Smoothness - and the use of the CA

[Bernd]

Hi everyone,
I read statements like: "I can't teach constant acceleration." "I can't aim for constant acceleration."

My question is can we produce casts in low, medium and high smoothness ratios on purpose and being consistent on each one?

I have very little experience with the CA.

But I am pretty sure I can cast different smoothness ratios on purpose.
The lower it will be (smoother) the more consistent I think it would be.

I don't see why an experienced caster wouldn't develop a feeling for smoothness in casting anyway.

Am not looking for the fact we can't hit a smoothness ratio of 1,0 = constant acceleration. Same with the SLP we never will hit it for the whole acceleration tip path.

Am also not looking for the perfect theoretical ideal to be constant here!

Thanks
Bernd

[Bobinmich]

Bernd,

I have struggled with this problem for years. I have seen all the models and heard all the theories. I even built a model which allows you to supply the input to a fly rod handle and see what the line does. In the end, I came to the following conclusion. I have spent years casting at night and I know what I feel when I am casting. It is not acceleration because acceleration cannot be felt. I cannot be timing because you need to adjust for different rods and lines and distance at night. I think (think being the operative word here) that you feel the force (or torque) you are applying to the handle. I think you learn to either keep that force constant (constant acceleration) or increasing (increasing acceleration). You avoid any abrupt changes and you avoid any motion that would decrease that force (torque). If you do that, the result will be constant or smoothly increasing acceleration whether you are trying to or not. I think it is really that simple and all the modeling that I and others have done is just adding fog to the process. I am not against trying to understand the engineering mechanics. That is a joy unto itself. But I don't think all the engineering mechanical solutions on earth can be of much use when trying to teach someone how to cast.

Just my opinion.

Bob

[Paul Arden]

Hi Bernd,

I think you have to ask first "how is the Smoothness Ratio" determined?

I believe that the Analyzer has potentially great significance as to how we further our knowledge of FC. It is currently doing so - our analysis of the results has certainly surpassed the original programmed understanding.

A 3D iPhone compatible wireless casting analyzer could be very useful right now. But the Analyzer is ahead of its time, because we haven't fully figured out what it means yet, let alone how to apply it to remote flycasting instruction. But we will.

Cheers, Paul

[Paul Arden]

Hi Bob,

cross-posted. I've put a few independent people in front of the Analyzer to ask for feedback. I've had some feedback that it makes them "interested" in flycasting. But you're right it could make them mechanical, and not dancers with the rod.

It sounds to me that you cast with feeling. I think that's mostly what we teach! Is there any way to make the Analyzer teach this feeling in your opinion?

Cheers,
Paul

[Bobinmich]

Paul,

I don't think the analyzer was ever designed to "teach" flycasting. It is an excellent tool to analyze what the result of a cast is. From that, a good instructor can help. But I don't think an electronic instrument will ever be able to "teach." Here is my experience with it. It really helped me.
http://www.hatofmichigan.org/uploads/Am_I_Really_a_Good_Caster.pdf

In all the books I have read and video's I have watched, I have never been able to match what I have learned from a good instructor. And though I enjoy learning about the physics and making math models, nothing here has ever helped my casting as much as a good instructor and hands on experience. I think it will always be that way.

The CA is a tool. Nothing more. An excellent tool but a tool none-the-less.

Godspeed,

Bob

[gordonjudd]

I think you have to ask first "how is the Smoothness Ratio" determined?

Paul,
I am not sure of the exact limits but I think they are just comparing the least squares linear fit about the 90% time point of the measured angular velocity curve to the fit obtained at the 10% point into the cast. Thus the limits for the two linear fits would be around 5%-15% and 85%-95%.

That would give you the ratio of the nominal angular acceleration at the 90% point to the 10% point. I imagine the 0% starting time point is taken as the half way point between the peaks and the 100% time limit is at the peak of angular velocity curve.

If you have some CA data you could eye ball the slopes at those two points on the velocity curve to see how it compares with their calculated value. Then you would just adjust the selected measurement points until you get values that match.

Maybe Bob could contact Noel and get the exact values they are using for their "smoothness" calculation as well.

"I can't aim for constant acceleration."

However they calculate it, I want my smoothness ratio to be around the value Korich and Rajeff are getting and not worry about getting an "ideal" value of 1 that would correspond to constant acceleration.

As noted here, striving for constant acceleration is the last thing you would want to do in distance casting. As Paul well knows, there is a reason for wanting to "hitting it after midnight" in distance casting.

Gordy

[Bernd]

I know what I feel when I am casting. It is not acceleration because acceleration cannot be felt. It cannot be timing because you need to adjust for different rods and lines and distance at night. I think (think being the operative word here) that you feel the force (or torque) you are applying to the handle.

Hi Bob,
I too think I feel the rate of force (not in total detail of course) that I am applying to the cast.
Since force equals mass times acceleration, I don't really understand why we could feel force but not acceleration?
When I cast with my eyes closed I would feel the mass (rod + reel + length of line) as well as the rate of acceleration both up to some degree. Of course I can't tell the exact levels of each one.
For sure I could immediately tell if I cast with a 10wt. or a 5 wt. combo. As well as I could tell if there is a huge or a small amount of line outside the rod. I also could feel the casting tempo to some degree.
And I think I can produce different rates of acceleration on purpose.
Could you explain more why you think we can't feel acceleration?
When we would put our rod hand to a casting robot which would do the cast, we couldn't estimate the rate of acceleration to be constant, slightly increasing, or significant increasing?
I think we could!
I also could think of a lot of examples about daily live situations where we feel acceleration rates to be changed like when driving a car.

I think you learn to either keep that force constant (constant acceleration) or increasing (increasing acceleration). You avoid any abrupt changes and you avoid any motion that would decrease that force (torque).

That matches perfect with my understanding of most of our casting especially when aiming for smooth consistent loops.

"I can't aim for constant acceleration."

However they calculate it, I want my smoothness ratio to be around the value Korich and Rajeff are getting and not worry about getting an "ideal" value of 1 that would correspond to constant acceleration.

Hi Gordy,
that sounds interesting to me!
On one hand you want to aim for the same smoothness like Chris and Steve have in their casting, and on other hand you don't want to aim for the form of acceleration which seems to be the "ideal" both Steve and Chris are getting close to.
Comparing tons of beginners, advanced and expert casters like Chris and Steve showed: The more experienced the caster was, the smoother his angular acceleration was.
That makes lots of sense to me.
I think the change in the rate of increasing bend in the rod effects tip path a lot. The more smooth this change is, the more easy it is to control tip path I think.
Now which form of acceleration would be the smoothest change in the rate of rod bend?
I think this goes in the direction of linear. If constant does not work for highest distance (which I have no doubt about), I think linear increasing might be better here. And maybe we have to make a compromise in order to be able to reach max possible angular rotation on distance casts.
However for average casting I think linear acceleration will give the smoothest change in rod bend.
Why do you think those expert casters get closer to constant acceler. compared to beginners who have higher rates of increasing accel.?
To me the answer is in producing as much tip speed for a given arc as possible while keeping the increase in rod bend as smooth as possible in order to maintain proper tip path.
Does that make any sense to you?
After all I still think teaching SMOOTH acceleration or SMOOTH force application helps pretty well and pretty fast to achieve great (consistant) loops, and yet I don't see why we couldn't feel smoothness or learn how to feel it to some degree.
We can't smell or taste a cast. And in my understanding watching it will always give best possibilities to analyze. But besides that I can hear and feel parts of my casting, too.
For example I can hear Paul's very fast rotation of his rod at the very end of his 170 stroke.
Besides watching the cast feeling is the second most important way of analyzing my casting. There are a lot of things I can feel to be good or bad in all my casting. Force application is just one.
Greets
Bernd
p.s.: Sorry, quiet long post...

[Bernd]

Is there a model available which (everything else being equal) shows tip path in relation to the change in the rate of acceleration for a cast using just arc?

Shouldn't this be the one to have when wanting to proof constant to be wrong as an ideal for aceleration in order to match an as straight tip path as possible?

[Paul Arden]

Why do you think those expert casters get closer to constant acceler. compared to beginners who have higher rates of increasing accel.?

[gordonjudd]

On one hand you want to aim for the same smoothness like Chris and Steve have in their casting, and on other hand you don't want to aim for the form of acceleration which seems to be the "ideal" both Steve and Chris are getting close to.
Comparing tons of beginners, advanced and expert casters like Chris and Steve showed: The more experienced the caster was, the smoother his angular acceleration was.
That makes lots of sense to me.

Bernd,
It would make sense to me too if I thought it was true that Chris Korich had a smoothness ratio of around 2 like Bruce is able to get. But from the measurements I have taken of Chris (I do not have any slo-motion videos of Steve) he is a long way from using constant acceleration in the accuracy games.

I hope you can see the calculated acceleration for curve he produced in a 40 foot false cast had a quadratic variation (the measured fit was accel= 0.6003 + 2.3158*t +2.3158*t.^2) deg/s^2 vs time as shown in the red curve below.

Looking at the acceleration values at the 90% and 10% points in that cast give a smoothness ratio of over 10.

I had some old data for Steve and Lefty taken at a 30 fps rate that showed a butt phase vs time curve that fit very well with a cubic (t^3) curve. That cubic variation in the butt phase was taken to be a typical exponential factor for good casters in Dr. Robson's paper as well. That would imply a quadratic variation in the angular velocity curve and a linear change in the acceleration vs time curve.

I don't know if Chris was using a different stroke when Bruce measured him, but everything I have of him shows an acceleration curve that is far from being constant. Maybe you could ask Bruce to post the measured curves he based his claim that Chris and Steve have low smoothness values on 40 to 50 foot casts. Based on what I have seen for Chris at least I do not think it will.

That is what I meant in my comment. Chris and Steve to not shock the rod with sudden changes in their applied acceleration (any shocks would show up by taking the derivative of the acceleration curve which engineers have affectionately dubbed as "jerk") but I don't think they use constant acceleration or get smoothness ratios in the 2-3 range as you have been led to believe.

Gordy

[Bernd]

Why do you think those expert casters get closer to constant acceler. compared to beginners who have higher rates of increasing accel.?

Hope this makes it more clear?
Greets
Bernd

[gordonjudd]

Shouldn't this be the one to have when wanting to proof constant to be wrong as an ideal for aceleration in order to match an as straight tip path as possible?

Bernd,
The only model we have at present just has one dimension. It will give a good estimate of the perpendicular tip deflection magnitude that is produced for a given acceleration function, but converting that to an actual tip path would need the rod bendform for that deflection and the hand path that was used for a particular cast.

In Grunde's high speed videos Mathias applied nearly constant acceleration using the Paradigm rod on a 10 meter cast, and had a linear variation in the cast made with TCR. Both casts produced nice loops, so I do not know how you could claim that one acceleration function was better than the other.

There are a lot of variables that impact tip path and or loop size and shape, so I do not see how you could say one casting style or acceleration function was "better" than another. I think most good casters use non-constant acceleration in their accuracy casts, and do so without tailing or producing screwed up loops.

I do not think there are any hard rights or wrongs in casting, and agree with Al Kyte that instructors should be inclusive of different styles and not get fixed on demanding the student should cast "just like him." That goes for the acceleration profile they prefer just as much as hand path or any other variable in casting.

Gordy

[Bernd]

But from the measurements I have taken of Chris (I do not have any slo-motion videos of Steve) he is a long way from using constant acceleration in the accuracy games.

I don't know if Chris was using a different stroke when Bruce measured him, but everything I have of him shows an acceleration curve that is far from being constant.

Hi Gordy,
I remember Bruce told me the purpose when measuring all the casters with the CA was "best loops" (pointy and tight).
That is significant from casting in accuracy tournament games.
In tournament games I mostly saw very good casters striving for total high line speed (in order to match windy situations as well).
Watching Paul aiming for accuracy and going fpr nice loops on a average length of line is quiet different!
His loops when being in the accuracy game are not as beautiful tight and pointy as they are when aiming for them to be.
In my understanding accuracy games and the often required high line speed here is a different thing.

Again Bruce and Noel ask all these casters to show their best loops. He did not ask for smoothness or everything like that.

For my own accuracy casting I can tell my loops are crap compared to when striving for my best loops.

About the smoothness ratio I remember Bruce saif verything below 8 was said to be good.
Above that tailing issues more and more took place.

Btw in distance casting I see way more loops not being nice in my book anymore compared to when the same experts try to strive for their best loops on average length of line. In the last competition I was (at Paul's place) there were (sorry guys) - me included for sure - lots of bad loops to watch :p . Tournaments are simply different I think.

[gordonjudd]

Hope this makes it more clear?

Bernd,
It would if it was that simple.

Chris Korich is a world class tournament caster (he even beat Steve for the all-round title once in the 1990's) so I would put him in the expert class and yet the angular velocity curve he produces does not look anything like the expert curve in your plot.

It is a nice theory, but I do not think that all expert casters produce a nearly linear velocity profile in their casting. Even the original expert 50 cast (that I assume was made by Bruce) had a quadratic response as shown below, so I do not know when (or why) the "ideal" curve became linear.


Have you seen any data that shows the loop shape or the way the leader straightens out is better with a linear angular velocity profile than it is for a quadratic profile? That is what I would want to see as proof that a linear velocity profile was the "best" way to cast.

I don't know what the criteria was for coming up with that curve, but I would expect that there are many expert tournament casters (at least on the West coast) who do not produce a linear velocity profile. Chris Korich's style is a case in point.

Gordy

[Bernd]

In Grunde's high speed videos Mathias applied nearly constant acceleration using the Paradigm rod on a 10 meter cast, and had a linear variation in the cast made with TCR. Both casts produced nice loops, so I do not know how you could claim that one acceleration function was better than the other.

If we would call linear acceleration to be an ideal instead of constant acceleration as just one form of linear acceleration, I'd totally be fine with that.

Way more specified than just "smooth".

Would that make more sense?