Rod unloading during acceleration

[Bernd Ziesche]

Hi everyone,

Paul claiming to not start the main speed up of his line hand (to haul) before the rod starts to straighten

I don’t think that’s what Paul said. I think he said,

I see the rod hand as doing two things; 1) rotating the rod (torque), which does load it. But mostly we accelerate later, arguably as the rod is unloading. 2) increases haul speed because haul is the separation of line hand from the stripper.

The rod is certainly unloading as we are hauling. We have known this for 24 years. And for as long we have been questioning whether the rod could be unloading while we are adding torque. One thing that was argued a long time ago was that as the rod angle changed from vertical to horizontal the load on the tip would decrease. And then some 15 years ago Server suggested the Self Deceleration Mechanism, which I think of as jumping down on a bed spring. That’s the “arguably” bit!

Can anyone explain me, why my rod would start to unload, while my line increases in speed and I am about to add max torque?

I thought the moment when I reduce force input is, when my rod starts to unload.

MCL isn't a measure for rod load, is it?

I ran a test:
My rod horizontal, specific weight on my tip, putting nylon tip to handle. As soon as I lift my rod, MCL decreases, while the load should remain the same since the weight on the tip wasnt changed. I thought this is, because I now add the force more to the thinner tip section = tip getting closer to butt.

Main questions:
When do we start to accel. our line hand and when do we max out in a) line hand speed and b) line thrue the guides speed?

I would have said to start accel. my line hand when I start main rod rotation and then max line hand speed happens slightly post max line speed thru the guides (because the angle guide to line hand gets less effective near the end).

Looking forward to stay corrected. Too long not having discussed these details. Probably I forgot some!
Thanks
Bernd

[Paul Arden]

It will be good to go back into this.

https://www.sexyloops.co.uk/theboard/vi ... f=8&t=3723

[Bernd Ziesche]

Thanks, mate! That was proper info. Allthough there seem too many variables to give one straight short answer. So I guess still video analyses is the best tool.

Can you provide a video showing such a late line hand hit, quite far behind main rod rotation was started?
Not sure, I have seen this in video, yet?
Thanks
B

[Paul Arden]

I’m not sure what you mean by main rod rotation. But Merlin and Gordy certainly have posted my haul timings, force application graphs etc. Ulrik and the Swedish Team also did a very involved study too. Both will be here in the physics forum. Termites on the water. Back later!

[NM]

Bernd,

Bernd,
You may find the tournament distance cast measurements (thanks to Gordy) and observations in the attached note relevant and interesting. There are some interesting differences between the 4 casters I compare (Chris, Henry, Paul, and me), some of that, but not all, is of course due to the different equipment used (9’ versus 10’ rods and long WF5 (MED) lines versus heavy shooting heads).

There appears to also be some interesting differences between what we perceive we are doing and what the measurements are showing we are doing, and that put concepts like the “hit” and “stop/stopless” in some perspective—the angular velocity measurements show us slowing down when we are trying to turn over the rod as fast as we can, with what Paul refers to as the hit starting just slightly before MAV (which happens when the rod is vertical), without trying to make any stop—we are rotating the rod butt well past RSP1. It would be interesting to figure out what causes us to slow down in angular velocity when we try to do the opposite. It must be because we are physically not able to accelerate the rod further nor even to continue to rotate it at the same speed at that point. Why is that? Is it because (a) we are at that point relying more on the wrist, which is too weak; (b) the rotational inertia of the fly rod and line system is increasing as we bend the rod and its resistance to further bending is increasing; and/or (c) as you argued in the power versus speed tread that the line hand as we haul may slow max possible rod rotation because the haul pulls against rod rotation?

You may also find the fact that Henry’s max haul velocity is measured to be at RSP1 interesting in light of that earlier max rod bend discussion you had.
Note also how different Hendry’s hand path is and how much shorter his stroke past rod vertical and MAV is compared to the rest of us. That explains some of the observed differences.)
Best,
Nils

[John Waters]

Hi Nils,

I think you’ve nailed in a) above. May I add too much focus on the in front of the shoulder hand acceleration, rather than behind the shoulder.

Excellent post,

John

[Paul Arden]

Yep that’s excellent work there. I remember seeing this and thinking that the key line acceleration phase is MCL and after, as opposed to leading up to RSP. While the rod tip maybe fastest at RSP, what we are interested in is our highest line speed as the rod tip starts to deviate away from the line path.

It feels to me like we are building up to inserting an impulse. Pull-back, speed-up-and-stop, microsecond wrist, powersnap, the “Hit”… these are all sudden accelerations.

When I think of impulse, I think of SDM (it’s very similar to S&M by the way, I don’t know if Server was trying to tell us something). That was explained to me as jumping down on a bed spring; you compact the spring and it unloads sending you upwards. The hit, the S-U-A-S, this is a little bit like jumping down on a bed spring.

Cheers, Paul

[John Waters]

Hi Paul and Nils,

Is there any data tracking rod hand speed?

Thanks,

John

[Bernd Ziesche]

I’m not sure what you mean by main rod rotation.

Hi Paul,
I kind of had to ask this myself in terms of what my brain tells me this is and what the camera sais about it.
Let's say I desire to start my stroke by translation. The camera of course shows, that slight rotation enters my stroke, too. Then at some specific point I start to rotate my rod on purpose in order to create the desired speed. Distance casting my MED5 this would be about adding massive wrist based rotation. The moment I start this "main rotation", I start my line hand pull, too. That to me feels like hauling towards the end (not starting straight away). Trying to start pulling my line hand when I already start slowing (decelerating) my main rod rotation (beginning of unloading I think), feels very confusing to me. I think of having a rope between my hands and want to break it in the main speed up. This means I fully start with both hands at the same time here. I think, I see this also in most videos.
If I would stop the cast just at that point, when I start main rotation, the line more or less just falls down. That is even though some rotation usually already creeped into my stroke (as video shows me).
I bet face to face on grass we are on the same page in 10 seconds. Just using words here make it obviously slightly harder. Even after 20 years.
Cheers
B

[VGB]

There appears to also be some interesting differences between what we perceive we are doing and what the measurements are showing we are doing,

Hi Nils

That observation also puts an interesting spin on teaching using feel as an objective.

Regards

Vince