Leader design can be an important aspect of fly-fishing success. Building your own monofilament leaders allows you to have broad design latitude and allows you to alter performance characteristics "on-the-fly," so to speak.

Leader Parts
A monofilament leader is typically divided into three sections: (1) the "butt," the large-diameter portion that attaches to the fly line; (2) the "taper," the transition section from the large-diameter butt to the thinner-diameter; (3) "tippet," the final segment to which the fly is attached. Butt section plus tapered section together form the "leader body." There are also "compound tippets." A compound tippet is made of two or more segments of tippet material, the last section(s) typically being shorter than the first (Figure 1). By altering the length and diameter of these three sections, as well as the material used in them, you can create leaders to handle a huge variety of angling situations.

Leader Knots

Knots are certainly a big part of customized leader construction. In my monofilament trout leaders, I typically use a mix of perfection loops, blood knots (including the 5/7 variation) and three- and four-turn surgeon's knots. I connect a foot-long piece of monofilament with a small-diameter (approximately 5/8-inch) perfection loop tied in the end of it to the end of my fly line. I tie matching perfection loops in the end of my leaders to allow loop-on/loop-off leader exchange.

To connect heavier butt and taper sections, I use a blood knot. Trimmed close, the knot is sleek and neat. For tippet sections, I typically use a surgeon's since it is quick, easy, and strong. There are a number of good knot resources out there, including Lefty Kreh and Mark Sosin's book, Practical Fishing Knots, and Bill Nash's Flycasting Systems booklet.

Leader Math
Leader material diameters are typically measured/designated in three ways: millimeters, thousandth's of an inch and "X." The thousandth's measurement and the X designation usually see the most use in the USA. An example of each that you might see on a spool of leader material would be as such: .009" (read as "nine thousandth's") and 2X (read simply as "two X"). The X designation has a relationship to the thousandth's diameter. This relationship will be explored a little further on in this article.

When connecting leader sections, you can often drop the diameter of each subsequent section by as much one-third (more in some cases). Dropping down quickly allows you to build leaders with fewer overall segments, thus speeding up the whole construction process. This is especially useful if you are building leaders on the water. So, instead of stepping a leader down from .020" to .018", to .016", to .014", etc, you can step down from .020" to .013" to .010" (notice that I wrote "can step down," not "must step down").

To make the math simple enough for mental on-the-water work, eliminate the decimals. In other words, a diameter like .009" would be thought of simply as "9." Then, take that number, multiply it by 2, and then divide it by 3 to get the next smaller size you can use. For example, 9 * 2 = 18. Then, 18 / 3 = 6. The number "6" corresponds to .006". Once you get "multiply by two, divide by three" going in your head, you can do one third step-down calculations with speed and ease.

This is a good place to introduce the widely used "subtract from eleven" rule. This rule gives you a simple, fast way to determine thousandth's diameter or "X" designation of a section of leader material, as long as you have one of the two numbers. The baseline for this rule is 0X, which is .011. To get either "X" or thousandth's subtract the other number from 11 (see conversion table).

When doing the math, it initially helps to view the thousandth's diameters sans decimals. First run the calculation on the baseline, which was identified as 0X or .011". Here is the math: 11 - 11(.011") = 0(X), or 11 - 0(X) = .011". At the other end of the scale would be this: 11 - 1(.001") = 10(X), or 11 - 10(X) = 1(.001"). Here is a third example, using a middle-of-the range diameter: 11 - 6(.006") = 5(X), or 11 - 5(X) = 6(.006"). Run through the rule a few times and you will have it.

Tippets given X designations beyond that of 10X (definitely specialty items) obviously cannot fall under this "subtract from 11" equation. In addition, materials larger than .011" are sometimes given an X designation. An example would be .012", which is sometimes described as "01X." In such cases, the X numbering scheme gains a "0" at the front and ascends as the thousandth's diameter of the material increases (.013 would be 02X, .014" would be 03X, and so on). You can work a variation of the "eleven" rule to deal with these designations: subtract 11 from the thousandth's diameter to get the X designation (for example, .012" - 11 = 01X) or add 11 to the X designation to get the thousandth's diameter (for example, 01X + 11 = .012").

Leaders for Dead-Drifting
The theory behind these leaders is quite simple: they must deliver the fly and then allow it to drift as naturally as possible. The seminal concept behind dead-drift leaders sprang from the fertile mind of George Harvey, who built the first such leader to fish terrestrial imitations drag free on the surface. He built a leader that turns over but does not straighten like a poker. It falls to the surface in a series of "S" curves; curves that the currents must straighten before the fly begins to drag.

To do this, Harvey used a thin-diameter butt section, a long, tapered section and a long tippet. The leader carries enough energy to get the fly out there, but not enough to completely straighten. The Harvey-style "noodle" leader has become the paragon of modern dry-fly monofilament leader designs.

The dry fly leaders that follow are built a bit differently than Harvey's (they use fewer segments), but the theory is the same. For size 10 through 14 flies, for example, a leader might be built with 1 foot of .017", 4 feet of .013", 1 foot of .010", and 4 feet of 4X (Figure 2). A dry fly leader to fish size 20 and smaller dries, for example, might use 1 foot of .017", 1 foot of .013", 4 feet of .010", 4 feet of 4X, and 1 foot of 6X or 7X (Figure 3).

A 15-foot leader to fish the western spring creeks with #16 imitations of Pale Morning Duns? Start with 5 feet of .017", add 5 feet of .013", 1 foot of .010", 3 feet of .007", and 1 foot of .005" (Figure 4). It's really windy you say? Try 10 feet of .017", 1 foot of .012", 3 feet of 2X, and 1 foot of 6X (Figure 5).

Leaders for dead-drifting nymphs along the bottom are a different story. They have to perform much differently than dry-fly leaders. The leader has to help control the strike indicator, fly, and split-shot. It must also allow for rapid sinking of the fly, but still be abrasion resistant (the tippet will be scraping over the rocks of the bottom).

For such work, start with four feet of .020", step down to 1 foot of .013", and add a 4-foot tippet of 1X or 2X. To the end of the tippet add 6 to 8 inches of 4X (Figure 6). The fly goes at the end of the 4X. The split-shot goes just above the knot that joins the 4X, the indicator goes anywhere on the piece of .013". The long tippet of 1X or 2X allows the fly to sink quickly and the fly drifts at the end of the 4X.

Leaders for an Active Retrieve When fishing leeches, big wet flies, mice, minnow imitations, and the like with an active retrieve, I use a shorter, heavier leader than when dry fly fishing or when nymphing. A typical, 7-foot, Active Retrieve Leader for a Strip Leech would consist of 4 feet of .020", 1 foot of .013", and 2 feet of 2X (Figure 7). If I needed to drop down to 3X or 4X, I would simply add a foot of it onto the end of the 2X. If I needed the tippet to be heavier than 2X, I would replace it with 1X or 0X. In Alaska, I may use 3 to 4 feet of .020" and 2 to 3 feet of .013", nothing else (Figure 8). You can certainly go shorter and thicker. For example, a stout 5-foot leader can be made by using 3 feet of .024", 1 foot of .015", and 1 foot of 0X.

Leaders with a Uni-Body
The "Uni-Body" leader comes from my father, Gary, who formulated it in the early 1980s as a way to conserve tying time while simultaneously allowing broad design latitude. Actually, the Uni-Body is not a single leader that does it all; rather, it is a way of thinking about the leader that allows the fly fisher to make rapid adjustments based on angling conditions.

The basic Uni-Body leader body (originally formulated using Maxima Chameleon brown) consists of 4 feet of .020" and 1 foot of .013" tippet (Figure 9). If you need a shorter or longer leader, shorten the leader body by decreasing or increasing the length of the .020" (see examples that follow).

For a Uni-Body system that is used to dead-drift imitations along the bottom or to work flies slowly along the bottom in stillwaters, use the basic Uni-Body and add a compound tippet consisting of 4 feet of .010" and 6 to 8 inches of 2X, 3X, 4X, or 5X to the leader body. If 6X or 7X is needed, add 4 to 6 inches to the 4X. The length of the finished leader will be approximately 9 1/2 feet (Figure 10).

To make a 24-foot Uni-Body Leader to sink a snail over a submerged weed bed in stillwaters use 18 1/2 feet of .020" and 1 foot of .013" (tippet consists of 4 feet of .010" and 6 to 8 inches of 4X) (Figure 11). A leader for use in fishing nymphs with a Bow and Arrow Cast would need to be shorter than the rod, so the leader formula could be 1 foot of .020", 1 foot of .013", 4 feet of .010" and 6 to 8 inches of 4X. The total leader length would be 6 1/2 feet (Figure 12).

To make a Uni-Body Leader for dead-drifting artificials at the film, add a compound tippet consisting of 4 feet of .010" and 2 to 4 feet of 2X, 3X, 4X, or 5X to the leader body. If 6X or 7X is needed, add 1 foot to the end of 4X. The total leader length will be between 11 and 15 feet (Figure 13).

A slight Uni-Body variation that keeps total leader length manageable, yet still allows for drag-reduction, is to add 1 foot of .010", 2 feet of 4X, and 2 feet of 5X or 6X. The total leader length is 10 feet (Figure 14).

To modify the Uni-Body Leader to fish leeches, minnow imitations, big wet flies, mice imitations, and so on with an active retrieve, add 1 to 4 feet of .010 to the leader body (Figure 15). If 3X or 4X is needed add 1 foot to the end of the .010.

For 1- through 3-weight lines, you may wish to use .017" or .018" in place of the .020 when building the body of the Uni-Body Leader (Figure 16). For heavier lines (say 7-weight or greater), you may wish to go to a butt section of .024 (or thicker), with the subsequent sections following suit.