Understanding Casting

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Rhithrogena

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'Partially' concave rod tip path!
Well, yes, granted.
1. Hand pulls rod down slightly during early power phase
2. Power is reduced (a 'slowing')
3. More power in a horizontal vector causing 'partially' concave tip path as loop is formed, creating the 'Tail'
 

Whinging pom

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1. Hand pulls rod down slightly during early power phase
Would you call that early power phase ? Just as that loops forming above and the hand seems to have paused forward, he seems to dip his hand for some inexplicable reason and that slight movement is then exaggerated in the line path above… along with a slight slackening of tension and I guess loss of power.
….. or am I seeing the wrong thing here?
 

Tangled

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Concave rod tip path
Agreed and you can see the concave rod tip path shown as an equivalent sized dip in the line. (It doesn't get any bigger than the rod tip movement - ie it's not amplified by anything.)

Do you think that shallow line dip is what is causing the tail though? If you look at 0.06 you'll see that this caster is doing what all demonstrators do when casting a tail. He's applied a lot of power very quickly and stopped applying it sharply at what he probably thinks is 12 o-clock. (0.06 is where the applied power peaks on the power graph underneath.)

In fact, because the rod is bent at that moment he's stopped the rod tip actually behind his head! That's created a big bull-nosed front loop heading upwards. The following line can only cross it because he's still holding the rod tip high and the loop is heading up.

It's a massively artificial cast - overpowered and shortened, very little rotation. The actual tailing dip is almost irrelevant. If you look at it frame by frame he's created a large closed loop at the front of the cast.
 

Rhithrogena

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Would you call that early power phase ? Just as that loops forming above and the hand seems to have paused forward, he seems to dip his hand for some inexplicable reason and that slight movement is then exaggerated in the line path above… along with a slight slackening of tension and I guess loss of power.
….. or am I seeing the wrong thing here?
His hand is pulling in a downward arc at first, pivoting at the elbow. Then a slowing, then a brief push out, horizontally, to the stop.
Tail every time. Just went and chucked a few out back to re-convince myself this is what is happening...
 

Tangled

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The energy is not amplified,

Agreed, the concave wave in the line retains roughly the same dimensions that the rod tip put in it. The video shows this.
James seems to think otherwise, but maybe I'm misrepresenting him.
 

ohanzee

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When the tip dips through poor application of power it also rises again when the power stops, this creates your concave, this is why a late haul prevents a tail by keeping the tip dipped.

Why is it not enough to know that this concavity caused by a misapplication of force results in a tail? and why do I feel all of this is constructed to discredit the concept of an SLP, it's all a bit de ja vooses.
 

Tangled

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When the tip dips through poor application of power it also rises again when the power stops, this creates your concave, this is why a late haul prevents a tail by keeping the tip dipped.

Again, we know this Allan.

Why is it not enough to know that this concavity caused by a misapplication of force results in a tail?

Well that's a good question. Having seen the video, do you still think that the small dip in the line caused by the rod tip path is the major problem with that cast?

and why do I feel all of this is constructed to discredit the concept of an SLP, it's all a bit de ja vooses.

I think that's because you're often very wrong about things like this. The SLP really is an essential (even though it's not actually achievable irl - side view that is.)
 

andygrey

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Agreed, the concave wave in the line retains roughly the same dimensions that the rod tip put in it. The video shows this.
James seems to think otherwise, but maybe I'm misrepresenting him.
James (as ever) is correct. In the 'perfect' cast energy is only applied in on direction. When the rod tip deviates from the SLP energy is input out of the SLP causing a tail. The tail contains energy which continues to act on the line as the cast develops. Any tail contains energy and will continue to want to travel in a different direction to the rest of the line causing the tail to increase in size as the cast develops. There are of course other factors acting on this energy such as gravity, air resistance and varying tension on the line.
The clip only shows a very small portion of the unfurling cast so doesn't really demonstrate this happening.
 

Tangled

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James (as ever) is correct. In the 'perfect' cast energy is only applied in on direction.

Agreed

When the rod tip deviates from the SLP energy is input out of the SLP causing a tail.
If you mean that it causes an dip in the line equivalent to the dip in the rod tip, I am with you so far.

The tail contains energy which continues to act on the line as the cast develops. Any tail contains energy and will continue to want to travel in a different direction to the rest of the line causing the tail to increase in size as the cast develops.

This is where we part company. I do not think that there is much further transverse propogating energy in the tail after the tail wave has past the rod tip that would cause it to widen significantly.

But this is very easily proven, do you have a video showing this happening? The one I posted shows the dip in the line staying pretty much constant, it's exaggerated by the front loop that has been sent upwards by the false stop of the cast. The line following that loop would go underneath it, tail dip or otherwise.

The clip only shows a very small portion of the unfurling cast so doesn't really demonstrate this happening.

Do you have a better one?
 
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ohanzee

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I'd be interested to see your 'working out' for this statement!

I'm guilty of early rotation when I get tired or just lazy, this can produce a tail, if I see or sense my doing it I fix it mid cast with the haul, sometimes tipping the wrist forward as I go, what I believe is happening there is I'm delaying or preventing the tip rising, an over compressed tip..then keep it compressed sort of thing.
 

ohanzee

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Well that's a good question. Having seen the video, do you still think that the small dip in the line caused by the rod tip path is the major problem with that cast?

Yes, there is nothing else there, tip dips and tail forms, what is so complicated here?

I think that's because you're often very wrong about things like this.

You reckon? :D
 

Tangled

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Mike earlier, and in his blog, referred to the flyline being towed. I had trouble following that concept. Ok the flyline is being towed by the fly rod tip up to the point that the rod tip stops moving and the flyline passes the tip, but then what's towing the line?

The analogy is that the car being towed has now overtaken the towing car because the towing car has abruptly stopped. It is no longer being towed, it's been catapulted.

Then I saw this brilliant video and you can see that each milimeter of the fly leg is towing the millimetre of line behind it. And when it reaches the end of its travel away from the rod tip it stops dead and throws the line behind it forward just a fraction. Just like stopping the rod tip creates the loop. At least that's what it looks like to me.

 

Tangled

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Yes, there is nothing else there, tip dips and tail forms, what is so complicated here?

I have mentioned that the caster has stopped the cast behind his head and the loop is now heading upwards (ie he's radically broken the SLP). It's not the small tail dip that's causing this problem, even if it wasn't there, he's cast a closed loop.
 

Whinging pom

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but then what's towing the line?
Surely the momentum of the loop is what’s towing the line ?
Isn’t the front of the loop the transferred energy from the casting stroke that produces a progressive fulcrum for the turn over . Anything behind this is towed, and will in a good cast, progress beyond this fulcrum and overtake it until full extension is achieved
.
 

Tangled

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Surely the momentum of the loop is what’s towing the line ?
Isn’t the front of the loop the transferred energy from the casting stroke that produces a progressive fulcrum for the turn over . Anything behind this is towed, and will in a good cast, progress beyond this fulcrum and overtake it until full extension is achieved

That's made me slightly clarify the idea.

The way I'm imagining it at the moment is to think of the line a long sequence of 1 cm sections independent but somehow connected together like a very long thin string of beads.

I think it's clear that when we cast, the rod tows the line forward - all the beads align and are given momentum by the force applied to the rod.

When the rod stops, the bead, A, closest to the rod tip also is forced to stop but because energy can't be destroyed it has to give up its energy into the rod tip and also into the bead behind it, B.

Bead B has it's own momentum but now also an amount from the now energy-less bead A so moves forward partly from its own momentum and partly from the donated energy from bead A. Kind of a continuous bump start.

Obviously the entire system is also losing energy as the wave moves forward too.

Needs work :)
 
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Whinging pom

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That's made me slightly clarify the idea.

The way I'm imagining it at the moment is to think of the line a long sequence of 1 cm sections independent but somehow connected together like a very long thin string of beads.

I think it's clear that when we cast, the rod tows the line forward - all the beads align and are given momentum by the force applied to the rod.

When the rod stops, the bead, A, closest to the rod tip also is forced to stop but because energy can't be destroyed it has to gives up it's energy into the rod tip and also into the bead behind it, B.

Bead B has it's own momentum but now also an amount from the now energy-less bead A so moves forward partly from its own momentum and partly from the donated energy from bead A. Kind of a continuous bump start.

Obviously the entire system is also losing energy as the wave moves forward too.

Needs work :)
Certainly thought provoking🤔….. but I can imagine there’s going to be some incoming flack . Get you thick skin on. 😁
 

Tangled

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Certainly thought provoking🤔…..

The entire point of the thread :)

but I can imagine there’s going to be some incoming flack . Get you thick skin on. 😁

Just business as usual here. It's frustrating as it slows things down and the juvenile bullying behaviour prevents people asking question and contributing. But it's just irritating noise to me.
 

ohanzee

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Mike earlier, and in his blog, referred to the flyline being towed. I had trouble following that concept. Ok the flyline is being towed by the fly rod tip up to the point that the rod tip stops moving and the flyline passes the tip, but then what's towing the line?

You are now taking the pis, when you throw a ball what is making it move after it leaves your hand?

Yes, the line is towed then the rod stops and the loop begins to form.
 
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