An experimental analysis of leader-tippet-fly knots

Oh we'll just "test some knots at the pub"? - well smack me in the face with a wet trout and call me the Sally, the devil IS in the details!  After considerable experimentation we eventually derived an apparatus that could be used to reasonably consistently measure knot breaking strengths:

Figure 1 - The Apparatus

The elements of the apparatus are described as follows...

The Test Subject

Figure 2 - The Test Subject

The test subject consists of a length of leader and a length of tippet, attached to each other by a certain 'leader-tippet' knot, as detailed below.  At either end of this line a fly hook is attached - at the tippet end to allow the tippet-hook knot to be tested, and at the leader end for convenience in order that the test subject may be mounted and dismounted from the apparatus with ease.

The Safety Line

Asides from, of course, wearing suitably thick brimmed eye protection, further safety measures were necessitated as we quickly discovered that upon breaking, the fly hooks were indeed flying all over the kitchen and becoming increasingly difficult to recover as the light of the day faded.  In the image below you will see the tippet-fly knot and two blue backing lines attached to the hook - one is the safety line (hanging loose), and the other is the loop that is attached to the bass bag below:

Figure 3 - Tippet-hook and safety line detail

The Weights

For weights, we needed a selection of uniformly weighted items that could be added to the bass bag relatively easily.  The Gold Flash Damsel insisted that it would be more realistic to use trout.  After much debate we settled upon cans of tomatoes (400g), pears (220g) and beans (200g).

Figure 4 - The weights

Calibration of the Weights

The weights advertised on the cans did not of course include the weight of the can itself, so we established an order in which the weights would be added, and used a luggage scale to measure the cumulative weight of the cans and the bass bag

Weight	Test 1	Test 2	Test 3
2 Tomato	1.10	1.07	1.10
2 Tomato, 1 Pear	1.34	1.35	1.35
2 Tomato, 2 Pear	1.62	1.63	1.65
2 Tomato, 3 Pear	1.91	1.90	1.91
2 Tomato, 4 Pear	2.17	*	*
2 Tomato, 5 Pear	2.47	2.43	*
2 Tomato, 5 Pear, 1 Bean	2.75	*	*
2 Tomato, 5 Pear, 2 Bean	3.01	*	*

Table 1 - Weight calibration
* the results of these measurements were not collected due to rum-distraction
Now, of course you, the illustrious reader, have noticed something awry and suspicious about the numbers above! Yes, it is true - the luggage scale does not appear to be entirely linear in its measurement!  The average incremental weight of pear cans 1,2 and 3 are 257g, 287g and 273g respectively.  We repeated the test several times with the cans in different order to confirm this astonishing result.
Experimental Method
The test subject is mounted in the complete apparatus as shown in Figure 1.  The intrepid angler then carefully adds weights to the bass bag until the line breaks

Figure 5 - The Wandering Rod's experimental technique
While recording Mr L's experimental technique, by a stroke of the most unexpected and gratifying luck, we did in fact capture an image of the very moment when the line had broken and the bass bag was suspended in air by nothing at all other than the temporal fixation of a photo image!  The reader will find close examination of the right-hand image in Figure 6 to be extremely rewarding.

Figure 6 - Mr L's experimental technique. Note the bass-bag 'in flight' on the right

The Keeping of Records
This is the most essential part of any experiment, and it is with great regret that I must admit the records were a little hard to decipher at first and so there may be some outliers in the results due to transcription errors.  Figure 7 shows the initial approach (left), and the refined approach (right) that we established once we realised how hard it was to extract meaning from the manic scribblings we had collected so far.

Figure 7 - Questionable (left) and systematic (right) record keeping

The Crash Pad
Now you, the most venerable and eagle-eyed reader, will of course be thinking "But what of this 'crash pad' that is mentioned in the schematic above?"

Figure 8 - Motivation for using a 'crash pad'
As can be seen in Figure 8, the act of repeatedly dropping cans of tomatoes, pears and beans onto a concrete floor will eventually yield a predictable and gruesome result.  In order to prevent further mésaventure avec des légumes, it was deemed sensible to put a pillow on the floor to absorb the impact of the bass-bag when it dropped

The Results

Figure 9 - The laboratory

With great pleasure, may we present the results of our experimentations.  Excluding obvious outliers from the results, the average breaking strengths of the knots are summarised below.  Note that a standard weight of two tomato cans was present in the bass bag before the pear cans were added.

Knot	Tier	# Pear Cans	Average Breaking Weight	% of breaking strength
Palomar Knot	The Wandering Rod	3,3,4,3,3,3	1.95kg	67%
Clinch (5 turns)	The Wandering Rod	1,1	1.35kg	47%
Clinch (7 turns)	The Wandering Rod	4,4,4	2.17kg	75%
Clinch	Mr L.	3,4,5,5,4,5,4	2.25kg	78%

Table 2 - Tippet-hook knot results

Conclusion: a well lubricated and dressed clinch knot, with 7 not 5 turns, performed reliably well.  It occurs to the author that the '5 turn' clinch knot, that performed so poorly, may have effectively been a 4 turn knot due to half a turn unwinding during the threading of the tag through the eye.

We can say with confidence that the Palomar knot has been proven to be weaker than the clinch knot.

Knot	Tier	# Pear Cans	Average Breaking Weight	% of breaking strength
Figure Eight in video at 3m54s	The Wandering Rod	3,4,4	2.08kg	72%
Figure Eight in video at 3m54s	Mr L.	4,3,5	2.17kg	75%
Surgeon's	The Wandering Rod	†,†,†,†	Unmeasurable	More than 75%
Surgeon's	Mr L.	†,†,†,5	2.45kg	More than 84%
Blood Knot	Mr L.	4	2.17kg	75%
Double-Clinch	The Wandering Rod	4	2.17kg	75%

Table 3 - Leader-tippet knot results

† indicates measurements where the tippet-hook knot broke and the surgeon's knot held.  These 'non-breakages' were not shown for the other knots.  The surgeon's knot proved to be the strongest knot and without a stronger knot to test it against, the breaking strength was not directly measurable!

The Blood Knot proved incredibly tricky to tie, particularly since the two lines being joined have different diameters (.3mm vs .178mm).  More often than not the tippet turned into a mess of line that wrapped itself around the leader, which itself had gone straight.  Mr L. laboured at great length and only produced one blood knot that he deemed of sufficient quality to be tested meaningfully.  We propose that this knot be relabelled "The Blood Sweat and Tears Knot"

Figure 10 - Mr L's "Blood Sweat and Tears Knot"

Admittedly, upon further analysis of the literature we realised that The Blood Knot is not recommended when joining lines of different diameters.  We concur.

Conclusion: the surgeon's knot outperformed the 'Figure of Eight', which is surprising considering the strong support that the Figure of Eight knot has in other forums.  Note that the Surgeon's knot can also be described as a 'two turn water knot'.

Summary and Observations

For the time being we will certainly be using the Surgeon's knot to join leader to tippet, and the 7 turn clinch knot to join tippet to hook.

The experiment raises some questions that should be investigated in subsequent sessions:

1. A means of testing the breaking strength of the surgeon's knot needs to be devised  
2. Would a 3 or 4 turn water knot outperform the 2 turn water knot a.k.a surgeon's knot?  
3. What are the breaking strengths of the clinch knot when a different number of turns are made?

It is raining so much outside, I expect to see fish swim past the window any moment now.