Originally Posted by BigCliff
Here's an illustration of what they're describing-
See what I'm referring to by "concave path of the rod tip"?
The "tail" in "tailing loop" refers to the shape of the loop, not what is done with the rod after the forward cast is complete.
I agree with what you have written previously about the causes of a tailing loop. I also like the illustration above and want to expand on it a bit.
The reason that the rod tip goes in a concave path is because the rod is a flexible lever, with the emphasis on flexible
. Most new casters assume that the rod tip remains at a fixed length from the caster's hand. It does not.
When a fly rod bends, it shortens
according to the amount of power or acceleration applied to it. It is this shortening that is responsible for the concave path.
A rod that shortens during the cast will bring the rod tip closer to the casting hand. Unless the stroke path of the casting hand is convex AND/OR the angle of the rod in the hand is adjusted for this shortening, the rod tip will follow a concave path.
The illustration below shows what happens when there is a sudden early application of power that causes the rod to shorten and the rod tip to dip. Notice the that the reel is going in a level path and so the rod tip dips toward the reel.
The following illustrations show this rod shortening and the convex path the stroke path must follow to compensate and keep the rod tip level. Notice that as the "effective rod length" shortens, the reel follows a convex path to compensate. In this illustration the reel goes up to prevent the rod tip from dipping down as the rod shortens.
In the illustration below we can see that depending on how far we are casting, we need to adjust both the stroke length of the rod and the convexity of the stroke path to compensate for the greater rod shortening on the longer stroke. Notice the up/down motion of the elbow and the flexion/extension at the elbow that causes the rod handle to follow a convex path.
In this high speed stop motion study, we see the actual bending of the rod and the stroke path of the hand, elbow, and shoulder. This compact overhead stroke is the foundation stroke that the FFF suggests as a beginning stroke. It is the same stroke that forms the basis for the teaching and casting of Mel Krieger, Gary and Jason Borger. This stroke is identical to the prior drawing.
Think of the elbow as the center of a circle and the forearm as the radius of the circle. As the elbow bends and unbends, the hand automatically follows the arc of the circumference in a convex path. The same thing happens at the shoulder joint so we have two convex motions added together to create an automatic convex rod tip path. Now choose a rod of the correct flexibility and your body anatomy automatically compensates for the rod shortening.
How remarkable is that? I happen to think that this correlation of body anatomy and stroke is the reason that some fly fishers seem to find a rod that just fits their casting stroke.