Author Topic: Research Project using a possible new knot  (Read 1771 times)

Tim

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Research Project using a possible new knot
« on: June 23, 2018, 12:50:25 AM »
Hi
I am a mature student doing an engineering degree. I am just starting my research project into a hitch that can give a splice a 'good run for its money' regarding its strength (to be used in extempore construction tensioning situations).

The tests so far have been hitch v hitch to determine the strongest hitch. I think I have found one that is new as I can't find it in ABOK, and it beats all other hitches I have tested it against.

Can anybody tell me if it has appeared in any books etc or has been referenced before?

It is two round turns followed by one half of a double fisherman's knot.

(I am guessing it can also be described as two round turns followed by a double overhand knot [I think]).

If it is found to already be in use or documented then I will use its given name in my research project. If there is no record or reference to it anywhere then I will call it 'The Stewart Hitch' (here's hoping).

I look forward to any replies.



« Last Edit: June 23, 2018, 01:03:46 AM by Tim »

SS369

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Re: Research Project using a possible new knot
« Reply #1 on: June 23, 2018, 03:42:00 AM »
Hello Tim and welcome.

If you would show us a loosened photo and the tying method, preferably step by step pictures, we can go forward.
The picture you have shared does not reveal enough details.

Thank you.

SS

Dan_Lehman

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Re: Research Project using a possible new knot
« Reply #2 on: June 23, 2018, 08:21:01 PM »
If you would show us a loosened photo and the tying method,
preferably step by step pictures, we can go forward.
??
The words
 "It is two round turns followed
  by one half of a double fisherman's knot."
should be perfectly perspicuous!
And "scaffold knot" be the indicated family.   ;)

--though as often with e.g. angling knots I'm puzzled
at how there could be (much of) any difference in strengths,
when so much force should be taken by the round turn(s),
and then pretty much anything I'd think would be ample
to do the job beyond that!?


--dl*
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Dan_Lehman

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Re: Research Project using a possible new knot
« Reply #3 on: June 23, 2018, 08:26:13 PM »
The tests so far have been hitch v hitch to determine the strongest hitch.
Can you present your results of this A-vs-B testing?
What have you tried, and how have the candidates
ranked?
Quote
I think I have found one that is new as I can't find it in ABOK,
and it beats all other hitches I have tested it against.
I think you've found the scaffold hitch, aka "poacher's
hitch"
, with an extra round turn or two --which
difference should be understood as trivial.

Let me ask you to try this, er tie this, "double overhand"
in the form of an anchor bend/fisherman's bend;
the thought is that the line is brought into the knot
more kindly to the noose's SPart than is done with
the strangle-knot form of dbl.oh..


--dl*
====

Tom_Zal

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Re: Research Project using a possible new knot
« Reply #4 on: June 25, 2018, 01:09:44 AM »
Would this be considered a tensionless hitch? It seems to meet the definition at http://www.animatedknots.com/tensionless/ if we can infer that the method of securing the free end is irrelevant (several alternatives are suggested).

I know the tensionless hitch is generally used with an anchor object much larger in diameter than the rope (and that in this case it theoretically maintains 100% of the strength of the rope). I don't know if tying it around a smaller anchor makes it a different knot...

agent_smith

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Re: Research Project using a possible new knot
« Reply #5 on: June 25, 2018, 03:24:38 AM »
Hello Tim,

There is absolutely nothing 'new' in this hitch that you have presented.

Looks like 'Tom_Zal' beat me to the punch and I concur with his view that all you have done is tied a 'tensionless hitch' (#2047).
Your depicted tensionless hitch is then secured with a strangled double overhand knot.

There are numerous ways to secure a tensionless hitch. The simplest method is as you have depicted - which is to tie a strangled double overhand knot around the SPart (standing part).
Link: http://www.animatedknots.com/tensionless/

A tenionless hitch operates in accordance with the capstan equation.
Link: https://ipfs.io/ipfs/QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco/wiki/Capstan_equation.html

This structure actually functions as a noose.

And Dan Lehman is correct that the noose is based on the Poachers noose (#409) and scaffold noose (#1120).

Mark G

Groundline

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Re: Research Project using a possible new knot
« Reply #6 on: June 25, 2018, 03:19:58 PM »
After inspecting and tying the knot in 5.JPG I see, get, a constrictor knot tied around its own standing part.
« Last Edit: June 25, 2018, 03:21:38 PM by Groundline »

knotsaver

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Re: Research Project using a possible new knot
« Reply #7 on: June 25, 2018, 04:20:12 PM »
After inspecting and tying the knot in 5.JPG I see, get, a constrictor knot tied around its own standing part.

no Groundline, not a Constrictor, but a Transom (or a Strangle) that is to say a Double Overhand... ;)

have a look at
http://igkt.net/sm/index.php?topic=1462.0
and
http://igkt.net/sm/index.php?topic=5258.0

Ciao,
s.



alanleeknots

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Re: Research Project using a possible new knot
« Reply #8 on: June 25, 2018, 05:29:50 PM »
       Hi All,
                Climbing with a pair of slipper ?
                 謝謝 alan lee.

                 http://www.yachtingmonthly.com/sailing-skills/strongest-sailing-knot-30247

Dan_Lehman

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Re: Research Project using a possible new knot
« Reply #9 on: June 26, 2018, 12:44:36 AM »

       Hi All,
                Climbing with a pair of slipper ?
                 謝謝 alan lee.

                 http://www.yachtingmonthly.com/sailing-skills/strongest-sailing-knot-30247
MANY THANKS, ALAN, FOR
 [edit : helping ME to...] FINDING THIS TEST REPORT!

(And, yes, climbing in sandals is worth a remark.   ;)  )

Now, who has read the report, and what
observations can you give about it?!

--dl*
====
« Last Edit: July 03, 2018, 12:25:22 AM by Dan_Lehman »

Dan_Lehman

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Re: Research Project using a possible new knot
« Reply #10 on: June 26, 2018, 01:40:44 AM »
The hitch I have mentioned does include some of the scaffold knot,
but because of the inclusion of the two round turns [i.e., just one more...],
I believe it is a new hitch,
 unless exactly the same hitch can be found in literature or reference elsewhere.
Tim, with respect, this is simply silly : adding one
more round turn (i.e., repeating what exists already)
does NOT win you (m)any points for inventiveness!
(You might gain something for presumably realizing
--though possibly in retrospect to trial&error-izing  ::) --
that the "tensionless hitch-ing" aspect needs this further
wrap against so smooth an object (vs. cavers e.g., tying
around the rough bark of a tree).)

Quote
My reasoning for the above paragraph is as follows:

The single overhand knot is known as 'The Thumb Knot'.
Add another overhand knot, it becomes a double overhand knot
known as a 'Blood Knot' (ABOK p84. Knots 515 & 516).

''The round turn and two half hitches is named by steel in 1794''.
A totally separate knot mentioned shortly after the first knot states
''Two round turns and two half hitches, so called by Dana in 1841''.
(ABOK p296. Knots 1720 & 1721).
Now you're definitely getting silly!
Firstly, you don't "add another overhand knot" to get a dbl.Oh
but add a 2nd tuck (in pretzel form) or --more insightfully/significantly--
a (first!) *wrap* in the strangle knot form, to do that.
(Doing what you say would be stoppering the initial overhand.)

Quote
I expect I could find more examples of different knot/bends/hitches
which> [that] are made up of parts of some other configuration.
Oh, heck, why go "different" : you can find the SAME knot
getting different names, if name-glory is what is wanted!   ;D
(... noting that e.g. "blood knot" attaches to other things, as well)

Quote
But my point is I still think my hitch may be new as I can't find anything exactly like it.

It is also of importance to be recognised as a separate entity
because of the fact it is not a fancy decorative knot,
it is a practical hitch that may have the potential to be used
in constructional tensioning applications in the future.
NO.  Rather, it is more important to have an understanding
of knots & their purposes and effects/workings such that one
can readily adjust to particular circumstances by such simple
means as furthering a structure (such as wraps) or adding
a stopper knot or ... .  E.g., when Heinz Prohaska presented
his --my name, here--> ProhGrip friction hitch (aka "Blake's h."),
he added the commentary that if the hitch can still not hold
so surely in stiff rope, then add a further wrap with the tucked
tail (i.e., a further 2-dia. wrapping); or if the slippage seemed
attributable not to inflexibility buy slickness, add wraps of
the single-diameter end of the structure.  I.e., he did NOT
merely introduce the JUST-THIS-#-OF-TURNS knot; he gave
us a good idea of a structure that could be manifest in various
forms!
Given an overhand, adding a wrap to it to get the
strangle is a significant gain, as the first knot has no
such press-against-the-crossing part; adding further wraps
is just furthering what the first addtion presented, but is not
additionally creative.
(And as far as hitching to something, one must beware
that not all objects will accommodate multiple turns!)

Quote
My decision to test which knot/hitch against which knot/hitch came about from
over 35 years of working with ropes at sea both professionally and leisure,
and from rock climbing for leisure. I was also drawn to an online article in
Yachting Monthly (May 2015) which was conducted by Marlow Ropes.
http://www.yachtingmonthly.com/sailing-skills/strongest-sailing-knot-30247
 
OH, and I just boldly and colorfully thanked Alan for this
--so much for quick scanning ... .  <sigh> :P  I'll go do an edit ... .

And did you read this report carefully, attentively,
eyes open and not kneeling to this apparent *authority*?!
Because there are some eye-opening assertions in this!
(I'll refrain for time and for giving others I hope the chance
to do some critical reading/thinking themselves.)

Quote
My pilot tests were as follows.

Bowline v Round turn and two half hitches
- The round turn and two half hitches won outright 4 times out of 4 (as expected, based on work and climbing experience, and also Marlow Rope's online testing).

Looped double fisherman's (Scaffold hitch) v Round turn and two half hitches
- The round turn and two half hitches won outright 4 times out of 4 (as expected, base on work experience and based on Marlow Ropes online testing).
[?? Expected based on Marlow?  Why, their (dbl.) scaffold --no RT-- beats RT+2hh]

Round turn and one half of a double fisherman's (Scaffold hitch with a round turn) v Round turn and two half hitches
- The Round turn and one half of a double fisherman's (Scaffold hitch with a round turn) won outright 4 times out of 4 (I did not know what the outcome would be here).

Round turn and one half of a double fisherman's (Scaffold hitch with a round turn) v My hitch Two round turns and one half of a double fisherman's (Scaffold hitch with two round turns)
- My hitch won outright 4 times out of 4 (I definitely was not expecting this outcome).
[Why not : the extra turn can only help, one might think.
(Possibly by enabling more slippage through the tightened knot
--i.e, an extra-turn-of-material's stretch to draw tight out through
the noose's knot-- could make it worse, but ... )]



'English Braids' have very kindly provided me with 200 metres of 4mm 12 stranded polyester dinghy control line to continue my testing.

... The next stage is to test my hitch against the splice under different environmental conditions.
[Again, I urge you test the re-casting of the dbl.oh knot's shape
into that of the anchor bend, its turns going AWAY from the object.]


Based on Marlow Ropes online knot test which the round turn and two half hitches is rated very highly against a splice, I have high hopes for my hitch as it outperformed the round turn and two half hitches by far.
[?? Directly, based on Marlow's finding a like noose so strong, getting their hightest break.]


Tim, consider this, with care :: What is the difference
between the RT&clove noose and your dbl.scaffold h. ?!!
THINK, l00k; further think.
Where do the test-reported breaks come?!
(Hint : what knot did I recommend you try --you didn't reply to that?!
Quote
Let me ask you to try this, er tie this, "double overhand"
in the form of an anchor bend/fisherman's bend;
)

Quote
I look forward to any replies

Tim :)
Now, this one's in your rear-view mirror.

--dl*
====
« Last Edit: June 28, 2018, 03:18:55 PM by Dan_Lehman »

NautiKnots

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Re: Research Project using a possible new knot
« Reply #11 on: June 26, 2018, 03:32:19 PM »
Now, who has read the report, and what
observations can you give about it?!
Startlingly poor testing methodology (revealing fundamental misconceptions of knots and cordage) that is used to draw unsupported conclusions which mislead unsuspecting readers. 

Can you tell that I'm unimpressed?

Shame on Marlow Ropes for participating in such a sham of pseudo-science just to get their name in print.

Regards,
Eric

Dan_Lehman

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Re: Research Project using a possible new knot
« Reply #12 on: June 26, 2018, 09:01:10 PM »
Now, who has read the report, and what
observations can you give about it?!
Startlingly poor testing methodology
 (revealing fundamental misconceptions of knots and cordage) ...
Regards,
Eric
But we should be specific & comprehensive, so to enable a correct
and helpful result be obtained.  And I think that it's not merely
a right-or-wrong citing, but maybe just an quite unexpected one,
too (along with right-or-wrong things)!
(Going from "testing methodology" to "test method" is a start!   :D  )


--dl*
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Dan_Lehman

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Re: Research Project using a possible new knot
« Reply #13 on: June 26, 2018, 09:14:07 PM »
Looks like 'Tom_Zal' beat me to the punch
and I concur with his view that all you have done is tied
a 'tensionless hitch' (#2047).
Your depicted tensionless hitch is then secured with a strangled double overhand knot.

Goodness, how amazing it is for the knot of this
noose to have so much tension in it, for to be a
"tensionless hitch" !!

(One should be noting behavior** more
than counting turns and likening the structure,
for the above assertion.
.:. The point of the tensionless h. is high strength
via the relatively mildly curved wraps & friction taking off
all of the load,
and thereby enabling release while loaded by
simply unclipping the trad. 'biner on the noose's SPart.
But in cases we're seeing in Marlow's test and presumably
w/Tim's, the >>knot<< is getting much tension --enough
to so constrict the >>noose's<< SPart (not the knot's)
that the break occurs there !

**Though, I'm usually against deciding knot type/class
by behavior vs. structure --as the former will differ so
much over circunstances, and we don't want to have
shifting categories/classes to match!)

!?

--dl*
====

NautiKnots

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Re: Research Project using a possible new knot
« Reply #14 on: June 26, 2018, 10:47:28 PM »
But we should be specific & comprehensive, so to enable a correct
and helpful result be obtained.  And I think that it's not merely
a right-or-wrong citing, but maybe just an quite unexpected one,
too (along with right-or-wrong things)!

Ok here are some of the problems that caught my attention:
  • It appears that the author tested only one sample of each knot in each type of cordage.  A sample size of one is merely anecdotal and not a valid basis for comparison.  Anybody even passingly familiar with statistics knows that you need a larger sample size to have any confidence in the result.  If you assume a Gaussian distribution, conventional wisdom requires at least 30 samples to have a 95% confidence in the mean and standard deviation.
  • The author did not identify the Dyneema and twisted cordage used, so we can only guess at what they might have been.
  • The author compared measured breaking load to rated breaking strength (average or minimum?  - didn't say).  He never broke a piece of unknotted cordage, but still reports strength reduction as a percentage.  That is fallacious.  From his results, one might conclude that knots weaken twisted rope less than braided rope.  Maybe that is true, and maybe not.  It might be that the batch of twisted line he used happened to exceed its rated strength by more than the double-braid did.
  • The author admits that he was supposed to preload cordage to 50% before testing but did not.
  • The author does not differentiate between knot strength and knot security.  Anybody who has attempted to tie knots in HMPE cordage knows that all the knots tested will slip.  The author, however, reported them as "breaking".
  • The author confuses core with cover in Dyneema line.  He repeatedly refers to "Dyneema cover" breaking.  This betrays a fundamental misunderstanding of rope construction.  Core-dependent double-braid line relies on the high-modulus core for strength.  The cover is made of a different material chosen for properties other than strength (such as handling, abrasion resistance, or UV stability).  It is no surprise whatsoever that when the Dyneema core slipped, the cover broke at a low percentage of rated strength.  It would have been much better to do stripped-cover-splices and knot the Dyneema core(s).
  • The author assumes that breaking strength is the primary consideration for selecting a knot. Everybody should know that you never choose a line with a breaking strength on the same order of magnitude as the working load.  Strength alone is a poor criterion for knot choice.  Jib sheets, for example, (especially on cruising boats) are far stronger than the sail they are tied to.  Even when knotted, they will rip the clew out of the sail before the line breaks.  Ease of untying is a more important consideration than knot strength.
  • In the text, the author notes that it is important to properly taper a splice, but (in the photo provided) it appears that he did not.  Now, I admit that the photo isn't perfectly clear, and I might be mistaken, but if he didn't taper the bury then that would explain why his splice broke where it did, and why it broke at a lower-than-expected load.
  • What about other knots?  The author said he tested the Carrick Bend, but did not report the results.  The Angler's / Perfection Loop would have been an excellent candidate to test, especially in stripped cover Dyneema.
  • Oh, and Get your knots right!  The author admits that he mis-tied the bowline in the twisted rope, but includes it in his test data anyway.  You can't test knots If you can't tie them correctly!
Given the number and severity of these issues, I think its wrong to draw any conclusions about "best knots" from these tests.

Marlow Ropes provided the test lab and presumably knows how to use it properly.  They should have given the author guidance on devising and performing tests that would yield meaningful results.

Such an obviousy flawed article makes me doubt the veracity of everything else published in Yachting Monthy.

Regards,
Eric
« Last Edit: June 26, 2018, 10:58:18 PM by NautiKnots »