1. How Much Strength Did the Line Lose With Each Knot?
The test was part of an online series by the Honda fishing club in Japan. It was done at the Tokyo office of the Japan Game Fish Association, which owns a machine that pulls line until it breaks. The line was ordinary nylon labeled "10 lb" (about 5 kg). Each knot was tied four times and pulled to the breaking point, and the site reports the average. Pulled straight with no knot, the line held about 5.4 kg, which counts as 100 percent [1].
Here is what each knot kept, as a share of that straight pull [1]:
- A single overhand knot tied in the middle of the line: 73 percent
- Clinch knot, tied to a ring or hook eye: 26 percent
- Improved clinch knot: 36 percent
- Double clinch knot: 84 percent
- Improved double clinch knot: 88 percent
- Palomar knot: 82 percent
- Uni knot: 68 percent
- Jansik Special: 68 percent
- Eizo Special (a clinch-style knot finished with several half hitches, invented by the expert the site interviewed): 96 percent
Two things stand out. The plain clinch knot, a classic taught to many beginners, did worse than a simple overhand knot in the middle of the line. And the individual trials varied a lot. The double clinch knot, for example, broke at anywhere from about 3.4 kg to about 5.3 kg [1]. With four tries per knot, these numbers show a pattern for this one line and this one setup. They are not a fixed score for each knot.
2. Why Does Any Knot Make a Line Weaker?
The Honda club's explanation is that a knot concentrates the load. When a strong pull comes, the force piles up at the knot, and the line finally breaks there as the knot cinches down on itself. The same page adds that friction heat appears as the line suddenly tightens, and that this heat also weakens the line [2].
Physics writing about ropes describes the same idea. In a straight rope all the fibers share the load equally. Where a knot forces the rope to bend, the pull is not shared evenly: some fibers take more of it, and the rope breaks there. For ropes in general, even the best knots lose about 20 percent of the strength, and a simple overhand knot loses more than 50 percent [4]. That is a statement about multi-fiber ropes, not about a single-strand fishing line, so it is a picture of why knots hurt and not a number for fishing line.
Sources do not agree on the overhand knot. A British fishing guide says a plain overhand knot ("granny knot") can halve the strength of any line [3], while the Honda test found 73 percent for one overhand knot [1]. The two used different lines and ways of testing, which is a good reminder that one number does not fit every case.
3. Why Did the Plain Clinch Knot Do So Badly?
The expert in the Honda test points to slipperiness. Modern nylon line is almost perfectly round when you look at its cut end, and many lines have a coating that makes them far smoother than older lines. A smoother line is easier to pull through a knot. In the test, the plain clinch knot was the one that slipped most, which fits its 26 percent score [1].
The expert's rule of thumb is that the more places where line touches line or touches metal, the more friction there is, so the knot slips less and holds more. The four clinch variants line up with that idea: passing the line through the ring twice (double clinch) brought the score from 26 up to 84 percent [1]. The British guide says knots fail for two main reasons: they slip under load, or they are built so that one strand cuts across another [3]. A simple way to picture it is that a good knot has the line grip itself and does not rely on one tight pinch.
One thing the test does not show is why the palomar knot did well. It has no wraps at all and still kept 82 percent, close to the double clinch knot at 84 percent [1]. Simple does not always mean weak.
4. Why Do Anglers Wet a Knot Before Pulling It Tight?
This is where heat comes back in. The Honda club advises moistening the knot with saliva or water before tightening, and tightening slowly: gently at first, then firmly at the end. Pulling hard right away makes a sudden burst of friction heat and can leave parts of the knot not fully tightened, and those parts can snap shut later when a big fish pulls [2].
The British guide gives the sharpest picture. In nylon and fluorocarbon line, friction can heat one small spot enough to melt the outer layer of the line, so the knot fails at once or leaves a weak spot that gives way later in the fight [3]. Wetting the knot makes the line slide more easily and keeps the rubbing cooler. None of the sources I read gives a temperature or measures how much strength wetting adds, so the effect is explained, not counted.
The same guide warns that braided line, which is more slippery, is less likely to melt but more likely to slide completely undone, especially when wet [3]. Advice about wetting a knot therefore applies to nylon-type line and should not be copied to every line.
5. Does a Bigger Knot Scare Fish Away?
This question is easy to wonder about, since a lump on the line might look suspicious under water. I could not find an experiment that tests how visible a knot is to fish, so this article cannot say yes or no. What the sources do show is that a good knot is mostly about holding, not about being small or hidden.
6. How Can You Test the Idea That Rougher Surfaces Hold Better, Safely at Home?
You can try a small version with household string. Choose two cords of about the same thickness, one smooth and slippery and one rough. Tie each with the same knot around a smooth rod or pencil, and tug gently to see which slips more. Different cords differ in more than their surface, so if one slips more, the surface may not be the only reason. Pull gently, because a hard pull can hurt your hands. If you would like to see real numbers, read the Honda page below and notice how many tries each knot had and which line was used.