Odds 'n' Sods of Information and Opinion

Leader Design

Making Your Own Leaders

When I’m reading questions about leader designs on various forums and in magazines, I’m often struck by how little thought has gone into the fishing aspect of the design as it seems that everyone is concerned primarily with turnover. A lot of the discussion sees to be centred around finding a single, all encompassing leader formula and once we have it, we’re off to the races, but no single leader formula can encapsulate all fishing situations.

As a principle, I always design my leaders more for how they perform in the water than how they perform in the air. The leader decisions are made stream-side based on the water conditions, the presentation dictated by those conditions, the fly I intend to use and how I intend to fish.

Leader Decisions

Rather than follow some arbitrary formula, leaders should be built or selected stream-side based on these questions.

  • Turnover - do we want the fly and leader to lay out straight so that it is under tension immediately or do we want the turnover to be only partially straight so that the fly can sink unimpeded for a while?
    • Sink or Float - do we want our leader to facilitate sinking or resist it?
    • Fly - is our fly hard to extract on the anchor and difficult to turnover due to size, weight and/or drag, or is it very easy to extract and turnover?
    • Separation - do we need to separate the fly from the fly line as much as possible thanks to clear water and/or spooky fish?
    • Droop - do we want the fly to run well below the tip of the fly line or are we content to let the fly stream straight back?
    • Strength & Abrasion - do we ned to construct a strong leader to hold up to big fish and tough conditions or is this not an issue?
    • Type of Fly Line - do we need to get deep with a floater or run shallow with a sinker?
    • Casting - do we have problems with blown anchors?

Questions 1 to 7 can be addressed by leader design, but question 8 should be solved by improving our casting. I don’t believe that leader design should ever be influenced by the need to make our casting easier.

Mono or Fluorocarbon(FC)

Anglers should be prepared to make leaders out of either material. Whenever I hear of someone claiming that, “I only use mono.” or “I only use FC.” it makes me think of how much added capability that they are missing. Each material comes with a set of strengths and weaknesses that can be exploited/avoided through appropriate use.

The primary difference between the two for swinging flies isn’t in their refractive properties, rather it’s in their respective densities. FC is much denser than mono so it sinks better. So obviously when sinking is paramount, only FC should be used. Conversely, when we’re trying to keep a fly from sinking too much, or not at all for example when waking a fly, then mono is the best choice.


FC gets criticized for poor knot strength, but the reality is that poor knot tying technique can cripple both materials. In the past, I’ve pulled tested all of my knots and still lost fish when the either the fish hit hard or made a sudden jerking maneuver. The sudden hard jerk causes the knot to slip a tad and pinch, producing a failure. For a while I was puzzled by this as these knots seemed solid when I pulled on them hard. The Uni-Knot (also called a Duncan Knot) and Perfection Loops didn’t fail often, but the Triple Surgeon’s knot for the tippet let go with distressing regularity. Later I learned a trick from an old guide to improve this knot. Snug the well-wetted knot down lightly while holding all four strands, then jerk it tight by pulling on the main lines only. This jerk-tight method tightened the knot much better than a strong pull on all four strands and it took up the slack within the knot. It also causes a poor knot to fail immediately before I tie on the fly and hooked a fish with it. From that point on, all of my knots, whether FC or mono became the least of my worries. I simply don’t have knot failures anymore.

Matching the Fly

This has to be one of the most critical aspects of leader design for if the leader doesn’t fit with the characteristics of the fly, we can be in for long, fruitless day on the water.

  • Big, heavy, high drag flies need short, thick leaders to both extract them on the cast and to turn them over. Trying to cast these flies on a long, thin leader will be an exercise in frustration.
    • Small light flies need a thin leader to retain their action. A thick leader will overpower the small fly and cause it to swim poorly.
    • Long, thin, FC leaders sink better then short, thick, mono ones, so when going deep with unweighted flies, use the thinnest FC leader practical.
    • Long, thin FC leaders, when coupled with fast sinking, down force flies, can swing the fly on the end of a floater, as deep as sinktip with a short leader. Long, thin leaders and fast sinking flies can be added to any line, not just floaters. It’s a great way to add depth to an intermediate or slow/medium sinker. These leaders also droop the fly and provide excellent separation between fly and line.
    • When trying to keep a fly from sinking too far or when hitching and skating flies, then look at using thick, medium length, factory made, mono leaders as the thick butt sections will resist sinking and help keep the fly up. They’ll also turn over straight and get the fly waking immediately. I prefer factory tapered mono leaders for use whenever I need a very straight turnover and minimal or zero sinking of the fly. The knots on a homemade leader produce their own wake and the fish could hit those (I’ve seen this).
    • When looking to suspend a slower sinking fly, a reasonably thick mono leader will help it stay up.
    • Avoid thick mono and long leaders when looking to sink a buoyant or slow sinking fly on the end of a fast sinking line or tip. In this case, the line has to pull the fly down quickly and a long or thick mono leader will work against this.

Casting Angle

One often overlooked aspect of leader construction involves what angle we intend to cast across the current. Sharply angled downstream casts will tend to present the fly first to the fish so short leaders with little separation won’t be a problem. However, a cast square to the current with this setup could result in the line arriving first and sweeping the fish away from the fly. So when making sharply angled downstream casts, we don’t need to worry about designing our leaders for separation, but once we start casting more square to the current or upstream, then we have to think about getting better separation through fly choice and leader design. When making square or upstream presentations, we need to get more separation between the fly and the line. We can do this by using a weighted fly + short leader and achieve a vertical separation or we can use a long, thin, FC leader together with a light, fast sinking fly and achieve both a horizontal and a vertical separation.

Strength & Abrasion

Simply put, I use the thinnest leader & tippet I can get away with, going as low as 6 lb. test when I need to get a small fly deep. I resort to thicker leaders and tippets only when circumstances or fly choice dictate their use.


I don’t really have any hard and fast formulas, but most of my long, thin, FC leaders are either 33% - 33% - 33% or 25% - 25% - 25% - 25% starting at 15 lb. test for the butt section. Shorter leaders tend to be two piece with a short tippet section. I prefer a two piece leader even when going as short as 3’ as it allows a break-off point if I snag up. With one piece leaders, I find that the Perfection Loop is weaker than the Uni-Knot so I end up breaking off the whole thing, leaving all that mono on the bottom or streaming from the fish’s mouth, plus it’s a pain to keep retying entire leaders.

Bottom Line

The leader has to be part of a comprehensive, matched system that works with the fly, the line, the casting angle and the desired presentation. More thought has to be put into their design than just simply tying on 4’ of mono and chucking it out there.