope joining knots:

    Old but good:
    https://user.xmission.com/~tmoyer/testing/EDK.html

    More recent:
    http://www.needlesports.com/content/abseil-knots.aspx
    http://oterescue.com/project/which-bend-for-joining-ropes/ (note: pdf from this link is attached below)
    http://blackdiamondequipment.com/en/qc-lab-what-is-the-best-rappel-knot.html

    Extra geeky:
    http://igkt.net/sm/index.php?topic=1706.0

    Video (French - digital readout displayed during tests is in decanewtons, or daN)




    * “standard” knot nomenclature corner - just for fun?

    I like the “Stacked” nomenclature introduced in the attached pdf from otrescue.com as it is more descriptive / intuitive than the knot-geek variations (e.g. “double offset overhand bend”). I see little value in promoting an esoteric “knot-geek” nomenclature where a more intuitive name might help promote learning and standardization. Thoughts?

    Note: Andy Kirkpatrick calls it the “double overhand knot” I don’t like this name because there are other "double overhand" knots quite different from the Stacked Overhand (see attached pdf for an example).

    Attached Files:

    Last edited: Jan 31, 2017
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  16. ratagonia

    ratagonia

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    "Stacked" - excellent!!

    Stacked nomenclature has been added to the appropriate tech tip.
    Last edited: Dec 5, 2016
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  17. ratagonia

    ratagonia

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    Great video.

    Do you know what unit the readout is in? I suspect kgs.

    at the end: Simple knot block on a rapid link? Yikes!!!!! I thought the skull and crossbones was going to pop up on that one, but I guess in France that is considered safe!!!

    :moses
    Last edited: Dec 5, 2016
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  18. ratagonia

    ratagonia

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    Sometimes it is, sometimes it is not. Yes, extraneous useless backups when found annoy me. But it definitely is not a RULE. Often, backups are not required; but sometimes they are.

    Tom
  19. LonePeak

    LonePeak

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    Okay, I’ll bight.

    My approach will be to suggest some strengths and weaknesses of knots and leading candidates for your consideration first, then let ease of verification follow as the best knots are adopted. Otherwise the tail wags the dog. I’ve worked with all these knots quite a bit after reading up on their uses, so I have brief observations to contribute. I also recommend my favorite, but I’m more interested in providing this overview for your consideration than in trying to debate whether it should be your favorite. YMMV. If there are significant problems with my selection, I'd like to hear about it. I’ll leave the tying directions and semi-scientific testing data to an easy google search (keywords: knot testing stability security efficiency, climbing, etc) and evaluation by the very experienced who have used them all extensively.

    1. Slide grip knots. Favorites: Distel Hitch, Bachmann, Prusik, situationally. You use them to back up your rap, right? They’ll save your life. Or not… You’d better test them thoroughly on each rope configuration and make sure they’re properly dressed and tightened, or they may not catch. I’ve tested proper autoblocks, French (Machard) Prusiks, Klemheists, Blakes', and others that wouldn’t hold my weight even on typical rope/cord setups (~8.5 mm nominal rope and 6mm accessory cord). Yes, a smaller cord to rope diameter ratio catches better, but it may not give you a sufficient safety factor when you need it to actually hold your weight: esp for ascending and passing a knot, but also for losing control of a rappel. So what works more consistently? In my experience, the prusik and the Distel Hitch, both with plenty of wraps. They can both be made to grip rope of the same diameter. The Distel hitch gives you well controlled release on descent, which I suppose is why arborists use it. The prusik has the significant advantage of bending the rope for better grip when passing a knot, but it doesn't release well when loaded and can bind so it can be inconvenient or dangerous as a rappel backup. If your safety doesn't slide well, you will fatigue and bounce, potentially damaging your rope. The Bachman is more convenient for moving the rope up when ascending, but in some configurations I've had it slip downward under my weight. Use a real grippy prusik cord or the Distel instead. Have you practiced ascending or passing a knot recently? That could save your life too. Be prepared to unweight your rappel device with a prusik or you can easily find yourself stuck on a rope when it jams, which is not a rare occurrence. It has been mentioned one should be prepared to climb any rope they descend, and if that's long, ascenders would be most efficient.

    2. Bends for loaded rap lines. Favorite: Offset overhand with an extra wrap. The offset overhand (EDK) translates well over 90’ edges on tricky pulls and is pretty secure, but it jam hard, significantly reduces rope strength, and has some instability. Back it up and leave long tails, that’s cheap insurance. Leave the thinner rope at the bottom and before tightening wrap it through the nip a second time above the thick one to make it significantly more secure and easy to untie. See page 32 of this excellent reference. http://www.paci.com.au/downloads_public/knots/01_Knots.pdf

    The offset figure 8 is much less stable. I doubt that the offset double overhand or offset stacked double fisherman’s add much more security or ease of untying, but they might possibly offer a little more strength. I’m not aware of non-offset knots that translate around sharp corners; all of the following have that disadvantage on tricky pulls.

    The figure 8 bend is simple and secure but tends to jam badly, and doesn’t translate around corners well. The double fisherman’s (grapevine) retains a remarkable ~80% of rope strength according to multiple studies, but is also hard to untie. The double dragon (a double sheet bend with the loose, usually left end tucked into the loop) is secure, easy to tie and untie even after heavy loading, and maintains good rope strength. I once wondered if perhaps I had invented it, but apparently, it’s commonly used in rigging. The Zeppelin (Rosendahl) is fairly strong and very easy to untie, but in my experience much less secure than reported. It can ratchet free under repeated load cycles, and if something catches the loop on either end, it will disintegrate like magic. The carrick bend is great even for string, but make sure your tails are diagonal from one another before tightening. I’m not a fan of the alpine butterfly bend (or loop). It can easily be tied incorrectly, and I find it frequently does jams despite its reputation, perhaps especially if tied around the hand as shown on grog.

    With any knot, look for at least two rope diameters through the nip and consider backing up with double fisherman’s. If you have to pull your rope and your knot isn’t offset, consider wrapping it with tape to make it more ‘aerodynamic.’ There are some exotic and complex knots worthy of consideration, but they’ll be hard to verify.

    3. End loops (e.g. climbing tie ins). Favorite: End Bound Single Bowline. The standard figure eight is easy and secure and retains 60-70% of rope strength, but it jams. What a pain! Try the end bound single bowline. It’s stable, strong, secure, easy to untie, and once you learn it, the properly dressed knot has a distinctive appearance. Other good candidates are Lees locked Yosemite Bowline, the Lee Zep Bowline, and possibly Scott’s Locked Bowline. The Yosemite bowline has been shown to be secure even when improperly tightened (but correctly threaded), but the locked version is apparently more secure. Note the final summary page of this detailed analysis. http://www.paci.com.au/downloads_public/knots/Bowlines_Analysis.pdf.

    4. Anchors: Don’t do the American Death Triangle! In your creative building, seek to employ the principles: Redundancy, Equalization, Non-extension, and an Angle well below 120 degrees, 60 is best. One loop of webbing with a water knot has at least 150% webbing strength and further equalized ropes add much more efficiency. If you’re concerned about weight and want to have plenty of webbing to fully extend multiple raps, in my opinion you could get by with 9/16” climb spec tubular webbing (with a safety factor above 15) but don’t leave it in trade routes. Pad narrow diameter turns to mitigate strength loss. Aggressively group pull test your anchor. People criticize rope quality, but a deadman's anchor or the like is the real weak link. Generally trees should be at least 4-5" inches in diameter, with some variation among species. http://blog.alpineinstitute.com/2015/12/tree-ratings-in-kn.html

    5. Rope retrieval: Favorites: Throw and go, biner block. Throw and go is much lighter with reasonably thin cord of double rap length. Nothing to catch on a pull, weight is split between two equalized cords. But you have to flake out and thread half your rope. A thinner diameter/sheath is offset by the disproportionately large decrease in wear by dividing the load by two. Don’t let the lines get twisted and tangled. The other major drawback is rope grooves if you don't extend webbing to a clean pull.

    The real winner for a secure rap line is the biner block. See Canyoneering USA’s tech tips. However, the hardware could potentially catch on something with a difficult pull, and you are likely to leave rope groves on any sandstone edges. What knots? Constrictor > triple clove > clove. Beware that these knots can slip away when pushed to a curved section of your carabiner! They should always be backed up by at least an overhand or double fisherman's knot, which naturally occurs when you securely tie a pull cord to the block side tail of your rope.

    A knot block could jam or pass through. If you have to do it, consider the E-Star block knot.

    Releasable knots inherently add risk. Don’t let the tag line take any weight, and keep it light on a long descent.

    Fiddlestick: I think Tom has covered this well, don’t you? Beware that things can go fatally wrong if not perfectly implemented by the very experienced. For example, the stick may get pushed out of the stone knot, or slip out when the rap line is unloaded or the pull cord is too heavy, or the pull side could get trapped by friction under the knot. Practice keeping the twist inside the knot and placing it strategically.

    Macrame. I’ve used it and I’d use it again if I had to, but make sure you insert three long bights of the pull end through the final loop to prevent capsizing, each smaller than the previous. Unlike a fiddlestick, rope can’t be accidentally pushed through the slip, it has to be pulled. It can be used to retrieve a double ended sling without an extra length of cord. Don’t assume that you can keep the main line weighted and pull once and only lose the first loop. They may all come at once with a good tug if the rap line is loaded. They say that the CEM is more secure, but I personally find it more difficult to dress properly and am a bit leery of complex sheepshank type knots with many friction points. As Tom points out, they’re both dependent upon rope friction properties, which must be tested every time by someone who knows what he's doing.

    Occam’s wire gate biner release. Fun trick, key use is for lowering a rope with a knot in it (core shot, extended rap, knotted hand line). It must be tested every time. The trick works for me at home, but I'd try to avoid it in canyons applications beyond a shortish hand line because just a tiny tug will release the main line when it is unloaded, however briefly.

    6. Webbing: Water knot, beer knot (water on steroids for homemade slings) and overhand bight. What else do you need? Just make sure that there’s plenty of tail, because they do ratchet slightly with repeated load cycles.

    7. Rappelling Tidbits: my SHHARK Checklist
    S.afety distel hitch or fireman's belay
    H.arness and Helmet. Check all connections.
    H.ang pack
    A.nchor inspect bolts, knots, webbing, rapides, anchor materials.
    R.appel device. Check biner locks too.
    K.not at end of rope

    Hang your pack below you on free hanging raps >50' &/or use a chest harness, especially if it's wet and heavy, or you may tire and invert! Be ready to tie off unexpectedly in such a way that nothing jams and you can continue on easily. The Critr shines here. Hang extra prusiks, accessory cords, slings, biners, and a knife from your harness and know how to use them to acscend, unweight a device, etc. Preparation could save your life.

    Extending your rappel device on a short (6-15”) sling really offers freedom of movement and a natural, secure hold on the rope with both hands in front of you. Beginners will cling to the rope for dear life instead of places they shouldn’t, and they don’t have to keep a hand awkwardly at the hip. This style enables a bare bones ascent by merely moving the prusik above the descender and tying a loop in the rope below. Make sure you can reach the descender easily for friction adjustments. Add a leg biner or a Z rig for increased friction if your rap device doesn’t have ears.

    8. Rope: Beware of up to 70% loss of knot strength with HMWPE dyneema/spectra cord, severe flex fatigue with aramids/technora/kevlar, and 15-30% strength loss with wet nylon. I'd incorporate minimum breaking strength (ave tensile str *80%), knot efficiency (*30-80%), flex fatigue (*50-100%), and wet strength loss (*75%) into a conservative safety factor calculation of at least 15* load (weight + gear). Inspect the sheath. https://user.xmission.com/~tmoyer/testing/High_Strength_Cord.pdf
    http://caves.org/section/vertical/nh/59/Rescue Knot Efficiency Revisited.pdf
    http://www.mountaineeringlife.com/w.../09/Graphs-of-cord-and-webbing-strengths1.pdf

    Question: how much sheath damage or core denting/warping does it take to make a rope unsafe for rappelling?

    I may continue to add to this over time.

    http://www.paci.com.au/knots.php
    http://www.animatedknots.com/
    http://igkt.net/sm/
    Edits: added info, detail, clarification.
    Last edited: Feb 10, 2017
  20. ratagonia

    ratagonia

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    Thanks for the generous feedback LonePeak.

    A new one to me: Distel Hitch - At Animated Knots

    LonePeak - Are you an arborist?

    :moses:
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