A Loaded Question

[Paul Arden]

Hi Merlin,

The acceleration is not linear, but increasing. I cue the sight of the rod butt vertical or later for my rapid acceleration. This is when I try to rotate it as fast as I can, there may be some thrust and it’s when I try to explode on the haul. I know immediately when I’ve gone too early, and the resulting loop is a catastrophe. It’s actually difficult to time and is a common experienced distance error to hit too early.

I also sometimes cue the top of the rod (not the tip) for this moment. Partly this helps my tracking but it’s mostly timing.

Cheers, Paul

[Merlin]

Paul

The analysis of the record I have tells that your peak translation speed (4 m/s) occurs slightly before the maximum rotation timing. Interestingly the peak torque value corresponds to maximum rotation speed (from the casting model); this is why you feel that you deliver your effort along the rotation speed level. The translation itself brings some little additional speed, but its usefullness lies in the maximization of hauling distance.

I understand the “hit” as the haul mechanism: you extend your rod arm forward to maximize the hauling distance and speed (around 12 m/s). Timing is key if you want to benefit from hauling speed, and you know it affects rod unloading (delaying it). Miss the perfect timing and rod tip path may dive (too much rod bending), hence a loop issue. Remember that hauling can reload the rod to a significant extend if made too early.

Before maximum rotation speed and very slightly after: rod bending increases
Maximum rotation speed: peak torque for the caster
After maximum rotation speed: tune the haul (maximum hauling distance, shortest timing), that is the hitting sequence.

George

Thanks for the images, a good help for understnading.

Merlin

[John Waters]

Hi Daniel,

Thanks for those speed calculations, very interesting data. Thank you for your time in analysing the cast, may I impose and request you calculate haul hand speed at the two stages of the haul in these two photos i.e. at or just before the haul hand is at the hip and later in the haul, at line release?

In advance, my thanks,

John

[Paul Arden]

Gordy measured my haul on a distance cast in KL and I think that the surprising thing was that acceleration peaked just after MCL and not just before RSP. Granted the little twist at the end I don’t think is easily measured.

It certainly made me think that key timing is just after MCL and not just before RSP. It would be interesting to see that frame by frame. However the caveat being that there is a possibility of improvement.

When I think about the “hit” on a distance cast I think about turning the rod butt over, around, down a line, over the top of a tree, domed. All of those things. It’s force to the rod, not the haul, although it is also the acceleration of the haul.

Cheers, Paul

[Merlin]

Hi John

I cannot calculate anything from the documents you posted, one needs a record with multiple frames and an analysis with a tracking software (which I do not have nor use). The video should be taken perpendicular to the casting plane to avoid parallax errors.

I'm going to dig into my files on hauling and see if I have something. What is the reason for your questions? Estimate the best release timing?

Merlin

[Merlin]

Paul

Studying the haul showed that the best speed is achieved when you can tune the peak haul velocity closer to MCL than to RSP. But sometimes (competition cast), the difference in time can be very small (50 ms) which makes the tuning pretty difficult.

OK, the hit relates to the rod hand, the haul to the line hand, and the hit contributes to maximize the haul speed value.

Merlin

[George C]

Your insights are incredibly helpful, Merlin.

I think there may be a semantics or frame of reference issue regarding the haul.
Does it refer to the movement of the line arm and hand, or does it refer to the movement of the line itself?
I'd think the latter.
Looked at that way, wouldn't a haul occur during a distance delivery cast even if the line was tied to a shirt button?

The rod acts like a pulley around which the haul is made. The apex of that pulley could be considered the leading edge of the bend in the rod as it unloads (the most forward spot on Torsten's circle of rotation)........and not the collector guide as commonly described. That center of rotation/center of pulley is moving up and forward away from the hauling hand (or shirt button), both from simple geometry as the rod is rotated and translated forward, but also dynamically as the rod unloads and the bend/load is shifted farther out the rod. Viewed in this context, James sense of the hit being related to a forceful separation of the hands fits well with Paul's (previous) descriptions of the backcast haul being determined by how fast the hands separate. The same thing each way, only less obvious with the delivery cast?

Perhaps this expands, as well, on your excellent explanations of the ideal the timing of the peak haul as outlined in post 36 of this thread viewtopic.php?f=24&t=3433&start=30
Based on the Walter and Dirk's explanations earlier in this thread, I'd guess that applying additional forces to the rod via the haul when it is rotated well forward and the line/rod angle is well past perpendicular is the reason a late haul has a less pronounced deflection effect and a more direct line acceleration effect than an earlier haul when the line/rod angle is wider.

Thanks
G

[John Waters]

Hi John

I cannot calculate anything from the documents you posted, one needs a record with multiple frames and an analysis with a tracking software (which I do not have nor use). The video should be taken perpendicular to the casting plane to avoid parallax errors.

I'm going to dig into my files on hauling and see if I have something. What is the reason for your questions? Estimate the best release timing?

Merlin

Hi Daniel,

Thanks for your reply, much appreciated. My two photos were to illustrate the positions of interest of the haul hand and I was wondering if you had any video of any hauled cast with the camera in the right position. The haul in fly casting is an interesting subject of study and my interest is not what it does to the fly line, but how it impacts the movement of the rod hand side of the body. It is a movement very similar to what a javelin thrower performs with the contralateral hand. Only looking for indicative data at this stage.

Again, my thanks,

John

[Merlin]

I agree with you George.

Merlin

[Walter]

Thank you, Walter and Dirk.
Much to think about.
From Tobias' video, can a case can be made that the rod is fully loaded at the point of maximum deflection and already starting to unload (the red circle moving up the rod) by MCL? As the butt passes perpendicular to the load from the line, the forces on the rod begin to shift from deflection to compression and the rod begins to straighten from the strongest part upwards? Phrased differently, does this mean that the rod is trying to unload thru the latter half of rotation rather than just at the 'stop' at the end of rotation? Or is the total load still increasing but just being moved further out the rod?

Thanks for helping me understand this.
George

“Load” and “fully loaded” are terms that are a bit confusing. From a physics or engineering view “load” is just another way of saying force, as in, there is a load/force of X pounds acting on the rod. Fly casting defines load as the amount of bend in the rod but it often gets confused with the physics definition. Equating rod bend with the amount of force sort of works in the static sense, where I apply a force to the rod and wait for everything to stop moving and make whatever measurement I choose. I could measure chord length or the point of deflection and angle of deflection, for instance, and as long as I wait for the system to achieve a steady state I will get the same results. The dynamic case it isn’t so simple because while I’m waiting for the system to achieve steady state I’m going to get very different results depending on when I take my measurements. Think of a spring that I hang a weight from and while the weight is bobbing up and down I try to measure the amount of stretch in the spring. The rod is even more confusing because the spring is acting in one dimension while rod bend is two dimensional. Unfortunately, simply measuring chord length is not a reliable measure of the amount of force acting on the rod at any point in time. If I bend the rod at right angles 6 inches from the tip it takes very little force. If I bend it at right angles 6 inches from the butt it takes a tremendous amount of force. In both cases the chord length is the same. In order to determine the amount of load acting on the rod at any point in time I would need to generate a bend profile for the rod and then compare any snapshots of the rod to that bend profile. Casters have observed for some time that the rod loads from the butt. Tobias has shown how it unloads (straightens) from the butt towards the tip. Tobias’ work also gives you an idea of when the rod begins to unload (apply increasingly less force to the line).

I hope this isn’t making things even more confusing.