Fly Leaders: Keeping Things Simple

There is a lot of confusion surrounding flyfishing leaders, how they are constructed and the basic mechanics of how they work. In this article Justin Duggan breaks down the jargon and shows that simple is often best with saltwater flyfishing leader construction.

I can clearly remember the daunting task I had as a new fly angler in trying to understand leader construction and the mechanics of a basic fly leader. Books were filled with terms like class tippet, butt section 4x and 10x, shock leader, tapered leader and so on. It was a big learning curve and totally confusing for the uninitiated like myself. In the following article I want to simplify leader construction and dynamics in a way that I wish had been explained to me all those years ago.
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You had better have a piece of shock leader on when fish with raspy teeth or gill rakers get onto the line.


It’s all about energy transfer

When we look at fly-casting in a simplistic form we are transferring energy from our arm and wrist to the fly rod. The rod bends and when stopped, it unloads, springing energy into the line (especially when the rod tip is travelled in a relative straight path). This unloading of the rod and subsequent loop of line that is formed forms the heart of the flycast. As the loop unfurls the energy is transferred through the flyline to the leader and subsequently the fly. So, to be simpler again, energy transfer is:- body, rod, flyline, leader, fly. For our purpose lets concentrate on the energy at the end of the flyline entering the leader and getting to the fly.
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A nail knot of 30b leader onto a six weight flyline, once again a nice taper that will encourage energy down the leader toward the fly.


Take me to your leader

A fly leader is usually constructed of monofilament or fluorocarbon line that is joined in different diameters to form a diminishing taper from the flyline to the fly. Think of the join from flyline to leader as the joining of electrical cables. Larger cables carry more energy than smaller cable. If you take a thick electrical cable and join it to a very thin one you will lose energy as it passes from thick “energy rich” cable into thin cable. Think of the fly as the end point for your electrical current. A bigger fly will need more energy to turn over (lay out straight at the end of the leader) than a smaller fly. The longer the “cable” the more the energy is dissipated and lost as it journeys up the line to the fly. With this in mind it stands to reason that bigger flies will work better when cast on shorter, thicker leaders whilst small flies can be cast with longer thinner leaders.
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Energy stored in the rod is transferred to the flyline and subsequently the leader and fly. Understanding leader construction and its effect on the transfer of energy to the fly is critical.


Tapering down

The part of the leader that joins the flyline is called the butt section. If you wanted to carry energy from the fly line to the butt section of the leader with only a small amount of energy loss then you should only vary the diameter of the leader butt running from the flyline by a small degree, say 20 percent. If you tapered from a thick flyline to a very thin butt then, like electrical cables, you would lose too much energy and the fly may not turn over. If you are fishing for spooky fish and need delicate presentations with small flies then you would construct a long leader by starting at the butt section and gradually tying diminishing line diameters towards the fly. Each join should generally taper by around 20% diameter, often less. In this situation its all about getting the smallest amount of energy to reach the fly, just enough to do the job, so the fly touches down like a butterfly with sore feet. The reverse will be true of say, a large bass fly or barra fly. We can afford to have the fly hit the water hard and being large flies they will require plenty of energy to reach them through the leader. For this reason shorter leaders of thicker material are ideal. The average leader for this sort of work would be around 6-7 feet long and may only consist of the butt section say 3 feet of 45lb monofilament and another piece of thinner line tied in front, say 3-4 feet of 20lb mono filament.
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Having a generous helping of leader material in multiple sizes and both  the stiffer fluorocarbon and hard and soft monofilament is essential.


Basic leader configuration and the rule of 5th’s

There is a minefield of information on constructing elaborate leaders for a whole host of applications. For the purpose of this article I’m going to keep things very simple and give you some basic ideas. Its not really possible to take a formula and apply it to every situation, instead, learn the principles and go out and experiment, learn and devise your own leaders for your own applications. A really good starting point is to aim to have the butt section of your leaders to be around 50% of the entire length of the leader, some stretch it to 60% on longer leaders. Slightly stiffer monofilament and fluorocarbon lines are said to transfer more energy, especially when used in butt sections, however, I have found super hard material for butt sections can form a hinging effect between the more supple fly line and the leader, so don’t go super stiff on that butt material! Stiffer leader material is also poor for nail knots as it doesn’t bite into the flyline coating very well so keep this in mind. So what diameter line do I start with for the butt section? Try the rule of 5th’s as a starting point. Multiply the rod weight by 5 and you have the approximate butt section line in poundage. For example most 8 weight lines would suit 40lb breaking strain line as the butt material (8 x 5 =40). 40lb line should come in somewhere around 80% of the diameter of most 8weight flylines.
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Throwing smaller flies on a clear tropical bonefish flat requires longer leaders, in this case a 12 foot all fluorocarbon leader was used with 12lb (5kg) class tippet.


Simple as 1,2,3

So what about configurations? Well, I’ll keep this really simple. If you need a leader around 10 feet and you have an 8 weight and you need to have the thinnest line (class tippet) as 10lb line then here’s how I think it out. I know, using the rule of 5th’s the butt will be around 40lb. I also know I like to have that butt at around 50% of the leader length which will be 5 feet. So I know I need to progress from 40lb at the butt down to 10lb at the front but I’ll need some taper in between the two lines for good energy transfer and also so I don’t tie knots from thicker 40lb to thin 10lb line, this can create weak knots. Knowing I’m going from 40lb down to 10 lb at I will use 5 feet of 40lb butt then around 2.5 feet of 20lb then the final 2.5 feet is my 10lb class tippet. This will turn over a simple small fly like a crazy Charlie or surf candy with no issue. A shorter leader will require less taper so for instance, a 6 foot leader would work with 3 feet of butt and 3 feet of class.
The ideas discussed here are exactly that, ideas. These are starting points to understanding basic saltwater leaders, they are by no means perfected or absolute. Get out there and use these basic ideas to experiment and gain confidence in your angling through good leader construction. challenge 2 (3 of 8)-2
Justin Duggan

About Justin Duggan

Justin is one of Australia’s leading Saltwater Flyfishing guides and Fly-casting instructors. Justin is the operator of Sydney Fly fishing Tours and has spent many years guiding anglers in a variety of other localities, including regular stints in Weipa where he works for Fish’s Fly and Sportfishing.


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