Rod unloading during acceleration

[Bernd Ziesche]

I had a go on rod butt rotation filmed in 250 fps. I applied quite some force, I think realistic to a distance cast.

Less weight makes it possible to use a smaller fraction for decel. though.

25% broomstick and 12% butt section... I would have expected to find thr 9' fly rod in between.

The additional section, I think goes to what Nils has described well.

What I yet don't agree on is, that we don't adjust the force we apply to the desired RSP1 position. That position is highly variabel, but we all make it happen pretty similuar.
It's not the rod, it's us making that happen!?


Merlin, are you saying the numbers for MAV are not very accurate?

[Merlin]

Not at all Bernd, your question puzzles me.

Merlin

[Bernd Ziesche]

The difficulty with such cast (and record) is that it is not possible to see exactly when rod butt is stopped, since deceleration ceases before the end and then a more or less constant rotation speed follows.

I did missunderstand this then. MAV recorded well = beginning of decel. clear, no? For the rest Gordy added the live graph also. Pls. explain what you meant.
Thanks,
B

[NM]

Peak haul velocity is just after MAV which is fine, Paul.

Merlin

Why do you want peak haul to be that close to MAV Daniel?

Nils

[NM]

The difficulty with such cast (and record) is that it is not possible to see exactly when rod butt is stopped, since deceleration ceases before the end and then a more or less constant rotation speed follows.

I did missunderstand this then. MAV recorded well = beginning of decel. clear, no? For the rest Gordy added the live graph also. Pls. explain what you meant.
Thanks,
B

Bernd,
As you can see from the videos, there's significant rod butt rotation (and haul) left after RSP1. The is me at RSP1:

Nils at RSP1.png (654.63 KiB) Viewed 264 times

and this is the same cast at the stop of the rod butt, and that stop happens because I have run out of arm, not because I made any effort to stop the rod.

My hand was moving forward and up during that part of the stroke. Thus, I run out of arm. If I instead had pulled the hand down as Henry does then I could as easily instead have had rod butt stop happening when, and because, I hit the ground.

[Bernd Ziesche]

Hi Nils,
It looks to me like your rod hand arm already was straight at RSP1, but you rotated your torso and the shoulder came further forward. Thus the rod hand came forward as much as the shoulder did?
Wouldn't you want to use as much distance for acceleration until RSP1 as possible?
Of course such slomos show what in normal speed looks just total perfect and still is brilliant casting.
Lasse recommended to have the line go early. I agree but are wondering what you hauling longer does to cf. Could be slightly reduced this way.
Regards
Bernd

[Merlin]

Pls. explain what you meant.

Here is the graphic corresponding to Paul’s cast and one can see that the end of rotation is not visible (red line). Consequently we cannot have a full analyzis of the cast.

Paul's competition cast.JPG (31.59 KiB) Viewed 240 times

The end of the record corresponds approximately to MCF, RSP2 cannot be seen for example. RSP1 occurs at 0.962 s for the model.

Merlin

[Merlin]

Why do you want peak haul to be that close to MAV Daniel?

I guess you remember the conclusion of the analysis of the haul: there are two phenomenons under competition:
• Direct speed addition effect which suggests having peak haul velocity close to RSP (line launch timing).
• Additional force applied to the rod (more elastic energy stored) suggests having peak haul velocity very close to MAV, with the potential drawback of a tailing loop.

The best compromise in terms of maximum speed achieved is to keep peak haul velocity rather close to MAV by comparison to RSP. If you look at the four examples mentioned by Nils, they all follow that rule. If you read Ulrick’s study on hauling, the conclusion is the same.

The “firing window” for peak haul velocity is between MAV and RSP. The size of this window depends on the speed of tackle. If you consider a given line and carry, the stiffer the rod is, the narrower the window is.

Merlin

[Bernd Ziesche]

Hi Merlin,
When MAV takes place around the middle of arc (50% accel./50% decel. for the rod butt or handle), and max hauling speed (line speed of line thru the guides) happens here, too - where does the end of the line hand path show up here?
I assume you don't recommend to run out of line hand pull, when the handle was just rotated half the arc!?
Thanks
B

[George C]

Peak haul velocity is just after MAV which is fine, Paul.

Merlin

Why do you want peak haul to be that close to MAV Daniel?

Nils

Hi Nils
I know Merlin responded already to your question.
If you or others have not seen it, Merlin provides a more detailed explanation in post #36 of this thread https://www.sexyloops.co.uk/theboard/vi ... 3&start=30
Something I found extraordinarily helpful.
G