Fly Casting- How straight is Straight Line Path ?

Making Adjustments on the Fly B.Gammel

a very astute casting student asked me recently, “I think I’m having difficulties keeping a Straight Line Path throughout the stroke. I must be doing something wrong ?”

i love these kind of comments. it shows the person is curious, really pays attention to what they’re doing and shows they’ve studied well. at this point i should say that his loops where ideal, nice and smooth, very close to parallel very nice loops, as nice as what we see Andreas Fismen performing in the 500fps slomo gif below. so, what was the problem then ?
since his casting was spot-on it obviously wasn’t anything he was doing wrong (loops don’t lie. they can’t) but simply his understanding of how rod tip travel should be for a textbook straight line cast but who could blame him ?
diagrams, books, videos and even in real, most instructors explain that just as in the diagram above, SLP (Straight Line Path) is a constant from one end of the stroke to the other. even in Jay and Bill Gammel’s awesome reference construct The Five Essentials of Fly Casting, this straight all-the-way-through concept is very easy to accept and take for granted.

“3. In order to form the most efficient, least air resistant loops, and to direct the energy of a fly cast toward a specific target, the caster must move the rod tip in a straight line.”

but is that what really happens ? lets take a closer look.

'SLP' Borger:Lovoll FC

first published in 2010, these findings aren’t anything new to some of us casting geeks but might be a sorta eye-opener for the non geeks, shedding some light for those who have asked themselves the same question as my student. just as we’ll see in the still below, in this study cast SLP is roughly a little bit more than a third of the overall stroke, most of the rod tip’s path has a mostly domed/convex shape with a somewhat flattened top. *
SLP length Borger:Lovoll

i won’t risk any absolutes but as far as i can tell, the only time we’re going to see a true, all-the-way-through SLP and its resultant tight loop will be when a non-flexible rod (the proverbial broomstick) is used to perform the cast. but even if the broomstick is somewhat frequently brought up in casting-geek circles and is a wonderful tool to understand a lot of casting concepts, it’s not something we use.
our ‘real’ rods bend, react to the forces we apply to them, get shorter as they bend and go back to their original length as they unbend and there’s the caster’s biomechanics and probably a billion other factors that are involved when considering rod tip path and even if they all where within my understanding, they’re not about today’s subject.

to conclude, after having shown this video and image to my student (ah, the beauty of bringing an iPad to lessons!) with a few explanations and demonstrations, you’ll most probably have already guessed it but here was the furthered response to his query.

– knowing this isn’t going to change your life, its just one of those ‘what we thought we where doing isn’t necessarily what was going on’ things.
– does this not-as-straight-as-we-thought SLP change anything in the way we should cast ? nope.
– provided you get the loop shapes you’re wanting to create, should you be doing anything differently ? absolutely not !
– if you want a straight line cast, keep on imagining your complete casting stroke is a straight one (and do all the other elements correctly) and you’ll get that tight loop and a straight line layout.

which in a certain manner, makes it resemble Saint Exupery’s elephant inside a boa drawing a lot more than your everyday ruler. at least in my eyes…
elephant-in-boa-SLP


top image from Bill Gammel’s brilliant Making adjustments on the fly
regiffed video and adjoining image via Grunde Løvoll. click HERE for more of Grunde’s slomo studies on Jason Borger’s site: Fish, Flies & Water
elephant/boa drawing from Antoine de Saint-Exupéry: Le Petit Prince

note- although the loop shape in the gif is textbook ideal, Andreas’ casting stroke seems to be quite long considering he’s only false casting 10m (32.8ft) of line. my guess is he was casting at a fast rate which necessitates a wider casting stroke, perhaps something to do with getting a good visual result with the 500 frames per second camera.

The Five Essentials of Fly Casting

via the International Federation of Fly Fishers – a reprint of the IFFF booklet ‘The Essentials of Fly Casting’ 1990

written by Bill and Jay Gammel, the ‘Five’ are as far as i know, the first serious document on fly casting mechanics.
it is indeed geared towards the Overhead/Vertical style of casting but i can’t think of any other style where these five basic elements don’t apply.

knowing them and continually studying how they work together will not only bear precise line control but eventually lead to the understanding of how to purposely deviate from the Essentials and apply them to the real nitty-gritty of fly presentation: Presentation Casts.
i like to make the analogy of the Essentials to that of music study. once one has understood the mechanics of score, tone, rhythm, form and harmony they can go on and improvise freely . (and as a bonus, without having to think about it. it just ‘happens’)

just like the Chinese Whispers/Telephone game, the Five seem to be distorted and pointlessly personafied every time its rewritten by a casting enthusiast so, here’s the straight up, undiluted original. enjoy !


“Through many years of studying modern fly casting instruction, we have identified what we believe to be the five essential elements of fly casting. Each essential element will be explained and the visual recognition of both a good and a bad cast will be discussed. Comparisons of the best fly casters in the country have shown that styles of casting are unique to each caster. However, the five essentials discussed in this booklet represent the common thread that ties all good casters together. If all of the following essentials are properly executed, good casting will be the result; if all the essentials are not correctly performed, you cannot be a complete caster.”

The Five Essentials are as follows:

1. There must be a pause at the end of each stroke which varies in duration with the amount of line beyond the rod tip.

In all types of casting, a weight is used to provide resistance against which the rod is bent to store energy for the cast. In plug or spin casting, it is the weight of the lure which bends the rod. This weight is concentrated in a relatively small lure which hangs a short distance below the rod tip. After making a back cast with such a lure, no pause is necessary before starting forward with the rod. Conversely, in fly casting it is the weight of the fly line which bends or loads the rod, and this weight may be distributed over ten, thirty, or even fifty feet of line. Because this line must be straight in order to properly load the fly rod a pause, which varies in duration with the amount of line beyond the rod tip, is essential to allow the line to straighten. (See Figures 1a and 1b). If the line does not straighten between the back and the forward cast, the potential casting weight of the line is reduced and the rod will not load properly. This will cause a weak, sloppy cast, or in extreme cases the loop will collapse.


Figure 1a. This short line is completely straight and is ready to be cast forward.

In order to achieve the correct amount of pause on the back cast, some instructors advocate watching every back cast. Certainly, it is appropriate to watch the back cast occasionally. However, we strongly recommend that the caster not watch every back cast. We have found there are problems associated with watching all of the back casts that are more difficult to correct than any slight problem with timing. As long as the line length is constant, the pause on the back cast is the same as the pause on the forward cast. If the caster keeps this in mind, he will learn to time the back cast pause simply by keeping it the same as the forward cast pause. The correct pause is essential for successful casting and therefore should be practiced from the beginning. You must also remember that the rod does not have to be motionless at the end of the back cast. Some casters advocate using a backward drift while others leave the rod stationary. Either style is fine as long as the rod does not drift forward before the line is straight. This is called creep, and is a common mistake which wastes valuable stroke length that cannot be regained without causing the rod to unload prematurely.


Figure 1b. With a longer line, the pause must be longer.

2. Slack line should be kept to an absolute minimum

To apply power to the cast, the line must be anchored either with the rod hand against the handle or more commonly in the line hand (the hand not holding the rod). If the line is not anchored, the line and rod will slide relative to one another and will keep the rod from bending or loading. Even though the line is anchored, slack may still be present and needs to be removed before the next cast is made. Slack in the casting system causes the caster to waste some of the casting stroke removing slack, without properly loading the rod or moving the fly. If there is no slack in the casting system the fly will move as soon as the rod tip moves. There are many causes of slack. A few of the more common ones are: movement of the fly line by outside forces such as water or wind, starting the cast with the rod tip too high, rough, jerky application of power, and poor timing between the back and forward cast. The most common cause of slack which many casters overlook, is the belly of slack that forms between the rod tip and the water when starting the cast from a position with the rod tip high in the air. This is illustrated in Figure 2. To prevent this from happening, start a cast with the rod tip pointing at the water. This allows you to start with the most efficient back cast.


Figure 2. Incorrect rod position, a common cause of slack line overlooked by most casters.

3. In order to form the most efficient, least air resistant loops, and to direct the energy of a fly cast toward a specific target, the caster must move the rod tip in a straight line.

Because the fly line must follow the rod tip, the straight line movement of the rod tip is the only way a fly caster can form a straight line cast. This is true for both the vertical and horizontal planes. In the vertical plane there are three common paths that the rod tip can follow. It can travel a straight line from one end of the casting stroke to the other, which is how a properly shaped loop is formed. It can travel through a convex path (one that is higher in the middle of the path than on either end) and the loop will be wide or fat. If the rod tip travels in a concave path (the tip is lower in the middle of the path than on either end), the loop will tail or cross. These loops, and the rod tip paths which produce them, are displayed in Figures 3a, 3b and 3c. the rod must also move in a straight line horizontally, without right or left deviations. A rod tip path that slices to the right will cause the line to curve to the right, while a rod tip path that hooks to the left causes the line to curve to the left. The most efficient way to make sure the rod tip moves in a straight line in the horizontal plane is to pick a target and make sure the line always moves straight away from the target on the back cast and directly at the target on the forward cast. To ensure the rod tip moves in a straight line in the vertical plane, you must combine the correct stroke length with the correct application of power. For instance, if you are having trouble with wide loops, either the stroke is too long or not enough power is being applied. Sometimes both errors are made. To correct this problem either the stroke must be shortened or more power must be applied.
Sometimes both errors are made. To correct this problem either the stroke must be shortened or more power must be applied. Sometimes both corrections are necessary. Stroke length is the first possibility to consider. If you are getting crossed or tailing loops, the stroke length is probably too short or the power is applied in a jerky, uneven manner, or possibly both faults exist. In this instance, the fault is probably with the application of power. Make every effort to apply power as described in essential five. The stroke may need to be lengthened if applying power correctly does not solve the problem.


Figure 3a. A good loop and the straight line rod tip path which produces it.


Figure 3b. A wide loop and the convex rod tip path which produces it.


Figure 3c. A tailing loop and the concave rod tip path which produces it.

4. The length of the stroke must vary with the amount of line past the rod tip.

If you are casting a short line you will need a short stroke to move the rod tip along a straight line. If you are casting a longer line the extra weight causes the rod to bend much deeper, and a longer stroke is necessary to keep the rod tip moving in a straight line. This is where the problem of creep arises. If the rod is allowed to creep forward there will not be enough stroke length to properly load the rod for a long cast. This is a common problem when lengthening the stroke for a long distance cast.


Figure 4a. Short line, short stroke.


Figure 4b. Longer line, longer stroke.

5. Power must be applied in the proper amount at the proper place in the stroke.

The amount of power needed for each cast is influenced by a number of factors including the amount of line to be false cast, the total length of the cast, wind direction, the weight of the line and rod and the type of cast to be made. As shown in figure 5, the majority of this power should be applied after the rod has reached a position perpendicular to the plane of the cast. In other words, the power should be applied slowly at first, gradually increasing to a peak at the end of the stroke. There should be a crisp stop at the end of the casting stroke forcing the fly rod to come out of its bend. As the rod straightens or unloads a loop is formed.


Figure 5. A to B, power is increasing; B to C, power is greatest; D is the end of the stroke.

These are the five essentials of good fly casting. these essentials will enable you to achieve the proper loading and unloading of the rod, which should be the goal of all good fly casting. The correct loading and unloading of the rod allows you to first store energy in the rod and then transmit it to the fly line. Letting the rod work for you in this manner is the most efficient way to cast a fly.