The Fly Casting Analyzer provides a scientific interpretation of the fly cast. It is important to understand what the analyzer measures and how to interpret the measurements. Think of the rate gyro as a speedometer that measures the speed at which you cast. Rather than measuring speed in say, miles-per-hour, however, the gyro measures the speed you rotate the fly rod. Thus, the 'speed' we measure is a rotation rate and that is reported in the units of degrees per second. There is a simple reason for this. About 90% of the speed developed at the tip of the fly rod comes from rotating the fly rod (a very long lever!); for a recap. see How it Works- The Science Behind the Fly Casting Analyzer. We refer to this rotation rate simply as the rod speed. We measure the rod speed and use the following terms to understand all the parts of your casting stroke

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The best casters usually have remarkable symmetry between their forward (or front) and back casts. The symmetry is reported as a number that compares the peak speeds of the front and back casts. A value of 100 means 100% symmetry (i.e. the back cast peak speed is the same as the forward cast peak speed). However, it is very common to see higher peak speeds on an angler's front casts. The back cast is sometimes thrown with inadequate power and, equally often, the forward cast is thrown with excessive power. If you see symmetry readings less than 80% it is likely that your back cast needs additional power or that your forward cast has too much power. The example shown below compares the symmetry of an expert's cast (100%) to that of student's cast (69%). The next figure shows that the student's peak speed (385 deg/sec) in the forward cast is substantially greater than the expert's (260 deg/sec) and this overpowered forward stroke is the root source of the asymmetrical student cast in this example.

Click image to enlarge. An example of symmetry.

An example of peak speed. The peak speed datais also reported on the 'Front Cast' and 'Back Cast' pages.

Very often, we cast with far more energy than required and doing so is both fatiguing and potentially injurious. The casting analyzer allows you to compare your casting energy with that of an expert caster or any other caster. To do so, simply select your comparison cast and then proceed to the forward cast page or to the back cast page and click on the "energy" button. The result you will see may look like the example below which compares a student cast to an expert cast. The energy bar graph in this example shows that the student uses 126% more energy to cast the same length of line as the expert. The casting energy function compares the kinetic energy of the rod for the two casts and reports the energy difference as a percentage. It is important to realize that the kinetic energy increases as the square of the rod speed. So if a student cast has a peak speed that is twice that of the expert cast, then it will also have four times the kinetic energy and we would report a 400% increase in kinetic energy as the result. It is not uncommon to see casts with well over 100% more casting energy when you compare to an expert cast.

Click image to enlarge. An example of casting energy.

The casting arc (or rod arc) is the total angle through which you rotate the fly rod in a stroke, measured in degrees. We report the casting arc for the forward cast as well as the casting arc for the back cast. Casting arc is relative; the longer the cast, the larger the casting arc should be. Casting arcs that are larger than they need to be often result in large or 'wide' loops. Casting arcs that are too small may result in tailing loops. Like symmetry, matching just the forward cast arc and the back cast arc to those of an expert does not guarantee a 'perfect' cast. Other attributes including acceleration, stop, and rebound must also be considered as detailed further below.

The casting arc graphic also shows "creep" and "drift," if they are present. Creep is a major cause of tailing loops and it is detected on the rod speed curve as early, slow and sustained rod speed in the same direction as the upcoming stroke; refer to figures below. Creep reduces the portion of the casting arc where you can apply power. As a result, power must be applied rather abruptly in the smaller (remaining) portion of the casting arc this often results in a tailing loop. Thus, creep will also often lead to a high "smoothness ratio" as defined later. In the example illustrated below, there is 20 degrees of creep in a forward casting arc of 65 degrees. Thus, power is applied rather abruptly over a short 45 degree portion of the forward arc.

Click image to enlarge. A visual example of creep in the casting arc.

For creep, the casting signature shows slow rod speed in the same direction of the next cast. This slow, sustained and premature rod speed produces the "creep" shown in the forward casting arc above.

Drift is the opposite of creep. Drift occurs when the rod is "drifted" slowly back in the direction of the stroke just made (after that stroke's stop and rebound). Thus, the rod is then moving slowly in the opposite direction of the upcoming stroke. Drift effectively lengthens the next casting arc rather than decreasing it as with creep. This is a desirable motion in nearly all casts because you can then apply power more smoothly over the resulting larger casting arc.

Click image to enlarge. A visual example of drift in the casting arc.

For drift, the rod speed begins moving slowly in the opposite direction of the upcoming stroke. Thus, this forward cast begins with slow rotation in the direction of the previous back cast after the stop and rebound of that back cast. This slow sustained backward rotation produces the "drift" shown in the forward casting arc above.

The smoothness ratio is a measure of how power is applied to the rod during the casting stroke. To make a good cast it is very important to accelerate the rod smoothly. Smooth acceleration leads to smooth bending of the fly rod and this enables the tip of the rod to track in a straight line. Keeping the rod tip on a straight path is the key to developing an expert casting stroke.

Smooth acceleration appears as a near-constant slope on the rod speed curve in the portion of the curve where power is being applied. This portion of the curve is illustrated in the two example forward casts below. The first slope drawn on each rod speed curve represents the (average) initial rod acceleration. The second slope represents the final rod acceleration at the end of the stroke. If these slopes are nearly the same, as in the case of the expert cast to the right below, then the power application is smooth. By contrast, if these slopes are very different, as seen by the obvious 'kink' in the student cast to the left below, then the power application is not smooth. The smoothness ratio is computed as the final acceleration divided by the initial acceleration. The smaller this ratio, the smoother the application of power. Experience has shown that expert casters achieve smoothness ratios of 8 or less. If your smoothness ratio is higher, you may be starting your stroke too early and then compensating by accelerating too quickly at the end of the stroke. A good example of this problem is illustrated in the student cast below where the smoothness ratio is 19.3. You may also simply be 'snapping' the rod with your wrist at the end of your stroke, thereby over-accelerating just at the very end.

Click image to enlarge. These rod speed curves illustrate the application of power for a student cast (left) and an expert cast (right). In each cast, the slope of the first line is the acceleration at the beginning of the stroke. The slope of the second line is the acceleration at the end of the stroke. The ratio of these two slopes is called the "smoothness ratio". When this ratio is small (8 or less), then the two slopes are similar and there is little visible 'kink', as in the expert cast.

The student cast above shows a very small initial acceleration (small initial slope) followed by a very large final acceleration (large final slope). The visible 'kink' where these two slopes intersect is testimony to a non-smooth application of power (large smoothness ratio of 19.3) in this student cast.

How the rod decelerates, commonly called the "stop," is critical to loop formation. The transition from acceleration (as power is last applied) to deceleration (when the stop begins) must be rapid and will result in the sharp "peak" on the rod speed curve previously described in "Symmetry Peak Speed and Casting Energy." Following this peak, the rod decelerates significantly. This deceleration reduces the rod speed to a minimum rod speed which we refer to as the "stop speed" or simply the "stop". Most often, this stop is not complete in the sense that the rod stops moving completely. In general, the rod actually continues to rotate, though at a very slow speed. Thus, the term "stop" is more accurately described by the phrase a "dramatic slow down."

This distinction aside, it is important to understand that this stop has considerable influence on the size of your loop. In general, the smaller the stop speed, the smaller your loop will be. Small loops have less air drag and therefore they can propagate farther than large loops that have greater air drag. However, small loops are not necessarily a goal in fishing situations. For example, close range delicate presentations may demand larger loops, while long range casts and casts into a headwind may demand very small loops. Knowing how to control the size of your loop is another key to expert casting and the casting analyzer can help you practice this skill. Below we review two example student casts that illustrate how we measure the rod deceleration and stop, starting with a cast that will lead to a large loop.

The stopping phases of a student cast (left) and an expert cast (right) are illustrated below. In each case, we report the deceleration during this phase which is the (negative) slope of the line on the rod speed curve. (Deceleration is reported in the units of degrees per second per second.) The student's deceleration of -1676 deg/sec/sec is substantially smaller in magnitude than the expert's deceleration of -2200 deg/sec/sec. As a result, the student develops an incomplete stop of 72 deg/sec, while the expert develops a more complete stop of 30 deg/sec. A fully complete stop would result in 0 deg/sec at the minimum (rod would be truly stopped) and thus extremely small loops (see next example).

Click image to enlarge. An example of an incomplete stop

In the above casting signature, the rod deceleration is the slope of the steep line from the peak speed towards the stop. The stop is the minimum speed at the end of this deceleration phase. Here, the student's smaller deceleration and incomplete stop produces a large loop. By contrast, the expert's larger deceleration and more complete stop leads to a significantly smaller loop. (See grey curve in background).

The next example illustrates a much more complete stop for the student cast. (The expert cast is repeated for comparison). The deceleration is now -3097 deg/sec/sec (nearly twice the prior student deceleration) and the stop is 9 deg/sec. Thus, at the end of the stop, the fly rod is still rotating forward, but at a mere 9 dec/sec which is essentially still! A complete stop like this will surely lead to much smaller loops. (In fact, it is also possible for the rod speed to go negative at the conclusion of a stop in the forward cast. Doing so leads to the smallest possible loops of the type one may desire only during practice or for tournament casting games.) We emphasize again that your goal is to learn how to control the size of your loops for the various fishing situations you encounter. Knowing how to control complete and incomplete stops is the key to this skill.

Click image to enlarge. An example of a complete stop

In this example, the student exhibits large deceleration and a complete stop. This type of stop is needed to form the smallest possible loops.

Rod load is an indicator of how much the rod bends when applying power. This number compares the peak speed (the maximum speed before the stop begins) to the smaller peak after the stop. The rod load is reported as a percentage of the smaller peak to the larger peak. The smaller peak measures how the caster rotates the rod in response to the rebound of the fly rod. Rebounds or rod load of 30% or more indicates significant rod loading which is desirable. The rod bends or "loads" in response to tension developed in the fly line. If the line is slack from a poor previous loop, there is little tension in the fly line. The result is a rod without much bend, hence little rod load would be measured.

It is very possible to have acceleration, peak speed and stops that look good, but if the measured rod load is low it means the rod did not bend much and the resulting loop will not be good. This typically happens if the previous loop was big and the line never straightened. One good cast leads to another and rod load is the best indicator of that. If rod load percentage is low (less than 25%) analyze the previous cast to determine why the previous loop was not good.

An example of rod load.

Now that you have reviewed the terms that we use to describe all the parts of a cast, it is time to put them all together. Below is a handy graphic that shows an example fly casting signature and the most commonly used terms.