Millions of school children have been told that Isaac Newton was sitting under an apple tree when an apple fell on his head, giving him the idea that led to his description of gravity and his laws of motion. I prefer to think that he was sitting under a tree pondering how Charles Cotton, who had written the fly fishing chapters of the Compleat Angler only a few years earlier, could cast such a light line. It's all about physics.
It turns out that the taper of a line makes the line tip speed up as it "turns over." The crack of a whip is a small sonic boom created when the tip actually breaks the sound barrier. Tenkara lines don't break the sound barrier, but the physics of cracking a whip and casting a tenkara line are very much the same. The energy stored in the line as it is cast helps the light line tip overcome wind resistance.
I don't want to get into the whole Force = Mass X Acceleration stuff, because once you get past assuming a vacuum, things get pretty complicated. Assuming a vacuum is a bit like assuming you have permission to fish the Upper Beaverkill. Things could get very complicated. Very complicated indeed.
The sad reality is that you're never going to cast in a vacuum (and you're never going to get permission to fish the upper Beaverkill). You'll always have to overcome wind resistance, which is the factor limiting how light a line you can cast. Charles Cotton was able to cast so light a line because a wet
is actually pretty dense, and has enough weight to overcome its wind resistance.
For modern line materials, fluorocarbon is quite a bit denser than nylon mono, so you can cast a lighter line if it is made with fluorocarbon than if it is made with mono. Whichever material is used, you want the end of the line to which the tippet is attached to be heavy enough to turn over the tippet and fly, yet light enough that it lands on the water softly. The minimum weight to turn over the tippet, however (particularly with fluorocarbon), is light enough that a whole line made from it would be too light to cast with even a soft rod.
To get a line where the tippet end is as light as possible and yet have a line heavy enough for the rods to cast, it is necessary to taper the line. This is particularly true for the stiffer rods like the Yamame or Hane. That is not to say that they can't cast a level line, it's just that a level line heavy enough for them to cast easily is heavier than necessary to turn over the tippet.
The softer 5:5 rods (for example the Daiwa LL36SF) do not require as heavy a line to cast easily. A level line that is heavy enough for them to cast is not so heavy that it causes substantial disturbance when it lands on the water. For them, a level line becomes a reasonable compromise - not too heavy, not too light, and not too complicated. I believe that is why in Japan, 5:5 rods are generally thought of as being level line rods. And that is not to say they can't cast a tapered line, it's just that getting the taper right so that there is enough mass at the line tip without making the whole line too heavy is a tricky business.
As a rule of thumb, and subject to your own personal preferences, I would suggest tapered lines for the 7:3 rods and level lines for the 5:5 rods. The 6:4 rods will cast either.
|Original Tenkara USA tapered line|
Most of the commercially available tapered tenkara lines cast well with just about all the tenkara rods. They do cast very nicely but there is a potential problem with lines that are extremely easy to cast. A line that is heavier is easier to cast. It loads the rod nicely and is unaffected by wind resistance. The only problem is that you can't keep it off the water's surface.
The same drag that makes Western fly fishing less effective than tenkara makes heavy tenkara lines less effective than light tenkara lines. Getting the weight right on a tapered line is very tricky. It has to be heavy enough to cast well with a 7:3 rod yet still be light enough to fish well in moving water with conflicting currents.
In addition to light weight, for me high visibility is critical.
Hi-Vis line needed here
I write about hi-vis lines a lot, and the photo above illustrates why. With a dark green forest background on both sides of the stream, there is no way I could see a green tenkara line while I am casting. If I can't see the line as I am casting, it will take precious time to find it after the cast. Because strikes occassionally come within seconds of your fly hitting the water, you have to be ready immediately, picking your line up off the water and taking the slack out of your line. If your line isn't easy to see, you'll miss some the drift and you'll certainly miss some of the strikes.
I think most tapered tenkara lines are made from nylon mono even in Japan. I prefer fluorocarbon to nylon because of its greater density (which helps to overcome wind resistance). For my own use, I tried to address my desire for a hi-vis tapered fluorocarbon line with my
artificial horsehair line,
which was made from bright pink fluorocarbon. Unfortunately, I ran out of the diameter that I used, and I cannot get more. I have tried to make the artificial horsehair line with my fluorescent orange Hi-Vis fluorocarbon, but the smallest available diameter is still too large to make a good artificial horsehair line.
I do have the right diameters of the Hi-Vis fluorocarbon to make very nice tapered
hand tied lines
from it though, which have the added advantage of not twisting or tangling when you have to break off a snag. And not only does it not tangle, it is still light enough to hold off the water's surface. Several people tell me it is now their favorite line.
If you have any questions about tapered lines (or anything else about tenkara, for that matter) please go to the
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