It is said that the size of the shock leader, which is mainly used in lure fishing, is better to use nylon or carbon line that is 3 to 5 times the size of the synthetic line used. Let’s find out why.
Let’s skip the explanation of the PE line and just learn about the knot strength of the fiber, which is related to today’s topic.
If you look up knot strength on the Internet, you will see that it refers to the tensile breaking strength measured when fibers or threads are combined.
To explain this a little more easily with a picture, number 1 represents tensile strength, number 2 represents loop strength, and number 3 represents knot strength.
Fibers generally have the characteristic of being weak in the direction perpendicular to the axis. Among those used for fishing lines, polyester, which is the material for braiding, has the weakest characteristic. Nylon, which has excellent knot strength, is also used to make automobile airbags and stockings by taking advantage of its characteristic.
When expressing the strength of a fiber, the unit called g/d is used, which means the load when a weight is attached to a fiber of 1 denier and the fiber breaks.
Now, let’s take a look at the knot strength of PE, nylon, and carbon lines.
As you can see, the knot strength of the braided line is superior to that of nylon and carbon lines, but when knotted, the strength drops to 40%, so when the nylon line and the braided line are directly connected, the calculations show that the strengths of the two lines are roughly the same.
However, the most important point here is that polyester is 4 to 7 times stronger than nylon or carbon, and yarns made from polyester are on average 5 times stronger.
In other words, the strength of a No. 1 braided line is the same as that of a No. 5 nylon and carbon line. This is why, when using a shock leader, it’s recommended to use a leader size that’s three to five times the size of the main braided line.
But here’s a curious question. When I listen to experienced anglers, they all say that shock leaders tend to burst at the knot.
Why is that? Let’s find out now.
As mentioned before, the tensile strength of the composite is only 40%, that of nylon is 85%, and that of carbon is 70%.
This means that among the knotting methods used when connecting shock leaders, the knot made by only turning the main line, the braided line, without turning the leader, is stronger.
To explain what I mean, looking at the picture, in the case of the FG knot, the leader monoline remains as is, and the yarn is wound to make a knot.
Ultimately, the strength of the monoline remains unchanged, but the strength of the braided yarn at the knot site is reduced by 40%. In contrast, the brad knot, as you can see here, involves twisting both the braided yarn and the monoline to form the knot.
That is, the strength of the knot area is reduced to 40% for the main line, the braided line, and to 85% for the leader, the nylon line.
Therefore, it is said that the FG knot is stronger than the brad knot or similar tank knots.
So, what is the strength of each knot? Let’s look at the test results from a Japanese fishing line manufacturer, as you can see here.
One thing to note here is that the knot strength, expressed as a percentage of the straight line strength of the knot, is based on the monoline used as the leader, not the braided yarn .
This can be seen in the results of an experiment conducted in 2017 by JGFA, the Japanese branch of IGFA, which manages world records for fish caught by fishing, which posted a video a few days ago. Since the story is getting long, I will introduce it next time.
As such, the knot strength of the fibers is weak in the perpendicular direction, so nets for catching fish generally use a knotless mesh.
To summarize the main point of today’s posting, the strength of the straight knot that connects the short leader refers to the ratio of the straight strength of the monoline, which is the leader, and using a number 3 to 5 times greater than that of the main line, the plywood, means that the tensile strength when pulled in a straight line is set to a similar value.
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