Author Topic: Knot Strength  (Read 16268 times)

Sweeney

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Knot Strength
« on: October 04, 2011, 11:22:24 AM »
I have started this topic because the Prusik loops discussion has started to stray into this more general issue. Knot strength in modern rope is rarely an issue as the reduction in breaking strain of rope is still well within the safe working load margin. However in fishing knots, where the line strength may be very low, both strength and security become far more important. This s an area of knotting not often discussed yet there are many fishing knots, designed to be tied in extremely slippery material, which will not work in rope. Mention was made of the uni knot (aka Duncan knot) which can be tied in both fishing line and rope. So for example is the uni knot either as a noose or used as a bend stronger than a (half) double fisherman's knot? I do find it easier to tie in monofilament but in rope/cord?

Barry

SS369

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Re: Knot Strength
« Reply #1 on: October 04, 2011, 04:20:55 PM »
I am thinking that all this poo-pooing about knot strength needs qualifying.

Knot strength can also be looked at the other way around. Not how strong it is, but how weak does it make the line it is tied in. A slight difference of contemplation.

For whatever the purpose of the particular knot in the particular use, we have the ability to decide the best knot with just the correct attributes tuned to the application.

We may hit upon something that is a "fit all" type of modification as we've been seeking in many of the threads.

On the question of whether the uni knot is stronger in a bend or noose, my supposition is that all things considered equal, it would be stronger due to the load sharing of the wraps (small, but there).

For a bend in mono, I prefer the blood knot.

SS

knot4u

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Re: Knot Strength
« Reply #2 on: October 04, 2011, 07:06:15 PM »
So for example is the uni knot either as a noose or used as a bend stronger than a (half) double fisherman's knot? I do find it easier to tie in monofilament but in rope/cord?

All other things being equal, my guess is a Uni Knot with 8 coils is stronger than a Half Double Fisherman (Double Overhand Noose).

Let's back up.  A Uni Knot is easy to tie and remember, which are important considerations when fishing.  (What good is an awesome knot if you can't remember how to tie it perfectly?)  In the strength department, however, other fishing knots have consistently outperformed the Uni Knot in Knot Wars.
http://www.fishingclub.com/knot-wars.aspx
(Note that Knot Wars doesn't test knots with few coils like the Half Double Fisherman.)

My personal favorites for line-to-lure are the Berkley Braid and the Palomar.  Both have tested stronger than the Uni Knot in monofilament, braided and fluorocarbon.

I suppose if I want to make sure a hitch is about as strong as can be, I could wrestle with tying a Berkley Braid in the rope.  Unfortunately, in rope, the Berkley Braid is an impractical monster.  Notice we are venturing off into a discussion that is awkward, at best, for rope applications.  Fishing knots are in a different world.
« Last Edit: October 04, 2011, 07:24:43 PM by knot4u »

TMCD

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Re: Knot Strength
« Reply #3 on: October 04, 2011, 10:53:41 PM »
Regarding fishing knots, the Palomar was widely regarded as the strongest hook to line knot and I think even won one of the Knot War series on tv. I used to be a diehard Palomar man, but since I've learned how to tie the Snell knot, I'll probably never use anything but the Snell. The Snell gives the fisherman tremendous strength but more importantly, it allows the hook to be set in a direct plane because it's actually tied around the shank of the hook. This direct plane relationship allows fisherman to catch more and miss less bites!!

Sure, it's probably slightly weaker than the Palomar, but not by very much at all. The negative to the Snell Knot, is that it takes a LOT of practice to tie correctly. It took me several weeks of tying almost EVERY NIGHT before I could routinely get it perfect. There's different ways to snell a hook but I do it the hard way, which is also the BEST way. In Des Pawson's book, Hand Book of Knot, Expanded Edition, he shows the correct way to snell a hook on pages 92/93. I just had a hard time following his pictures, but I hunkered down and finally became an expert on this knot. The Snell Knot is frequently used in Deep Sea Fishing, it's an unbelievable knot once you get the hang of it. I think it's the same thing as perfected whipping.

The Uni Knot is desirable because of it's diversity. You can use it as a snell, a bend, and a hitch. It's touted as a system of knots and is very popular because of this concept. I personally find it hard to tie in light weight mono but easier to tie in heavier mono. Since I use 4lb and 6lb test, I'm a panfisherman(crappie/shellcracker and bluegill), I stay away from the Uni Knot. It would be good for a catfisherman where heavier line is desired. Thirty lb test would probably be a piece of cake to tie in Uni fashion.
« Last Edit: October 04, 2011, 10:57:42 PM by TMCD »

knot4u

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Re: Knot Strength
« Reply #4 on: October 04, 2011, 11:07:26 PM »
Attached are test results from Knot Wars for 2009 & 2010.

Sweeney

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Re: Knot Strength
« Reply #5 on: October 05, 2011, 09:33:15 AM »
The negative to the Snell Knot, is that it takes a LOT of practice to tie correctly.

That's right - especially with eyeless hooks. Many years ago when I did a lot of what's known in the UK as coarse fishing (using line of 3lbs to 5 lbs test) I used a hook tying vice -  a small contraption which made snelling a hook very simple though I tended to buy what were - and may still be - match casts ie 2 small hooks about 2 inches apart attached to  line with a machine made loop at the end to be attached to the main line. It may well be that anglers are the biggest users of knots these days, perhaps they deserve more attention?

Barry

Dan_Lehman

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Re: Knot Strength
« Reply #6 on: October 05, 2011, 09:16:06 PM »
[ BROUGHT HERE FROM THE "Prusik Loops" THREAD WHERE WE'RE "OT"  :-]

My educated guess is that there are fishing knots that can be tied in rope that are stronger than the Strangle Noose and the Butterfly Loop.  To be clear, by "strength", I mean the propensity to resist rope breakage.  I have no hard data, but who does?  If I had to put my money on strongest hitch, I'd put my money one of the fishing knots if they're up for consideration.  The Berkley Braid versus the Strangle Noose, that's not even fair.  Do we even have to run a test for which is stronger?

"Educated" --how so?

...by analyzing test results from Knot Wars and drawing reasonable conclusions.  I hate to burst your bubble, but this is not quantum mechanics.  How are you educated on the issue of strength for these knots?

1) An analysis of available test reports should move one
to question more than quote them --YMMV, but as noted
previously, they tend to leave a lot of relevant factors
UNstated.

2) The difference between materials --fine fish line and rope--
is huge, and one should suspect at best only some small
corresponding match of behavior in knots.

3) re #2, the forces that are brought to setting the knots
for testing --in terms of relative-to-material-strength %--
differ greatly : angling knots are typically set to a significant
% of line strength, rope knots not.

My examination, as best I could do from pausing the videos,
of the Knot Wars testing showed those knots to be what
I'd call "**spar** hitches" --not **ring** ring hitches,
which is what I'd presumed !?  I.e., the materials there
were considerably smaller in diameter than the tied-to
metal for the tests.  (Thus, one changes what one looks
at, in the knot --more at how the hitch-part SPart is
received, than where it *goes* ("hitch-part SPart"
distinguishes from "noose" SPart : the line runs directly
to turn back around the hitched object, and then
hitches to itself, so to speak --the *knotting*
comes of line upon line, with only a turn on the object).

And the similarity between the Berkley Braid & strangle noose
is that they both u-turn, reach back far on their line,
and then overwrap back towards the object;
and they differ in that the BB does this with twinned
line around twin, and then just tucks the end out by
the object vs. running it up through the wraps.
But, because of the use of twin line, the BB will still
be turning around 2 diameters, as does the other.

(Frankly, I'd think that the BB would be suspect in thin
lines ("spar" vs. "ring" hitching), given the simple tuck
beside the object only!?)


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xarax

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Re: Knot Strength
« Reply #7 on: October 06, 2011, 12:36:13 AM »
...the forces that are brought to setting the knots for testing --in terms of relative-to-material-strength %-- differ greatly : angling knots are typically set to a significant % of line strength, rope knots not.

    I do not see/understand why the strength with which the knot is set, should have any relation with the maximum strength of the knotted line.
This is not a knot.

Dan_Lehman

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Re: Knot Strength
« Reply #8 on: October 07, 2011, 07:37:44 AM »
...the forces that are brought to setting the knots for testing --in terms of relative-to-material-strength %-- differ greatly : angling knots are typically set to a significant % of line strength, rope knots not.

    I do not see/understand why the strength with which the knot is set, should have any relation with the maximum strength of the knotted line.

... because with setting one can effect geometry
that won't obtain otherwise (think about this, and
it should be obvious [eg]).  Come loading, the SPart wields
100% force into this structure; now, if one has gotten,
in setting, 60% or so on other parts, they have thus
a gain that cannot be taken away (and the overall knot
a state that doesn't need to shift with increased forces,
generating frictional heat from the movement).

[eg] Consider e.g. the common "nail knot" --which is just
a (multiple) strangle hitch  tied with the aid of inserting
a "nail" (your implement might differ) to ease the tucking
of the end through all the overwraps : now, lightly set (to
close), the SPart then exerts this powerful force into it;
but with low-strength line one can much more fully set
the knot by loading SPart vs. tail, and the tail will thus
effect tightenings et cetera that otherwise wouldn't exist
(i.p., its turn around the SPart at the entry will be tighter).


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xarax

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Re: Knot Strength
« Reply #9 on: October 07, 2011, 09:33:06 AM »
... with setting one can effect geometry that won't obtain otherwise.
... if one has gotten, in setting, 60% or so [of loading] on other parts, they have thus a gain that cannot be taken away.

  I understand that this might be true in some (not all...) convoluted knots,IF we do load their tails  hard enough - as we have to do, indeed, on some fishing knots with many wraps/coils, in order to dress them correctly. Any fisherman knows that, if he will not dress and load a complex  knot correctly in the first place, later on this knot will never come back - by its own - in a proper form. However, with our relatively simple  practical knots tied on ropes, it is very difficult - and rare (?)- to load the tails  so hard that the geometry will change in a way that can not be taken back afterwards - during the normal loading of the knot by the pull of its standing part(s). This is my opinion, but it is based upon a very limited knotting experience, with a very limited variety of materials. Things might be different with older, less slippery - or with modern, less flexible - ropes than those few I had the chance to use till now.
This is not a knot.

TMCD

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Re: Knot Strength
« Reply #10 on: October 07, 2011, 01:28:41 PM »
The negative to the Snell Knot, is that it takes a LOT of practice to tie correctly.

That's right - especially with eyeless hooks. Many years ago when I did a lot of what's known in the UK as coarse fishing (using line of 3lbs to 5 lbs test) I used a hook tying vice -  a small contraption which made snelling a hook very simple though I tended to buy what were - and may still be - match casts ie 2 small hooks about 2 inches apart attached to  line with a machine made loop at the end to be attached to the main line. It may well be that anglers are the biggest users of knots these days, perhaps they deserve more attention?

Barry
I'm sure with your knotting skill, you'd master the "proper snell" or "common snell" in no time flat. It just took me some extra time because I didn't understand the complicated hand movements involved. If you don't get the hand movements just right, you're going to tie a knot that simply won't be the proper snell.

Regarding anglers, you're correct. I'm a serious angler myself and have at least five different knots in current use on my little 14foot jon boat. I have two truckers hitches alone, cleat hitches, and a variety of hitches for my four anchors. Then comes the anglers choice in knots for his hooks/lures/jigs. For any hook, I'd go with the snell...a jig, I'd tie the Palomar or improved clinch. For a lure, which bass fisherman commonly use, I'm not sure. Maybe a Perfection Loop would work because it would allow the lure to swim more naturally.

I've got a book devoted to fishing knots and lets just say there's hundreds of fishing knots available. The angler community deserves much attention regarding knots. They wouldn't have done a knots war series if they didn't think this to be true.
« Last Edit: October 07, 2011, 01:30:18 PM by TMCD »

Sweeney

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Re: Knot Strength
« Reply #11 on: October 08, 2011, 11:05:08 AM »
I've got a book devoted to fishing knots and lets just say there's hundreds of fishing knots available. The angler community deserves much attention regarding knots. They wouldn't have done a knots war series if they didn't think this to be true.

I too have a couple of books on fishing knots one of which is Lindsey Philpott's (Squarerigger) which is well illustrated. I too found the knot wars interesting though the difference between winners and losers seemed narrow in many cases. It would be nice to see the test in slow motion with a close up of where the knot broke (repeated several times) as well as magnified pictures of how the knot was dressed (there is probably more lost through poor dressing that the choice of knot). Whereas breaking 9mm climbing rope would take a mighty piece of equipment monofilament provides low breaking strength material (which is also very slippery) which could perhaps be used more to study the behaviour of a knot under tension before and while it breaks or slips. Need a powerful magnifying glass though!

Barry

SS369

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Re: Knot Strength
« Reply #12 on: October 08, 2011, 02:28:56 PM »
This topic rises and falls with the regularity of almost lunar fullness.

Let's say we all want to be part of a great test of knot strength. Say 10 members at least. Why don't we decide some things that could be common, in that the materials, procedures and hopefully the results that are hence shared here, are not all over the galaxy.

Materials: Small cord, but of sufficient size to show details of the knot. Also able to be broken at some achievable force. Approx. 1/8"/3mm, perhaps both braided and laid up.
Inexpensive polypropylene comes to mind.

Procedure: We can chose any knot(s), the standard toolbox items(?) to start and add as we test them. Define the procedure with the parameters, such as, slow stretch, oscillating tension, hard jerk, un-tensioned banging, marking the cord, length of test subject, etc.

Results: Photo (before, under tension and after failure), data about the material, test procedure and results peculiarities. 

The cord that I have that is 1/8" comes from the big box stores and I believe is available most places has a working load limit of 40 lbs/18.1Kg. I think that a simple and possible method to tension this to the point of failure is well within the realm of possibilities for most of us here.

Let's collectively design the inexpensive test apparatus, procedural criteria and give it a go.

SS

TMCD

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Re: Knot Strength
« Reply #13 on: October 08, 2011, 02:46:13 PM »
The knot war series was a great idea, but I believe they only used 12lb test line. That's pretty thin mono, had they used 30lb test, it would've allowed the demanding viewer to really see things a little better IMO.

Speaking of mono, I've tried tying some of Ashley's recommended hook knots and they simply slip right out in today's slippery mono line. Ashley's book is a GREAT and obviously wonderful achievement, but it's definitely lacking in angling knots. The one's he presents, are simply outdated and many flat out fail in today's materials.

xarax

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Re: Knot Strength
« Reply #14 on: October 08, 2011, 11:19:08 PM »
  we all want to be part of a great test of knot strength.
  Let's collectively design the inexpensive test apparatus, procedural criteria and give it a go.

  So be it ! 
  [ Note :  I thing that it might be better if we use a material that :
  1. does not allow the cross section of the cord to be flattened beyond a certain degree. With such a material, the loaded physical knots remain, more or less, geometrically similar to their corresponding ideal knots.The deformations of the cross section due to curvature and/or local pressure will still be present and visible - they could be easily seen, if one examines the knot - or its picture - in more detail.
   2.  its outer surface / woven mantle is relatively smooth, so that the geometrical boundaries of the cord segments and their deformations will be clearly visible , even if we use thin auxiliary cords (2-4mm).]
   
« Last Edit: October 08, 2011, 11:23:29 PM by xarax »
This is not a knot.