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Topic: Energy Sources in the Haul, Filling in slide 26 of Grunde's Talk

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Post Number: 11

Paul Arden

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Posted on: May 25 2009,13:23

You're welcome Gordon and thanks for your willingness to assist moderating it! I think Jakob makes a very valid point. One thing I would like to see properly measured is peak haul speed on a big distance cast. I think Rajeff and Hartman both have very fast hauls and I think this is a major key to distance. 10m/s sounds very low to me - that's only about 20mph. Cricket balls and baseballs are thrown to 100mph - 44m/s. Surely a top distance caster is likely to have a considerably faster haul than the 10m/s we commonly hear stated?

Cheers, Paul

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Post Number: 12

gordonjudd

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Posted on: May 25 2009,15:15

Skip to the previous post in this topic.

QUOTE

Isn't it so that if you start the haul while still translating, your rod hand-movement adds to the distance and speed of the haul. If I move my hands apart 5m/s each, they are moving away from each other at 10m/s.

Jacob,
That is true, and is the reason Grunde measured his haul speed by looking at the distance from the first stripping guide on the rod to the haul hand. Since the distance from the stripping guide to the tip top of the rod is fixed, the distance change he measured would be the same as the distance change from the rod tip to the haul hand.

Grunde says the haul hand was moving out of the x-y measurement plane (to the side of the body) so his distance measurement in the x-y plane was a bit shorter than the true distance as he could not measure the off plane position of the hand (along the z-axis). Consequently the haul speed he calculated from the hand position might be a bit smaller than the true haul speed.

As a check he also measured the haul speed by looking at the change in the distance from a marker on the line to the tip top of the rod. Those movements are in the same plane, so as long as the rod casting plane is nearly vertical his numbers for the haul speed and the tip speed should be accurate.

The key point is that up to RSP the line speed should be equal to sum of the tip speed plus the haul speed as long as the haul speed is measured with respect to the tip of the rod.

Gordy

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Post Number: 13

Marc LaMouche

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Posted on: May 25 2009,15:37

(gordonjudd @ May 25 2009,16:15)

QUOTE

Since the distance from the stripping guide to the tip top of the rod is fixed, the distance change he measured would be the same as the distance change from the rod tip to the haul hand.

hi Gordy,

how could this be so if the rod is bending ?
isn't the chord distance continuously changing throughout the stroke ?

cheers,
marc

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Post Number: 14

gordonjudd

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Posted on: May 25 2009,15:43

QUOTE

Surely a top distance caster is likely to have a considerably faster haul than the 10m/s we commonly hear stated?

Paul,
I agree, and I think the haul speed is going to vary with the ability of the caster and the distance you are trying to cast.

I also think that just as with angular acceleration of the butt, distance casters are going to maximize their haul speeds by waiting to start their haul and then apply a varying amount of acceleration of the form:

QUOTE

haul_accel=ao*t.^(exp power)
where: ao is some fitting constant
t is the time variable
exp power is proportional to the how the acceleration is varying with time (constant=0, linear=1, quadratic=2, etc)

so that they get the maximum amount of velocity over the distance the haul hand can move.

In Grunde’s data the acceleration of the hand away from the stripping guide was nearly constant so the exponential power in that cast was 0. You had an exponential power of around 3.4 in the angular acceleration of rod butt on your distance cast, and I would bet that your haul acceleration has a reasonably high exponential factor as well.

We just need some data taken from some all out distance casts to confirm that this is true.

Gordy

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Post Number: 15

Paul Arden

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Posted on: May 25 2009,15:51

I'm quite sure of it too. Am I right in saying that so long as the line hand is still accelerating there must be a bend in the rod?

Thanks, Paul

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Post Number: 16

gordonjudd

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Posted on: May 25 2009,16:10

QUOTE

how could this be so if the rod is bending ?

Marc,

Obviously, just because the rod is bending, it does not mean the length of the rod is going to change, just its shape.

The line will follow the curved shape of the rod so by adding the fixed length from the stripping guide to the tip top to the change in the distance from the haul hand to the stripping guide you can get the distance from the tip of the rod to the hauling hand.

QUOTE

isn't the chord distance continuously changing throughout the stroke ?

Certainly, but the cord distance (straight line distance) is not what is being used to measure the haul speed. The haul speed is being measured from the change in the distance from the rod tip to the haul hand. That distance involves the line path around the curve shape of the rod, so the haul speed is being properly measured in Grunde’s data.

If you just measured the hand speed, then you would miss half of the line speed increase that would come from moving the casting hand as Jacob mentioned. The tip speed would include the speed from the casting hand movement, but the distance from a marker on the line to the rod tip will also be shortened by the increased distance from the rod tip to the haul hand. You need to take that distance into account when measuring the length of the haul.

If you were only measuring tip speed and hand speed, then you would miss part of the casting hand velocity effect on the line speed. Grunde did the correct measurement by measuring the distance of the haul relative to the stripping guide on the rod so he would take the movement of the casting hand into account.

Gordy

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Post Number: 17

Marc LaMouche

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Posted on: May 25 2009,16:13

thanks Gordy

i guess i'm not thinking straight today

cheers,
marc

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Post Number: 18

gordonjudd

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Posted on: May 25 2009,18:39

QUOTE

Am I right in saying that so long as the line hand is still accelerating there must be a bend in the rod?

Paul,
That is probably the case, but it is probably better to look at the acceleration of the hand (and hence line) causing added tension in the line. That added tension would probably cause some additional bending of the rod (I think that is related to the indirect energy source in Grunde’s presentation but he would have to confirm that is the case).

Obviously if the rod was horizontal then the acceleration force or tension from the haul would not cause any bending of the rod. Thus the increase in the bending of the rod is going to depend on the pull angle of the line relative to the angle of the rod butt.

Grunde has yet to confirm that the indirect energy component of the haul is going to result in an increase in the tip velocity. But assuming that is the case then that added energy may not be a big factor as the tip speeds he measured for the short cast made with and without a haul were nominally the same.

Gordy

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Post Number: 19

gordonjudd

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Posted on: May 25 2009,18:45

QUOTE

i guess I'm not thinking straight today

Marc,
I have the same problem, as it took me quite a while to sort through what the error would be if you tried to get the haul speed by just measuring the velocity of the haul hand.

As you might expect, Grunde did the correct measurement, but my first inclination would have been to look at the hand speed, and thus missed the effect of moving the casting hand an additional distance from the haul hand.

Grunde would not make such a "rooky" mistake.

Gordy

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Post Number: 20

grunde

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Posted on: May 29 2009,20:00

First post in the new forum

QUOTE

Grunde would not make such a "rooky" mistake.

I do stupid mistakes all the time

just hope that I'm able to learn from some of them.

Learning new stuff is part of the fun, after Scotland I'm definitely going to implement some elements of Pauls distance cast (with a twist) :pirate

I'm also really happy that we now have a separate forum for technical casting and tackle discussions, and it's great that Gordy and Torsten have joined as moderators (whatever that might imply

)

On the out of plane stuff:
Gordy have a sharp eye, and rightly noticed the "inconsistency" in the graph on page 22. This "haul measurement" was included in the figure to indicate the timing of the start of the haul. When I did the talk I told that the absolute value was not correct due to out of plane hand motion, but this info was left out of the slide for "aesthetic reasons".

If you look at the video you can see that Mathias is casting with his elbow pointing towards the camera, so when he hauls around the left hip he is way out of the image plane (maybe 70 cm or more)...

This is a new version of the plot on page 22 where the haul speed is measured using the distance between the tip and the first tracking point on the line.

And you can see that just before RSP
v_line = v_tip + v_haul
(as it should). The problem with this measurement is that the tracking point on the line is not in the image frame when the haul starts.

Indirect additional work caused by the haul:
Hauling gives additional bend in the rod -> Additional torque on the rod hand, which then give an additional work contribution.
By the way, hauling is good even after end of haul-acceleration. This is because hauling through "the stop" haul hinders line from catching up with the tip before the important (first) part of the unload...

Cheers,
Grunde

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20 replies since May 18 2009,18:28

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