Author Topic: Non slipping bend in Dyneema  (Read 67073 times)

xarax

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Re: Non slipping bend in Dyneema
« Reply #60 on: January 26, 2014, 01:38:28 AM »
  Tie interlocked Buntline hitches ...

  It should be examined if it would be better to tie possibly tighter hitches, instead of the old Buntline hitch : the "Buntline extinguisher" = Constrictor noose (1), or the "Serpent noose" -shown at the attached pictures.
« Last Edit: January 30, 2014, 03:08:05 AM by xarax »
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allene

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Re: Non slipping bend in Dyneema
« Reply #61 on: January 26, 2014, 07:39:05 AM »
Both versions with the buntline hitch slipped on Estar's setup.  I guess I can prove that a knot slips, but I cannot prove that it does not slip.

The constrictor replacement slipped when the tails were taken through the center, both loops.

What we need is a good noose but we also need a lot of holding power on the tail.  Gripping the tail seems to be what keeps the knots from slipping. 

So far the "best" bend is what Estar is calling the first in the series.  It is the one that is similar to a double fisherman's but with clove hitches instead of just loops.  It does not slip but it's efficiency is only 35% ish.  By contrast, the double Estar is 45 to 50%.  The best we can hope for is 50% so 35% is not  unreasonable.  Strength is usually not an issue with this line as it is typically used for its stretch characteristics and ends up being way stronger than it needs to be.  For example, I have a long line that I call a preventer.  It takes a shallow angle to the thing it is holding so a small stretch can cause a fair movement in the boom, which it is intended to hold.  By the time you satisfy that, the line is strong enough to life my 12,000 pound boat.

Anyway, I am sidetracked.  The feeling is that no slip is more important than stretch as the only thing that is going to possibly load the line significantly is probably a shock load and we know from testing that the faster you load these lines, the more likely they are to slip.

I guess I could try the constrictor replacement with the tuck through the opposite constrictor.  That is the next test.  It just isn't as easy as tucking through the center.

Allen

Correction, I tried the second one.  Just tried it with the tuck through the opposite loop.  Not to hard to tie and didn't slip for me.
« Last Edit: January 26, 2014, 08:00:41 AM by allene »

SS369

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Re: Non slipping bend in Dyneema
« Reply #62 on: January 26, 2014, 03:40:36 PM »
Hello estar and Allen.

Since the hunt is still on and you seem to be willing to configure and test all manor of tangles, give this a try if you'd care to.

As with your tying two clove hitches, use prusiks on the opposite lines and tuck the tails through the gap between them, draw them together tight, cinching the tails before loading the sling.

SS

xarax

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Re: Non slipping bend in Dyneema
« Reply #63 on: January 26, 2014, 04:16:11 PM »
Since the hunt is still on... use prusiks on the opposite lines and tuck the tails through the gap between them

The hunt, SS369, not the fishing:) :) What you describe is a fine fishing knot ! We would better remain in the area of max-two-tucks ( tuck-tuck ) or max-two-spins ( spin-spin ) knots, and exhaust all the possibilities there, before we retreat to fishing or decorative knots - tuck-tuck-tuck ( 3 times )or spin-spin-spin ( 3 times ) tangles. A simple rule of thumb for what a simple easy-to-tie-on-board bend is.
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SS369

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Re: Non slipping bend in Dyneema
« Reply #64 on: January 26, 2014, 04:43:21 PM »
Hi xarax.

I think that what I suggested has merit considering the examples of what has been tried and that Allen and estar are not novices to knot tying. Two prusiks, as I have offered is not in the realm of the unthinkable, nor are they so complicated that one can not inspect them easily. and they have the tails tucked between them to provide additional locking (potentially, using that slippery material). Those knots are something they and others know.
It produces a nice, linear knot with the double standing part gripping (good enough deformation) that seems to be a good thing.

And if it does not work, perhaps the suggestion can be a springboard to something that does. And multiple lines of thought here are not inexcusable.
Let's not put limitations in the way.

So if fishing yields the end result or hunting produces a desired outcome,,,, game on.  :)

SS
« Last Edit: January 26, 2014, 05:13:02 PM by SS369 »

Sweeney

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Re: Non slipping bend in Dyneema
« Reply #65 on: January 26, 2014, 04:59:16 PM »
Although this may not work, again it may lead to something which does. Tie an ordinary reef (or square) knot but tuck the 2 tails down through the knot by lying the knot flat and taking the tails through from top to bottom (or around and back up again). When dressed and tensioned the knot compresses the tails very tightly - this works in nylon monofilament fishing line (treated with soap for least friction) though it is fiddly to tie in something so thin it is easy to tie in cordage/rope.

Barry


xarax

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Re: Non slipping bend in Dyneema
« Reply #66 on: January 26, 2014, 05:06:56 PM »
Two prusiks, as I have offered is not in the realm of the unthinkable, nor are they so complicated that one can not inspect them easily.

  No... but just COUNT the number of tucks and/or spins !  :) When you go over 2, you return to your drawing board - until all really easy-to-tie AND simple topologically and/or geometrically knots are exhausted. A fishing or decorative knot can be very nice, as you know, and, of course, very secure. Nobody said that such a knot is difficult to learn or remember, or that it will not work, but that is not what we need ! Most, if not all, convoluted enough fishing knots are easy to remember ( as they are relying on mere addition /repetition of spins, mainly = spin-spin-spin-, etc... ) and they will work, just because they are meant to work, they are designed to work on very slippery fishing lines, Spectra / Dyneema included.
   I do not put limitations, and I had often been criticized for tying too complex knots !  :) I just suggest to start from the simple and proceed to the more complex, because we are looking for the simpler, or one of the simpler, knots that will work, not any, however convoluted tangle, that works... If you are just hungry, before you go fishing, see if there is any fish already cooked in your refrigerator.
 
« Last Edit: January 26, 2014, 05:09:29 PM by xarax »
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SS369

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Re: Non slipping bend in Dyneema
« Reply #67 on: January 26, 2014, 05:33:35 PM »
I am only offering possibilities, since I do not own any of this slippery material to try, yet.
As well, I am trying to use relatively common knots to keep in the theme of this post. Knots most likely to be easily configured by the interested.

The simplest affair would be to choose the least complicated knot that slipped least, so far, and just add a stopper type knot (or back up type) to both tails. Not elegant, but will work.

Example: Choose a Sennit bend. Nice neat streamlined bend. Add a stopper, say a double overhand. The combination should work while maintaining a non-bulky profile. This being a criteria, the non-corpulence, I have set for my own exploration here.

Quote
I just suggest to start from the simple and proceed to the more complex, because we are looking for the simpler, or one of the simpler, knots that will work, not any, however convoluted tangle, that works...

Same type of thinking, just the other direction. We should end up somewhere middled.  :)

SS


« Last Edit: January 26, 2014, 05:34:06 PM by SS369 »

xarax

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Re: Non slipping bend in Dyneema
« Reply #68 on: January 26, 2014, 05:42:31 PM »
The simplest affair would be to choose the least complicated knot that slipped least, so far, and just add a stopper type knot (or back up type) to both tails.

 This is addition of knots ( = compound knot ). I prefer the addition of tucks - provided that, if possible, we will not go over 2, in total...

 The simplest affair would be to choose the least complicated knot that slipped least, so far, and just symmetrically re-tuck it.

 
Same type of thinking, just the other direction. We should end up somewhere middled.  :)

 I wonder what kind of creature can be caught by a hunter and/or a fisherman !  :) :)
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SS369

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Re: Non slipping bend in Dyneema
« Reply #69 on: January 26, 2014, 05:50:41 PM »

Quote
This is addition of knots ( = compound knot ).
   
To me, most bends are compound knots (not all). Or composites of knots. (Dan, be nice.)

 
Quote
The simplest affair would be to choose the least complicated knot that slipped least, so far, and just symmetrically re-tuck it.
That remains to be seen with testing.

 
Quote
I wonder what kind of creature can be caught by a hunter and/or a fisherman !  :) :)

As long as the prey can offer sustenance.....   :)

SS

Sweeney

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Re: Non slipping bend in Dyneema
« Reply #70 on: January 26, 2014, 06:02:55 PM »
tuck the 2 tails down through the knot ...
 taking the tails through from top to bottom (or around and back up again).

  Through which opening of the already tied simple knot ? When we are talking about re-tucked simple knots, we need to show pictures, or describe them accurately - there are many ways you can re-tuck an already convoluted tangle with many crossings, many openings through which you can drive the ex-tails.

Picture attached showing the loosely tied knot with the tails taken around and up from below the original knot.
« Last Edit: January 26, 2014, 06:03:45 PM by Sweeney »

xarax

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Re: Non slipping bend in Dyneema
« Reply #71 on: January 26, 2014, 06:40:23 PM »
   Thank you, Sweeney.

  I had once used to call this bend, along with some other similar ones, a "Reef-Ashley hybrid", because of the way the Tail ends act as pivots within the knot s mechanism, leaving the nub towards the same direction ( in a Thief-Zeppelin hybrid, they leave the nub towards opposite directions ). See :
  http://igkt.net/sm/index.php?topic=2085.0
 
  I believe this is a more systematic enumeration of all possible Zeppelin-like such bends ( 20, in total ) which I now call & bends, from the general shape of their links :
  http://igkt.net/sm/index.php?topic=4445

   Personally, I prefer the more symmetric / balanced Zeppelin-like ( and Hunter-like ) orientation of the Tail ends, from the Ashley-like ( and Alpine butterfly s -like ) one.   ...

« Last Edit: January 29, 2014, 03:50:57 AM by xarax »
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allene

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Re: Non slipping bend in Dyneema
« Reply #72 on: January 26, 2014, 07:16:13 PM »
I have tested this latest knot in 7/64 Amsteel with a very fast pull, about 3 seconds I would estimate.  It did not slip.  I also tried to test it against a triple fisherman's but messed up so nothing broke.  I think this is at about 1500 pounds, which would be a very strong knot but it could have been lower.  It is hard for me to know because my setup is only A-B.  If Estar isn't totally sick of bends, I will get some calibrated data at some point.  Here is a write up of the knot http://l-36.com/bend_knot.php

It is pretty easy to tie.  Easier than the ones with the buntline hitch.  I think having the constriction be a single loop rather than the two loops of the clove hitch is helpful.  Being based on a hitch should give it the added strength.  At least I hope so.  This is probably the last knot we are going to test.

allene

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Re: Non slipping bend in Dyneema
« Reply #73 on: January 26, 2014, 11:31:32 PM »
More test results.  First, I am basing this knot on a suggestion by Xarax on the Serpent noose and the work of Estar, the Estar knot, and all the testing he has done.  The knot starts by interlocking two Serpent nooses  and then interlocking the tails by tucking them through the loop on the opposite knot.  This is a nice knot because the Serpent is just a figure of eight stopper knot around the bright and everyone knows how to tie that.

I tested it on 7/64 Amsteel.  All I can do it comparison tests, go no go tests so there are not numbers here.  Numbers need to come from Estar if he has any Amsteel left :-)  I did 3 tests.

1) the knot did not slip in a 3 second pull.  That was a straight pull with the knot between two splices.
2) On a spliced line with two knots, one the last bend (the name I am using) and a triple fisherman's knot.  The triple fisherman's knot slipped.
3) On a spliced line with two knots, one the last bend and the other back to back Estar hitches.  The line broke at the Estar hitch.

I am done, this is the last bend I am testing.  Thanks to this group for explaining that you need an understanding of what is going on.  I developed theories that seem correct in that they led to this knot. Of course, with the guidance of Xarax and others on this site.

Two basic theories.

1) This line is so strong that the energy released by friction in snugging up most any knot will cause surface liquefaction and the knot will slip.  To create a non-slipping knot, you need to grab the tail very hard and you need good holding power on the main part of the knot.  These are two processes. The first part of the knot reduces the tension in the tail and the tail holds the knot so that when it starts to slip as it locks up, the tail holds, and the knot does not slip.
2) You want to use basically a double hitch structure so that the tension on the constrictor is half what it is in a linear knot like a fisherman's knot.  We know from other work that this 1x radius bend of the line as it is doubled over its mating hitch does not hurt the strength of the knot.  The reduction in strength is about 50% but the line is only half loaded there so it is just not a concern.

I await the efficiency numbers from Estar but either way this is the last bend I am investigating.  It is as good a bend as I can think of for Amsteel.

Now, the question has come up what this might be used for.  Some times we want small loops.  Loops too small to get the 72 diameters needed for a splice.  If this knot has an efficiency near 50% as I expect, then a loop can be made that is as strong as the line it is made of.  This line is so strong that this is almost always just fine.  If you need more strength go up a size.  Afterall, you could make a loop out of 1/8 inch Amsteel that is 2500 pounds.  Most things you would be holding down 1) want larger line just to make it easier to work with and 2) the thing being held would blow up first.  But it is nice to have a knot that is strong and will not slip.

Allen

allene

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Re: Non slipping bend in Dyneema
« Reply #74 on: January 27, 2014, 02:09:15 AM »
The average failure is at 39% of breaking strenght on a sample of 5.  This is a vast improvement over the triple fisherman's bend.  In the test, two slipped at 35% but held after a 30 second pause and went on to break at around the 39% number.  The fisherman's slip as low as 25% by comparison.

The test was done on 3/16 line and the average break was at just over 2,000 pounds on a straight pull which means a knot between two eye splices.

Improving on what was (is) the industry standard has to be good enough.  Thanks to everyone here for all the great ideas and coaching.

The failure was probably at the 180 degree bend and probably caused by the line compressing to less than 1 diameter.  It would have to stay at 1 diameter to reach 50%.