Our objective was to define a set of terms which we can use to isolate and describe the elements that go together to make fly fishing casts. Wherever possible we have used terms as they are already used by instructors and professionals within the fly fishing community.
Overall Stroke and Casting Stroke
To differentiate between actions whose purpose is to position the rod and/or line and those whose purpose is to apply force to the line in order to make a loop we need a distinction between a Casting Stroke and an 'Overall Stroke' or just 'Stroke'. The Casting Stroke covers only those motions whose purpose is to apply force to the line in order to generate a loop. The Casting Stroke has one crucial result: a loop of line.
An Overall Stroke includes a Casting Stroke and those motions needed to position rod or line before and after the Casting Stroke.
We have retained the conventional meaning of Casting Arc, which measures the change of rod-angle at the rod butt during the Casting Stroke.
There is no obvious reason to change the generally accepted meaning of Stroke Length. However we felt we needed to make the length of the Casting Stroke explicit, so we have coined the term Casting Stroke Length to mean rod translation during the Casting Stroke.
We are aware of the debate around the contribution due to rotational and translational components of the Stroke and Casting Stroke. So, without prejudging the debate we have introduced the term Drag to mean rod translation with little or no rotation during the early part of the Casting Stroke. The inclusion of Drag does not preclude any argument being right or wrong on the matter of power but precludes a set of definitions based around the premise that the argument has already been decided.
Component parts of the Overall Stroke.
An Overall Stroke includes a Casting Stroke and those motions which may be required to reposition rod and line before and after the Casting Stroke. These components are divided into rod positioning motions (which have little or no effect on the line) and line positioning movements. While line positioning means moving the line it does not involve or include forming a loop, so although line positioning movements must mean moving the line, their purpose is not loop formation and they therefore fall outside of the Casting Stroke.
We have adopted the term Drift for rod positioning and Sweep for line positioning. Specific forms of Drift and Sweep can be named, eg Slide - where the rod runs along the line towards the line hand and does not move the line is a form of Drift. Sweep is used often, eg the lift on a pickup and lay down; setting up a static D-loop; many motions in Spey casts and aerial mends are all examples of Sweep.
One fault definition
We believe that in our fly fishing context Creep is commonly understood as a fault and we have defined it accordingly.
We believe that these definitions will describe most if not all commonly used casts. The definitions are neutral on outcomes, meaning that the common fault finding processes can be applied to each element making the definitions not only descriptively powerful but also analytically powerful.
The use of soft boundaries between the component definitions reflects the judgment instructors in the field use when they seek to correct faults or offer advice to students. For example, what instructor would mistake rod repositioning (Drift) for a Casting Stroke?
The definitions retain the common understanding of the terminology used by most casting instructors; they therefore do not require a re-education process and are consequently more likely to be accepted by a broader base of instructors worldwide.
You can download these definitions here.