A Quick Analyzer Post for the Casting Geeks

Been way too long since I had an appropriate level of casting geekery here at FF&W, so here you go…

In digging back through the mountains of electronic files and folders lurking on my hard drive under the heading “Fly Casting,” I came across a stack of images from April of 2000. Among them were some Casting Analyzer (CA) graphs from the first prototype Analyzer back in the day. Some of the images were used in the first edition of my now-out-of-print Nature of Fly Casting book, and some others have just been sitting quietly for a decade.

I figured that a few of my fellow geeks (at least those who don’t already have a Casting Analyzer of their own) might like to check out an interesting comparison that was done once the graphs were post-processed: a standard Overhead Cast (top) versus a standard Roll Cast (bottom), each made with the same length of line. The lighter, left-hand side of the graph isolates both casts up to their respective points of maximum rod-butt rotation speed (and for those who can already read CA graphs, you know what all the stuff is on the darker, right-hand side).

I realize that some readers may have just said, “Casting Ana…what?” If so, don’t fret! Basically, the CA is cool little device that outputs the rotation rate of the butt of the fly rod. As the Cast Analysis site says:

…this sensor measures angular speed and in the units of degrees per second

So, the more rapid the rod-butt rotation, the steeper the angle on the graph (a rod butt that is not being actively rotated, such as during the pause between backcast and forward cast, appears mostly “flatlined”). Yes, there is more to it than just that, but if you use the steeper=more rapid relationship, you can get a certain sense for how the two casts shown above relate to each other. Notice anything about moving line through the air, versus launching it from a static position off the water?

Over the many years that I’ve taught fly casting, it has been very interesting to see how certain people react to different technologies. Some find the CA to “jive” with their thought patterns, others not at all. Some find motion-capture to be the ticket, and others still prefer straight video. Of course, it all has to relate back to “hands-on” and eventually to “fish-on” for it mean much in the real-world. But, if you enjoy the techno aspects of casting as much as I do, then this kind of thing is like a casting drug, and you can never quite get enough of it!


  1. Henry says:


    As a geek, I found the graphs very interesting. I never realized that there was a difference between a roll cast and a standard cast in terms of casting dynamics. We are often told that the roll cast is just 1/2 of a standard cast and they are identical. Apparently there are differences that I think are significant, and it explains to me why beginners find a good roll cast to be difficult.

    If I remember my physics correctly:

    I would guess the higher peak and more rapid angular acceleration is needed in a roll cast, because a greater force over time is required to both lift the line up against the pull of gravity and to break the line free of surface tension. Force over time is work, so the forward roll cast takes more work than the forward half of an in-the-air cast.

    If I remember correctly, work should be the area under the curves for both these graphs. Work is the integral of force over time. But the difference in not only the total amount of work done for each cast.

    The graphs also show that the main application of the angular acceleration is contracted into a shorter time frame for the roll cast than with the in-the-air cast. I don’t know if this is true, but this suggest to me that timing is more critical with a roll cast than an in the air cast. This is another way of saying that the acceleration is smoother with the in-the-air cast, and the roll cast requires the extra “umph” at just the right time and in just the right amount.

    Don’t know if I am right about my musings. We need a professor of physics to sort it all out.

  2. JB says:

    Astute observations, Henry. And I would say that, yes, a Roll Cast, while it may not necessarily use a different overall forward stroke than, say, an Overhead Cast or an Elliptical Cast, does require one to provide enough “umph” in order to work properly. The issue is the small, usually static “D-Loop” that we have with the Roll and the fact that the anchor—that line remaining on the water outside of the D—can be quite long. Having to “pull the anchor” with a relatively small amount of accelerated line means that the cast may also have to be accelerated differently. In the case above (which was a vertical Roll, not an Elliptical or other variation), the wrist is applying what has become to be known as “delayed turnover” or “enhanced turnover” in some casting circles. The stroke itself would not look very much different than an Overhead Cast stroke (i.e. there is no additional “rolling” type of motion, outward throwing motion, etc.), but what was happening as far as rod rotation inside the confines of the stroke would indeed be different.

    When teaching the overhead-style Roll these days, I usually have clients practice using a bit of Layback (raising the elbow, while allowing the rod tip to drop—or lay—back a few degrees. This provides a bit of extra stroke length, but also expands the casting arc, and sets up the wrist to come into play more significantly at the end of the stroke.

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