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Maximum Rod Bend

Moderators: Paul Arden, Bernd Ziesche, Lasse Karlsson

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Bernd Ziesche
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Re: Maximum Rod Bend

#61

Post by Bernd Ziesche » Wed Jan 13, 2021 10:04 pm

Merlin wrote:
Tue Jan 05, 2021 10:39 am
Let’s say we aim at peak haul velocity just as the line speed is at maximum, about 15 ms before RSP1. In that case the peak haul acceleration should occur just before MCL.
Merlin
Hi Merlin,
for me hauling is all about pulling the line thru the guides. I can do this a) by moving my line hand only, b) by moving my rod hand only or most likely (and best) c) by moving both hands in a way that the lowest guide and my line hand gain speed away of each other.
Let's have a look on c), since this is what I use in fishing.
I believe, that my rod hand plays a huge part in making the line run thru the guides since I have a short part of my fly rod available to speed up the lowest guide. Now AFTER the lowest guide has hit max speed, the rod tip is still accelerating due to further straightening of the rod. I don't think I can in any way position max speed for the lowest guide close to RSP1. There has to happen ca. 2/3 of rod straightening....
In that regard I have no clue how I can position max hauling speed (max speed of the line thru the guides) such close to RSP1.

Maybe you understand the haul as just be done by the line hand and only refer to line hand speed? Please help to understand those figures.
Reading this thread reminded me that before starting a discussion it might always be very helpful to define the terms in use. :)
Regards
Bernd
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gordonjudd
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Re: Maximum Rod Bend

#62

Post by gordonjudd » Thu Jan 14, 2021 6:53 pm

While the rod tip acts as a pulley post MCL it also does so at any time that the rod is not directly pointing down the line IMO.
and
how can the rod tip per se act as a pulley post minimum chord length = during straightening?
Bernd,
That pulley reference was a quote from Paul so I am not the one to answer your question.

I see the tip top guide acting as a pulley only in terms that it changes the direction of the force from the haul hand to the direction of the force on the line.

There would be a 2:1 pulley effect on the velocity of the load in a typical pulley configuration where the lines going from a fixed attachment to the pulley and the pulley to the load are vertical. In that case if the pulley is moved an "x" distance vertically then the load will move a "2x" distance so there is a 2:1 effect on the velocity of the load vs the velocity of the pulley.

It is not clear to me that the same thing happens when the rod straightens out from MCL since the direction the tip top is moving is different than the direction the fly is moving. Also the line distance from the haul hand to the tip top is changing as the rod is rotating and straightening so that would have an effect those relative velocities as well.

The only constraint that I see in a casting is the length of line from the haul hand to the fly remains constant. How that length constraint affects the velocity of the fly relative to the velocity of the tip top is beyond me.

Gordy

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Bernd Ziesche
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Re: Maximum Rod Bend

#63

Post by Bernd Ziesche » Fri Jan 15, 2021 8:43 am

gordonjudd wrote:
Thu Jan 14, 2021 6:53 pm
It is not clear to me that the same thing happens when the rod straightens out from MCL since the direction the tip top is moving is different than the direction the fly is moving. Also the line distance from the haul hand to the tip top is changing as the rod is rotating and straightening so that would have an effect those relative velocities as well.

The only constraint that I see in a casting is the length of line from the haul hand to the fly remains constant. How that length constraint affects the velocity of the fly relative to the velocity of the tip top is beyond me.
Hi Gordy,
I seem to miss something here.
I understand your fine description of how a pulley works.
In order to have my fly rod work as a pulley in regard of doubling speed of the line thru the guides, I have to move the first guide straight away from my line hand (holding the line). What the tip does imo has nothing to with this! I can move my rod tip all around while holding the line in my line hand without moving the line thru the guides at all. Only when I start pulling my line out of the lowest guide, it's a 1d object. I pull out 1cm and at the tip it moves in 1cm, too. Doesn't matter, if I pull my line out of the lowest guide by moving my line hand, my lowest guide by rod hand or both, it remains 1 to 1. Thus when I reach MCL my butt section is about to be stopped now, while the upper parts still have to straighten. Thus the lowest guide will be stopped way before the tip. So the tip still will increase it's speed while I have stopped to use the pulley effect for (almost) doubling speed of the line thru the guides by moving the lowest guide (almost) opposite to my line hand.
I don't see how I can use the tip but the lowest guide for the pulley effect on line speed of the line thru the guides. Of course I will not double, since I can't move the first guide exactly straight away of my line hand and vice versa. I don't think we can for example match max possible line speed of the line thru the guides and max tip speed to happen at the same time.
Does that make sense to you?
Thanks,
Bernd
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Merlin
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Re: Maximum Rod Bend

#64

Post by Merlin » Fri Jan 15, 2021 9:31 am

Hi Bernd

I see what you mean. Maybe Gordy could use the data of Paul’s cast record to split the rod hand and line hand contributions to line haul speed understood as the speed measured by reference to the stripping guide. Not an easy task since all is not in the same plane (line hand, rod hand). The record data I use correspond to the speed relative to the stripping guide, Gordy can confirm if I fool myself or not on this point.

I am pretty sure that the “peak stripping guide speed” occurs early in the cast, somewhere before the end of the translation part of the cast, and then the line hand takes the lead. Consequently to get the peak haul speed (by reference to the stripping guide) very late it is a matter of line hand speed timing, not stripping guide forward speed. The modeling exercise is a bit academic and does not consider if such a speed timing is practical. It is just to see what may happen in extreme situations.

Again I do not think that the reference to a pulley mechanism is adequate since nothing can stop the rod to unload, tip included.

Merlin
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Bernd Ziesche
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Re: Maximum Rod Bend

#65

Post by Bernd Ziesche » Fri Jan 15, 2021 10:03 am

Hi Merlin,
thanks for your fine answer.
So by "hauling speed" in your charts etc. you usually refer to the speed of the line hand relative to the stripping guide (not line speed of the line thru the guides), right?
What do you think about percentages of max line speed of the line thru the guides done by rod hand and line hand?
Seems you think the line hand has the significant bigger impact?
I think it would have to be this way for being able to get the line speed max of the line thru the rings very close RSP1.
Regards
Bernd
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The first cast is always the best cast.

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Bernd Ziesche
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Re: Maximum Rod Bend

#66

Post by Bernd Ziesche » Fri Jan 15, 2021 10:07 am

Merlin wrote:
Fri Jan 15, 2021 9:31 am
I am pretty sure that the “peak stripping guide speed” occurs early in the cast, somewhere before the end of the translation part of the cast,
Merlin,
Why would that be?
I thought rotating the butt section is what speeds my stripping guide most?
Thanks
B
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The first cast is always the best cast.

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Merlin
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Re: Maximum Rod Bend

#67

Post by Merlin » Fri Jan 15, 2021 10:39 am

Good point Bernd

I need the data analysis of Paul's cast to get a better idea, I do not have all the original data.

Merlin
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Charles Ritz, A Flyfisher's Life

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Paul Arden
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Re: Maximum Rod Bend

#68

Post by Paul Arden » Fri Jan 15, 2021 10:53 am

Hi Bernd,

It wasn’t me who brought up the concept of pulley. That I believe was Gary and Morsie. However in as much as a pulley can change the angle of the force (not double the speed?!) I pointed out that any angle the rod makes to the line during the haul changes the angle of the force and therefore the rod tip could be regarded as being a pulley (and not only when the rod tip is in front of the caster).

Cheers, Paul
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Re: Maximum Rod Bend

#69

Post by Mangrove Cuckoo » Fri Jan 15, 2021 2:50 pm

I so apologize for salting the well with this pulley idea. It was not meant as a corollary to casting theory - I just blurted it out when I "saw" it while experimenting in my imagination.

I am grateful, however, for the subsequent discussions as it has further incited more mind experiments. I have been curious about hauling for some time but I had not focused down on the relation between the line hand and the stripping guide. Apparently, Bernd has.

It made me realize there are many different scenarios as to when and what happens during different casts:
- the line hand and stripper guide may move in parallel, and no line moves through the guide
- the line hand may move toward the guide (in the case of "feeding" it is obvious), but if it done not purposely, then it might be an inefficient haul
- or similarly, the rod hand may move purposely toward the line hand... as in slide
- and then there is a "good" haul when both move away from each other...

But then, again as Bernd has pointed out, there is the angular relationship between the line and the stripper guide. It gets a bit curious for me at this point. It seems "hauling" is not optimized until the stripper guide is perpendicular, or beyond. And the guide could have gotten there via rotation, translation, or both. And... perpendicular to what: the ground or the line hand?

I have always been a long-hauler. I started the haul early in the translation/rotation phase and continued to attempt to maximize haul speed until the end. (And, of course, that led me to be very suspicious of slide.)

Now I realize (or at least I think I "see") that hauling early, well before the stripper guide approaches perpendicular, is maybe not such a good idea... it definitely would seem to be at least less efficient than delaying.

And that leads to scratching my head over what might be the better alignment for the hands when the haul begins...

Plenty of stuff to work out... both in my imagination and in the field...
"Technique is the proof of your seriousness"

Wallace Stevens

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Bernd Ziesche
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Re: Maximum Rod Bend

#70

Post by Bernd Ziesche » Fri Jan 15, 2021 3:09 pm

Paul Arden wrote:
Fri Jan 15, 2021 10:53 am
It wasn’t me who brought up the concept of pulley. That I believe was Gary and Morsie. However in as much as a pulley can change the angle of the force (not double the speed?!) I pointed out that any angle the rod makes to the line during the haul changes the angle of the force and therefore the rod tip could be regarded as being a pulley (and not only when the rod tip is in front of the caster).
Hi Paul,
in fact it was me who came up with the idea of the rod being like a pulley in terms of creating speed of the line thru the guides via the rod hand. That was over 10 years ago, when I started to understand hauling to be done by both hands and the rod hand to use rotation of the rod until the first guide as an extra. Here is an old picture, I made at that time.
http://www.first-cast.de/WebPics/BZhauling1.jpg
There is an old thread about it somewhere. :)
Ok, when only talking about direction of force, the tip of course is coming in. When talking about line speed of the line thru the guides only the first stripping guide matters.
When it comes to the level of force a single pulley can't do anything. Those three we have to understand seperately, I think.
We probably see the rod as being a rod, not a pulley. :)
Regards
B
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The first cast is always the best cast.

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