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2. Casting mechanics and techniques

Below are two articles authored by Bruce Richards, MCI that appeared in previous editions of The Loop. They are included here (italicized text below) because they are replete with information necessary for all instructors.

1. Gammel’s Five Essentials Revisited by Bruce Richards (The Loop, Fall 2023)

In 1990, Bill and Jay Gammel developed the “Five Essentials,” which have been foundational for those wanting to cast and instruct well. Knowing these essentials and how they affect every cast is necessary for casters who want to truly understand fly casting. In this article, I’d like to add some detail to each of the essentials and modernize them a bit to include the official FFI fly casting definitions which were adopted in 2015 and updated in 2024. I would not meddle with the Gammel Essentials without Bill’s blessing, which I got!

The First Essential: In order to form the most efficient, least air resistant loops, and to direct the energy of the cast to a specific target, the caster must move the rod tip in a straight Line. This essential is actually what results when the other four essentials are done properly.

The loop we use most when fly casting is a narrow loop with a straight fly leg. These loops are most energy efficient and can be cast most accurately. To achieve this kind of loop the rod tip must travel in a relatively straight line during the casting stroke. The rod tip path during the casting stroke largely determines whether the fly leg is straight or not. If the rod tip path is curved; up, down, right or left, the fly leg will be similarly curved, and less efficient, less accurate. When the rod tip path during the casting stroke is relatively straight the most efficient loops are formed.

Tip path deviations in the vertical plane (up or down) are typically caused by rod bend issues. Horizontal tip path deviations (right or left) are normally caused by rod tip tracking errors. The rod tip path during the casting stroke determines what the fly leg will look like, and what the rod tip does after the casting stroke ends and the loop has formed determines what the rod leg will look like. The fly leg is moving much faster than the rest of the loop must be straight for the loop to be efficient and accurate. So, what must a caster do to make the rod tip path and fly leg straight?

Second Essential: The size of the casting arc must vary with the length of line past the rod tip.

This essential states that it is the length of line being cast that determines the size of the casting arc, which certainly is part of the story. When we cast, we pull the fly line with the fly rod. The mass of the fly line resists the motion of the flexible fly rod causing it to bend. If there is more fly line being pulled there is more line mass and the rod will bend more, all else being equal. But if the line is simply thrown harder/faster the rod will bend more also. It isn’t just the length of line that determines how much the rod bends, but also how hard it is thrown, how much force the caster applies. This essential would be stated a little more clearly if it said: the size of the casting arc must vary with the degree which the rod bends.

Why is this important? The path of the rod tip during the casting stroke largely determines the shape of the fly leg of the loop, whether it will be curved, or straight. By matching the width of the casting arc to rod bend we can control the rod tip path to get the fly leg shape and loop size we want. Most of the time we want the fly leg of the loop to be straight and the loop to be narrow.

The casting arc is the angle change of the rod butt during the casting stroke. The casting stroke starts when rod acceleration becomes sufficient to result in forming a loop. The casting stroke ends when the loop forms. That is when the rod unbends and straightens, the rod tip slows, and the fly line overtakes the rod tip (rod straight position 1: RSP1). The change in rod butt angle between those two points is the casting arc.

Look at the 3 drawings below. The first shows a cast where the casting arc is properly matched to the rod bend. You can see that the rod tip path throughout the casting stroke is straight and that yields a narrow loop with a straight fly leg. (See Graphic #1)

The next drawing shows a cast made with the same maximum rod bend but a casting arc that is too wide. You can see that this causes an upward curving tip path and a wide loop with upward curving fly leg. To straighten the tip path and the fly leg the caster should simply narrow the casting arc to match the rod bend. Another option would be to increase rod bend (more force) to match the casting arc but that would also increase line speed significantly. (See Graphic #2)

The third drawing shows a cast made with the same rod bend but a casting arc that is too narrow which results in a rod tip path that dips downward which causes a tailing loop. To straighten the rod tip path, the caster should widen the casting arc. Another option would be to reduce rod bend to match the casting arc but that would decrease line speed significantly and probably be too slow. (See Graphic #3)

Graphic #1, #2, and #3

Third Essential: Power must be applied in the proper amount at the proper place in the stroke.

One thing that is necessary for the rod tip path to be straight is that the rod bends in an evenly increasing way during the casting stroke. For that to happen, the rate of rod acceleration needs to be about the same from the beginning of the casting stroke to the end. That is called

“constant” acceleration. To achieve that, force (“power”) must be applied in a smooth, constant way also. Of course, the right amount of force must be used to accelerate the rod and line to the needed speed.

If the acceleration is not reasonably constant, the rod tip path will not be as straight as we’d like. It is very common for casters to accelerate the fly rod too slowly early in the casting stroke then much faster later in the casting stroke. Slow acceleration doesn’t bend the rod much. Fast acceleration bends the rod much more. If the rod is accelerated as just described, here’s what the tip path looks like. (See Graphic #4)

Graphic #4

If the rod is accelerated in a constant manner, with more constant application of force, the rod bends as in Graphic #1, and the tip path, and fly leg, is straighter. (See Graphic #1)

There is a common misunderstanding that continues to negatively affect casting instruction. Sometimes instructors confuse rod speed with rod acceleration. Every fly cast starts with the fly rod going slowly and ends with the fly rod going fast. It is how we move the fly rod from slow to fast that is most important. That is acceleration, the change in speed (more accurately, velocity). Some instructors still ask their students to accelerate the fly rod slowly in the beginning of the casting stroke then accelerate it quickly at the end. That is one of the two most common causes of tailing loops, inappropriate application of power/force. For a straight rod tip path, the rod must accelerate at near the same rate from the beginning of the casting stroke to the end.

It is sometimes claimed that tailing loops are also caused when a caster accelerates the rod too quickly early in the casting stroke then slows rod acceleration later in the casting stroke. While

this would cause a tailing loop it is very difficult to do, and I’ve never had a student make this casting error.

Fourth Essential: Slack line should be kept to an absolute minimum.

Efficiency is important when fly casting. When picking up the line or false casting, the straighter the line is when we start the casting stroke the more efficiently we can cast. The more directly aligned this line is with the intended tip path of the coming casting stroke the more efficient the cast will be.

When we pull on the line with a fly rod a couple things happen. First, the line moves. Second, the rod bends against the mass of the line. But if the line isn’t fairly straight neither of those motions are efficient. Part of the line doesn’t move and only part of the mass of the line works to bend the rod so it bends less.

Try this horizontal, on the ground casting drill…. Lay out 40 ft. of fly line on the ground but with the fly only 20 ft. away. There will be 20 ft. of slack in the middle of the line as seen below. Try to make a cast. (See Graphic #5)

Graphic #5

When the caster pulls on the line with the rod only the part of the line connected straight to the rod moves initially, the line beyond the slack does not. Also, only the part of the line connected straight to the rod offers much resistance and causes the rod to bend. With slack, only part of the line is moved, and rod bend is much less than if the line was straight. For most efficient casting we want all the line to move when the rod moves and all the mass of the line to bend the rod. Now try the same cast again but pull the line out straight to 40 ft. Now when the rod tip moves all the line moves also and the mass of all the line works to bend the rod.

The same thing happens in an overhead cast. If there is slack, the line doesn’t move as it should, and the rod doesn’t bend as it should requiring the caster to apply more force. (See Graphic #6)

Graphic #6

Another form of slack is when the fly line is straight but not aligned with the intended direction of the cast being made. For most efficient casting, the line must be aligned as much as possible with the intended tip path of the coming cast when the casting stroke starts. This is called the “180 Degree Principle. The line can be out of alignment in any plane, high, low, right or left. Alignment that is too low is shown below. (See Graphic #7)

Graphic #7

When the line is 180° aligned with the direction of the coming cast all the energy of the cast goes to moving the line in one direction. When alignment is off some of the energy of the cast goes to pulling the line into alignment with the rod tip path so the cast is less efficient. Also, when the line is not 180° aligned line momentum will cause the fly leg of the coming cast to be curved rather than straight, again reducing efficiency.

Fifth Essential: There must be a pause between each (casting) stroke, which varies in duration with the amount of line outside the rod tip.

This essential is actually a subset of the fourth essential regarding slack. If the pause between casting strokes is too long or too short slack will result as the line will be curved not straight. Only if the timing is just right will the cast be most efficient. Two factors determine the proper pause duration, line length as the essential states, but also line speed. Obviously, when casting any length of line, the higher the line speed the shorter the pause will be. The drawings below show how pause affects slack. In the first, the loop has not yet fully straightened and there is obvious slack in the line. In the second, the loop has fully straightened and started to fall, again, slack. In the last drawing, the loop has just fully straightened, if the next cast starts precisely at this point there is little slack and a much more efficient cast. (See Graphic #8)

Graphic #8

Acknowledgment We have Bill and Jay Gammel to thank for explaining these fly casting essentials so many years ago. The Essentials are as important today as they were then, and every good caster and instructor needs to understand them. And I want to thank Bill for reviewing this article!

Additional references Bahadur, S. Casting Masters Then and Now: Bill and J.W. (Jay) Gammel. The Loop, July 2016 Gammel, B., Gammel J. Making Adjustments on the Fly, The Loop, Summer 2010 Gammel B., Gammel J. Five Essentials by Bill and Jay Gammel. The Loop, Summer, 2009; reprinting of the original booklet. _________________________________________________________

Bruce Richards’ article below helps us better understand the importance of the STOP and the effect it has on loop shape. Understanding the role that rod acceleration and deceleration play in the Stop is central to learning how to cast efficient loops. Learning when to stop, and at what rate, will greatly improve loop control, which is a major component of the Casting Instructor Exam.

2. Fly Rod Deceleration “The Stop” by Bruce Richards

When we fish, we use a lot of different loops depending on what we are trying to accomplish. But the loop that is most efficient, used most often and is the loop we all strive to cast most of the time is a narrow loop with a straight fly leg.

When we cast, we accelerate the rod butt then decelerate it (“the Stop”). When we do that, the rod bends, of course, and the rod tip also accelerates. When we decelerate the rod butt, the rod unbends, and the rod tip continues to accelerate until the rod is straight (rod straight position – RSP 1) when the loop forms. These rod motions are collectively known as the casting stroke. To make the best, most efficient loops, the rod tip path during the casting stroke must be as straight as possible.

We know that when we accelerate the rod butt in a very smooth, constant way that the rod tip path will be pretty straight during that phase of the cast. But how should we decelerate the rod to continue that straight rod tip path? See Graphic 1A to view an ideal cast.

(For this article, we will assume that rod acceleration is good/constant and not the reason for any loop problems.)

1 Please note that the FFI definitions define Stop as deceleration of the rod (not the rod butt) resulting in loop formation.

Graphic 1A

There are two things we control when we decelerate/stop the rod butt: when we start deceleration and the magnitude of the deceleration.

If we stop the rod at the wrong time, too early or too late, the rod tip path at the end of the casting stroke won’t be as straight as it could be and neither will the fly leg of the loop. If we stop the rod too early, the casting arc will be narrowed, the rod tip path will rise during the deceleration phase causing a dip in the tip path, and a tailing loop will result. This is not a common problem with typical students. Graphic 2A.

If we stop the rod too late, the casting arc will be too wide, the rod tip path will curve down at the end of the casting stroke, and the fly leg of the loop will curve down. This is a very common problem. Graphic 3A.

Graphic 3A

Stopping the rod at the right time is important. Stopping it quickly enough is also important. Remember that “the stop” is the process of decelerating the rod butt. The rod butt doesn’t ever stop instantaneously, humans aren’t capable of stopping the rod that fast. Assuming rod butt deceleration starts at the right time, the faster the rod is stopped, the straighter the rod tip path will be.

Assuming that our goal is to cast loops with very straight fly legs, the rod can’t be stopped too fast. Stopping the rod slowly will cause the rod tip path to curve at the end of the casting stroke and that will curve the fly leg. For most typical fly fishing, that isn’t a big problem. We don’t need the most efficient loops to fish effectively at typical fishing distances. But for casting long distances, or casting in the wind, very straight fly legs are necessary.

Stopping the rod too slowly yields the same result as stopping the rod too late. Remember that we can’t stop the rod butt instantaneously; that means that the rod butt continues to rotate as it decelerates. The more the rod butt rotates during the stop, the more curved the rod tip path will be which will cause the fly leg to be more curved also. Graphic 4A shows three casts where the rod butt was decelerated at different rates, and the resulting rod tip paths.

It seems there is some confusion about how fly rods should decelerate to make the best loops. Many instructors instruct their students to make a “positive” stop. I’ve read dozens of dictionary definitions of the word “positive” and not one of them relates to how something should decelerate. As instructors, we need to use words that clearly mean what we want to say; “positive” doesn’t do that. Rapid deceleration, or abrupt deceleration are much better descriptors. I’ve heard it said that stopping the rod too fast will cause tailing loops, but that isn’t true either. If deceleration starts at the right time and the stop is very fast the rod top path will be straighter as will the loop fly leg.

I’ve talked about stopping the rod at the right time and rate, but how do we know we’re doing that? I’m sure there is some way to mathematically calculate that time but there is no way to practically use that information while casting. But it is easy to determine if you’ve gotten it right just by observing the fly leg of the loop.

First, make sure that you are stopping the rod very quickly, that is easy to do. Most casters don’t make a concerted effort to stop the rod very quickly. If your stops are slow, “lazy”, it will be difficult to tell if you are stopping at the right time. When you are sure that your stops are abrupt just look at the fly leg of the loop. If it is curved upward (convex), your casting arc is too wide because your stop is too late. If the fly leg is curved downward (concave, tailing loop) your casting arc is too narrow. Adjust when you start your “stop” until your fly legs are straight.

To control our loop shape, how we decelerate the rod is as important as how we accelerate it. If we stop the rod too early, we will get a tailing loop. If we stop the rod too late, we will get a loop with a convex curved fly leg. If we stop the rod very quickly (at the right time/place), we will get a straight fly leg. The slower we decelerate the rod, the more curved the fly leg will be. Fixing stop related loop problems is really quite easy when it is well understood. Learn to read loop fly legs and how they are affected by rod deceleration, and you will be able to fix your own loops, and those of your students, very quickly.

b. Varying Casting Arc and Trajectory

A wide variety of casts must be made well to pass the CI exam. General performance standards require that most of these loops have relatively straight fly legs and be narrow. Some of the casts are delivery casts, so loop trajectory must be adjusted so the fly is delivered effectively. To maintain the needed loops and trajectory, a candidate must understand how to adjust the casting arc, both width and orientation, to achieve the needed result.

To make loops with relatively straight fly legs, it is necessary for the rod tip path during the casting stroke to also be relatively straight. Fortunately, we cast with flexible fly rods which allow this to happen. The graphic below shows the relationship between rod bend and casting arc for three different casts. The green rod isn’t bent very much, and you can see how narrow the casting arc must be to keep the rod tip path straight. The red rod is bent dramatically and to keep the tip path straight, the casting arc is very wide.

When we cast, we apply the amount of force needed to the rod to make the desired cast. The force will change dramatically as we make the wide variety of casts we often make in a day. Other things cause rod bend to change too. How much line we carry, heavy or wind resistant flies, cast speed, etc. As all of those things change, rod bend also changes, and we must know to adjust our casting arc to maintain a straight rod tip path and good loop.

How do we know if we’re adjusting correctly? All we must do is look at the fly leg of the loop. If it is relatively straight. then the caster has adjusted the casting arc to rod bend properly. If the fly leg is curved, up or down, the adjustment wasn’t quite right. If the fly leg curves up the casting arc is too wide. If the fly leg curves down (tailing loop), the casting arc is too narrow for the amount of force applied. Yes, that is a bit simplistic but the most important skill we can have as instructors is understanding how to analyze loops to determine what is wrong with a cast to correct it.

Once you’ve mastered the ability to adjust your casting arc to match the rod bend, you will need to know how to adjust trajectory to effectively deliver the fly to a target. Here is a typical fishing cast with an initially horizontal trajectory. When the loop is cast horizontally it will fall a bit, but when it opens the fly will still be far above the target and will have to fall a considerable distance to get to the water. The odds of the fly falling straight down to the target are not high, especially if there is wind.

To greatly improve accuracy, we need to adjust the trajectory of our cast, so the line and leader unroll with the fly much closer to the target, so that it falls only a short distance to the target. The cast we make is the same with the only difference being a change in trajectory. To change trajectory, we simply need to tilt the casting arc, so the rod tip path aims down toward the target. The fly leg of the loop goes where the rod tip path points. You can see the result in the drawing below.

How much we change trajectory depends on the distance of the cast. For very short casts, the trajectory will have a steep pitch, up in back and down in front. For a long cast, the trajectory change will have a shallower pitch. Tasks 12 and 13 on the CI exam call for accuracy casts at three distances, each target requires a change in cast trajectory for consistent accuracy. The next time you cast, experiment with changing trajectory to see how it affects fly delivery at different distances. Try aiming to targets at 20 ft., 30 ft. and 45 ft.

Knowing how and why to change casting arc to achieve the loops we need is a key skill for any caster/angler/instructor. Knowing how to change the orientation of the casting arc to change loop trajectory for effective deliveries is another necessary skill.