Author Topic: Another Bend for Dyneema  (Read 5617 times)

NautiKnots

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Re: Another Bend for Dyneema
« Reply #15 on: July 26, 2017, 07:53:11 PM »
BTW. you might try a bowline where the fundamental
"nipping turn" is in fact a "cloverhand" --i.e., its an mis-tyed
clove hitch form (with the crossing of ends on the opposite
side of each other, which ... is just an overhand oriented to LOOK
like a clove hitch.  This seems to make a nice base, per SPart
curvature and all; maybe it will help?!
I think I understand what you mean by "cloverhand" -- ABoK 1253 without the final turn and tuck (the arrow), correct?  I'm having difficulty seeing how to connect a collar to that in order to make it the nipping turn of a Bowline structure, though.  Can you refer me to a picture or drawing?

Here are some other nipping structures that I have tried (pictured below in order):
  • An Angler's / Perfection Loop minus the final tuck.
  • An Overhand and Collar (like a Bowline but with an overhand knot as the nipping turn).
  • A loop with intertwined nipping turns, so that a pull on any leg constricts the others.
  • An Overhand Knot with the working end passed through it.
Would anybody like to venture a guess as to how these knots fared when tied in Dyneema?

Regards,
Eric

Dan_Lehman

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Re: Another Bend for Dyneema
« Reply #16 on: July 26, 2017, 10:35:25 PM »
BTW. you might try a bowline where the fundamental
"nipping turn" is in fact a "cloverhand" --i.e., its an mis-tyed
clove hitch form (with the crossing of ends on the opposite
side of each other, which ... is just an overhand oriented to LOOK
like a clove hitch.  This seems to make a nice base, per SPart
curvature and all; maybe it will help?!
I think I understand what you mean by "cloverhand" ...#1253 ...
Yes, that's a good reference --which I see comes quickly
from this forum, to wit:
https://igkt.net/sm/index.php?topic=3174.0

And one simply goes in & out ("rabbit around the tree")
as for the water or (common) bowlines --you should
find that inviting, not tricky!?

--dl*
====

Dan_Lehman

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Re: Another Bend for Dyneema
« Reply #17 on: July 26, 2017, 10:40:47 PM »
Here are some other nipping structures that I have tried (pictured below in order):
  • An Angler's / Perfection Loop minus the final tuck.
  • An Overhand and Collar (like a Bowline but with an overhand knot as the nipping turn).
  • A loop with intertwined nipping turns, so that a pull on any leg constricts the others.
  • An Overhand Knot with the working end passed through it.
Would anybody like to venture a guess as to how these knots fared when tied in Dyneema?

Regards,
Eric
I'll guess the 2 loops fail miserably; this is what
we'd call the bad version of the Myrtle --the
turn of the tail should be away from the eye.
(Were the tail to be inserted from the opposite
side --which is what I'd call determining the knot
as an "anti-bowline"--, then the turn should be
TOWARDS the eye.  And in both cases, making  --edit correct
a 2nd turn greatly helps stability.

And otherwise I'll guess that the more involved of
these knots --ones with an overhand component
clamping down on parts-- will do better.

--dl*
====
« Last Edit: July 27, 2017, 02:13:47 PM by Dan_Lehman »

NautiKnots

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Re: Another Bend for Dyneema
« Reply #18 on: July 27, 2017, 12:56:35 AM »
Yes, that's a good reference --which I see comes quickly
from this forum, to wit:
https://igkt.net/sm/index.php?topic=3174.0

And one simply goes in & out ("rabbit around the tree")
as for the water or (common) bowlines --you should
find that inviting, not tricky!?
But both ends of the "cloverhand" exit from the interior of the nipping turn structure.  If one of those ends is the standing part, and you run the collar around it, then  instead of stabilizing the collar, the collar capsizes the cloverhitch, pulling it apart.  What am I missing from your description?

Regards,
Eric

NautiKnots

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Re: Another Bend for Dyneema
« Reply #19 on: July 27, 2017, 01:50:46 AM »
I'll guess the 2 loops fail miserably; this is what
we'd call the bad version of the Myrtle --the
turn of the tail should be away from the eye.
(Were the tail to be inserted from the opposite
side --which is what I'd call determining the knot
as an "anti-bowline"--, then the turn should be
away from the eye.  And in both cases, making
a 2nd turn greatly helps stability.
Just to be sure we're talking about the same knot, I attached it again as image 1 below.  This knot began as ABoK 1034 1/2 but instead of taking the final tuck downward through the nipping loop, I tucked upward.  The two nipping loops can be viewed as the crowns of an overhand knot. 

In my testing, this loop knot did ok in Dyneema under low load.  The problem came at moderate load, when it capsized into the form of a constrictor knot tied around the standing part (see the second photo below).Then, the eye immediately drew up.  With increasing load, the knot began to roll and it came apart.  When I tied two such loops with intersecting eyes, both rolled until the knot untied.  Then I tried the knot shown in the third picture.  Again, the eyes slipped until the two constrictors butted up against the central square knot.  At that point, however, instead of rolling apart, the bend held.  Some of the fibers in the center of the knot ruptured, but (like my 2 bends above), my end attachment broke first.  See the last image.

This bend seems as if it might be strong and secure like my 2 bends above, and would likely benefit from a different middle structure (perhaps a 2-strand Matthew Walker).  Someone who is more familiar with the Constrictor Knot than the Angler's Loop may find this bend easier to remember, but I feel it is needlessly bulky.

I hope that is interesting,
Eric
« Last Edit: July 27, 2017, 02:52:55 AM by NautiKnots »

Dan_Lehman

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Re: Another Bend for Dyneema
« Reply #20 on: July 27, 2017, 02:16:58 PM »
But both ends of the "cloverhand" exit from the interior of the nipping turn structure.  If one of those ends is the standing part, and you run the collar around it, then  instead of stabilizing the collar, the collar capsizes the cloverhitch, pulling it apart.  What am I missing from your description?

Regards,
Eric

You know, I myself had a PITA getting the knot formed
last night, upon thinking this over.  BUT IT WORKS (it
can work)!  Fiddle with it some more.  One can even try
tying it in reverse so that there is this formed bight
(U-turn of tail) to hold the inchoate cloverhand being tied.

Again, the version appears to give a nice curvature to the
SPart, and more security --maybe more than is helpful
when trying to UNtie it, but ... .

 ;)

NautiKnots

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Re: Another Bend for Dyneema
« Reply #21 on: July 27, 2017, 04:58:38 PM »
Dan,

I've tried to put a collar on the cloverhand, and the knot below is what I wind up with.  Is that the form you mean?  If so, then yes, I have tried this form before.

Regards,
Eric
« Last Edit: July 27, 2017, 05:09:02 PM by NautiKnots »

NautiKnots

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Re: Another Bend for Dyneema
« Reply #22 on: July 27, 2017, 05:19:20 PM »
Here are some other nipping structures that I have tried (pictured below in order):
  • An Angler's / Perfection Loop minus the final tuck.
  • An Overhand and Collar (like a Bowline but with an overhand knot as the nipping turn).

Along the way, I tried terminating each of my "Birthday Bends" (et. al.) both without the final tuck (form 1 above) and with a collar instead of a half-hitch (form 2 above).  Those were attempts to make it possible to untie the knot after loading.  In all cases, I found that the resulting bends were still secure (i.e. they did not slip) and they were still impossible to untie once set.  Because I like the overall form of the Angler's Loop finish (the half-hitch) better, I discarded these variations.

Regards,
Eric

Dan_Lehman

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Re: Another Bend for Dyneema
« Reply #23 on: July 28, 2017, 08:36:57 PM »
Quote from: NautiKnots link=topic=5935.msg39988#msg39988 date=150117111 Is that the form you mean?
[/quote
Quite "no" :: there's no cloverhand to be found, here.
The form must exist, geometrically (not merely being inherent
in the overhand   :P ) !
Push those ends around-away from each other such
that they go side-by-side through the belly / crossing part
as though --but on wrong sides (left/right)-- a clove.
You should have TWO nipping turns, this way (as does the
water bowline via the actual clove).

--dl*
====

NautiKnots

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Re: Another Bend for Dyneema
« Reply #24 on: July 29, 2017, 02:30:09 AM »
Push those ends around-away from each other such
that they go side-by-side through the belly / crossing part
as though --but on wrong sides (left/right)-- a clove.
You should have TWO nipping turns, this way (as does the
water bowline via the actual clove).
I see the clove hitch in the water bowline, and it draws up to form a nipping turn.  Because the working end passes over the standing end of the clove hitch, they stabilize each other and hold the clove hitch in place.

A cloverhand, however, has the standing part and working end parallel rather than crossing.  When I make the eye, the descending leg pulls the bottom loop of the cloverhand away, leaving only one overhand knot as the nipping turn.

Can you please post a picture, or drawing, or a link to a picture or drawing of the "cloverhand bowline"?

Thanks,
Eric

NautiKnots

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Re: Another Bend for Dyneema
« Reply #25 on: July 29, 2017, 03:06:17 AM »
The problem with the knot in the first photo below, is that under load (even when tied in polyester), it capsizes into the form shown in photo 2.  You may recognize it as the overhand knot with the working end passed through it that I posted previously (in brown rather than blue).  Under load, there is nothing except the nip of the overhand knot to keep the end from pulling out.  This almost a backwards slip-knot, so one would expect it to untie itself quickly.

I tried tying it opposite the stable overhand and collar knot (shown in a previous post) -- as illustrated in the third image below.  I fully expected the overhand nip to pull apart but, much to my surprise, it didn't.  The eye hitch holding the two knots together provided sufficient slip resistance for the overhand to nip the bitter end securely.  The last photo below shows the results.  The eye leg descending from the overhand knot shows quite a bit of deformation, but both knots held.  The overhand and collar knot broke first.

I think that's a pretty clear indication that in order to hold in Dyneema, a knot needs high nip, not additional crossings.  Toward that end, I evolved a dirt-simple, ugly bend with multiple nips that is straightforward to tie and easy to remember.  Initial testing suggests that it is secure and possibly the strongest one yet.  I want to try some variations next and I'll post pictures when I get a chance.

I hope that was interesting,
Eric
« Last Edit: July 29, 2017, 03:19:03 AM by NautiKnots »

Dan_Lehman

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Re: Another Bend for Dyneema
« Reply #26 on: July 29, 2017, 03:55:53 PM »
Quote
... water bowline via the actual clove).
I see the clove hitch in the water bowline,
and it draws up to form a nipping turn. [ TWO, actually]

 Because the working end passes over the standing end of the clove hitch, they stabilize each other and hold the clove hitch in place.

A cloverhand, however, has the standing part and working end parallel rather than crossing.
Sorry, but I'm temporarily de-camera'd, alas (some file-managing
business & other yet to deal with).

Just note that the two knots above should differ
by only the relation of the parallel-ish parts of
entering SPart & departing-eye-leg working end,
which are just the other way (left/right) from one knot
to the other, each structure having a "crossing part"/bridge.
(I.e., in forming a clove h. --WORKING LEFTWARDS, say--
one would make the first turn and go left crossing over that make
a 2nd like turn, the working end going out now parallel but left of
the SPart beneath the crossing part; for the cloverhand though,
that end would go out RIGHT of the SPart --and superficially look
much alike, just left/right differing.)

Maybe it would help to tie the cloverhand --again, as a
mis-oriented clove h.-- around a finger or other object
so to hold form awaiting the returning eye leg's entry to make
the U-part/bight closure?!  And then work the knot into shape.
But you definitely the **clove** aspect there (befitting the name)!

--dl*
====

NautiKnots

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Re: Another Bend for Dyneema
« Reply #27 on: July 31, 2017, 04:25:40 PM »
Photo 1 is a "cloverhand".
Photo 2 has a collar added.
Photo 3 is the knot dressed.
Photo 4 is the same knot, tied as an eye.  Is this what you mean by a "cloverhand bowline"?

NautiKnots

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Re: Another Bend for Dyneema
« Reply #28 on: July 31, 2017, 11:50:49 PM »
I think that's a pretty clear indication that in order to hold in Dyneema, a knot needs high nip, not additional crossings.  Toward that end, I evolved a dirt-simple, ugly bend with multiple nips that is straightforward to tie and easy to remember.  Initial testing suggests that it is secure and possibly the strongest one yet.  I want to try some variations next and I'll post pictures when I get a chance.

Here is a very simple bend with lots of nip but without many crossings.  As illustrated in the first image below:
  • Start by putting three overhand knots in the end of one piece of Dyneema.  Put one overhand in the other.  Leave plenty of tail on each (this knot swallows a significant amount of tail when drawing taut).
  • Pass the working end of each line through the last overhand of the other.
  • Make an overhand knot between the two middle knots (around the other line) and pass the working end through the adjacent overhand.
  • Repeat the last step
Dress the knot snugly as shown in the second image.  All the overhand knots shown were tied right-handed and the crowns are aligned.  You can see that in the views of the two sides.  This bend could be made symmetric side-to-side by alternating the crowns.  I doubt it would make a difference in security. 

Note that each working end is nipped by the other standing end.  This is vital to the security of the bend.  If the running ends nip the standing ends, then the knot may slip.

The third photo below shows the bend after placed under load; and having been loaded to the breaking point.  You can see that four central overhand knots drew up into two separate Water Knots (ABoK 1414).  The distance between them indicates how much tail was drawn into the knots as they tightened.  If you don't leave enough tail when dressing, this bend will pull apart.

This bend gets its security not from multiple crossings, nor from u-turns, but from each end having three good, hard nips on the other.  It may not be pretty, nor compact, but it is straightforward to tie and easy to remember.  This bend appears to be roughly equivalent in strength to my earlier "Twang Bend".

I tried substituting Strangle Knots (ABoK 1239) for the Overhand Knots, and was able to get by with four nips instead of six (although it swallowed more tail drawing up).  I don't personally see much benefit to the strangles.  The regular overhands are more straightforward to tie and I'd trust 6 nips more than 4.

I hope you like it,
Eric
« Last Edit: August 01, 2017, 08:54:02 PM by NautiKnots »

Dan_Lehman

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Re: Another Bend for Dyneema
« Reply #29 on: August 01, 2017, 03:55:34 PM »
BUT, you loose the pull-together aspect at the ends
of the knot --where SPart enters :: and where your
knot broke.  I.e., I would have put that broken green
overhand on the INside (i.e., towards knot center)
the corresponding red opposite.

(And one might even wonder if some other knot put
at the knotted extremes (SPart-entry points) by your
scheme
would yield more strength --a fig.8, strangle
(you did try this, in some way), fig.9 ... ?! )

--dl*
====