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 | * | * |
Figure 6 - Mr L's experimental technique. Note the bass-bag 'in flight' on the right
Figure 7 - Questionable (left) and systematic (right) record keeping
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"
Admittedly, upon further analysis of the literature we realised that The Blood Knot is not recommended when joining lines of different diameters. We concur.
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:
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:
- A means of testing the breaking strength of the surgeon's knot needs to be devised
- Would a 3 or 4 turn water knot outperform the 2 turn water knot a.k.a surgeon's knot?
- 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.
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