X System vs Pounds

[Tony Buzolich]

Trying to keep these two questions seperate but still understand each.

What is the reason for the X System? 3X, 4X, ??? Whatever?

Why isn't everything in pounds that people can understand? This is a question that never stops coming up. Line vs. tippet? and Pounds vs. X System?

I've been around fly fishing for a long time but have never found a good answer for these two questions.
TONY

[Rick J]

Hi Tony,
The main reason for x designation is often what is important is diameter rather than pound test - various manufacturers have different breaking strengths per diamter. The x designation is a rule of 11 - subtract the x from 11 to get the diameter in thousands of an inch (and vise versa).

For trout fishing the rule of 3 or 4 governs - divide hook size by 4 for freestone and by 3 for spring creeks to select tippet size for the hook in question

[jfkowalski]

I learned the rule of 4 as"divide by 4 and add one" This give you roughly the same as the rule of 3 or divide by 3 and don't add anything.

[Hairstacker]

Specifically, the "x" system is a holdover from the days when gut was used for leader material. In those days, gut was drawn through ever smaller holes to obtain the final desired diameter: One draw was 1X or .010". Three draws resulted in a 3X rating or .008", and so on. We've retained this sytem, I suppose, because each "x' number is associated with a very specific diameter which, as Rick noted, is the key in designing a tapered leader with specific performance requirements. And maybe "4X" is easier to remember and talk about than ".007 inches." :wink:

By the way, you might be amazed at how much test poundages vary by manufacturer for a given diameter of monofilament. For example, I've seen 1X tippet material vary anywhere from 4 pounds to 13.5 pounds, depending on brand. :shock: Therein lies the problem in using test poundages to denote size -- for example, if you were to select, say, a 4 lb test tippet, for one manufacturer you'd be selecting a 1X tippet and for another manufacturer you'd be picking a 5X tippet and, as you know, there is a huge difference in the performance characteristics of 1X versus 5X tippet.

Leaders also vary significantly between brands in stiffness as well, of course. The ever-popular LeaderCalc (freely available on-line) program provides some of this information regarding relative test poundages and stiffness between brands if you're interested.