As I warmed up for the Turkey Shoot this year (a handicapped tournament at Golden Gate Angling and Casting Club), I overheard one of the instructors in a nearby lesson tell one of the students, “Slow, slow, fast.”
It’s been a long time since I had heard those words. The last time was at Manzanita Lake when a guy told his friend, “Remember what the guide said: Slow, slow, fast.”
I’m glad that I don’t hear this phrase often. It’s not right.
When most people hear these instructions, they translate the rod forward slowly and then rotate the rod with their wrist once the arm is extended forward. This is not what the best casters do for typical fishing casts.
As I toyed with the idea of making “slow, slow, fast” a blog post, a couple weeks later, a caster at the Oakland ponds suggested that the cast was a constant acceleration.
“Stefan” explained that force is the product of mass and acceleration. In retrospect, I think that he was arguing that, since the mass of the rod doesn’t change much during the stroke, force and acceleration are proportional. I guess that he felt that the force that he applied during the cast was constant, so he thought that acceleration must also be constant.
I don’t feel like the force that I exert during a front or back stroke is constant. Isn’t the magnitude of the force changing if I add some wrist towards the end of my power snap? Moreover, the beginning of my front stroke (when my arm rotates down at the shoulder) is aided by gravity, so if acceleration is somewhat constant at other times, it would be a coincidence.
Another important point to make is that the direction in which I apply my force changes (and hence that of acceleration) throughout the stroke: after all, I am rotating the rod.
At the beginning of my front stroke, I am trying to “get the bend out of the rod”. I am rotating the rod in such a manner that I am trying to make it bend as much as possible without accelerating the line too much. I imagine bending the rod over my shoulder as if it were a fulcrum.
By creating a center of the rod’s rotation above the rod handle, I am accomplishing two critical goals. First, I am bending the rod so that it can’t bend much more. Essentially, I am trying to make the rod as stiff as possible so that I can apply as much force as I want or need during the power snap without any fear of forming a tailing loop.
This is the secret for casting a soft rod: bend the rod (without accelerating the line too much) so that it becomes stiff before the power snap. People who learn to cast on a fast rod don’t need to “get the bend out of the rod”. Consequently, when they switch to a slow rod, they have troubles casting it. That was me.
Back then, I hated soft rods. I had to cast them so cautiously because tailing loops formed so readily. One time, I had more wind knots than false casts that I had made. Before I knew the secret, maybe I was using a constant force to make a cast.
In retrospect, this is why Chris told me to practice on his FF86… a rod that felt more like a noodle than a stick. When I am casting well and I get the bend out of MF, I transform the rod into a much stiffer one. And when that noodle becomes stiff, my loops finally (FINALLY!) look tight.
The second goal that I accomplish by making the initial center of rotation above the handle of the rod, is that I keep the velocity ratio low. (Here’s a link that explains velocity ratio with diagrams. A brief description follows.)
The velocity ratio is how much the rod tip moves in relation to the amount the handle moves. When the center of the rotation for a broomstick is half-way up the rod, the rod tip moves the same amount as the rod handle (albeit in the opposite direction), making the velocity ratio essentially one.
For a soft rod, due to its flex, the rod handle may move more than the rod tip causing the velocity ratio to be less than one.
As the center of the rod’s rotation moves down towards the handle, a small movement of the handle creates a larger and larger movement of the rod tip (ie. a higher velocity ratio). As the rod’s center of rotation moves farther down past the handle, the velocity ratio begins to decrease… down to a value of one when the center of rotation is an infinite distance below the handle and the rod simply translates.
At the beginning of the front stroke, when my rod is laid back, I don’t want to accelerate the rod tip too much. If I do, I send the line upwards. A large, upwards acceleration for a loop that needs to be straight ahead or slightly downwards opens my loop and wastes energy.
What I want to do is to rotate the rod so that the butt is almost perpendicular to the intended trajectory – without prematurely accelerating the line too much before I start my power snap. For this reason, I want a low velocity ratio while I get the bend out of the rod.
If I get the bend out of the rod and I position the butt of the rod appropriately for the desired trajectory — before the power snap begins — another benefit is that creating a straight path for the rod tip (to form a tight loop) is easier, compared to an unbent rod in which the rod tip can still move down and up with more or less tension.
During the power snap, I believe that the center of the rod’s rotation moves – at least for me. It starts below the rod somewhere near my elbow since I use that joint for the power snap. By increasing the distance between the hand gripping the rod (where force is applied) and the center of rotation, I increase torque.
However, as the center of rotation moves away from the hand holding the rod, the velocity ratio decreases. As a result, there is likely a sweet spot where torque and velocity ratios are optimal. Where that is, I do not know. But, it is not at infinity, nor is it at the handle.
Towards the end of the power snap, as I use my wrist, the center of the rod’s rotation likely moves up since the rod is being rotated by the elbow and now the wrist.
It is this manipulation of the rod’s center of rotation (starting above the handle, moving below the handle, and finishing near the handle) that makes a soft rod harder to cast than a fast rod.
A fast rod can form tight loops without getting the bend out of the rod because it doesn’t bend that much. Consequently, a fast rod with lots of line outside the tip can form tight loops by maintaining a single center of rotation near or below the handle.
Now, don’t misunderstand me. I am not advocating that a fast rod be casted with a single center of rotation, but my point is that the center of rotation doesn’t have to move as much as for a soft rod.
Although “slow, slow, fast” also represents a large change in the center of rotation, it moves from an infinite distance below the handle to the handle: two non-optimal positions for the rod’s center of rotation.
When we understand velocity ratios, we can appreciate that the center of the rod’s rotation must remain around the handle of the rod. Otherwise, we no longer use the rod as an effective lever.
Chris has told me that there have been analyses of center of rotations and that they mapped them to some weird places. I wonder whether the translation during the cast (weight shift, etc) and the bending of the rod make mapping the center of rotation difficult and inaccurate.
I will concede that I am not a physicist and that I have described where I think that the center of rotations should be located. I may be wrong. However, I believe that the concepts that I have discussed are sound.
Let me know what you think, Stefan.