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General => New Knot Investigations => Topic started by: NautiKnots on July 21, 2017, 10:55:20 PM

Title: Another Bend for Dyneema
Post by: NautiKnots on July 21, 2017, 10:55:20 PM
In http://igkt.net/sm/index.php?topic=4756.msg39862#msg39862 (http://igkt.net/sm/index.php?topic=4756.msg39862#msg39862), I showed a bend that does not slip when tied in Dyneema (I used 3mm Amsteel Blue).  I've played a little with variations to see if I could improve the strength, and the knot below seemed to fit the bill.   All I did was add a half-hitch around the standing part before the last tuck.  This version is only slightly more complicated (still much simpler than any other Dyneema bend I've seen) and seems to be stronger.  I don't have any measurements, but in every test I've done, my previous bend broke when this one was only beginning to show signs of strain.

In the photo below, I tied the two legs of the bend in opposite chirality to show both faces of the knot in a single picture.  I don't see any reason why that would make a difference in performance though.  It wouldn't be necessary in real-world application.

I also tried doubling the final tuck instead of hitching around the standing part.  That variation also did not slip, but it broke before this one.

I speculate that the additional half-hitch strengthens the knot for two reasons:

Does that sound reasonable?

Most of the proposed bends for Dyneema involved additional tucks, trying to make the knot better by adding more crossings -- and those attempts don't generally seem to pan out.  These bends involve tighter nip instead, and they hold.  That gives me some ideas for other candidates -  more compact bends with high nip.

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: Birchhatchet on July 22, 2017, 09:28:37 AM
Hi Eric,
I have used the attached little bend for years in Dyneema rop.

There are also some modification shown under
https://igkt.net/sm/index.php?topic=5564.msg37805#msg37805

Maybe this would be a stimulus for your investigations.

Cheers, Karl
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on July 22, 2017, 03:09:59 PM
I have used the attached little bend for years in Dyneema rop.
Karl,

I tested your knot in 3mm Amsteel Blue and it slipped under relatively low load.

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on July 22, 2017, 03:50:08 PM
I've been trying other candidates as well, including two nice, compact bends composed of interlocked Strangle Knots (ABoK 1239).  Ultimately, however, those bends either slipped or broke at lower load than the Angler's Loop based bend.  They were also not any simpler to tie, nor could they be untied after loading.  I think that the success of the "Twang Bend" (and the variation I posted above) is due to the way that each knot is loaded on three legs, not just two.  Tension causes it to draw tighter rather than to slip (or roll).

I also tried "Two Bends" (ABoK 1454) and the Two Bowlines Bend (ABoK 1455).  I can't explain why, but 1454 slipped whereas 1455 held. 

For what it's worth, the Two Bowlines isn't a bad bend for Dyneema, especially if the loops are eye-hitched (square knotted) together as shown below.  I loaded that knot until it broke, and was still able to untie it afterwards -  without needing any tools.  Out of curiosity, which photo do you prefer, the black background or the white?

The "Twang Bend" (as I'm calling it until a better name arises) and it's variations are stronger than the Two Bowlines Bend, but they cannot be untied easily.

Regards,
Eric

Title: Re: Another Bend for Dyneema
Post by: SS369 on July 23, 2017, 02:05:46 PM
To my eyes, the black background allows more details. But, the white background may allow for better printing.

SS
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman on July 23, 2017, 06:59:08 PM
I speculate that the additional half-hitch strengthens the knot for two reasons:
  • The half hitch provides another point of constriction, thereby spreading the load over a larger surface area, and/or
  • The hitch around the standing part straightens the entry to the knot, so it can bear a higher load before breaking.

Does that sound reasonable?

I liks your thinking about what might make a difference
& why, vs. just throwing out different knots & hoping ... .

Have you tried the fisherman's knot extension that I suggested
in msg.#168 (current latest) in the other thread?  My thinking
on that is that putting the tail to be nipped hard by the
SPart might give all of the other places of "nip" some
help to hold, and that this hard nipping doesn't put
a sharp deflection in the SPart, so ... hopes for strength.

(But skinny HMPE stuff sure seems to defeat a lot of knots!)

--dl*
====
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on July 23, 2017, 09:07:27 PM
Have you tried the fisherman's knot extension that I suggested
in msg.#168 (current latest) in the other thread? 
Dan,

I tried following your instructions, but depending on how I make the final tuck (through the center of the overhand knot alongside the standing part, or through a crown of the overhand knot so the running end does not touch the standing part), I get two different knots.  I tried both, and each one slipped under relatively low load.

Dyneema does confound our regular notions on knots.  Take the Bowline (ABoK 1010), for example.  Conventional wisdom says:My tests with Dyneema, however, yield the opposite results:
I speculate that the best bends for Dyneema, will have two characteristics:
Bends made from conjoined loop knots have this second property, and I'm looking for ways to incorporate that into more compact knots.  Of course, I could be completely wrong.  After all, ABoK 1454 should be a good bend according to these properties, but I can't explain why it slipped when 1455 did not.

Does that make sense?
Eric
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on July 24, 2017, 04:58:23 AM
Well, I spent the day evolving more compact bends for Dyneema (it's my birthday and I'll tie if I want to) and after discarding numerous attempts to create new knots with the above characteristics, I decided to try to shrink the "Twang Bend" instead.  So, I removed the legs from the middle of the knot, and joined the two overhand knots together directly.  I tried a few variations (each time I tried to tie a bend, it came out differently) and settled on two viable candidates.

The first begins with a 2-strand Matthew Walker Knot form and finishes with the same final hitch as the Angler's / Perfection Loop on each end.  The second ties two overhand knots together slightly offset, and again finishes both ends like the Angler's Loop. 

I tied them inline with 3mm Amsteel Blue and tightened them up on my bench winch.  Although the two bends look very similar in flat form, they draw up into quite different geometries under load.  The first takes on a diamond form with the tails opposite each other.  The second becomes barrel-shaped with the tails exiting the same side.  See the photos below of the two bends after loading.

Both bends had some tail migration as they drew up, but then settled and held position thereafter.  I put as much force as I could on my winch, taking 6 wraps of 7/16" (11mm) double-braid polyester (all that would fit) around the drum in order to tail the load.  Just when I thought I couldn't winch any harder, one of the end loops (not either of the knots) broke.  That's the first time an end failed in all my testing of Dyneema bends.  Every other bend I've tested has broken first.

These are both definitely the strongest bends for Dyneema that I've tried.  If you look closely at the first photo below, you'll see that some of the fibers in the knot have ruptured, but those that remain still hold.  The second photo doesn't show any breakage.  Both bends exhibit high strain on their central crossings.

The first one is probably easier to tie, as it begins as a well-known knot, but I like the looks of the second one better.  Neither is overly complicated.  Both are compact.  Neither one can be untied after loading.  Overall, I'm happy with my "birthday bends" - they're a nice present to myself.

I'll post pictures of the flat forms tomorrow.

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on July 24, 2017, 06:41:14 PM
Below are front and rear views of the two bends in flat form.  The top two pictures are of the first bend (the one that draws up into a diamond shape).  The bottom two are of the second bend (barrel shape).

The photos make the knots look more complicated than they are.  Both are simply a twin overhand bend with a half-hitch finish (angler's loop style) on each end.  The trick is that not just any overhand bend will do.  These two knots retain the 3 bearing leg structure of the "Twang Bend" internally, and exhibit similar security.  Overhand bends that don't have a load-sharing structure - even ones with good constriction (and I've tried several) - don't seem to hold in Dyneema, even with the final nipped half-hitches.

I'll post tying instructions soon.

Regards,
Eric
Title: Dyneema Bend 1 Instructions
Post by: NautiKnots on July 24, 2017, 09:06:38 PM
OK, here are instructions for tying the first of the two more compact bends for Dyneema: I don't have a name for this bend.  Any suggestions?

Regards,
Eric
Title: Dyneema Bend 2 Instructions
Post by: NautiKnots on July 24, 2017, 09:23:01 PM
Here is how to tie the second more compact bend for Dyneema:
I think this is a more attractive, and possibly stronger form than the bend above.  The fourth photo below shows the crown of the bend.

I don't have a name for this bend either.  Any suggestions?

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on July 24, 2017, 10:47:21 PM
Here is one of my rejected candidates.  It began as ABoK 1031, tied as a bend instead of a loop.  With the ends finished with the same half-hitches as the others, it became a very handsome bend with a herringbone look.  I had high hopes for this knot, but unfortunately it did not hold in Dyneema.  At moderate load, the bend rolled off its tails.  In hindsight, I can see how the interlocked overhand knots do not have sufficient "counter-pull", which is why I think it failed.

Perhaps this bend can find a home as a decorative knot, since it doesn't appear to be very practical.  It might make a pretty start to a wide knotted bar.  Right now, I'm thinking of calling it a "Herring Bend", both for the herringbone pattern, and because it was a "red herring" in my search for Dyneema bends.

In order to test my "counter-pull" speculation, I tied other two-overhand-knot structures that looked like poor candidates (including the Reef Knot and Thief Knot), finishing them off with the same half-hitches.  They all slipped under relatively low load.

So, I guess the message here is that beginnings are important.  The two (I said "more compact" previously, but "less bulky" might be a better term) bends above are the most secure ones I have yet evolved.

I hope that was interesting,
Eric
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman on July 25, 2017, 12:53:19 AM
when tied opposite each other,
 the Bowline breaks before the Perfection (Angler's) Loop, and
the Bowline breaks at the entrance to the collar.

!?  Sorry for being w/limited attention here,
but "tied opposite each other" means interlocked eyes,
or rather the "twin" structure where between nubs run
the would-be-eye-legs of each and are *shared* by the
knots (like Ashley's "twin bowlines" but you had one be
the perfection loop).

As for where the break came,
hmmm, the collar would have to be *dang* tight to
cause rupture at entry --might be a matter of being
hard to discern!?

Note that bowlines w/eyes around a metal "pin" have
slipped.

Thanks,
--dl*
====
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on July 25, 2017, 03:20:14 AM

!?  Sorry for being w/limited attention here,
but "tied opposite each other" means interlocked eyes,
or rather the "twin" structure where between nubs run
the would-be-eye-legs of each and are *shared* by the
knots (like Ashley's "twin bowlines" but you had one be
the perfection loop).
I've attached a photo showing what I mean by tying the Bowline opposite the Angler's / Perfection Loop.  I've done destruction tests on this exact configuration and its equivalent (Angler vs. Bowline) in 3mm Amsteel Blue at least a dozen times.  Not once has the Angler's Loop failed.  Every time, the Bowline has either:Therefore, I'm convinced that the Angler's / Perfection Loop is both stronger and more secure than the Bowline when tied in Amsteel Blue (Dyneema SK75).  That is the inverse of previously published results in other materials.

Quote
As for where the break came,
hmmm, the collar would have to be *dang* tight to
cause rupture at entry --might be a matter of being
hard to discern!?

I retract my statement about breaking at the collar.  I looked at broken Dyneema Bowlines after destruction testing and recall having seen both ruptured nipping turns, and intact nipping turns.  Unfortunately, I have not kept the broken knots for review, and my attempts to recreate the results today have failed.  All my Bowlines slipped.  Only one broke (after slipping) and it was so entangled in the other Bowline I tied it to (which had also slipped) that I couldn't make out for sure where it broke.  I think it was at the nipping loop.

So, what I really meant to say is that tension transfers through knots in Dyneema differently than other materials and in ways that are sometimes contrary to prior tests and explanations.  My second example is flawed, and probably mistaken.  I stand by the first one, though.

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman on July 25, 2017, 11:20:07 PM
So, what I really meant to say is that tension transfers through knots in Dyneema differently than other materials and in ways that are sometimes contrary to prior tests and explanations.

Indeed !!  By firstly being sooo much less frictive,
so force isn't *shared* with adjacent parts,
and then by being so INelastic, so there isn't
some elongating at knot entry point AND THEN ...,
but force goes deep immediately!?  <argh!>

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?!

Thanks,
--dl*
====
Title: Re: Another Bend for Dyneema
Post by: NautiKnots 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):Would anybody like to venture a guess as to how these knots fared when tied in Dyneema?

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman 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 (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*
====
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman 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*
====
Title: Re: Another Bend for Dyneema
Post by: NautiKnots 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 (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
Title: Re: Another Bend for Dyneema
Post by: NautiKnots 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
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman 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 ... .

 ;)
Title: Re: Another Bend for Dyneema
Post by: NautiKnots 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
Title: Re: Another Bend for Dyneema
Post by: NautiKnots 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
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman 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*
====
Title: Re: Another Bend for Dyneema
Post by: NautiKnots 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
Title: Re: Another Bend for Dyneema
Post by: NautiKnots 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
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman 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*
====
Title: Re: Another Bend for Dyneema
Post by: NautiKnots 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"?
Title: Re: Another Bend for Dyneema
Post by: NautiKnots 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: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
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman 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*
====
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 01, 2017, 04:32:37 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.

Just to be clear, the green line that broke was the standing end.

Nipping the working end with the standing part is critical to knot security with Dyneema.  If you arrange the overhand knots to form 3 water knots instead of the two water knots and two overhands (as shown), then the bend might slip (I had mixed results in my testing).   An overhand knot formed by the working end tied around the standing end does not have opposing pull and will not develop as tight a nip.

Quote
(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 ... ?! )

Some other terminating knot (such as a double-overhand or a strangle) might make the knot stronger, but such embellishments defeat the purpose of this bend - which is to be as simple as possible to remember, yet still secure.

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: knotsaver on August 02, 2017, 02:55:52 PM
3. A loop with intertwined nipping turns, so that a pull on any leg constricts the others.
4.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?

Hi Eric,
I was just curious about the Myrtle (your intertwined nipping turns n.3) and about the Honda (your n.4) tied as in ABoK #1454. The Honda in that configuration is known as Bend X
(http://igkt.net/sm/index.php?action=dlattach;topic=1870.0;attach=6242;image)
(here in a binder version).
You could retuck the ends as in the Blackwall Bend
(http://igkt.net/sm/index.php?action=dlattach;topic=5314.0;attach=17624;image)
I'm curious about that too.
Thanks.
Ciao,
s.
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 02, 2017, 06:03:32 PM
I was just curious about the Myrtle (your intertwined nipping turns n.3) and about the Honda (your n.4) tied as in ABoK #1454. The Honda in that configuration is known as Bend X

I haven't tried those knots specifically tied opposite each other (as in ABoK 1454), but I have tied them with intersecting eyes (as in ABoK 1455).  Both slipped.  I don't see any reason why omitting the eyes would improve the security of the bends.  After all, 1455 itself held better than 1454 (but still not reliably).

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 03, 2017, 12:00:39 AM
When I developed the bend described in post 28 (6 nips) and in discussing it, my working hypothesis was that knots hold in Dyneema when they develop very high nip, not because they have multiple crossings. 

Consider the two bends illustrated below.  According to my hypothesis, the first bend should hold and the second should slip.  Well, I decided to put that hypothesis to the test.  I tied both bends in 3mm Dyneema, and loaded each one to the point of failure.

It turns out that I was wrong.  The first bend pulled apart even though all six overhand knots set up hard.  The second bend held even though the overhand knots did not tighten up evenly.  It broke at the central pair of overhand knots, which were the most constricted.

I have stated that (in order to hold) Dyneema bends need to have the working ends nipped by the standing ends, but clearly that is not so.  Now, the termination doesn't appear to me to be as important as having an effective central structure that jams and resists rolling.  Just what makes that structure effective is still a mystery to me.  In my previous attempts above, some have worked and others have not.

I speculate that my "6 nips" bend held because the interspersed overhands (that drew up to water knots) added a jamming component to the nipping force I was after.

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 03, 2017, 01:17:58 AM
With my last tests in mind, I decided to find out a couple of things:
So, I tied the knot shown below in 3mm Amsteel Blue.  It is simply a Carrick Bend (ABoK 1439) with a Bowline (ABoK 1010) on each end.  Think of it as a cross between the Hawser Bend (ABoK 1446) and the Bowline Bend (ABoK 1455).  I've simply substituted Bowlines for the seizings.

I've tried eye-hitched Bowlines in Dyneema before.  They always drew up snug to each other, so I anticipated that this bend would too.  I wasn't disappointed.  Under load, the Bowlines' eyes shrank until they consisted of just the Carrick Bend.  Then the Bend drew tight and held until one of my end loops broke.

At that point, the Bowlines were hard, but - with the aid of a pair of Vise-Grip pliers - I was able to pry the collars back and untie the ends.  I was then able (with Vice-Grips again) to untie the Carrick Bend.

The knot didn't dress-up pretty but it was:
This may be the closest I've come yet to a practical bend for Dyneema.  A lock finish to the Bowlines might even make it stronger.

edit:  Upon further testing, it turns out that the Bowlines can capsize, making them harder to untie and potentially altering the strength and/or security of the bend.  That makes the knot untrustworthy to me so I cannot recommend it (or other bends terminated with Bowlines) for use in Dyneema.  See reply #41 for details.

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 03, 2017, 04:45:23 PM
Below is a variation of my previous bend.  The difference is that the Bowlines are formed by leading each working end to the opposite standing end (rather than to the same line).  That causes the Carrick Bend to rotate 90 degrees with respect to the Bowlines.  This bend is to my last one as ABoK 1454 is to 1455.

Since my earlier trials showed 1454 to be less secure than 1455 in Dyneema, I didn't expect this bend to do as well as the one in my previous post.  In testing, though, the Bowlines did not get drawn as tightly to the central Carrick Bend.  I speculate that either the opposing pull kept the Bowlines farther apart as the Carrick Bend tightened causing it to jam before fully shrinking the "eyes", or the Carrick Bend simply tightens more readily with sideways pull than lengthwise.  The bend broke at one of the Bowlines.  I was able to untie both Bowlines (one of them and what was left of the other) by hand without any tools.  I needed Vice-Grips to untie the Carrick Bend.

I tried again, this time tying a Scott's Locked Bowline on each end.  I hypothesized that because the nipping loop was larger in diameter:I couldn't guess whether the Bowlines would be more secure (because of the additional tail tucks), or less (because of the reduced nip).

When tied in 3mm Amsteel Blue, both my hypotheses were borne out.  The Bowlines drew up to the central Carrick Bend at lower tension, and the knot held up until one of my end eyes broke instead.  One of the Scott-Locked Bowlines capsized into a big slip knot.  The other held its geometry.  The locking tucks seemed to improve security -- very little tail was swallowed as the bend loaded up.  I was able to untie both Bowlines without tools, albeit with more difficulty than the standard Bowlines.  Again, I needed Vice-Grip pliers to untie the Carrick Bend.

Given that the collapsed Bowline still held, I suspect that other terminating knots (such as a constrictor) might work as well -- and may well be stronger.  They probably would not untie, though.

I hope that was interesting,
Eric
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman on August 03, 2017, 09:52:51 PM
Consider the two bends illustrated below. 
  • The top bend consists of three overhand knots tied in each standing end, and the working ends rove through the center of the other line's knots.  This produces a bend where the overhand knots are pulled away from each other.  Tension on the standing ends tightens the overhand knots.  Security depends entirely on the nip that the overhand knots develop.
  • The bottom bend consists of three overhand knots tied in each working end around the other line's standing end.  This produces a bend where the overhand knots are pulled into each other.  Tension on the standing ends does not directly tighten the overhand knots.  Security depends on the overhand knots jamming tight.
According to my hypothesis, the first bend should hold and the second should slip.  Well, I decided to put that hypothesis to the test.  I tied both bends in 3mm Dyneema, and loaded each one to the point of failure.

It turns out that I was wrong.
This doesn't surprise me.  But I'd like to see the ending
result of the one that held --for it's essentially a backed-up
SINGLE fisherman's knot, hardly a candidate for great security
(in tests of trad. kernmantle, e.g., it has shown slippage
and req'd back-ups/stoppers)!

Rather than you first, I'd have done SOMEwhere (center
or ends?) a fisherman's opposition of the overhands
and then had your grip-the-passed-through-line in the
others.  (Once your top knot started slipping, there was
nothing to alter that --given its slippage, i.e., things were
no longer being more tightly nipped.)

I've a general idea of tying some 1408-like knot where
the exiting-adjacent tails are knotted in an overhand to
stopper their being pulled out through the knot (and thereby
make the base knot tighten further).  One could try this, e.g.,
with a same-side-exit blood knot (the blood like the
dbl.harness can be tied with tails either going opposite
or together.

--dl*
====
Title: Re: Another Bend for Dyneema
Post by: knotsaver on August 03, 2017, 10:28:25 PM
With my last tests in mind, I decided to find out a couple of things:
  • does the Carrick Bend provides sufficient entanglement to serve as an effective central jamming component, and
  • if the terminations aren't critical, would a Bowline finish work, and might it be possible to untie after loading?

Hi Eric,
did you try replacing the central Carrick bend by a Zeppelin bend and seeing what happens - the result would be similar, in performance, but somewhat less ugly, after heavy loading...
---
With reference to my previous post I will post as soon as I can a picture  of a retucked Honda loop.
---
Ciao,
s.
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 03, 2017, 11:53:28 PM
did you try replacing the central Carrick bend by a Zeppelin bend and seeing what happens - the result would be similar, in performance, but somewhat less ugly, after heavy loading...

Given the Zeppelin Bend's reputation for not jamming, I thought it would be interesting to try as the central structure for this style of knot.  I tested two variations -- one with the working ends tied to their own standing ends, and one with the working ends tied to the opposing standing ends.

Both drew the Bowlines up snug to the central Zeppelin Bend, and both held (after swallowing a fair amount of tail) up to the point where the strands in the Zeppelin started breaking.  You are correct that the dressed knots are more attractive than the Carrick-centered versions.

Things did not, however, go so well when it came to untying.  In each case, both Bowlines capsized while drawing-up, leaving them in a geometry that was not easy to release.  I had to resort to the Vice-Grips on all four to get them undone.  Likewise, the Zeppelin Bends had pulled so tight that Vice-Grips were needed (on both sides) to open the knots up enough to untie them.

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: knotsaver on August 04, 2017, 02:08:35 PM
Things did not, however, go so well when it came to untying....  Likewise, the Zeppelin Bends had pulled so tight that Vice-Grips were needed (on both sides) to open the knots up enough to untie them.


In fact, we shouldn't call that a Zeppelin Bend (Xarax would say that this is NOT a Zeppelin Bend) because both ends are loaded! However, I don't know why I'm more attracted by the #1454 version even if it is to be considered the difficulty of loadbalancing the two legs with an equal pull...so what about two (pseudo-)Zeppelin in a #1454 version?
or what about the use of the #1459-1460 structure with Bowlines instead of seizings?
and #1457? :)
Ciao,
s.
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 04, 2017, 03:00:41 PM
I'm more attracted by the #1454 version even if it is to be considered the difficulty of loadbalancing the two legs with an equal pull

I don't think balancing the legs is a concern in Dyneema.  There's enough slippage during draw-up that they tend to balance themselves.

Quote
...so what about two (pseudo-)Zeppelin in a #1454 version?

The two configurations that I tried were analogous to ABoK 1454 and 1455.  Both fared the same (the Bowlines capsized and all the components needed tools to untie).  For what it's worth, the capsized Bowline appears to be stronger than the normal geometry.

Quote
or what about the use of the #1459-1460 structure with Bowlines instead of seizings?
and #1457? :)

What leads you to think that the round-turns and half-hitches (1457), Whatknot (1459), or Whatknot and half-hitches (1460) would make a better central structure than a reef knot?  In my previous tests, two Bowlines eye-hitched (reef-knotted) together was unreliable.  Sometimes it held and sometimes it slipped.

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 04, 2017, 09:47:55 PM
After speculating that:I decided to try out a central Granny with Bowlines on each end.

In both forms (like ABoK 1454 and 1455), the Bowlines slipped a little, capsized, and then slipped the rest of the way.  At that point, the bend held.  It was possible, but not easy, to untie the capsized Bowlines and Granny Knots.  Pliers were necessary.

That got me to wondering about why the Bowlines capsized on the Zeppelin and Granny, but not the Reef and Carrick structures.  So, I experimented some more, and discovered that Bowlines can capsize on the other bends too.  The propensity to capsize seems to be related to how close one dresses the knots initially.  If the Bowlines have little distance to migrate, they have less opportunity to capsize.

I do not, however, trust knots whos properties change depending on how closely or snugly you dress them -- especially in high-load applications (like you'd use Dyneema for).  Therefore, I'm no longer enamored of the bends in replies 34 and 35, unless something can be done to prevent the Bowlines from capsizing.

The Overhand and Collar I showed before, and the Angler's Loop do not capsize under load -- but they both jam.  The Overhand and Collar (does it have a name?) can be untied with pliers, but the Angler's Loop defies me.  Is there a Bowline variant that resists capsizing yet remains easy to untie?

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman on August 05, 2017, 05:36:13 PM
After speculating that:
  • a Granny Knot might be easier to untie after loading than others, and
  • given that I'm loading the knot on both ends, there's no difference between the Granny and the Whatknot,
I decided to try out a central Granny with Bowlines on each end.
Good for you.  I've eyed this structure's appearance
when loaded --i.p., how the apex turn is over space
(between the crossed ends)-- and thought that it should
work well thus!

Quote
The propensity to capsize seems to be related to how close one dresses the knots initially.  If the Bowlines have little distance to migrate, they have less opportunity to capsize.

I do not, however, trust knots whose properties change depending on how closely or snugly you dress them
 -- especially in high-load applications (like you'd use Dyneema for).
 [Except that unless you can show us actual loads at which
   you're working, here, one might reply that knots don't
   come up to adequate for benefiting from HMPE's strength!]
  Therefore, I'm no longer enamored of the bends in replies 34 and 35, unless something can be done to prevent the Bowlines from capsizing.

The Overhand and Collar I showed before, and the Angler's Loop do not capsize under load -- but they both jam.  The Overhand and Collar (does it have a name?) can be untied with pliers, but the Angler's Loop defies me.  Is there a Bowline variant that resists capsizing yet remains easy to untie?
[/quote]
I'll suggest (a) using the "left-handed" bowline
or (b) putting in a  complementary collar (extend
the common knot by having the tail collar the "outgoing
eye leg" (i.e., the continuation from nipping turn)).
ALSO, one could putting the eye knots close to the
center knot and running the tails through the center
and tucked out through the opposite eye knot's body

(nipping turn) !?  This gives 3 vs 2 diameters in the
nipping loops of the eye knots, and clamps a 2nd time
(opp. eye) and 3rd (center knot) on the tails.
--though sometimes it seems that such stuffing of
a part for further nipping comes with a downside
of lessening the nip effect given the now increased
number of parts nipped there.

--dl*
====
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 05, 2017, 10:51:18 PM
I tried the Cowboy Bowline - ABoK 1034 1/2 (* see note below).  It also capsized.  What about its structure made you think it was resistant to capsizing?

* I generally choose to use Ahsley's names for knots but I dislike the moniker "left-handed bowline".  There are right- and left-handed versions of the actual Bowline (ABoK 1010);  and right- and left-handed versions of the "left-handed bowline" for that matter.  Ashley's name for this knot seems awkward and confusing (dare I say "gauche"?).

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 06, 2017, 09:36:50 PM
Consider the knot in the image below.
 
(http://igkt.net/sm/index.php?action=dlattach;topic=5935.0;attach=21715;image)

It is a Reef Knot (tied left-handed) with Bowlines (tied right-handed) on each end; and with the tails tucked through the center of the Reef Knot and then through the nipping turn of the opposite Bowline.  The knot was tied in 3mm Amsteel Blue (Dyneema SK75).

Because each turn in the Reef Knot and the nipping turns in each Bowline now encompass 3 strands instead of 2, I expected that:than the untucked version I had tried previously.  Given that the previous bend had occasionally slipped, I anticipated that this bend would slip too.

Well, I tried it twice.   The first time, one Bowline drew up tight and the other not quite snug.  When the standing end on the not snug side started to break (strands fracturing) I stopped pulling and inspected the bend.  Both Bowlines had partially capsized.  The nipping turns had migrated into the knots, but had not pulled through the collars and so did not fully invert.  The location of the partial breakage was at the entry to the collar, not at the nipping turn as is the typical failure point for a Bowline.  The central reef knot was not nearly as tight as the untucked version.  I was able to untie both bowlines and the reef knot by hand (no tools) without much difficulty.

On my second try, both Bowlines drew up snug to the Reef Knot.  One of my end loops (an Angler's Loop) broke first.  This photo shows the bend after loading. 

(http://igkt.net/sm/index.php?action=dlattach;topic=5935.0;attach=21717;image)

Both Bowlines had partially capsized, just like the first try.  I had left fairly long tails on the bend, but it didn't swallow much of them when tensioned.  Again, I untied the entire bend by hand (no tools needed) without difficulty.

This bend is a bit bulky and complicated, but it did hold and - unlike all previous attempts -  could be readily untied after hard loading.  That is something I began to doubt was possible with Dyneema.

Regards,
Eric

Title: Re: Another Bend for Dyneema
Post by: knotsaver on August 07, 2017, 03:40:09 PM
Hi Eric,

Quote
or what about the use of the #1459-1460 structure with Bowlines instead of seizings?
and #1457? :)
What leads you to think that the round-turns and half-hitches (1457), Whatknot (1459), or Whatknot and half-hitches (1460) would make a better central structure than a reef knot?  In my previous tests, two Bowlines eye-hitched (reef-knotted) together was unreliable.  Sometimes it held and sometimes it slipped.

Do you really see Whatknot there? I only see nipping loops! ;)
---

About your last post, do you think a Surgeon Bend will perform better than the Reef?
But above all, please try tying these variations (look at the attached pictures). They are based on a 3 nubs structure, two Standard Bowlines and the central part is formed by a 2 bights locking mechanism that bites/locks the 2 ends (after that we could retuck the ends through the nipping loops but perhaps the bend becomes too bulky...). We can tie the internal hitches close to the nipping loop of their loop, or close to the nipping loop of the other loop. I don't know which will perform better in Dyneema...
Here the 4 variations.
If the bends are not in tension the ends could not be so stable, we could add other turns (as in ABoK#523) or we could tuck the ends through the nipping loops or through the collars...
Ciao,
s.
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 07, 2017, 06:20:39 PM
Do you really see Whatknot there? I only see nipping loops! ;)

Yes.  If you pull the two nipping loops of ABoK 1459 together (as will happen in Dyneema), then you get a Whatknot.  In fact, in the description, Ashley says "mechanically the knot is the exact duplicate of the Whatknot...".

Quote
About your last post, do you think a Surgeon Bend will perform better than the Reef?

No.  I previously tried the Granny / Whatknot as the central structure, hoping it would be easy to untie, but that idea didn't pan out.  The Reef Knot, however,  is easy to untie.  One can either pull the end bights apart (just like rolling the collar of a Bowline), or capsize the knot by tugging an end back.   A Ligature (Surgeon's) Knot would put a bulkier,  asymmetric structure in the center of the bend.  It should still untie easily by capsizing but I generally prefer symmetric bends to asymmetric ones.

Quote
But above all, please try tying these variations (look at the attached pictures).

Please don't take this the wrong way.  I really appreciate your interest and suggestions, but I can't try out every possible bend.  In addition to the time spent, each test takes about two dollars worth of Amsteel Blue, and I don't have a limitless supply.  I'm happy to conduct trials provided there's something to be learned, but I can't justify the expense otherwise.

Each of the bends you've pictured have nothing to prevent the Bowlines from capsizing, and they have nothing to secure the tails' tucks until the Bowlines are drawn together.  Those attributes make me highly doubtful that any of them will yield practical bends.  Given that, what do you hope to learn from testing them?

Sincerely,
Eric
Title: Re: Another Bend for Dyneema
Post by: knotsaver on August 07, 2017, 10:19:57 PM
Do you really see Whatknot there? I only see nipping loops! ;)


Yes.  If you pull the two nipping loops of ABoK 1459 together (as will happen in Dyneema), then you get a Whatknot.  In fact, in the description, Ashley says "mechanically the knot is the exact duplicate of the Whatknot...".


Eric, if the ends are seized, to my mind, the knot (the knot structure) works differently! But maybe I miss the point and I really don't know how the Dyneema rope works.

Thinking about  ABoK# 1454 and #1459 I tied the bend in the attached picture, surely it is a known knot and you can find other similar bends by searching the forum (for instance at
http://igkt.net/sm/index.php?topic=2871.0 )

I tied another bend based on ABoK #523, but it is a little bit bulky and I think it is untiable! maybe I will post in another occasion about fishing bends! :)

About your last post, do you think a Surgeon Bend will perform better than the Reef?
...   A Ligature (Surgeon's) Knot would put a bulkier,  asymmetric structure in the center of the bend.  It should still untie easily by capsizing but I generally prefer symmetric bends to asymmetric ones.
Sorry, here I meant a symmetric Surgeon, that is to say, double Half Overhand down and up.

But above all, please try tying these variations (look at the attached pictures).

Please don't take this the wrong way.  I really appreciate your interest and suggestions, but I can't try out every possible bend.  In addition to the time spent, each test takes about two dollars worth of Amsteel Blue, and I don't have a limitless supply.  I'm happy to conduct trials provided there's something to be learned, but I can't justify the expense otherwise.

Each of the bends you've pictured have nothing to prevent the Bowlines from capsizing, and they have nothing to secure the tails' tucks until the Bowlines are drawn together.  Those attributes make me highly doubtful that any of them will yield practical bends.  Given that, what do you hope to learn from testing them?

Sincerely,
Eric

I wrote "please try tying..." (not "please try testing") ;) , so if you consider them interesting you can test or not (it's up to you obviously)...oh I'm only curious and because I appreciate the power of the 2 bights locking mechanism I think the structures I showed could perform very well. About the instability of the ends if there isn't tension, we could tie the loops very short ( for instance just 2 rope diameters) and maybe we could only put the ends through the 2 bights without the internal hitches (maybe) ...

 I don't know the Dyneema rope behaviour (I repeat) and so I don't know why the Bowline capsizes, but a well dressed knot is of fundamental importance...I think you will agree with me.

Happy tying.
Ciao,
s.
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 08, 2017, 12:11:39 AM
Thinking about  ABoK# 1454 and #1459 I tied the bend in the attached picture...

The knot pictured raised an interesting question:  if the tail is tucked through the opposing Bowline's nipping turn, do you need the central structure at all -- or are the Bowlines themselves sufficient to back each other up?  I thought that was worth trying, so I tied the bend (like ABoK 1454 but with mirror-image Bowline structures and with the tails passed through each other's nipping turn) and put it on the winch.  I tested it and under moderate load, the bend rolled apart.  Afterwards, I realized that I hadn't looked to see if the Bowlines had capsized, so I tried again.  The Bowlines did not capsize, but they rolled.  Thinking back, I recall much higher tension on the line at the point where Bowlines capsized.

Quote
I tied another bend based on ABoK #523, but it is a little bit bulky and I think it is untiable! maybe I will post in another occasion about fishing bends! :)
I look forward to seeing it.  I too was trying to evolve bends that involved each working end taking nipping turns around both its own and the opposite standing end.  Then I tried the 6-nips (3 Water Knots?) which worked and is much simpler.

Quote
I don't know the Dyneema rope behaviour (I repeat) and so I don't know why the Bowline capsizes, but a well dressed knot is of fundamental importance...I think you will agree with me.

Lol, I don't understand Dyneema rope behavior either.  I certainly agree that proper dressing is important, but I've also found that Dyneema can easily re-dress a knot for you, no matter how carefully and firmly it is set up.  The Double-Dragon Loop, for example (even when dressed and pulled as tight as I could get), capsized and failed at relatively low load when tied in Dyneema.  The Angler's (Perfection) Loop, on the other hand, has drawn up tight and secure to the same geometry (swallowing very little tail) every time I've tied it in Dyneema.  I've used it for the end loops in attaching to my test rig many times, so I've certainly exceeded the sample size needed for statistical confidence.  I feel that a knot must be "self-dressing" (that is, it must draw up consistently to the same geometry on its own) in order to be trustworthy in Dyneema.

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman on August 08, 2017, 12:46:44 AM
Please don't take this the wrong way.
I really appreciate your interest and suggestions,
but I can't try out every possible bend.
Indeed, I was about to say the same thing.  Much of
what is put forwards here is just stupid --e.g., MY idea
for the further-tucked bowline should not have passed
"the smell test," in that --THINK, THINK, THINK!--
the SPart has 100% tension and multiple parts coming
out of the nub imply a split of tension further than the
50-50% normal for two eye legs, and THAT requires
more offloading via friction in the nipping turn than
one can expect w/HMPE (which has been shown to just
*flow* out through even the dble. turn of the double bowline
in one Brion Toss testing!).  BTW, a sort of water bowline
but w/cow vs. clove as the compound nipping structure
DID hold, to break (at what Brion thought was not great force,
but w/o calibration read-out to confirm).

So, one must first have a reasonable expectation that
the candidate knot brings something to the table not
seen in the many failures.

Now, the bowline variation where the nipping turn
is the cloverhand IS something new, in that it makes
a doubling of nipping structure in a way different than the
slipping dbl.bwl and maybe more sure like the holding
water(-like) bowline !?

And I've found --and will soon post-- an image to go with that
extended fisherman's knot I described, and which was tested
but MAYBE not quite in desired form?!  That knot brought to
the table the tucking of tail at U-turn of SPart --presumably
a heavily loaded nipping point.


--dl*
====
Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 08, 2017, 04:17:35 AM
Much of what is put forwards here is just stupid...

Well, I'm willing to try ideas that may seem stupid as long as I can learn something from it.  After all, my experiments so far have disproved several of my own hypotheses about what makes a knot secure in Dyneema, and I'm sure that my current understanding is still flawed.  I can't explain why some knots roll under moderate load while others that look less secure hold at much higher tension.  High nip is not the answer.  Neither is complication (extra tucks), nor reversal (u-turns).  Jamming (backing up one knot with another) apparently plays an important role, but cannot be the sole factor.  I have a feeling that there at multiple interacting variables and that the real answer is too complex for conventional wisdom to explain.

I can see how tucking a tail through the center of a Reef Knot, and through the nipping turn of a Bowline might make them stronger, but it seemed strange to think that it might increase security.  I fully expected such tucking to make the Bowline less secure, and almost didn't test it.  But then I admitted to myself that I didn't really know the answer and tried it out.  The result surprised me.

Regards,
Eric
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman on August 08, 2017, 09:11:03 PM
Much of what is put forwards here is just stupid...

Well, I'm willing to try ideas that may seem stupid as long as I can learn something from it.
We should be advancing a rationale for WhyTestThis? and
what we think will happen.  That's a good way to put into
contrast the reality --so far as we can know it-- with the
beliefs.  --and a boon to learning from the efforts.

Attached are images for that extended fisherman's knot
discussed (& tested, like it shows?) above.

NB : The white rope stands in a mirroring orientation
to the illustration; the orange-to-black is in like orientation.
(And in both cases they are less helpful than the drawing.)

motto :: "HMPE, Abandon All Hope ye who try knotting this!"

Cheers,
--dl*
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Title: Re: Another Bend for Dyneema
Post by: NautiKnots on August 17, 2017, 03:02:52 PM
Is this what you mean by a "cloverhand bowline"?

I finally figured out how to tie a "Cloverhand Bowline".  I was looking at the Water Bowline (which is like a Double Bowline except that the nipping turns form a Clove Hitch) and didn't like how pull on the eye tends to separate the nipping turns.  In looking for a similar structure that pulled the turns together instead, I inadvertently came up with a knot that I recognized as a Cloverhand with a Collar, i.e. the "Cloverhand Bowline".  My previous efforts failed because I was tying the Cloverhand as shown in Ashley's diagram (running left-to-right, or downwards) when I needed to tie it reversely (right-to-left, or upwards).  With the standing end exiting from the bottom and the working end from the top, the Cloverhand does make a stable platform for a collar.

See the first image below.  It shows both sides of the "Cloverhand Bowline" (left and center).  The knot seemed to be crying out to have the working end tucked up through the collar (as shown on the right).  I doubt that the extra tuck has much (if any) effect on the strength or security of the knot, but it fills a gap in the collar and looks nice.

The second image below is the Double Bowline (front, back, and with the working end tucked through the collar) for comparison.  The two knots have a very similar appearance, but look closely and you'll see that the "Cloverhand Bowline" has an additional part on the side of the nipping turns.

I put "Cloverhand Bowline" in quotes because a purist might argue that this knot does not belong in the Bowline family.  It is not "Post-Eye-Tieable" (PET).

Anyway, I tried both the Double Bowline and the "Cloverhand Bowline" (with and without the collar tuck) in 3mm Amsteel Blue.  Both eye knots held (with little slippage during draw-up) in both configurations to their breaking points, which seemed similar.  I was able to untie them all without tools after loading.  The Double Bowline untied easily whereas the Cloverhand took some wiggling to let go.

Twin Double Bowlines (untucked) tied in the form of ABoK 1454 drew together under load and then jammed.  I was unable to untie them.

Twin Double Bowlines (untucked) tied in the form of ABoK 1455 with the eyes hitched (Reef Knotted) held without drawing together.  The nipping turns did not capsize, but one of them did pull through its collar, and I couldn't untie it.  When tied with the running end tucked through the collar, the knot seemed more resistant to pull-through.  I didn't perform enough tests to be confident, but in the few I did, the Double Bowline retained its dressed geometry.

Twin "Cloverhand Bowlines" (tucked or untucked) tied in the form of ABoK 1455 with eyes hitched (Reef Knotted) held without drawing together and seemed quite resistant to changing geometry. 

From a security/strength standpoint, the hitched twin "Cloverhand Bowline" bend seems the best so far, but the hitched twin collar-tucked Double Bowline bend is very close and is significantly easier to tie (the Double Bowline being PET) and to untie.  As an aside, the collar-tucked Double Bowline is also tiable in the bight (TIB).

I've come to the opinion that holding without drawing together under load is preferable.  You don't want a bend that starts moving once it reaches a certain tension, even if that movement is still secure.  First off, the bend may be somewhere you can't inspect it (like at the top of a mast), and secondly, movement may cause undesirable loss of tension (like in a halyard).  Therefore, I prefer these bends to my previous eye-hitched twin Bowlines with ends tucked bend.  All of them, however, take a fair amount of line to tie.  Given enough line, an end-to-end splice would be superior in every way.  I'd only tie a bend in Dyneema if something kept me from making a splice.

I hope that makes sense,
Eric
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman on August 22, 2017, 01:09:05 AM
Anyway, I tried both the Double Bowline and the "Cloverhand Bowline"
(with and without the collar tuck) in 3mm Amsteel Blue.
Both eye knots held (with little slippage during draw-up) in both configurations
to their breaking points, which seemed similar.
It's worth pointing out that this video is of a dbl.bwl.
NOT holding, but feeding material out into its SPart
(and with the tail stoppered against slippage) :
www.youtube.com/watch?v=ZFRQcExLA34 (http://www.youtube.com/watch?v=ZFRQcExLA34)

So, beware attaching behavior to a *knot* vs. to some
knotted line !

--dl*
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ps : Did your interpretation of my tying guidance
for the re-tucked single fisherman's knot match
my later-posted images?  (I sob, if so, for it means
that that knot slipped.)   :(
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman on September 06, 2017, 09:15:32 PM
Here's yet another attempt,
though it I suppose falls into the set of those knots
with simply extra nipping zones,
which this hard-to-knot material has been shedding.
Still, what I've tried to do in this knot is put in many
rather hard U-turns, in hopes that not only pressure
of constriction but also resistance in bending will get
the slippage arrested (eventually)!?

NB: The tied/photo'd knot is what is only described
in my notes --i.e., the tails take that guidance to cross
over opposite SParts, unlike what I've sketched in ink.


--dl*
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Title: Re: Another Bend for Dyneema
Post by: Andreas on September 26, 2018, 04:26:19 PM
Hi! Iike to try this one, maybe retucked. It's like a bloodknot, but with nipping loops in the middle.
No dyneema available..
Title: Re: Another Bend for Dyneema
Post by: Dan_Lehman on September 28, 2018, 12:46:19 AM
Hi! Iike to try this one, maybe retucked.
It's like a bloodknot,
but with nipping loops in the middle.
No dyneema available..
NO, it's not like that --except by many of the quite
misguided images that float around, ignorant of what
the blood knot should be!  And I don't think
that your knot has much hope in HMPE, and maybe
not so much for even traditional rope, without some
careful setting.

I like the idea (presumably) :: of incorporating some
gripping coils for distributed nip and presumably good
strength; I've done similar things (but without testing
basis for really showing that they can work).  Tying it
now in some marine polypropylene monofilament kernmantle,
I find that I can get more of a *hitch* in that one side
will grip the other leaving the other side's coils quite
loose --the first side's nipping turn &  coils are gripping.
So there is this sort of "race condition" to deal with
in setting the knot, to try to achieve balanced loading.

Note that, contrary the true (angler's) blood knot,
your knot's coils *coil away* from compressing the
center tuck area.  Working in fishing line, one can
tie the knot with the coiling in either direction, as the
setting will convert *away* coils (Barnes called them
"outcoils" or at least the "outcoil method", IIRC) to *to" coils.
But in rope, they can remain *away* and as such will tend
to have enough grip to pull apart (from each other, and
the center tucks) rather than clamp tight on the center
tail-tucks!

Now, for rope, this *away* behavior is consistent with the
goal described first, above; but it likely will take some
careful tight dressing and then setting so that the coils
take load immediately, in hopes of building grip before
some almost inevitable SPart slip --and once slippage
occurs, I think it then reigns as far as denying the
coils that hoped-for gripping benefit.
YMMV per material?

But in my quick testing of this ? 5/16" (8mm) line,
I'm seeing coil-to gripping, as for a rolling hitch.
 ???

(Btw, regarding HMPE, I've come to suspect that frictional
heating --high pressure-- might lead to slippage by making
surface melt, and lead to rupture otherwise!?  --in some
cases, anyway.)


--dl*
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