Tenkara line numbers. What do they mean?

[drolfson]

Okay, I ordered a rod. I am now dying for it to arrive and thus spending too much time reading, which only gets my rod arm twitching and makes it worse.

One thing that keeps coming up that I have yet to find an explanation of the various (level?) line 'sizes' that are referenced. They are referred to as #3, #3.5, #x.y and whatever. At first I thought that was the length, then I saw someone referring to a fishing trip where they used different lengths of #3.5 line on a rod. That got me searching and I (think I) have read all the different line explanations, but have yet to find a clarification on that line sizing designation. I know one of you has the answer for this, or knows where it is explained and I have yet to find. Please enlighten me.

Thanks!

Don

[Bob9]

Long rods, big flies = 4 or 4.5
Average rods (11-12'), normal flies = 3 or 3.5
Short rods or finesse rods = 3 or smaller
Line length depends on casting ability. Best to start with line the length of the rod, plus 3 or 4' of tippet.
All of this is subject to change, as your experience grows.
Hope this helps.

Bob

[drolfson]

Thanks Bob. That does begin to clarify things.

I am wondering what the numbers relate to. I know it is not a pound test, but is is a diameter or a mass per certain length (like flyline is supposed to be) or some other such thing?

Thanks,

Don

[Bob9]

It's a Japanese rating system. Their lines and hook sizes have much smaller number ratings, than similar U.S. products. Not sure what they base them on.

Bob

[CM_Stewart]

I once had a link to a site that explained how the Japanese line size system was originally developed, but the history of it doesn’t tell you what you need to know now.

For all practical purposes, you can multiply the Japanese line size by 4 and get the equivalent pound test for US fluorocarbon spinning line, so size 4 line is essentially 16# test, size 3.5 is roughly 14# test and so on. That holds until you get down to tippet material, where advances in technology make the smallest sizes stronger than that quick ratio would suggest.

The tippet size equivalents are as follows:
X number – Japanese line size
1X – 2.5
2X – 2
3X – 1.5
4X – 1
5X – .8
6X – .6
7X – .4

[drolfson]

I think I found just what I was looking for. It appears that Jason Klass has put together a little chart that lists what I was expecting, along with what Chris has replied above.

It can be found here: http://www.tenkaratalk.com/2013/03/t...el-line-chart/

Hopefully it helps others also.

Thanks,

Don

[tenkara.cz]

Also look at http://www.tenkaratimes.com/tenkara-...-western-scale for more information about japanese line sizes.

[dwalker]

..One thing that keeps coming up that I have yet to find an explanation of the various (level?) line 'sizes' that are referenced. .. I (think I) have read all the different line explanations, but have yet to find a clarification on that line sizing designation. ..
Don

Hello Don and the FAOL Tenkara group. I am new here but not new to Tenkara. I have been Tenkara fishing about 4 years. Since this is my first post here I hope I get the process correct.

I have studied the the Japanese/Asian line sizing system a lot. Here is the short answer:
When fly fishing/Tenkara fishing we cast the line not the fly. So we need to know something about the size or weight of the line. The Japanese line numbering system tells us about it in a very simple way.

The line numbers are the ratio of the line weight referenced to size no. 1 line. Or the ratio of the Cross Sectional Area of the different sized line referenced to the Cross Section Area of no. 1 line.
For example:
no. 3 line will have 3x the weight of no. 1 line ( 3/1).
no. 4 line will be twice the weight of no. 2 line (4/2).
no. 4 line will be 1.33x the weight of no. 3 line or 33% percent higher.
no. 2.5 line will be .833x the weight or diameter of no. 3 line or 16.6% less.

Simple and useful information. Of course after a while you'll develop an intuition about what line size to use with which flies or which rods. But that is the engineering behind the the system and understanding it can help you make educated choices, not just guesses. about what line to buy and use. No need to be like a politician pulling budget numbers out of his...... er..... out of the air. : - 0, There is logic to the system.

Maybe this clarified how the line numbering system works and what the numbers mean, and how to use them to make logical line choices.


The LONGER ANSWER ( only for those interested in the finer details :
For historical reasons having to do with how silk was measured since ancient times in the 1950s line size no.1 ( １号数, Issue Index 1) was set as the reference size of nylon line. Other sizes of line or other types of line, such as Fluorocarbon line, really have no standard other than the honor system or the integrity to produce a quality product.

All the other different sizes of line are referenced to size no. 1 (１号). Which is .165 mm in diameter. A line this diameter will have a Cross Sectional Area ( CSA) of .02138 mm square.

The index number of the line is the ratio of the CSA of the other line sizes referenced to size no. 1 line.

For example:
size no. 2 line will have a CSA of .04337 mm^2. Or 2 x the CSA of no. 1 line. .04337/.02138 = 2.
No. 4 line CSA = .0855 mm^2. .0855/.02138 = 4.
5x tippet is line size no. .8 with a diameter of .148mm and CSA = .0172. 00172/.02138 = .8. And so on.

A second way to look at the line numbering system is that it is the ratio of the weight of the line, reference to the weight of no. 1 line.

In the textile industry it is difficult to keep an exact diameter over the length of the line. But it is easy to keep the diameter of the line to an average diameter that meets the standard for that size line. A line made in a given diameter, from a given material, will have the same weight for a standard length of the line. The textile industry uses 2 different measures. The Denier, that equals the weight of the line in grams for 9,000 meters. Or the dtex , that equals the weight of the line in grams for 10,000 meters.

The denier for no. 1 line = 340 grams/9000meter. This is the reference weight.

So for example :
Denier for 5x = 272g/9000m. 292/340 = .8 Therefore no. .8 line will be 80% of the weight of no. 1 line.
Line size no. 2 Denier = 680g/9000m. 680/340 = 2. Thus no.2 line is 2x the weight of no.1 line.
Line size no. 3 Denier = 1020g/9000m. 1020/340 = 3. Or 3x the weight of no. 1 line.
Line size no. 10 Denier = 3400g/9000m. 3400/340 = 10.

In summary the Japanese line numbering system tells you the ratio of the line CSA or the Line Weight referenced to line size no. 1.

The Denier value for a given size line will vary from one line manufacturer to another because they use different chemical formulas for their nylon or fluorocarbon line or other type lines. The above Denier values are from the yoz-ami website , the only place I can find that provides this information. Most other websites I find that discuss this topic more often than not also reference the yoz-ami web pages.

The yoz-ami website also provides a good description, in English, of the different ways Japan/Asia, the USA, and Europe measures their line. Japan/Asia system uses the ratio system, The USA the pound test system. Europe uses a system that is, more or less , a mix of the other two systems or standards.

See http://www.yoz-ami.jp/english/line_t...ogy/index.html

You can see the standard line diameter values, and their denier values for their line on the following Japanese language webpage. You only need to look at the table at the bottom of the page. The first column is the line Index Number or Issue Index (号数) . The second column is the standard line diameter in mm. ( all the companies use these standard line diameters. The next column is the Denier values for nylon line ( ナイロン). You will be most interested in the next column for Fluorocarbon line (フロロカーボン). The last column is for PE line.

http://www.yoz-ami.jp/line_technology/040.html

Note Two Things. 1) the fluorocarbon specific gravity they use is 1.78. That means fluorocarbon is 78% heavier than water. Other companies may use different specific gravity values for FC line. , and 2) the line for size 1 line is in Red. Because it is the Reference value.


fwiw,
David