- Paul's cast records.JPG (23.38 KiB) Viewed 2641 times
And so what? This general appreciation does not tell us what is going on during a cast. More technical approaches told us that there can be four mechanisms involved for which we use the names: swing, spring, whip and haul. Let’s take one after the other:
*swing: Michael mentions it as a wave “swing being the vibration and overswing a too low of a rod stopping position”. If I look at the rod input from the caster, the speed profile is somehow wavy (a kind of sine function). But you can swing a rigid rod and there is no vibration involved. It is a generalization of anything which has an up and down trend. Overswing is not a question of rod position; it is due to the mechanical characteristics of the moment of inertia of the rod. The last bit of energy in the rod is there (in the tip) and it has to be spoiled by any mean, and this mean is the overswing (which we call counterflex).
*Spring: the rod reacts to the caster’s input with characteristics directly linked to its vibration properties (frequencies), load included when applicable (carry). Typically an input corresponds to several modes, e.g. 3Hz, 5Hz, 8Hz, with decreasing intensity. Those figures were taken from a specific analysis technique (Fourier analysis) applied to some casts. That confirms the vibration aspect of inputs. The rod response can also be made of different modes (fundamental and the next two which may appear and generate wobbles). You can see some (S shape in a rod) sometimes.
* whip: this one is more difficult to capture, it is the consequence of the variation of angular momentum along the rod shaft as the rod is cast: you “load the butt” first, then the middle, and finally the tip but part of what was in the butt at the beginning moved upwards along the shaft. At the end there is no momentum anymore in the butt. Again, a wavy aspect.
* haul: the input can be assimilated to a sine function, but the rod and line response is pretty complex. There are some threads devoted to that. Best results depend on tackle characteristics and generally speaking, one aims at placing maximum haul speed after rod maximal angular velocity and before RSP. There is a direct efficiency (speed transmission from hand to line) and an indirect one (effect of the rod on rod load). The latter is on the wavy side, it is a question of tuning in between events: the haul dynamic characteristics and the rod response already guided by the input of the cast.
If I consider all these elements on the wavy side, I could say there is some synch to find in between inputs (swing, haul) and rod response. Said differently is it what Michael is referring to when he speaks of an adequate mix of waves (but we do not have sound in our domain of thinking)? We do not twist the rod voluntarily to improve (if that is possible) the distance achieved although Paul has been using “torque twist”; rod twist often appears for a repositioning of the line (Spey). Today rods are twist resisting, more than 30 years ago. I can neither see how I can use twist to improve a cast, nor by how much, maybe I should try Paul’s torque twist to get better understanding of it. I guess it is because Michael is using long rods and Spey casts that twist is something common for him, but for single hand average casters like me it is not something I practice very much. I use roll casts and overhead casts basically.
Studying the four mechanisms mentioned above is helpful for casting properly or for rod design for example. There are technical characteristics of the tackle which can be linked to casting results bearing in mind the incredible number of possibilities giving similar results. Understanding those mechanisms explains why people have created a line scale, and a general consideration about the wavy aspects of things cannot do that. Technique needs numbers, not only concepts, as smart as they can be.
I remember having spent hours in trying to figure out the climbing wave effect on the rod shaft. There are wavy aspects like flexural waves or momentum variations along the shaft (from butt to tip). Given the amounts of energy involved, there is no chance to see all the energy given to the line passing through the rod first (a kind of Big Spring approach). A bow and arrow cast is close to that if you can absolutely clamp the handle of the line somewhere, your hand cannot be so strong. But in general we do not use bow and arrow casts. We use the rod to impart energy to the line with various mechanisms, some are direct some are indirect; which may have a wavy aspect in general terms. With the help of the loop that energy is spent against air drag to put a fly forward in the distance. There are also strange looking mechanisms involved in the unrolling process of the line, and they are not so easy to identify. That may be explaining why line taper design is still based on testing more than on computer design. There are too many variables involved and some observations like the DN (Dolphin Nose), which can be encountered with other mechanical systems (string shooter, falling chains) remains rather hard to understand, if not mysterious: how does this particular wave appear? Why is it stable? Is this particular wave a soliton? We can interpret the DN in many ways; the problem is to prove that what our imagination produced has something to do with reality. I have no suggestion to make for DN and blunt statements make me smile.
Up to now I cannot see how a general wave approach can be translated into practical terms, especially in the domain of rod design. Or is it simply a different way of thinking to describe the technicalities in general terms, without being able to explicit them? One must go into details to understand the hidden issues, and the various mechanisms mentioned above can help. But there are others which are of little use to the caster and great use for the designer. Stability for example (wobbles in the rod tip after line launch). If uncontrolled they are unpleasant, if controlled (wig wag to put slack in the line on water and delay drag of the fly) they can control the line for specific purposes.
Like others IMHO, I am frustrated by the lack of explanations which would allow application of benefits coming from this “superbubble” concept, if any. A concept is fine, now if someone has perceived the way for an improvement through Michael’s description of his concept, thanks to share with others friends of the angle. At this time, this is purely intellectual for me and lacks of practical details.
Merlin
