Adjustable Loops

[xarax]

   Indeed, I see in your pictures that the diameters of the two coils are equal, which means that there remains no slack in the nub. I had not loaded your loop so much, and that is why the second / higher collar remained more loose.
   However, I still believe this second collar is an overkill. We use two collars when we want the friction between their parallel and adjacent wraps to keep them "locked" - but here you have the nipping loop itself to do this. I do not believe that two collars grip / nip / immobilize a penetrating line more than a single one ( and, in any case, such an effect, if it exists, it has not been demonstrated by any test, ever ) - because one single collar "bites" harder into the surface of the line, but two, although they provide a more extended area of contact, they also provide a more extended area on which a line can slide, because they can not penetrate into its surface so deep.
   I think that if you tie the much simpler knot I had shown in my previous post ( with the vertically oriented coil, which is loaded more directly by the returning/second eyeleg ) you will see that it is no less tight and secure, although it uses one, only, collar. 

[xarax]

   On the other hand, anything hanging from the rim of the nipping loop ( like this/those turns on the returning/second eyeleg, before the collar ) tends to pull the nipping loop wide open - so, perhaps, what this eyeleg gains, regarding friction, in its way "up, it loses it in its way "down" - because the "loaded" nipping loop may not be able to nip it as tightly as when it was left undisturbed...

[Mobius]

This thread started life as a fun 'knot wars' idea.

Later it metamorphosed into a thread about adjustable loops

For several weeks I was not around here so that didn't help much either. At some stage I will try and pull the bones out of it and do something along the lines of what I intended. My new test rig is both good and bad, I can test much bigger loads, however the finer detail of when a knot breaks (i.e. what %mbs) disappears in the press of a button.

Where a knot breaks is more interesting anyway perhaps, and is not so much to do with the 2 diam vs 3 diam debate from what I have seen.

Cheers,

mobius

[alanleeknots]

唯恐天下不亂嗎?

[Mobius]

唯恐天下不亂嗎?

Hi Alan,

If that was a question for me, in Chinese doesn't help me much answering it

Cheers,

mobius

[Mobius]

From another thread:

Hi all,
        Mobius, when I present the Triple overhand knot-based adjustable loop
        at Reply #92   http://igkt.net/sm/index.php?topic=5383.90.
        I have tie another version of Double overhand knot-based adjustable loop, I didn't post it because it will jam on heavy load.
        I have the load test here to show the difference between your version and my version.

        Picture #3 and #4, I loaded it till your SP-Tail Reversed loop just start to jam and I release the load to check on both loop,
        your  SP-Tail Reversed loop just kind of hard but manage to untie, but my loop is very easy to untie.

        謝謝  alan lee

Thanks, I was almost sure the knot I came up with was one I had seen before.... one of yours

Is the 'Triple overhand knot-based adjustable loop' the best one you found? If not, what was better?

I played some more with the Double overhand style loop you first showed us and added a second collar. The collar is more about introducing a 3rd diam through the turNip to see if that lessened the double overhands jamming potential while still allowing enough nip. Here is what I found happened:

Image 1 left: A simple double overhand double collar which slips, so reject this one. The 3rd diam did not look promising

Image 1 right: The tail is tucked in one of several possible ways. The knot tails loads to an 'L' shape at 500kg and didn't jam. However the collar closest the eye was too loose for my liking so I reject this one too. The 3rd diam. idea seems to work better this time

Image 2: Another try at re-tucking the tail. The tail becomes an 'L' under load

Image 3: Under load at 500kg. It untied easily in my rope (messed up the focus a bit, sorry). There are no loose bits in the nub, the collars and other loops are doing something load wise and nub form looks good to me. The 3rd diam through the turNip need not be dismissed it seems.

Seen any of these double overhand adjustable loops before Alan? The last one looks ok, what do you think?

Cheers,

mobius

Edit: added a 4th Image, much better focus of the same knot as Image 3 at 500kg

[alanleeknots]

Hi All,
         Mobius Thank you very much for fixing the thread problem. Since you ask me about you knot, and I owe you a favour.
        I try my best to answer you. The additional collar will lengthen the collar near the standing part
        and also the three rope diameter on the nipping loop can push the main collar more upward,
        that mean we have a nice main collar and easy to untie.
        Now the main collar is fine, but there is a problem, additional collar will lock on the the nipping loop.
        When you load the loop,for softer rope it will lock on early, for stiffer rope can hold better, but it will jam on heavy load.
        unless you dress the additional collar loosely,then it will not jam on you.
        My own opinion any good knots should dress it as tight as you can before you use.
           謝謝  alan lee.

[Mobius]

Hi All,
         Mobius Thank you very much for fixing the thread problem. Since you ask me about you knot, and I owe you a favour.
        I try my best to answer you. The additional collar will lengthen the collar near the standing part
        and also the three rope diameter on the nipping loop can push the main collar more upward,
        that mean we have a nice main collar and easy to untie.
        Now the main collar is fine, but there is a problem, additional collar will lock on the the nipping loop.
        When you load the loop,for softer rope it will lock on early, for stiffer rope can hold better, but it will jam on heavy load.
        unless you dress the additional collar loosely,then it will not jam on you.
        My own opinion any good knots should dress it as tight as you can before you use.
           謝謝  alan lee.

Thanks for the feedback. I will try my double collar knot (the last one shown) in both my 3mm poly braid and 6mm marine grade pe/pp blend and see if it jams. The 3mm poly braid I use likes to jam (it's size makes it hard to untie even if it is smooth and stiff) and so does the frictive surface of the 6mm marine 3ply (very stiff). I don't test in soft rope, so lots of knots would jam in softer rope that otherwise would not in stiffer rope I suppose.

We may need different knots for different ropes, especially when it comes to adjustable loops.

Cheers,

mobius.

[alanleeknots]

Hi All,
        Yes or no,  knots would jam in softer rope that otherwise would not in stiffer rope,  knots also would jam in stiffer rope
         that otherwise would not in softer rope.

         謝謝  alan lee.

[Mobius]

Just to follow up on what I said I would do. Below are some 'other material' trial images of the double overhand, double collar adjustable loop I proposed earlier.

It actually works far better than I thought it would when I first started playing with it. That the 3 diams allow the turNip to hold as well as it does was a surprise. Then I was pretty sure Alan would be right and the eye collar would jam once I got it under heavy relative load (50% mbs) rather than the 500kg (20% mbs) load I tried before. However, the knot still looks very good to me: Doesn't slip, doesn't jam, doesn't deform under load.

The 3mm poly I use is shown at >100kg and the 6mm pe/pp is >300kg. Both images 2 & 3 show the knots were tight. I could get both knots apart by hand after these loads with relative ease. The collar closest the eye was the hardest to loose (as Alan said it would be), however I still think the knots were what I consider as being 'easy to untie'.

I have some reasons why this DODC Loop seems to work as well as it does, however those can wait for now.

Cheers,

mobius

[alanleeknots]

Hi All,
         Mobius, let said we have a standard bowline here, we add one or two tuck or may be a second collar to the nub, by doing that,
         we have to gain something, have to be better then the standard bowline, otherwise it don't make sense to have though those unnecessarily
         parts add in to the nub. Any way I like your effort.
         謝謝  alan lee

[alanleeknots]

Hi All,
       Happy New Year
       Here is another variation of loop that belong to the same class and I didn't post it the last time,
       see here reply #128  http://igkt.net/sm/index.php?topic=5383.120 , because the last three loops their rope flow in to the nub are smooth
       then this one here.
       Now I have more free time to look at it again,I think this loop is not that bad at all. this loop is well secure and easy to untie,
       and the tail of this loop was nipped by the top collar with full force, make it little more secure.
       It is important have the last defend as Xarax alway said.
       
       謝謝  alan lee

[Dan_Lehman]

Just to follow up on what I said I would do. Below are some 'other material' trial images of the double overhand, double collar adjustable loop I proposed earlier.

Heinz Prohaska proposed using the anchor bend structure
qua eye-knot base some decades back, in response to the
infamous Lynn-Hill accident (where she was distracted from
tying in and simply didn't tie her intended (per her book)
bowline, but which some (mis)took as the case where
a left-in-rope-for-next-tying fig.8 (single-strand, SPart)
awaited the new tyer-in person's "rethreading" to complete).
So <whew>, Heinz thought that this base is one that could
work even if only the first tucking-tail-into-knot was done
and nothing further!
(IMO, that is fine-tuning an error point to a too-small range.)

Perhaps if the additional loop around the SPart is made
away from the eye --so that it will press into the other--,
jamming will not occur (or as much) ?!


--dl*
====

[Dan_Lehman]

Hi All,
       Happy New Year

Yes, thank you --and may it be so!
(but rumblings all over this world are worrying)

... this loop is well secure and easy to untie,
and the tail of this loop was nipped by the top collar with full force, make it little more secure.

Hmmmm, the severe curves in the S.Part worry me,
and it stands thus in sharp contrast to a somewhat
similar-looking "locktight" eye knot --and one that
Alpineer also formed, naming it "...tresse...".  Although
the knots I present here

http://igkt.net/sm/index.php?topic=4476.msg29741#msg29741

show a pretty sharp U-turn for the S.Part, so too does the
blood knot which nevertheless seems to fare well
in nylon monofilament --and breaks, per Barnes, not at
those turns but in the center where S.Parts pass on either
side of the nipped tails (!).

(One of those locktights has a broader collar for the sake
of stiff, low-elongation ropes (I think I was fiddling with some
well-used Bluewater II, which resists bending!).'  I like to put
the tail so that IT is what the severe turn of the S.Part bites
into (as the tail lacks tension and so can deform under such
pressure, which I presume is beneficial to the SPart).
)


--dl*
====

[Mobius]

Perhaps if the additional loop around the SPart is made
away from the eye --so that it will press into the other--,
jamming will not occur (or as much) ?!


--dl*
====

I think the first image below is one way to revise the double collar knot I showed a few posts ago. A good suggestion from DL I believe, I will trial this revised knot in due course. I like the way I feed the tail through the nipping turn, but there may be better ways to do it. I don't think this knot will jam as I show it.

Image number two is a PET eye knot that to my mind can still be called 'adjustable'. A moot point perhaps. I have trialled this knot in a  preliminary fashion and it does hold at 200Kg in dynamic rope so far. The collar around the eye can be left loose, the knot appears to be secure regardless.

Image three is both PET and TIB. It holds at 200Kg in dynamic rope as well. Note that for TIB to be a significant attribute, I believe an easy TIB tying method also needs to be available. Easy to me means: the knot can be held in your hands and tied in total darkness in less than 30 secs (eye knot). 30 secs is probably generous, but I hope you get the idea of what i mean by 'easy'.

None of these images I claim as new.... Alan Lee (in particular)  has a lot of knots out there, some of which I recollect as at least being similar

Cheers,

mobius