Knot breaking strengths and theories - again

General Discussion
21

Derek

I dont think I look or behave like a “lurker” and I use it only in the context of forum postings, now I believe I am a “newbie” which is almost as bad, ho hum.

Angling knots and their relative strengths, wet or dry, are discussed internationally and there are thousands of them. If you wish to expand the public awareness of the IGKT you could not find a larger market begging for independant assessment of useful knots.

Incidentally braid is commonly used in saltwater game fishing, and the number of knot applications in kite flying will be relatively low compared to the many in use in angling.

If anyone wants to boost the profile of this organisation, properly test common knots on various types of commercially available monofilament line and make the results available to the editors of angling publications world wide. They will be published.

22

I can sense immediately the distancing starting to happen from certain quarters, with mutterings of “We don’t want the Forum overrun with fishermen”,

This is not a valuable argument, you may as well say “we dont want the forum overrun with climbers or yachtsmen” The knots are used, end of story. Who uses them is hardly relevant when you are examining their physical or indeed theoretical characteristics. In any event, it is an international market and anglers are all knot tyers, why would you want to keep them out.

The current doyen of angling knotologists is a chap called Bill Nash in the USA. I have no doubt that Bill could make a very useful contribution to this forum and there could be no possible reason to exclude him solely on the basis that he is also an angler. A quick google,“Bill Nash, knots” will take you there, its very interesting…

Incidentally I am interested in knots from an entirely non angling professional perspective too, just in case anyone thinks I may be banging on too much about fishing. :slight_smile:

23

Hi Stoatstail,

I am sure that you appreciate that I would not support any move to restrict any knot using group from this forum and in fact have pushed on several occasions to improve the forum to attract as many other users as possible, covering all ages, interests and levels of proficiency. Having said that, you wouldn’t want your daughter to marry a climber or a yachtsman would you? so perhaps we should not encourage these types too much – :cry:

Your reference to Bill is great and I was interested to find a reference to a 100% strength knot http://members.aol.com/billsknots/loop100.htm and that Bill guaged this by the line breaking away from the knot.

Do you know Bill? Could you introduce him to this thread?

24

I dont know Bill, but I have posted on the Dan Blanton site on the subject of 100% strength claims.

I’m sure we could get him interested.. :slight_smile:

25

Stoatstail,
Welcome.
We would like all knot tyers to feel home here and I think there is room enough for a lot of fishermen.
If many come, we will find a way to handle that, without getting overrun.

Willeke (past moderator)

26

There never has been, nor will there EVER be, any attempt to restrict the membership of this Forum. Anyone who is genuinely interested in knots and knot-tying in any shape of form is welcome.

27

Who else would have such a depth of feel for some of these things; than those that really test them at all angles etc. and/or putting everything on the line? Also, a lot of these knots are from these fields.

28

Hi KC,

Indeed, only those who trust their lives on rope and knots genuinely appreciate the need for a sound scientific understanding and assessment of knot performance and weakness. If you are at sea, up a tree, down a hole or hanging off The Fin at Gib Torr you will tend to have developed a keen awareness of the need to understand the structures that may stand between you and death. I dare say an angler who has just hooked a once in a lifetime catch is likely to offer up a similar prayer to the god of knots, that he has chosen his knot well and tied it correctly.

All these people who use knots for anything other than decorative purposes, know in their hearts that the IGKT is the RIGHT place, if not the ONLY place to take up this challenge and shape up projects which can then be handed to trusted testing facilities, then review and pull together the reliable information they generate.

Nobody gives a fig for the knot that held a nasty slip from The Fin, or the knot that held through the fiercest storm or the knot that took the extreme load in a touch and go recovery mission or the knot that kept my bean canes firm and saved my crop. Yet put a well tied MWK or TH on the coffee table and you can be assured of a WOW party stopper. If you follow “Go on then – show me a knot” with a perfectly set Strangle Loop (the bowstring loop), one of the strongest and most reliable knots I know, you are likely to be rewarded with a polite “Hmm, yes, thats nice”. But tie a few trick knots or a pretty button knot or a quick bracelet or flick the Jug Sling together and you might just get that Wow response.

Few would argue that the ‘Fancy’ knots are generally regarded (rightly or wrongly) as the pinnacle of our craft, and this tends to be borne out by the fact that the IGKT seems mostly to be populated by folks highly skilled in tying decorative structures. But I would argue that the Birthright of knots is ‘To Hold’ and only secondarily ‘To Adorn’.

Anyone who relies on knots will know that the fields of Knot Strength and Knot Reliability are a shambles. The bedrock of our field is littered with fragmented attempts to grasp the science at it’s heart. Today ONLY the IGKT can put that situation right and it might be done in one of three ways.

  1. The members can form voluntary working groups to research and test.
  2. The IGKT officials can promote formal research through recognised agencies and promote funding.
  3. Both of the above can occur in synergistic support of one-another.

To make a situation change we have to ask – What can I do?

Perhaps now is the time for us all to start posting what we feel we each can contibute, who can we influence, what skills do we have.

Any takers?

Derek

29

You are talking about some very passionate groups of knotters that rely on these lacings with their lives and/or livelihoods. “Build it and they will come..” and expand on it (over time). To these peoples stopping by on their own searching journies; the guild and it’s site are not what they expect and they are gone(okay, i can’t do anything right!). Just as any other group they have their own contribution and following; why lose any non-negative of those to the end/target cause. Especially those so potentially potent.

i think the knot tests are important to show the patterns of design of what is greater and lessor to take to the field; so they are the beginning to cracking these codes/not the end. To me, a 7,000 test line; that i try to have a 10/1 SWL (Safe Working Load) safety ratio maximum (to prevent overloading by miss-calculation, unexpected forces etc. and not run into numbers that dramatically (d)effect the cycles to failure against me); it doesn’t matter about 3 or 8 % tensile strength differences. Maybe i like a certain knot more, more sure about it’s manufacture, it’s smaller etc. But, i do care about wide differences, and would like to make and deal with certain mechanical classes that are stronger as a group of knots similar in manufacture at key points, thus serve under the same forces; and set rigging etc. to these forms. By staying within a similar mechanically alike class; i get faster at making all of them (once i force myself to see all of them as i make any of them); and investigate any to see all in these groups of mechanically similar lacings.

Also, we need to know which take dynamic forces better, and how knots differ in static and dynamic lines i think. We drift into only static awareness; in a macho how much/ bigger-better mode; and forsake the whole elastic-forgiveness/deform but still hold part of the equation. There should be more awareness and embracing that an elastic line/length of a weaker line can save the day compared to the same line 4x as strong/or with 4 supporting legs of same line. with the higher tensile/support legs; there is more shock to the support and load under dynamic forces. i think some knots operate similarly; and so dynamic consequence and the load’s (especially live cargo) and support’s ability to take the impacting/dynamic input forces not buffered by the receiving dynamic properties of the system, line and knot(?) too.

30

In fact–readily ascertained by reading relevant forums’ knots chatter, and reviewing their literature–,
these users typically have hardly much of a clue and surprisingly little care or sound understanding.
Dogma thrives. That is why we find the state of the art/practice in an arguably deplorable state.

All these people who use knots for anything other than decorative purposes, know in their hearts that the IGKT is the RIGHT place, if not the ONLY place to take up this challenge and shape up projects which can then be handed to trusted testing facilities, then review and pull together the reliable information they generate.
??? Most are ignorant of the IGKT's existence; and if they looked to it for answers, they'd be dismayed at what they found.
Anyone who relies on knots will know that the fields of [u]Knot Strength[/u] and [u]Knot Reliability[/u] are a shambles. The bedrock of our field is littered with fragmented attempts to grasp the science at it's heart.
Hmmm, this assertion comes in contrast to the first, above. Frankly, again, one should be rather surprised at how little the user communities are re knots research, of how readily they accept summarily offered figures of strength w/o critical consideration of the basis for any such assertion.
Today ONLY the IGKT can put that situation right and it might be done in one of three ways.
  1. The members can form voluntary working groups to research and test.
  2. The IGKT officials can promote formal research through recognised agencies and promote funding.
  3. Both of the above can occur in synergistic support of one-another.

To make a situation change we have to ask – What can I do?


I made a reasonable suggestion for ready ways people could take a step to improving the state of the pratice
above: “Let’s start by listing test reports”. And I started. Then came a gratuitous diversion into major whining,
which serves no purpose but to depress interest. (This was briefly relocated to its own thread, where its lament
could be indulged, but apparently someone wants this whining to intrude where others are interested in another
topic and have to read it! Heckuva way to (ab)use a forum! >:( )

Perhaps now is the time for us all to start posting what we feel we each can contibute, who can we influence, what skills do we have.
Or to follow up on [b]1) building the list of test reports, and 2) contributing to critiquing them[/b] as a means to develop test guidelines that can be promulgated to those with the resources to do such testing (and as a way to improve our understanding of the (limited) information that we are occasionally given. In particular, some of those testers might be interested to understand where they fall short of clarity, usefulness. They might even be willing to entertain some testing regimen suggested by the IGKT. --or to reply to our critique with insights that enhance [i]our[/i] understanding. Understanding is an iterative process of give'n'take.
Any takers?

… or givers.

–dl*

31

I agree with much you have said Dan and apologise for for my whining intrusion. I have deleted my “gratuitous diversion” so that others do not have to read it and hopefully you will continue to collate your list of test reports.

Derek

32

I have a great deal of respect for the IGKT and would very much like to be able to access knot information - rather like a knowledge bank.

My angle has - and probably always will be - knots used in human life support (ie mission critical applications).

I respect those who use knots for decorative purposes, but that is not my personal area of interest. If you tie a decorative knot incorrectly, there wouldn’t be catastrophic failure with attendant death or disablement.

In climbing, abseiling, caving, mountaineering and rescue applications, get the knot wrong and you could be staring down the barrel of a real catastrophe.

Here are the knots that I would like to put to the guild as a starting point for analysis:

KNOT	                 ABoK No.	    CATEGORY	        ALTERNATIVE NAMES
  1. Figure 8 loop # 1047 End line knot Figure 8 on the bight, Figure 8 follow-through
  2. Re-threaded figure 8 #1047 End line knot Rewoven figure 8
  3. Double figure 8 loop #1085 End line knot ?Bunny ears? (a truly ridiculous name)
  4. Clove hitch #1178 Mid line knot
  5. Double fishermans knot #498 & #1415 Joining knot (bend) ‘Double English knot’ & a ‘Grapevine knot’
  6. Prusik Hitch #1763 Sliding friction knot
  7. French prusik #1758, #1764 Sliding friction knot ‘Machard Tresse’
  8. Tape knot #1412 Joining knot (bend) Ring bend, Water knot
  9. Alpine butterfly knot #331 & #1053 Mid line knot Linemans loop, Butterfly
  10. Munter hitch #1195 & #1818 Load control hitch ?Italian hitch? or ?HMS? or ?Mezzo Barcaiolo?
  11. Rosendahl bend N/A Joining knot (bend) Zeppelin bend

Note: Knot number #11 is controversial. There are conflicting ideas about which ‘bend’ is optimal in mission critical applications (ie if the bend fails, death will result in accordance with Newtons laws of physics).

Not all user groups would have need of all 11 knots. Classes of users who undertake multi-pitch lead climbing on cliffs would arguably have need of all 11. Indoor ‘plastic pullers’ would use only one or two knots at best.

Mine rescue teams would use most but not all of the 11 knots (the tape knot is not used by many Australian rescue teams on account of the wide availability of heavy duty sewn web round slings).

I’m going to re-assert the 4 S’s which are:

  1. Suitability to task
  2. Stability (very important)
  3. Security (very important)
  4. Strength (not as important serials #2 and #3)

Dan Lehman might have a word or two to comment about this… but serial #1 is important to me. In any situation, there will be a knot that is best suited for the job. For example, there are instances where a clove hitch or a butterfly knot might work, but one might give optimum performance. In another example, the optimum knot (ie bend) for uniting two ropes may be in contention - double fishermans, Rosendahl, offset over-hand bend (OOB) also known notoriously as the ‘Euro death knot’. In mission critical applications, serial #2 & serial #3 is of paramount importance. But, someone might need to properly define these concepts.

There is much needed data on ‘slide & grip’ hitches (ie sliding friction hitches) such as the Prusik and French prusik.

In Australia, controversy is raging at present on the optimum diameter of accessory cord to form a hitch around the parent rope. Some argue the diameter ratio is 50% - that is, a cord used to tie a prusik hitch will reach optimum performance when it is 50% of the parent rope diameter.

There appears to be general agreement that three (3) wraps provides optimal grab in the prusik hitch class.

French prusiks require a greater number of wraps - the exact number is dependent on the length of the loop and the cord/rope diameter ratio. Generally, if the wraps are too few or too loose, there is a risk of unexpected slippage with potential slippage.

Here is another link for you Dan: http://www.forestry.gov.uk/forestry/kirn-5lebje
Report date: 2002
Title: Ropes and Friction Hitches used in Tree Climbing operations
Author: Paolo Bavaresco, Treevolution

Its a bit slow to load, so it might be best to right click and choose “save target as”. Some interesting results in there…

Here is another report by Ron Farmer in Australia: http://www.chockstone.org/TechTips/ProtectingAnAbseil.htm

Again, some interesting conclusions drawn.

These are prime examples where the tester was ignorant of the existence of the IGKT.

I personally am an advocate for using 6mm diameter accessory cord across the range of friction hitch species. I am also a made keen rock jock climber and prefer to climb with double ropes (ie I use two ‘half’ ropes - each 9mm diameter).

I have found that 6mm cord grabs and reforms well under cyclic loading on parent rope diameters in the 9-11mm range.

I would be keen to to receive feedback and wisdom from the IGKT on this subject…

agent smith

33

Don’t forget other practical uses of knots, such as commercial fishing–which unlike angling uses ropes of equal
and greater size than life-support applications; although in most cases knot failures in ComFish shouldn’t result
in personal injury, you can imagine that those whose very engagement in the whole activity DOES have some
considerable (asserted to be highest …) risk, and whose livelihoods depend on results, do not have great
tolerance for cordage failure, BUT, OTOH, have some experience and that also can be edifying. (I think that
were some new rigger to make a trawl of lobster pots and then those trawls be pulled up losing all the pots
that it might become a personal-injury matter!)

Here are the knots that I would like to put to the guild as a starting point for analysis: KNOT ABoK No. CATEGORY ALTERNATIVE NAMES
  1. Figure 8 loop # 1047 End line knot Figure 8 on the bight, Figure 8 follow-through
  2. Re-threaded figure 8 #1047 End line knot Rewoven figure 8
  3. Double figure 8 loop #1085 End line knot ?Bunny ears? (a truly ridiculous name)
  4. Clove hitch #1178 Mid line knot
  5. Double fishermans knot #498 & #1415 Joining knot (bend) ‘Double English knot’ & a ‘Grapevine knot’
  6. Prusik Hitch #1763 Sliding friction knot
  7. French prusik #1758, #1764 Sliding friction knot ‘Machard Tresse’
  8. Tape knot #1412 Joining knot (bend) Ring bend, Water knot
  9. Alpine butterfly knot #331 & #1053 Mid line knot Linemans loop, Butterfly
  10. Munter hitch #1195 & #1818 Load control hitch ?Italian hitch? or ?HMS? or ?Mezzo Barcaiolo?
  11. Rosendahl bend N/A Joining knot (bend) Zeppelin bend

I regard #1 & 2 as identical knots, different tying methods. (An interesting field study would be
to see if in fact the so-tied knots actually do generally result in identical knots, or, rather, if each
method has a bias toward one vs. another version of the Fig.8. E.g., the most natural/easy way
to begin “re-threading” is a way that could lead to the Weak Perfect form; and sometimes it
seems that torsion build-up in tying in the bight leads to an imperfect completion.) Interesting
that the Fig.9 is missing, though [i]LoaL asserts that it’s regarded as dominant in the UK.

Hmmm, I wonder at not having some variation of Two Half-hitches in the set: what if one needs
to tie off w/o access to the rope end? 2HH w/stopper finish (Slip-knot, for bight tying), or the
Anchor hitch w/similar stopping, makes a handy way to effect this. One can also tie a variation
of Bowline. --or mere Hhitch w/bight through bight … & Slip-knot finish.

Note: Knot number #11 is controversial. There are conflicting ideas about which 'bend' is optimal
One can re-tuck ends, which might both bump strength and further remove loosening => untying risk.
(the tape knot is not used by many Australian rescue teams on account of the wide availability of heavy duty sewn web round slings).
And they join any such slings by metal? I'm still waiting for someone to figure out that a multiple "girth hitching" (a name I do NOT like for this, but it's in the parlance currently) of slings makes seeming sense, at least until/if testing shows some reason to avoid it.
I'm going to re-assert the 4 S's which are: 1. Suitability to task 2. Stability (very important) 3. Security (very important) 4. Strength (not as important serials #2 and #3)
I guess #1 is pretty much the obvious: if one is going to tie two rope ends together (say, to make an endless loop/sling), a stopper knot or hitch is not going to be used. It otherwise is the entire consideration! As to the importance of the others, one might challenge the idea that a knot for tying in needs to be [i]stable[/i], if one keeps the eye small--i.e., that the chance of any "abnormal" loading is effectively removed. In the same way, I could see that [i]security[/i] in the sense of [i]untensioned security[/i] might be deemed irrelevant where the task at hand didn't have any untensioned period--and were it some heavy loading, untiability might be a key characteristic (slack-security, stability, material efficiency all being put aside). But this direction entails knowing [i]knotting[/i] more than merely being able to index from a list of predetermined tasks into a set of knots, really.
For example, there are instances where a clove hitch or a butterfly knot might work, but one might give optimum performance.
... or not; or the trade-offs might be too hard to evaluate to any reasonable degree of clarity. (or even depend upon material!)
Here is another link for you Dan: http://www.forestry.gov.uk/forestry/kirn-5lebje Report date: 2002 Title: Ropes and Friction Hitches used in Tree Climbing operations Author: Paolo Bavaresco, Treevolution
Yes, I need to submit some analysis & questions re this to Paolo. I find some of the results confusing/inconsistent (but might be misunderstanding the test configuration).

Now, about critiquing these various test reports, that remains on the to-do list.
A general critique is that they don’t show exact knots/knot-geometry at play; this means
that one can only guess at the significance of the test results. On break tests, a general
criticism (or wish item) is that they don’t say where the break occurs. E.g., for a Sheet Bend,
is it usually the bight or the loop part that breaks? –that much would be easily told
(which rope …), as opposed to exactly where in the bight/loop it broke.

–dl*