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Simon Gawesworth on How to Fly Cast

Breaking down the forward stroke of fly casting.

Simon Gawesworth on How to Fly Cast
The results of good casting are clear. You'll have less frustration on the water, and spend more time effectively presenting your flies. Photo: Simon Gawesworth

[Simon Gawesworth is one of the world's finest casters and more importantly, a gifted teacher. What follows is an excerpt from his book Single-Handed Spey Casting (Stackpole Books, 2010). While Spey casting is an advanced technique — named after the river Spey in the northeast of Scotland — the fundamentals of a basic forward cast are a required foundation for all casting techniques including Spey. What follows is chapter 1 "The Basics." Understand the principles of how a rod flexes, and how acceleration affects your loops, and you'll get on a fast track to better casting. The Editor.]

Fly Rod Casting: Flex

A fly rod is designed to flex, and it is this flex that should benefit the caster. At the very start, when making the backcast of a regular overhead cast, the rod flexes down toward the water as the rod is lifted and accelerated smoothly and continuously up and back (the loading move). Assuming the fly line is tight and straight on the water, the rod is bending (loading) against the grip the water has on the fly line combined with the weight of the fly line outside the rod. At the critical moment of the backstroke, the caster changes the nature of the load by snapping the wrist back and making a positive stop of the rod (the power arc).

The wrist snap releases the built-up energy (flex) in the rod and transmits it into the fly line, while the positive stop of the rod ensures that the energy transfer is fast and efficient. It also helps control the size and shape of the loop as we shall see shortly.

With a properly executed backcast, you have enough speed to ensure the line unrolls completely in the air and straightens out. If you have 30 feet of line outside the rod (including the leader), you need enough energy to make the fly travel more than 30 feet behind. (If you had just enough energy for the fly to travel the 30 feet, it would start to lose momentum and fall as the inertia ran out.) If casting with 60 feet of line, you need enough energy for the fly to go back more than 60 feet, and so on.

At this stage of the cast, and at the very start of the forward cast, we have an interesting derivation of rod flex. The rod flexes from three separate loads: 1) the slight pull of the fly line as it travels backwards, 2) the weight of the line as the rod drives against it, and 3) the air resistance against the rod thickness (and, though to a lesser extent, the line surface).

I see no need here to get into the subtleties of the load achieved by the pull of the line or of the air resistance on the rod and line. Instead, I want to concentrate on where the majority of the load comes from the weight of the line behind the rod. In simple terms, the caster making a 30-foot backcast has less line weight to load the rod than the caster making the 60-foot cast, so the rod will have less flex as it is driven forward.

This is fine for a short cast, but for distance you will need more than a loaded rod tip to help and, if the rod won't give you the entire load, the effort must come from you. In other words, your work effort will need to increase.

Fly Rod Casting: Leverage

The rod is a lever. A longer rod will generate more line speed throughout the power arc (rotation) than a shorter rod assuming the lever is not so long that it requires too much effort to rotate it. This is easily demonstrated with a simple picture (see diagram #4).

During the rod's rotation, the longer lever will travel faster. However, when driving a rod forward with no rotation (prior to the power arc), a longer lever will travel at the same speed as the shorter one.

I mention the leverage aspect at this stage only to illustrate that it is part of line speed, load, and distance, but in reality no one is going to change the length of the lever in midcast.

An aside note is that two rods of the same length don't necessarily have the same leverage. If you took a nine-foot rod that was very fast and a nine-foot rod that was very soft and slow and you loaded them up with identical line weight and length, the fast rod would actually be a longer lever. My dad, who was a teacher of math and physics before he became a fly-fishing instructor, showed me this one day while trying to give me an understanding of fly casting. The easiest way to see this is through illustrations #5 and #6.

Fly Rod Casting: Acceleration

As mentioned above, acceleration is critical to increase the load in a casting stroke. As long as the rod accelerates during the loading move and finishes with a slightly faster power arc, the cast will be effective. Other factors, such as loop size, rod action, line size, leader/fly combination, and weather conditions influence how effective the acceleration is, but if you can remember to keep a smooth, constant acceleration throughout a casting stroke, you will have a solid foundation on which all fly casts can be built.


A lot of fly-casting instructors use the phrase "long line, long stroke; short line, short stroke," and the simplicity of this statement should not be forgotten. The main reason for this statement is obvious. If a caster has a loading move of six inches prior to the power arc, very little flex will be put into the rod, leaving little possibility of reaching a high speed through six inches of acceleration. If the same caster has a loading move of four feet, the rod will flex much farther down (storing more energy), and the length of the acceleration will generate a higher speed at the end of the stroke. The end result, obviously, is that the long stroke gives a much greater load into the rod and, therefore, more distance.

Acceleration comes from many parts of the body. It should come from the arm, the wrist, the shoulder, through body rotation and the transfer of body weight/mass during the casting stroke.

Simply put, it comes from you — the caster — and you should never forget how important acceleration is to a casting stroke.

Many years ago, when I was doing the demonstration circuit of fly-fishing shows in the UK, I had a routine that showed it was possible to cast without any rod flex. I took my old pool cue and whipped a couple of rod rings (one at the tip) and a reel seat on it. During the demos I would cast a WF7 fly line with this cue. I could cast it 50 feet or so, but it took effort to do this as there was no flex in the cue to help. The pool cue was five feet long, so the only way I could generate any line speed to make a cast was to utilize arm and wrist speed and the five-foot length of leverage to basically throw out the fly line. I could throw a very tight loop but had to really work at getting the cast to go any distance.

Another part of the demonstration was to put the pool cue down and thread the fly line through a one-inch split ring. I cupped the split ring in my right thumb and index finger and proceeded to cast with only my hand, arm, and wrist. Again, there is no flex or spring power when casting this way, and I had negated the five-foot length of leverage. This shows that it is possible to cast without any flex or leverage length and that the power only came from my arm and wrist speed. However, it could never be called efficient!

If you break the amount of power applied in a casting stroke into two parts — rod power and caster power — you will have a ratio. I call this the energy ratio. The ratio is simple: If the rod contributes 70 percent of the power needed to make the cast, the caster needs to add 30 percent of power. This is mostly through the amount of acceleration and energy imparted by the shoulder, arm, and wrist. If the rod only contributes 10 percent of the power, the caster is going to have to work much harder to get the same result. In my demonstration with the pool cue, I would have had some contribution just through the length of the lever; however, in the split ring demonstration, I had no assistance from a rod, so I had to apply 100 percent of the power.

Fly Casting

Fly Casting

Fly Rod Casting: Loop

The shape the fly line takes at the end of each casting stroke is called a loop. Like people, loops come in all different shapes and sizes, and there isn't a perfect loop for every situation.

Good casters can control their loop size and shape according to the fishing requirements. In almost every situation, the loop needs to unroll fully and straighten out, with just enough power to make that happen. Too much power is a waste of energy and can result in a savage kick of the line. Too little power and the loop fails to unroll and will collapse on itself.

The shape and size of the loop is controlled by the path of the rod tip, the rod action, the stop at the end of each stroke, and the acceleration throughout the entire stroke.

We've already looked at the part of the casting stroke I call the power arc. One other thing about this power arc is that it is the foundation of the size of the loop. During the loading move, the rod can travel in quite an arc, but for a tight loop, the power arc must be contained and, actually, form not so much of an arc.

The rod tip, during this vital stage of the cast, needs to travel in a straight line and finish with a stop that is both decisive and firm. The straight line can be in any plane — vertical, horizontal, or tilted at any angle in between — but straight and true it must travel.

Conversely, to make a larger, rounded loop, the rod tip arc should be opened up and the straight line path ignored. You can do this by using a softer, deep-flexing rod for the situations that need these wider loops, or you can just do it by slowing down the casting stroke, hinging your wrist more throughout the power arc, and softening the stop.

The final part of the loop's role is the turnover. A loop can only turn over (unroll from the elongated U shape to a straight horizontal line) if the bottom part of the loop travels slower than the top. This allows the top half of the loop to overtake the bottom half and unroll. If the bottom half were to travel at the same speed as the top half, there would never be any overtaking, unrolling, or turnover. The line would just run out of energy and collapse.

Fly Rod Casting: The Direct Relationship

One thing I like my students to understand is the direct relationship between the load and the loop. As casters get better, they strive for the narrowest, tightest loops.

Catalogs, brochures, and ads by professional fly-fishing companies show casters with tiny loops. They're like supermodels — the thinner and tighter they are, the sexier they are! There's even a web site (an excellent one, at that) dedicated to the best in casting tips and techniques called Sexy Loops.

The bottom line in casting circles is that the better casters are, the tihter the loops they want to cast. Bigger is not better here. The reason I mention this is that I want to finish by stating that the more power a caster puts into a fly rod, the bigger the loop will tend to be.

Any caster with a bit of experience can cast a loop three inches wide with only six feet of fly line outside the rod tip. You make tiny little rod tip twitches, and the line will form a deliciously small loop, but with little line speed. To do it with a long line takes a lot more ability. Try casting 70 feet of line with only the same tiny rod tip twitches!

You can, if the rod loads from the fly line, but you can't if the rod loads from a caster's power. Get an energy ratio of 90 percent line load and 10 percent caster's effort, and you can get the sexiest loops in the world!

Simon Gawesworth is the marketing manager of RIO Products in Idaho Falls.

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