ArboristSite.com Sponsors
 
 


Whats this Knot

Discussion in 'Arborist 101' started by derwoodii, Oct 3, 2009.

  1. derwoodii

    derwoodii Addicted to ArboristSite

    Joined:
    Mar 20, 2009
    Messages:
    5,836
    Likes Received:
    3,798
    Location:
    Victoria Australia
    For 25 years I have used this. Unsure rope terms, call it a running hitch and non locking so good to secure limbs for lowering or say pulling over trunks. I hope to share and have peer reviewed as a simple quick easy knot for tree timber handling. I could whip the rope around a limb and tie the knot with one hand so it was high use when I was climbing for a living. Its never failed me and always easy to unlock even after heavy tension. I'll try to explain how its tied but pictures are always better. The only trick hard to show or explain is the turn/twist a loop that the line end passed though.
    Why I ask? it was never shown to me, I just muffed it one day and it worked but not seen it else where.
     
    SINGLE-JACK likes this.
  2. blewgrass

    blewgrass ArboristSite Member

    Joined:
    Oct 13, 2008
    Messages:
    79
    Likes Received:
    7
    Location:
    maine
    I'd call it a figure eight slip knot.
     
    derwoodii likes this.
  3. derwoodii

    derwoodii Addicted to ArboristSite

    Joined:
    Mar 20, 2009
    Messages:
    5,836
    Likes Received:
    3,798
    Location:
    Victoria Australia
    Thanks cool your right its is just a figure 8 but I have tied it around the rope to make the running loop/hitch.
    I must say it thinking now it worries me that for 30 years I been climbing dismantling trees with very few knots in the kit.
    I was shown the usual clove, bow line, prussic & timber hitch (which I think was how I goofed this one) Even handy with the trucker trap and can splice a eye. But I have kept my knots knowledge at the sallow end of skill pool.
    Next life I should try harder.
    Give this one a go it is quick and simple has worked for me. The look you'll get when you send it down to your groundies is worth it... Huh LOL what???
     
  4. lego1970

    lego1970 AboristSite Guru

    Joined:
    Jul 14, 2009
    Messages:
    504
    Likes Received:
    39
    Location:
    Blue Springs, Missouri
    That's simple. It's a Derwoodii knot. :cheers:
     
  5. Rftreeman

    Rftreeman Addicted to ArboristSite

    Joined:
    Apr 11, 2007
    Messages:
    3,317
    Likes Received:
    294
    Location:
    huntsville al
    what happens if it tightens up and you can't untied it? I will always use the bowline, been using it for 21 years and put some heavy loads on it and never had it once get to tight to untie.
     
  6. pdqdl

    pdqdl Not old enough yet to know better

    Joined:
    Feb 26, 2008
    Messages:
    7,091
    Likes Received:
    1,121
    Location:
    Kansas City
    I'd call it a slipped figure eight knot, but... "slipping a knot" is generally done to facilitate untying it quickly, the slipping portion is invariably a tuck of the final tail through a loop of the knot. In this particular case, your knot should never slip out, as the loaded end of the rope can only slip out when the log is removed.

    I don't think that I would use this knot . The figure 8 is a very reliable knot, but it is not designed to hold itself together surrounding some other structure. In this case, it would be possible for the load to put a pulling-separating force into the middle of the figure 8, and it might just pull the tail out.

    If you do a little research, you will discover a way for tying the bowline one handed as well. Then you will be doing an industry-standard knot, rather than making one up that might prove unreliable.

    It's probably great for light limbs, though.
     
  7. Wishie22

    Wishie22 ArboristSite Operative

    Joined:
    Jan 25, 2009
    Messages:
    344
    Likes Received:
    12
    Location:
    Eastern CT
    How about a clove hitch with a bowline (with a yosemite tie off on large pieces)?
    Secure and easy to untie.
     
  8. outofmytree

    outofmytree Addicted to ArboristSite

    Joined:
    Jan 24, 2009
    Messages:
    1,779
    Likes Received:
    128
    Location:
    Perth, Western Australia
    I read and reread this mate and I just can't see how this knot would be less reliable than a bowline for example. The force on the leg from loop to knot would be drawing the knot tighter rather than spreading it apart as far as I can see. Do you mean constant force over a period of time or shockload? You could probably test this quite easily with a truck and a decent anchor.....
     
  9. derwoodii

    derwoodii Addicted to ArboristSite

    Joined:
    Mar 20, 2009
    Messages:
    5,836
    Likes Received:
    3,798
    Location:
    Victoria Australia
    Ok thanks all, I put it out and got excellent feed back.
    At this stage its goofy invention only tested by myself.
    As there are many proven industry adopted knots lets not give it a name or use it over any-ones heads.

    My 25 years experience, its hard to lock up and I have not seen it drop apart but...insert caveat here.

    When I get the time I might try a bit of destructive testing and shock and loading see how it performs vs. my diesel 4x4 & send in the pictures.
     
  10. pdqdl

    pdqdl Not old enough yet to know better

    Joined:
    Feb 26, 2008
    Messages:
    7,091
    Likes Received:
    1,121
    Location:
    Kansas City
    Ok...look at this situation in another way.

    Tie a simple figure-8 on the end of a line. No bight, no follow through, just a simple figure 8. Attach a carabiner to one of the loops of the knot, then throw the near end of the rope over a branch, and call that your termination knot for your lifeline.

    Good idea? I don't think so.

    The forces on the knot while snugged down to a large diameter log will be similar to hanging a carabiner on one end, and pulling on the tail from the near side of the loop to the carabiner. It will tend to spread the knot apart, then subsequent failure. Why bother with the risk? Other knots are better, and just as easy to tie.

    Engage brain, avoid risk.
     
  11. davej

    davej ArboristSite Operative

    Joined:
    Jan 15, 2007
    Messages:
    116
    Likes Received:
    3
    Location:
    STL
    Oops... I occasionally use that knot when tying a trucker's hitch but I wouldn't consider it too safe. It can capsize into a form that will loosen. In a trucker's hitch that doesn't matter.
     
  12. TheTreeSpyder

    TheTreeSpyder Addicted to ArboristSite

    Joined:
    Dec 31, 2001
    Messages:
    3,763
    Likes Received:
    53
    Location:
    Florida, USA
    This fig.8 noose would deform the Standing (Tension) Part like a Running Bowline. Both, should also pull perpendicular to the limb; if inline pull (angle from rope to limb), should be preceded by Marl / Half Hitch.

    But i'm personally more with DBY as tried in true, seating nicely in all but the stiffest of our lines.
     
  13. outofmytree

    outofmytree Addicted to ArboristSite

    Joined:
    Jan 24, 2009
    Messages:
    1,779
    Likes Received:
    128
    Location:
    Perth, Western Australia
    I still dont agree with your synopsis pdqdl but I need to draw this out to explain what I am thinking. Gimme a day or so and then we can follow up on this.

    :cheers:
     
  14. pdqdl

    pdqdl Not old enough yet to know better

    Joined:
    Feb 26, 2008
    Messages:
    7,091
    Likes Received:
    1,121
    Location:
    Kansas City
    Whether or not I am right is somewhat irrelevant.

    Why bother with the risk? Other knots are better, and just as easy to tie.
     
  15. derwoodii

    derwoodii Addicted to ArboristSite

    Joined:
    Mar 20, 2009
    Messages:
    5,836
    Likes Received:
    3,798
    Location:
    Victoria Australia
    Ok I grabbed some tag line 10mm poly double braid and hooked one end using the goofy figure 8 to a stump the other with a bow line to hitch of a 4x4.
    Snap broke at the bow line ??
    Same again & again snapped the bowline. The goofy was tightened up but was I able to unlock with a tool.

    So reversed it to the tow hitch put a bow line on the stump. Snap bow line again.
    The goofy surviving 4 shocks was cooked but intact some quite cursing and a good screw driver I was still able to unlock it.

    All, this was a very quick test and without good control.
    I'll go see a local rope maker and ask them to conduct a few fair dinks bench tests take out my subject bias.
    I will advise and report results.
     
    ray benson likes this.
  16. TheTreeSpyder

    TheTreeSpyder Addicted to ArboristSite

    Joined:
    Dec 31, 2001
    Messages:
    3,763
    Likes Received:
    53
    Location:
    Florida, USA
    i'd think it'd break at Bowline; but be more an even battle if it was a Running Bowline? The fig.8 being a shrinking eye (rather than a fixed eye like Bowline); might impart some re-stabilazation of the Bent Standing Part, but we usually don't see that so much until a round Turn around Standing (without Round Turn around host/mount).

    These are running knots/nooses. Just as a simple Noose is Overhand around self to form eye, and a Dbl.Noose/ Scaffold / 'Dbl.Fisherman's is an Anchor around self to form eye; this Fig.8 Noose is just Fig.8 around self to form eye (and Bowline is just SheetBend to self to form Fixed/ non shrinking eye, but Hitch of Sheet is turned into more properly a Half Hitch).

    But, the strength reduction (as a percentage of tensile strength of the line) is generally from the destabilizing deformity/bend in the fully tensioned Standing Part. On a Bowline, this would be the bend to form the Half Hitch, but on Running Bowline, would be where the eye deforms the Standing like the other running knots mentioned.
     
  17. outofmytree

    outofmytree Addicted to ArboristSite

    Joined:
    Jan 24, 2009
    Messages:
    1,779
    Likes Received:
    128
    Location:
    Perth, Western Australia
    Nice one derwoodii.

    Some people prefer to stick with what they are told, some like to experiment to see if there is a better way. I am the latter.

    [​IMG]

    Not the best drawing but if you follow the lines of force you see pull and resistance. The knot is a sliding knot so the forces are linear rather than lateral. Rather than pull the knot apart the force is going to set it resulting in a stronger rather than weaker bond when used in this fashion.
     
  18. Rftreeman

    Rftreeman Addicted to ArboristSite

    Joined:
    Apr 11, 2007
    Messages:
    3,317
    Likes Received:
    294
    Location:
    huntsville al
    experiments can get people killed.


    the running bowline is a sliding knot so wouldn't it have the same effect that you're trying to explain?
     
  19. TheTreeSpyder

    TheTreeSpyder Addicted to ArboristSite

    Joined:
    Dec 31, 2001
    Messages:
    3,763
    Likes Received:
    53
    Location:
    Florida, USA
    i think he is speaking to the lock of the fig.8 being pulled open or closed.

    Usually we see a fig.8 as a superior form than an Overhand, by virtue of the simple extra twist of the 8! One place this can backfire i think is as a stopper, for a stopper is best jammed up against the knot to insure proper seating, this is harder with 8 than Overhand IMLHO. Also, the profile that stops/ jams is the same at that seating. Once again the old ways can be the best, 2 Half Hitches seated tight as per custom..

    The strength of these Running Knots is of 1 leg of support; less it's destabilizing deformation (by the eye of either). Now if the deformation is less, that is better. If the same deformation is over a longer distance ; the deformation seems to happen with less impact against the strength (like a Double Bowline is stronger than a Bowline). This and several other factors cause a 'destabilizing' effect; that drops the tensile strength to below 1xTensile Strength (always calculating a percentage (really just the infinity between 0 - 1) X a potential.

    Now, if we go from a Single Noose (Overhand around self to form shrinking eye) to a Double Noose(Anchor Hitch / Double Overhand around self to form shrinking eye) we get a stronger knot. But; if the we come around the host/spar/mount with a Round Turn (before making Anchor to self); the effect (of the knot being stronger/ 're-stabilized'(?)) seems all but lost. So, i think a Single Noose, or this Fig.8 Noose could give stronger results on some pulls that Running Bowline, because the cinching up effect (to help restabilize/ fortify like rubber boot on electrical cord at base of a unit?) around Standing could give extra edge here.

    But, the strength of these Running Knots/ eyes can also be characterized by how 'flat the tepee' is. For, a taller point / tepee is more relaxed/ leveraging the Standing Parts force less vs. when same is flattened against the load/mount/spar. This is witnessed by the subsequent tighter grip on said load from same pull etc. An eye that shrinks close can cinch up and stay tighter, than an open eye that can loosen later after tightening up etc. But, then the increased frictions from a sudden loading can pull the line thru the shrinking noose with more frictions, giving more dampening of force there... So, many ways to go; people can witness different things by using different lines, dressing and loading strategies!!
     
    Last edited: Oct 11, 2009
  20. moray

    moray AboristSite Guru

    Joined:
    Dec 29, 2006
    Messages:
    592
    Likes Received:
    59
    Location:
    Maine
    Yesterday I pulled over 3 trees and found myself trying to come up with a good mid-line loop knot to attach to the tow hook. There are plenty of secure knots, but I also wanted it to be easy to untie after a big load. When I saw this thread, I thought this running figure 8 might be worth checking.

    I have now tied this knot 20 or 30 times and can certify it is extremely easy to tie. It is easiest to tie it as a mid-line knot even if it is at the end of the rope.

    Today I subjected it to a break test. In derwoodii's picture below, I have added a green arrow to show the sharpest bight in the knot. This sharp bend around the knot's tail also experiences more tension than any other nip in the knot.


    [​IMG]



    I made up one short rope in Yale Blaze with a running 8 at each end; each knot was held by a 3/4-inch steel shackle pin. For comparison, I made up another rope with a running overhand at each end. All 4 knots had tails of 4 inches or more.

    The next pic shows one of the running overhands at about 200 lbs. tension.


    [​IMG]




    The next pic shows one of the running 8's at about 200 lbs. tension. Even under such a low load the knot is hard to recognize as the same one in derwoodii's picture.

    [​IMG]
     

Share This Page