Understanding Casting

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Whinging pom

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As the duffer on the side lines I’d like to say this has been a most frustrating turn today …which is such a shame.
I was beginning to feel like I was really getting to understand a few things and appreciating the knowledge available here.
But it’s just turned into such a confused mess.
Tangled why are being like this with people??
I cannot for the life of me understand what you have to keep disagreeing with, and why you are undermining people who obviously have the knowledge and the experience and are lucidly sharing it with us. (Even poor bloody Isaac Newton isn’t spared the Tangled treatment 😁).

Everything seems clear and straightforward and beautifully explained and illustrated and you come in and derail it . Why?!

Have you not noticed they’re not falling out with or contradicting each other ?! It’s just you , please don’t mistake it for prejudice or conspiracy. It’s just simple cause and effect, action and reaction.

(If someone ever said to you “the whole world loves a smartarse” it really wasn’t an endorsement!😎)

Please try and reign it in! It’s such a waste of what could have been in the right hands a great discussion and valuable resource. I’ve tried to be supportive but seeing your performance today….. its just so frustrating.

If you can’t see “It”.
It doesn’t mean everyone else is wrong.
It means your not getting “it”.
And instead of berating others (like professional teachers🤦🏻‍♂️) maybe you need to accept you might be just a bit slow on the uptake here.

You seem, from an outsiders perspective, to be saying, the perceived wisdom is wrong and I’m going rewrite this in my terms.

To Andy James,Lasse, Brian, Paul, Allan, mark, Rithrogena and anyone else whose patiently persisted to bring understanding and clarity, Thankyou, the duffer and I am sure others on the side line, have learnt some valuable sh.t and insight into about our pastime and correcting our faults, but sadly observed some rather pathetic insight into human nature.

Such a shame. Quite tragic really.
 
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LukeNZ

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Rod as lever and as spring.

What I said in a little more detail and context.

"Let’s now consider the relative contributions of the rod as a lever and the rod as a spring to casting a fly line. A few years back a real physicist named Grunde Løvoll ran the numbers. What he found was that by using a flexible fly rod instead of an inflexible fly rod a good caster managed to get about 20% more tip speed. In other words the spring effect was good for an extra 20% of tip/line speed over a broomstick rod that didn’t bend. Line speed is what we use to beat gravity. Speed comes from the Force we apply which puts kinetic energy into the fly line. It follows that more speed implies more Force.

It is a bit more complicated than this but, simply stated, on a longish cast about 80% of we get from a fly rod is due to leverage and only about 20% is down to energy stored when the rod is bent and then released when it unbends. The exact proportions of lever effect and spring effect don’t really matter to us. What matters is that leverage is by far the major contributor. [My emphasis}

Each cast has an energy “budget” to do the job of propelling the line to reach our target. In making budget, the proportion of leverage to spring storage and release of energy changes depending on the type of cast we are making. However, for most people and most of their casting, the rod as a lever accounts for most of the energy put into a fly line. Allow me to explain that a bit more.

The bow and arrow cast is exceptional in that we use spring energy more than leverage but of course that’s a very different beast from a standard overhead cast. With short overhead casts, just the leader and a metre or two of fly line, the rod may not bend very much so unbending contributes very little to line propulsion. As we lengthen the cast the rod will bend more and so contribute more spring energy when it unbends. However, it’s probably not until we go seriously long that spring energy will make a meaningful contribution and even then it’s only about one fifth of the total energy budget. Given this it makes no sense to me to talk about rod loading as the engine and therefore our primary objective when casting a fly line. Leverage is the primary engine of a cast and our objective is using it to best advantage."

If you want my primary source: <http://www.flycastinginstitute.com/e-libraryfiles/FCI_E-L_Rod_Cast_102507.pdf>

Oh and Grunde was on my advisory group for the Einstein Series, the primary objective of which was to provide an accessible and accurate account of the mechanics of fly casting for the few people who are interested in and can be aided by, understanding the relevant physics.

Cheers
Mark
Hi Mark,

A carbon rod with line attached, acts as both an accumulator, and a damper.

A spring is simply an accumulator; which is why it fails as a good analogy, for a fly rod.

🙃
 

LukeNZ

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Rod as lever and as spring.

What I said in a little more detail and context.

"Let’s now consider the relative contributions of the rod as a lever and the rod as a spring to casting a fly line. A few years back a real physicist named Grunde Løvoll ran the numbers. What he found was that by using a flexible fly rod instead of an inflexible fly rod a good caster managed to get about 20% more tip speed. In other words the spring effect was good for an extra 20% of tip/line speed over a broomstick rod that didn’t bend. Line speed is what we use to beat gravity. Speed comes from the Force we apply which puts kinetic energy into the fly line. It follows that more speed implies more Force.

It is a bit more complicated than this but, simply stated, on a longish cast about 80% of we get from a fly rod is due to leverage and only about 20% is down to energy stored when the rod is bent and then released when it unbends. The exact proportions of lever effect and spring effect don’t really matter to us. What matters is that leverage is by far the major contributor. [My emphasis}

Each cast has an energy “budget” to do the job of propelling the line to reach our target. In making budget, the proportion of leverage to spring storage and release of energy changes depending on the type of cast we are making. However, for most people and most of their casting, the rod as a lever accounts for most of the energy put into a fly line. Allow me to explain that a bit more.

The bow and arrow cast is exceptional in that we use spring energy more than leverage but of course that’s a very different beast from a standard overhead cast. With short overhead casts, just the leader and a metre or two of fly line, the rod may not bend very much so unbending contributes very little to line propulsion. As we lengthen the cast the rod will bend more and so contribute more spring energy when it unbends. However, it’s probably not until we go seriously long that spring energy will make a meaningful contribution and even then it’s only about one fifth of the total energy budget. Given this it makes no sense to me to talk about rod loading as the engine and therefore our primary objective when casting a fly line. Leverage is the primary engine of a cast and our objective is using it to best advantage."

If you want my primary source: <http://www.flycastinginstitute.com/e-libraryfiles/FCI_E-L_Rod_Cast_102507.pdf>

Oh and Grunde was on my advisory group for the Einstein Series, the primary objective of which was to provide an accessible and accurate account of the mechanics of fly casting for the few people who are interested in and can be aided by, understanding the relevant physics.

Cheers
Mark
...so what you have stated actually defies physics...

There is no 20% extra. A rod is not a generator of energy; it is a transmission and conversion component.

The rod's damping through it flexing is the key to it's usefulness.

The damping created through flexing of the rod slows the energy transmission, and in so doing, amalgamates all the peaks and troughs of energy, it netts out and re-combines them within the moving mass.

Any extra distance you get (your estimate of 20%) is energy that is not now lost in process; rather than energy that was created, or gained (over input energy).

There will always be less energy delivered, than has been input - the damping through rod flex is simply reducing some of those energy losses, by allowing time (during rod flex) for them to be re-captured and re-integrated into the moving mass, and so be used.

The more in time with rod flexing that the energy is flowing, the smoother the wave, and potentially the more optimally the line will travel.

When the peaks and troughs of energy are un-combined (not damped) then various mis-casts are the result.

🙃
 
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brian_mcg

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You haven't seen the explanation! Really? Others contributors did see it and said it was clear and concise - Newtons first law. I also said the wave analogy (yes, it's only an analogy - I only use it because others do) breaks down at times (many times in fact). Line has been put in motion in a direction that is perpendicular (roughly speaking) to the direction of the cast. Newtons 1st says it will continue to move in that direction unless another force acts.

Then there's the films from Lasse - these cannot be clearer in showing that the dip in the fly leg grows - there's 4 photo's from the same cast of Lasse's above - are you saying you cannot see the fly-leg dip increasing in size in that sequence? Are you just ignoring stuff that doesn't fit with 'Tangled' view, as with your other threads.
Happy with that. Thanks
what we call tailing loops are not actually tailing loops
Ok,lets rename them after you "A Tangle"
It's a tail thrown during a normal fishing cast. ie unintentionally, not one thrown by someone trying to demonstrate a tail
Its a "Tangle"
Everything seems clear and straightforward and beautifully explained and illustrated and you come in and derail it . Why?
Hmm? “They seek him here, they seek him there. Those Forumites seek him everywhere. That demned elusive Tangled”

What Tangled is showing ,and it may be deliberate,is that his experience in casting seems to be non existant.Here is my advice to Tingled,fwiiw. Go out and cast,then come back and read this thread.Any clearer?
An open Invitation to Tangled and my treat. This weekend,If you are hiding in Scotland,near Perth, and fancy giving or getting a lesson in casting.Come along to the Game fair at Scone. Contact me by PM for details.
To the rest of the contributers. You have been Tangloed!!
 

andygrey

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The line has been put in motion perpendicular to the cast. ie the cast is forward, the rod is now bending so the first movement force is downwards - how much? maybe 6"? The rod then restores itself so there is an equal and opposite force upwards. The concave wave has been formed, it's the size of those two movements and I'm saying that there is no more energy in it. The energy in the first dowered force being more or less cancelled by the recoil upwards.
The above statement is a great example of a little bit of knowledge being a dangerous thing...It's not truly 'equal and opposite' as the energy input comes at different times and therefore at a different points on the fly line. The downward dip continues to move downwards and the upwards continues to move upwards! Therefore the tail continues to grow as the cast develops.
Just because you don't understand it doesn't mean it doses't happen!
 

James9118

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...so what you have stated actually defies physics...

There is no 20% extra. A rod is not a generator of energy; it is a transmission and conversion component.
Hi,

I think you've misinterpreted Mark's point and Grunde's original model there. The model is concerned with speed, not energy. What Grunde first modelled was the portion of the line speed that was attributed to simple leverage and what was attributed to the spring action. His model didn't contain anything as complicated as a caster - just a simple function where you could set the (constant) initial acceleration and second constant acceleration where the lever was stopped.

It did not calculate losses (although later people, myself included, added in damping functions).

When the model is used to calculate a 80% - 20% figure, what some one has done is as follows: They've decided a set of starting conditions and then set the spring constant to a huge figure to make the 'rod' effectively a rigid lever. The model then spits out a number that gives the tip speed (a fairly simple geometric calculation when it comes to a rigid lever). Then the spring constant is adjusted to something more representative of a bendy fishing rod. The model then kicks out another number for the tip speed (using the same initial conditions i.e. the input accelerations). You can then compare the lever only result to the lever/spring result. The lever/spring tends to give a higher speed result than lever only.

No conservation of energy laws are broken - the extra speed of the lever/spring isn't for 'free' it still comes from the input. But because the input specifies accelerations and not forces applied, the drive force will adjust accordingly.

It's a simple model, and not meant to be taken as an exact interpretation of fly casting. However, I do know that when a group of us (including Grunde himself) cast a rigid rod (the bottom 3 section of a stiff carp rod) we couldn't cast it as far as a normal fly rod (we got great looking loops though :) ).

James
 
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aenoon

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A classic crossover loop, delivered perfectly, line goes out as straight as a poker, and a long way too.
Now, is it required?
You bet your life it is in this form of casting!
The late Peter Anderson. R.I.P.
1632327527001.png
 

geenomad

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The model is concerned with speed, not energy. What Grunde first modelled was the portion of the line speed that was attributed to simple leverage and what was attributed to the spring action. His model didn't contain anything as complicated as a caster - just a simple function where you could set the (constant) initial acceleration and second constant acceleration where the lever was stopped.
Exactly. And the point from a casting POV is that we would be much better served by thinking of the rod as (predominantly) a lever that amplifies the movements of our rod hand - good and bad alike.

Thinking about it as a spring that we boink to make a cast is not helpful and it's also bs. The kindest thing I can say about rod loading in view of its persistence is that it is a useful fallacy but from my personal perspective it's just bs.

Cheers
Mark
 

andygrey

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Exactly. And the point from a casting POV is that we would be much better served by thinking of the rod as (predominantly) a lever that amplifies the movements of our rod hand - good and bad alike.

Thinking about it as a spring that we boink to make a cast is not helpful and it's also bs. The kindest thing I can say about rod loading in view of its persistence is that it is a useful fallacy but from my personal perspective it's just bs.

Cheers
Mark
There is a link in the 'Understanding Rods' thread that explains very well the whole rod flex thing. I'll see if I can find it (veterans of this particular thread will know it makes War and Peace look like a brief read...). Basically it explains how the rod acts as a flexible lever and how rod flex helps make the cast work.
 

Tangled

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There is a link in the 'Understanding Rods' thread that explains very well the whole rod flex thing. I'll see if I can find it (veterans of this particular thread will know it makes War and Peace look like a brief read...). Basically it explains how the rod acts as a flexible lever and how rod flex helps make the cast work.

It's in Mark's (aka geenomad, aka the curious fly caster, aka the guy you're replying to's blog)

 

LukeNZ

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There is a link in the 'Understanding Rods' thread that explains very well the whole rod flex thing. I'll see if I can find it (veterans of this particular thread will know it makes War and Peace look like a brief read...). Basically it explains how the rod acts as a flexible lever and how rod flex helps make the cast work.
I like to think of the caster as another 3 progressive sections of the rod.

Leg section, torso, and arm - then the progression of rod sections on the end of that.

We need to consider the whole action - as in the stiff/rigid rod experiment already mentioned; in order to make a cast, the flex is not really eliminated (just moved to another section of the mechanism), as the caster with a rigid rod, has to increase his emulation of rod flex to compensate for the now - stiff/inert section incorporated within the (whole) casting mechanism, in order to effect a flowing cast?

🙃
 
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ohanzee

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Exactly. And the point from a casting POV is that we would be much better served by thinking of the rod as (predominantly) a lever that amplifies the movements of our rod hand - good and bad alike.

Thinking about it as a spring that we boink to make a cast is not helpful and it's also bs. The kindest thing I can say about rod loading in view of its persistence is that it is a useful fallacy but from my personal perspective it's just bs.

Cheers
Mark

I agree..I think... the concept of the rod as a spring has for years smothered the important job that the rod bend does for the cast.
 

Tangled

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I agree..I think... the concept of the rod as a spring ...
Surely there's nobody alive that still thinks of the rod as a spring? I've been here 6 years and never heard anyone say it. (I've seen the words 'spring', and 'load', trigger a few land mines but I've never had the impression that the user thought that rods were just catapults,

Time to just let it go. Boing.
... has for years smothered the important job that the rod bend does for the cast.
Can you explain this a bit more?
 

ohanzee

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Surely there's nobody alive that still thinks of the rod as a spring? I've been here 6 years and never heard anyone say it. (I've seen the words 'spring', and 'load', trigger a few land mines but I've never had the impression that the user thought that rods were just catapults,

Time to just let it go. Boing.

Can you explain this a bit more?

The 80/20 thing keeps the spring alive, 20% of it anyway, has it taught you anything?

The bend of the rod does a lot for the efficiency of creating a loop, you would be better served looking up the respective threads on Sexyloops than ask me, but just as an obvious compare casting with a rigid rod as opposed to a bendy one, the first thing that should be immediately apparent is the bendy one makes an SLP easier just by bending.

Also, never ever discussed, a bendy rod makes it possible to rotate it without stretching a tendon, that in practical terms means you can impart more power quicker with less effort.
 

Whinging pom

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Somewhere along my journey to cast I was told it was a spring,And like with a golf spring you need a good solid anchorage for the most effective power .
it’s still passed down as gospel from some older experienced fishermen to beginers!!

This is I guess what led to me over griping it and pumping everything with the elbow, a ridiculously stiff wrist and no rotation from the shoulder. That seems to be my default setting still when things go astray and I can feel things go stiff and anchor down, and speed up…. and what I am trying to totally erase from my system.
it’s a curse !
 

ohanzee

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Somewhere along my journey to cast I was told it was a spring,And like with a golf spring you need a good solid anchorage for the most effective power .
it’s still passed down as gospel from some older experienced fishermen to beginers!!

This is I guess what led to me over griping it and pumping everything with the elbow, a ridiculously stiff wrist and no rotation from the shoulder. That seems to be my default setting still when things go astray and I can feel things go stiff and anchor down, and speed up…. and what I am trying to totally erase from my system.
it’s a curse !

I can't remember who it was that showed me but a brilliant session I had once was, I think it was an instructor, told me to make a cast about 40 or 50' and make the cast collapse, just run out of steam, I couldn't do it, I turned the power down and down and still the damn thing rolled out, couldn't get my head around it at the time, all the time the instructor was saying things like 'better, just a bit less power' etc, when I was at the minimum amount of power I could do guess what I was seeing?
 

Tangled

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The 80/20 thing keeps the spring alive, 20% of it anyway, has it taught you anything?
Not really, I can't understand how anyone ever thought the rod was primarily a spring. Even if you know nothing about levers you can prove it wrong in 2 minutes in your back garden.
The bend of the rod does a lot for the efficiency of creating a loop, you would be better served looking up the respective threads on Sexyloops than ask me, but just as an obvious compare casting with a rigid rod as opposed to a bendy one, the first thing that should be immediately apparent is the bendy one makes an SLP easier just by bending.
The logic being that that the bending rod allows the rod tip to stay horizontal longer I guess. The downside is larger loops and more recoil.
Also, never ever discussed, a bendy rod makes it possible to rotate it without stretching a tendon, that in practical terms means you can impart more power quicker with less effort.
hmm, that one is less obvious, distance casters don't use bendy rods.
 

ohanzee

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The logic being that that the bending rod allows the rod tip to stay horizontal longer I guess. The downside is larger loops and more recoil.

I'm comparing 'bendy' with completely rigid as an example, the bend is smoothing out the path and as you say making it longer...than something that doesn't bend at all...just to illustrate the point.

Stiff rods also bend...just enough to achieve the same advantage.
 

ohanzee

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hmm, that one is less obvious, distance casters don't use bendy rods.

If the tip bends past 90 degrees(enough to allow you to pull a line through a flat plane) does it need to bend more to do the job?
 
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