Author Topic: Modified Water Bowline  (Read 10746 times)

allene

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Modified Water Bowline
« on: January 22, 2014, 01:51:54 AM »
This is a modification of a bowline that will not slip in Dyneema.  In testing, we found that all other bowlines, including the water bowline that this knot is based on, slip.  I cannot find any reference to this variation so I submit it here.  The literature describes two ways to tie a water bowline. One is much more secure than the other.  The basis of a water bowline is that the normal "rabbit hole" is a clove hitch.  It  should be tied so that pulling on everything closes the two loops of the clove hitch rather than spreading them apart.  Once the clove hitch "rabbit hole" is formed, the working end goes through the hole, around the "tree" and back through the hold.  That is a water bowline but it slips.  Now take the working end and put it through the loop formed by the "rabbit" going around the tree.  It will be between that loop and the "tree".  This knot does not slip with Dyneema.  I have tested it to the failure of a figure of eight knot that formed the other loop and was able to then untie the knot although with some difficulty.  I have attached two pictures.


Dan_Lehman

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Re: Modified Water Bowline
« Reply #1 on: January 22, 2014, 06:40:47 AM »
This is a modification of a bowline that will not slip in Dyneema.
Congrats!  We've discussed this knot and various
similar ones, and are glad to see it survive the test.
(HMPE is an amazing material to see knots work in,
isn't it!?  One just can't believe what is happening,
it's sooo slippery, inelastic, strong !!)

I take it that --as you wrote-- this knot exceeded
the strength of a fig.8 eye knot, in a sort of A-v-B
test?  Next thing to check is exactly which orientation
your fig.8 had --there are various ways ... .

Quote
In testing, we found that all other bowlines, including the water bowline that this knot is based on, slip.
How did they slip?

I had a quite-similar-to-water bowline variant tested
in which it did not slip, but held to rupture; it was simply
a cow hitch vs. clove hitch base.  I wouldn't expect
this to make much difference.  IIRC, the tail was UNknotted,
so that resisted being pulled out just by the knot's nip.

cf. www.youtube.com/watch?v=Fy6Y2Xoo4Ak
[ Brion Toss's test of a Cow-bowline (rec'd was Mirrored)
 in 5/32" HMPE 12-strand ]

Quote
The literature describes two ways to tie a water bowline.
One is much more secure than the other.  The basis of a water bowline
is that the normal "rabbit hole" is a clove hitch.  It  should be tied
so that pulling on everything closes the two loops of the clove hitch
rather than spreading them apart.
!!!
In what literature did you find this novel way of
tying the knot?  (As I said, we've discussed it in
this forum, but I'm unaware of it being presented
anywhere else (I don't think that the PACI document
has it)!?  So, please, where have you found it?
(I can say that I've seen the difference in the
hitches when used in securing a line that runs
through netting to a groundline/headline done
both ways, and that as you note, the one way
results in a tighter-set knot.)


Quote
I have tested it ...

Are you able to do further testing?

Cheers,
--dl*
====

allene

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Re: Modified Water Bowline
« Reply #2 on: January 22, 2014, 06:59:19 AM »
I was not able to find this knot in the literature.  What I was referring to was the two ways of tying a water bowline.  It was my idea, apparently not unique, to take the working end and tuck it next to the "tree".  In terms of slipping, the loop closes itself as I recall.  It is possible that if you continued to pull that the knot would hold but we considered it a failure once the loop started to strangle the test line.  The water bowline is shown correctly in animated knots.  If you google water bowline and look on images, you can see both ways of tying it.  But the know I posted is not a waterbowline.

There is a very active thread on Sailinganarchy right now on knots and webbing.  The fellow who started it bought a test setup and can test up to 10,000 pounds.  My testing is all A-B as what I have is a 40 power winch on a 4x4.  Most of my testing has been on soft shackles and I have a web site L-36.com that has a lot of information on them and some new designs as well that I came up with.

By the way, that video was not by Brion Toss, he just made a comment on the video.  Brion is active on the thread on Sailinganarchy by the way.  He also helped me test my soft shackles and teaches people how to make them in seminars he gives.  I am not completely sure what knot is in the video but I believe we tested the knot Brion mentioned and it slipped.  Almost everything slips with Dyneema.

The figure of eight knot was formed by making a loop and tying a figure eight using both strands.  Like tying a stopper knot kind of figure of eight.

I hope this answers all the questions you raised and adds a little at the same time.  Can you give a link where this knot was discussed?

Dan_Lehman

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Re: Modified Water Bowline
« Reply #3 on: January 23, 2014, 08:52:16 AM »
I was not able to find this knot in the literature.
What I was referring to was the two ways of tying a water bowline.
Okay, thanks --wrong sense taken from the words.

Btw, I note that EStar claims to have NO slip in
the waterbowline (in that quite active thread)!?
YMMV, eh?
And yet you saw the eye (let's drop "loop" for an eye,
and leave it for the nipping part of the bowline, e.g.)
collapse --as is seen for the double bowline in the
video entited "Bowline #1" (think that's the title).
(And seeing this just amazed me : "back to the drawing
board!" was my thought, new-knot bubbles bursting
at the realization of that slippage!)  :o

Quote
By the way, that video was not by Brion Toss, he just made a comment on the video.
Well, maybe he didn't hold & own the camera or post
the video, but the knot that held is the one (well, not
quite) of the few I referred to him during a Treebuzz.com
forum discussion while he was out on-site w/test device
and 5/32" HMPE 12-strand to play with.  So, he got it
tied and tested, and I suppose asked for the upload.

(The mirrored bowline was what was supposed to be
tested; this would be that that was WITH the tail making
a reciprocal/"mirrored" collaring of an eye leg and so
running a 3rd time through the double nips of the
knots central "loops" --gaining a diameter of material
there, hoping for a (slight) strength bump and locking
the tail well.  That it didn't need the lock for security
we can see; might it have helped, otherwise?  Brion
could only guesstimate that the break came at low
forces --there wasn't (?!!) calibration on that (or
none reported) (seems odd, doesn't it?!).)

Quote
Almost everything slips with Dyneema.
Only if "everything" is limited to what is commonly
found in knots books; I had 5 eyeknots tested by
NER in a blue-coated Dyneema (5/16") and none
slipped (as I expected them not to).

Quote
The figure of eight knot was formed by making a loop and
tying a figure eight using both strands.
Like tying a stopper knot kind of figure of eight.
You gotta figure that that much I know; "orienatation"
starts from this point and indicates which of those
"both strands"' ends was loaded, and how the knot
was dressed.  E.g., one can see in EStar's tested knots
one fig.8 unbroken that was loaded in what
I've called "the strong form" (based on one testing
by someone who seemed aware of the difference),
and others not (I don't hold that the difference
really matters so much, but I want it recognized
and tested!).  There are different ways to dress
the knot (and so many knots books do not show
this at all --i.e., don't show a viable dressing, but
a perfectly traced "8"!); Dave Merchant does it
in an awkward way, e.g..

Quote
Can you give a link where this knot was discussed?
Um, perhaps.  (Xarax is Mr.FIND-IT extraodinaire!)
But I can say that it wasn't discussed so much more
than noted as a possibility.


Cheers,
--dl*
====

xarax

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Re: Modified Water Bowline
« Reply #4 on: January 23, 2014, 02:16:45 PM »
  Alan Lee has recently tied a lot more of different bowline-like eyeknots I had tied in my life, ever, so he is the one we should ask about such variations. He is the master of driving the working end through any path within the bowline s nipping structure I had imagined !  :) Moreover, he had used this special kind of the final locking of the collar structure used in this reversed-Clove-hitch bowline - which reminds me of the lock we meet at Perfection / Angler s loop. That mean s that the "second" collar, the part of the collar structure which meets the continuation of the Standing end as it goes "upwards",  is not a "proper" bowline s collar, like the one we meet at the Mirrored bowline. The legs of the "second" collar are not parallel to each other, as when they are inside the common bowline s nipping loop, but meet each other at a right angle, just like the Tail end of the Angler / Perfection loop. We have seen that this is a most effective way to force two lines bite each other hard and deep, and prevent their mutual slippage. DDK has used similar locks in the "locked" bowlines he tied (1). Alan Lee has tied many such bowlines, and even I, too, have used this kind of locking the Tail end ( within the rim of the nipping loop, not the rim of the collar, as DDK and you do ) once, in the Fontus bowline ( seen in the attached picture ).

   Now, Allen, you should better see your eyeknot as made from two parts, the nipping structure, and the collar structure - and we should try to see which part is responsible for which line of the remarkably efficient defence against slippage you report.
   The first part is the nipping structure. Here you make the wise choice, and you chose a very tight nipping structure - which is so tight, that jams !  :) We have seen that the nit-reversed Constrictor loop ( which, by the way, you can also use, in place of the reversed Clove hitch - with the same good results IMHO ), is veeery tight - I suppose you had already read the references to the reversed-Clove hitch based loops I have already provided . If not, do not be shy, do it now ! :) We have avoided the use of the reversed-clove hitch, and Mark Gommers states the danger of jamming explicitly in his "Analysis of bowlines". However, with this slippery snake you brought to us, we have to use any kind of trap able to fulfil the mission - and a jamming nipping structure is just such a Standing Part-locking trap.
  (  Notice that, by shear coincidence, we have discussed a similar reversed-Cow-hitch based nipping structure a few days ago, at (2) ! Have a look there - I  wrote a final post, which I supposed that you had read, just to complete a reply that could had been addressed to your knot - if it was not tied on this material ! )
   The second - but not very secondary - part, is the collar structure. Here, as I had tried to explain previously, you have used an Angler s / Perfection loop s right-angle crossing - again a wise choice, because, at this final point and with this kind of material, you need something stronger than the mere constriction offered by a nipping loop - and the Angler s / Perfection loop s way seems that has enabled you to achieve your goal.
  So, a reversed Cow-hitch-based nipping loop, and a Angler s / Perfection loop s DDK s-like lock at the collar structure - there is no new mechanism in any of those, but their combination, in one eyeknot, may be new, indeed. I hope Alan Lee will tell us if he has already presented this loop, which I do not recall it now.
   
1. http://igkt.net/sm/index.php?topic=19.0
2. http://igkt.net/sm/index.php?topic=4746
« Last Edit: January 23, 2014, 02:27:27 PM by xarax »
This is not a knot.

allene

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Re: Modified Water Bowline
« Reply #5 on: January 23, 2014, 05:10:48 PM »
^^ There is a lot in your post.  Thank you (I think) as it is a little hard to follow by this sailor :-) 

Regarding knots slipping in this material.  It is dependent somewhat on how they are tested.  The material tends to get hot as the knot tightens and that seems to make it more likely to slip.  It is hot to the touch.  If you pause there and let the knot cool down, it holds better.  It is, therefore, not surprising that Estar might find a knot to hold where I find it to slip.  He just found that a knot he thought did not slip actually does when he ran 12 tests on it.

bowlines tend to be easier to tie than some other knots.  As I said in another post, I can tie a bowline with one hand behind my back.  Some of the knots that are being proposed in the other thread are much more difficult to tie particularly in small line.  This line is very strong so small is not uncommon.  1/8 inch line is rated at 2,500 pounds for example.

Regarding this knot locking up.  I was able to untie it after pulling to the breaking point of the figure of eight knot of unknown predigy.  It wasn't easy like a bowline in StaSet, but it was possible.

Dan_Lehman

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Re: Modified Water Bowline
« Reply #6 on: January 23, 2014, 05:14:02 PM »
Can you give a link where this knot was discussed?
Xarax has brought up a URLink to a collection of
"bowlines" that was compiled by Mark Gommers
of Australia, whose focus is on kernmantle ropes
such as are used in rockclimbing, caving, & SAR.
www.paci.com.au/downloads_public/knots/Bowlines_Analysis.pdf
(I've not checked that this particular URLink gets to
the latest version --there were several, as comments
on this forum fueled additions & revisions.)

It will show some simple ways of securing the
bowline which can be employed further.
(I will caution that IMO some of the images
are of knots overly tightened --collars hauled
too tight (vertical visual space being small in
the document!).)  And, i.p., the "mirrored
bowline"
is presented, which I think is a good
candidate for use not only for rockclimbers
wanting durable, when-slack security, but
for HMPE needing when-loaded security.


--dl*
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Dan_Lehman

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Re: Modified Water Bowline
« Reply #7 on: January 23, 2014, 05:33:55 PM »
^^ There is a lot in your post.
Thank you (I think) as it is a little hard to follow by this sailor :-)
Yes, but there is much to say, much that has lonnnng
not been (openly?) considered about knots!  (And I might
find my own words --esp. ones written in some haste &
excitement-- hard to follow myself; clarifications can come.)   ;)

Quote
Regarding knots slipping in this material. It is dependent somewhat on how they are tested.
The material tends to get hot as the knot tightens and that seems to make it more likely to slip.
It is hot to the touch.  If you pause there and let the knot cool down, it holds better.
This goes to the discussion @sailinganarchy regarding
test standards.  Brion asserted that a common standard
is needed for comparison.  While that might be true,
we need to do testing that is relevant to expected use!
Of what value is a slow loading that avoid the heat
issues that come from rapid loading
if the in-use behavior more nearly matches the latter
circumstance --rockclimbers, esp., produce rapid loading.

I think that there lies a problem in this with some of
my thinking about knot geometry : that designing
a knot so that the S.Part takes a gradual curvature
into the knot (and maybe beyond this, that there
isn't a "jamming" binding that would render the
knot "welded"/permanent) will tend to (or perhaps
more strongly, necessarily ... ) produce a knot in
which there is considerable movement of the
heavily loaded part (and relaxation enables it to
"un-move" and so generate much back'n'forth
movement on cyclical loading), generating heat.
Dave Merchant (who I think comes from a caving,
SAR interest) has claimed to have seen such
differences in finding e.g. that the fig.9 and
less so the fig.8 eyeknots have lesser strengths
in rapid loading whereas the simpler overhand loop
knot
suffers much less.

I'm glad that you've brought this information about
the felt heat in the HMPE, and that material has so
little headroom for heat!


--dl*
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allene

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Re: Modified Water Bowline
« Reply #8 on: January 23, 2014, 05:54:09 PM »
the "mirrored
bowline"
is presented, which I think is a good
candidate for use not only for rockclimbers
wanting durable, when-slack security, but
for HMPE needing when-loaded security.

I tested the mirrored bowline against the bowline I presented.  There was no slippage in either knot.  The line broke where it entered my bowline. The mirrored bowline does not look stronger by inspection so I would not draw a conclusion about which is stronger from this, only that neither slipped.

Allen

Dan_Lehman

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Re: Modified Water Bowline
« Reply #9 on: January 23, 2014, 06:39:22 PM »
the "mirrored bowline" is presented, which I think is a good
candidate for use not only for rockclimbers
wanting durable, when-slack security, but
for HMPE needing when-loaded security.

I tested the mirrored bowline against the bowline I presented.
To be sure : the m.bwl. has collars around both
the S.Part (the usual) and an eye leg (and with the
cow hitch/ larkshead base, hence the moniker
"mirrored"  :) ).
Just to be sure, for Brion Toss managed to omit the
latter tuck, and what's in that on-line video is thus
a compromise, nipping 2 vs 3 diameters (but it held).
(And noting that EStar has presented an extra wrap
in what he's called "triple" fisherman's knot
--as I note in the thread here on end-2-end knots
(3-2 ought to yield 1 ; "triple" less "double =>"single").
... just some minding of details!

Quote
There was no slippage in either knot.  The line broke where it entered my bowline.
The mirrored bowline does not look stronger by inspection
so I would not draw a conclusion about which is stronger from this, only that neither slipped.
Allen, IMO, the inspected aspect that should/could
suggest a bump in strength is the curvature of the
S.Part in its initial turn, which with the m.bwl.
turns around 50% more material --which doesn't
ensure such a difference in geometry, but might
be oriented to do so, with care (YMMV and all).
That said, I know that even with moderate loading
--what I can do is load w/5:1 lousy pulley and thus
get some "serious" forces--
what one thinks will be, from simple image & tying,
changes to something unexpected with the heavy
forces (and maybe stretch --but HMPE should limit
that).

OTOH, the case of the blood knot (in nylon fishline)
shows that other structures can be strong --there,
the binding/pressure/gripping of the overwraps.
I recall one person's testing of the strangle noose
(a "half-a-dbl.fisherman's tied around line making a noose)
in 3/8" Bluewater low-elongation caving rope around
a standard-size (about 10mm dia) carabiner breaking
at the S.Part of the noose --i.e., where
the line was initially constricted, not bent !!
(And I think that some similar testing of the knot
in thicker, arborist rope, had the break in the turn
around the anchor, or maybe in the knot.)

After seeing the slippage of HMPE, I opted to test
not the fig.9 eye knot but this in reverse,
to try for a broader, more gentle curvature.  It in
fact did best of the five I tested, slightly.  More
interestingly, it seems to have broken beyond
the initial U-turn of the S.Part, where eye legs bore
across the continuation of that loaded part!?
(Hard to tell,  I sewed into the line some marker
threads --one at an expected weak point, and another
some measure past that, anticipating movement
of the line in loading (and markers at all ends at
the boundary of the knot, to show movement of
material --and any slippage-- out of the knot during
compression.)

BTW, insofar as I've been able to judge where the
breaks in knots come, it seems to be that material
on the inside of a turn is crushed and ruptured
--NOT as has been sometimes suspected that the
outer fibres bear all the load and rupture.  This
assessment comes in looking at 3-strand/laid rope
where often 1 strand breaks and the test is stopped
and the broken strand can be traced back to a point
in the knot where rupture likely occurred.  In braided
rope, that's another challenge ... .  Just to the point
of a general location of the break, using some
marker (I use bright threads) and photo of the knot
at high load showing location of the marked points
then can be a help, though the ruptured line
is often an explosion of material, defying easy
examination.


--dl*
====

allene

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Re: Modified Water Bowline
« Reply #10 on: January 23, 2014, 06:52:50 PM »
^^ regarding my inspection.   At first, from the drawings, I thought the mirror would be stronger because I incorrectly thought that the standing part entered and went through the loops before turning.  Upon examining some samples I tied in larger line, I did not see a significant difference in bend radius and if there was one, mine had a more gentle bend as on the mirror bowline the bend around the larks head knot is around a single strand where on the water bowline, it is around two strands.  But as the mirror one held, I just said don't draw any conclusions about strength.

As you know, these kind of knots break at the first bend.  Nothing else matters.  The bend that is the subject of another post has each standing end going through three loops before it experiences a turn, one of the things I like about it.  Too bad it actually does slip.

Dan_Lehman

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Re: Modified Water Bowline
« Reply #11 on: January 23, 2014, 07:38:49 PM »
^^ regarding my inspection.  ...
Thanks.  Might be that setting can affect
what follows. YMMV.

Quote
As you know, these kind of knots break at the first bend.
Nothing else matters.
"first bend" needs to be more severe than some
slight deflection.  As noted, in the break in a version
of reverse fig.9 eyeknot, it appears that the break
came a little past the U-turn, which was past some
compression on the S.Part.  (attch'd)  See the point
of the gold thread in top, survivor of two opposed...,
knot, and see the point of rupture show below
--of course, presuming that it had a like position
(these were by-pulley set prior to shipping to NER
for testing).  Yeah, I found this surprising.
(note the limited & even feed of material out of
the knot of the eye legs --white threads--, and
greater feed into the S.Part, with the initial point
pink thread spot moved from the the point that
the gold is in upon rupture into the turns of the
eye leg *roots*.  (And this about sums up my
skill at sewing, so no requests for fancy garments,
please.   ;D )

Quote
The bend that is the subject of another post has each standing end going through
three loops before it experiences a turn, one of the things I like about it.
Too bad it actually does slip.
One concern about such turning-into-a-helix
is torsion : one can examine  loaded knots
and see e.g. all of the strands going in one direction
arched up, soooo slack, and ... there goes 50%
of your (well, on surface at least) material on
lunch break!  (With laid rope, the effect is not
the same in terms of division of fibres, though
there might be an effect re strength for other
reasons, I'd guess.)

To this other knot, I'd try taking the respective
tails into their opposite halves (a red tail tucked
into the white rope's --were ends so colored...--
coils, e.g.) in a manner like the tucking done for
Blake's hitch (Prohgrip), where the rotation of the
coil pulls the tail ever tigher (of course, barring
slippage).  This might stand a chance of success!?

In addition to the close-up of the tested rev.fig.9
eye knot are photos of two sides of my five knots
prepared for testing, marker threads and all.


--dl*
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xarax

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Re: Modified Water Bowline
« Reply #12 on: January 23, 2014, 08:27:38 PM »
BTW, insofar as I've been able to judge where the breaks in knots come, it seems to be that material on the inside of a turn is crushed and ruptured -NOT as has been sometimes suspected that the outer fibres bear all the load and rupture. 

  Dan Lehman s theory : Knots brake because of compression, not tension !  :) If knots were made of rods and not of ropes ( i.e., if there were shear forces that would had been able to bent and "cut" the solid rods ), this theory might even be wrong !  :) Place a portion of a rope into of a cylindrical pot, load / compress it with a piston with a force equal to the force any strand of the rope "feels" at any deflexion area of it around another, and wait for it to boil - of course, you should not look at it, because a pot you look at does not boil...  :)
   Noope, unfortunately materials, in general, have nerves and bones, and fiber-made materials have more nerves and more bones than the rest - they are not homogenous substances, that will reveal a fracture at the exact point of their maximum loading ! You press here, and they become hot, the heat moves along the nerves and the bones, and they melt there. You can not judge which area suffered most, by just looking at the material, and see which area broke.   
This is not a knot.

allene

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Re: Modified Water Bowline
« Reply #13 on: January 23, 2014, 09:08:11 PM »
^^ I refer you to this research.  I have a copy of it on my web site here http://l-36.com/read_pdf.php?file=rope/8_strength.pdf&title=Knot+Strength:+The+Study+of+Knot+Performance

It is on the web other places as well.

xarax

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Re: Modified Water Bowline
« Reply #14 on: January 23, 2014, 09:21:36 PM »
   This is common knowledge - but that does not mean it is not wrong... :) Dan Lehman will not yield to such schematic / simplistic explanations, I guess, so I was careful enough to say something (vague enough... :) ) about heat, because you had mentioned that particular aspect of the breaking process in the case of Dyneema...
 
   Curves Redistribute the Load and Weaken the Knot
   
   Any curve in a loaded segment of rope distributes the load unequally on the fibers. The load falls more heavily on the outside fibers of the curve than on the inside fibers. By stretching some fibers and compressing others, a curve loads the fibers unevenly. The uneven distribution of load creates strains that weaken the knot at that point. The outside fibers, carrying more of the load than the inside fibers, are placed under greater stress. Under an excessive load, these outer fibers are stretched until they break, just as they are in a green stick if you bend it to the breaking point. The inner fibers, unable to support the increasing load, break soon after. In this way, the curve of the stem creates a weak point that causes a knot in an overloaded rope to fail.

   
This is not a knot.