Rod unloading during acceleration

[NM]

You don’t aim to stop your hand at the point where you release the ball or a javelin when throwing those, do you? So why would you do something different when distance fly casting?

A ball, a javeline, a stone, a dart and all these are free to move as soon as they left our touch.
We don't touch the fly line, but the handle of the rod. With positioning the rod movement we adjust loop shape and trajectory. Also the loop will still be attached to the rood via shooting line. There are differences though.
I never saw a fly caster do this post letting go:

That's a great throwing motion Bernd. Superb shoulder layback and a great example of the stretch and release. I am working hard on better incorporating that into my distance casting stroke. There’s some limitations due to the hauling hand, and the need to track straight, including during the follow through, but that is manageable.

[John Waters]

You don’t aim to stop your hand at the point where you release the ball or a javelin when throwing those, do you? So why would you do something different when distance fly casting?

A ball, a javeline, a stone, a dart and all these are free to move as soon as they left our touch.
We don't touch the fly line, but the handle of the rod. With positioning the rod movement we adjust loop shape and trajectory. Also the loop will still be attached to the rood via shooting line. There are differences though.
I never saw a fly caster do this post letting go:

That's a great throwing motion Bernd. Superb shoulder layback and a great example of the stretch and release. I am working hard on better incorporating that into my distance casting stroke. There’s some limitations due to the hauling hand, and the need to track straight, including during the follow through, but that is manageable.

Hi Nils,

Glad to see you're using stretch and release in your casting. I've never generated such tight loops and high line velocity before. With the correct acceleration and braking sequencing everything rotates, except your hand path, so tracking is not a limitation. Nor is the haul. With a minor change to the conventional haul movement it will both increase line speed and assist contralateral side the braking.

Good luck with it. It's different, but effective.

John

[Paul Arden]

Fantastic use of “Torque Twist”. I was curious as to why many US casters turn their thumb in, as Gary mentioned some time ago. This is not something I can remember seeing outside of the US. I suspect it may come from baseball pitching as children.

I utilise the twist in the opposite direction for my high speed shots. I’ve tried incorporating it into my distance stroke of course but I have learned how to track the tip perfectly straight (yet). I would love to solve it.

Cheers, Paul

[Merlin]

Gordy

Since the timing of the haul relative to MAV or RSP1 varies so much for different casters I expect the optimum timing window could be quite large.

Something like 90 ms to 150 ms, this is not so large and is rod and cast dependant. The variation in speed between a peak haul velocity between MAV and RSP is small in fact, a few percent.

From a work energy (force applied over a distance) standpoint I would think you would want to apply the added force from the haul to be applied to the line when the tip velocity was around its maximum value. That way the distance the force from the haul was applied to the line would be also be maximized.

Not sure it is that simple, the extra force takes places at some time and is not a constant. The principle is correct but the interaction with rod bending and unbending is very difficult to interpret.

The problem with that formulation is how you determine the added force from the haul since the force from the acceleration of the haul also impacts the bend in the rod.

The added force from the haul corresponds to the variation of momentum of the line (mass, speed) induced by the haul. But it is not the single force at play.

Practically speaking I suspect that timing the haul so it peaks just after MAV or just before RSP1 is not all that critical to getting the maximum casting distance.

Oh yes, there are so many variables for the line flight that a small difference in launch speed is likely invisible in terms of distance achieved. I just looked at a few files and effectively, contrarily to my belief, the best speed is achieved slightly before RSP1, something in the 20 ms to 40 ms range. Why did I thought it was something closer to MAV, I cannot tell. Maybe by looking at a fishing cast, I shall dig into my files.

Merlin

[Bernd Ziesche]

Practically speaking I suspect that timing the haul so it peaks just after MAV or just before RSP1 is not all that critical to getting the maximum casting distance.

Hi Gordy,
That seems spot-on to me.
Watching Ronny Landin compared to Bernt Johansson in the WC, they used very different styles.
What both had in common, compared to most others, was a fully unrolled back cast into a heavy tail wind exactly when the rod was repositioned in the perfect start position to deliver.
The precise haul timings within a few milliseconds can't have been anywhere near the importance of the unrolled and straight as possible bc.
Both achieve this in pretty different ways though. Has nothing to do with different timings of the haul.
Regards
Bernd

[Bernd Ziesche]

That's a great throwing motion Bernd. Superb shoulder layback and a great example of the stretch and release.

Hi Nils,
It really is impressive. Not sure those extreme pitchers would still do it again after having come into age though. I assume many will pay a price on day!
I now start to pay a price for all those thousands of hours in super fast stripping for coastal Sea trout.
Regards
Bernd

[gordonjudd]

The added force from the haul corresponds to the variation of momentum of the line (mass, speed) induced by the haul. But it is not the single force at play.

Merlin,
As you know the speed of the fly leg of the line is equal to the velocity of the rod tip plus the speed of the haul. Initially the force from the haul can cause the velocity of the rod tip to decrease (while it increases the bend in the rod) and thus the speed increase of the fly leg will not be equal to the speed of the haul. Unfortunately, determining the momentum change of the fly leg is very much impacted by what the rod tip is doing.

The principle is correct but the interaction with rod bending and unbending is very difficult to interpret.

Agreed. Thus I don't know how you could sort out how the momentum change in the fly leg is impacted by the timing of the haul.

I just looked at a few files and effectively, contrarily to my belief, the best speed is achieved slightly before RSP1,

That seems to be in agreement with Ulrik's thoughts on the optimum haul timing.

Gordy

[John Waters]

That's a great throwing motion Bernd. Superb shoulder layback and a great example of the stretch and release.

Hi Nils,
It really is impressive. Not sure those extreme pitchers would still do it again after having come into age though. I assume many will pay a price on day!
I now start to pay a price for all those thousands of hours in super fast stripping for coastal Sea trout.
Regards
Bernd

Hi Bernd,

The angle of the forearm is like all aspects of casting technique, it is coachable and with the right training, achievable by everyone. Of course the earlier it is introduced, the better, but it is not impossible to achieve at 73 years of age. It is not just the shoulder capsule that should be the focus. Injury potential needs to be understood by instructors and mitigated against through coaching. I have just finished a comparative study of casters and javelin throwers each of whom used a fly rod and line for the first time. The throwers achieved the same external shoulder rotation as baseball pitchers.

Fly casting is only unique only if you let yourself be limited by that incorrect premise.

John

[Merlin]

Gordy

When using Lagrangian equations you need to know all external forces before calculating the mathematical solution numerically. The terms corresponding to the force induced by the haul have differential terms, and then the solution depends on the timing of the haul since that force varies with time. You cannot consider the problem as being solved by the introduction of a force on top of a non hauled situation by a simple superimposition for example. The output you are after (line speed) depends on the timing of the haul and it is the same for rod deflection. Depending on haul timing, you may increase rod deflection in synch with the non hauled situation, or you may delay rod unloading because you introduce an extra force after the rod has started to unload. All that goes along with a change in fly leg speed.

This morning I gave a look at files corresponding to a fishing cast with a progressive rotation speed increase (Matthias’ cast), and a mild haul. The (marginally) best line speed is achieved for a peak haul velocity occurring just before MAV (36 ms). However there can be a tail in the line with such an early haul and it is wise to have the peak haul velocity after MAV. That confirms my memory about placing peak haul velocity close to MAV, I do not think “distance” but “fishing” intuitively. And that shows that the caster’s input in terms of speed pattern interferes with the optimum peak haul velocity timing. An exponential rotation speed pattern needs a late peak haul velocity, just before RSP.

Merlin

[Paul Arden]

One thought… maybe hauling aggressively too early causes the rod to bend as opposed to later when it simply slows unloading?

Cheers, Paul