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Loop morph & water tension

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gordonjudd
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Re: Loop morph & water tension

#11

Post by gordonjudd » Mon Sep 27, 2021 6:30 pm

The shape's traces are in yellow, showing the evolution from a quite subtle initial bump.
and
What causes the overtaking though?
Dirk,
I see that as a transverse wave that gets larger as it propagates towards the fly end off the line and finally appears to turn into a loop as it reaches the end of the line. With no more medium to propagate in, it appears to disappear as the end of the line is pulled through the disturbance just as it did in Alejandro's early tail example years ago.

Thus it is just one more example of a dangle that starts out as a slight disturbance in the fly leg of the line. I have no idea of why the shape of that wave gets larger as it propagates, but it could be an effect of the tension in the fly leg going to near zero as you get to the fly end of the line. The linear mass density of the line would also affect the shape of the wave, but that is probably a secondary effect.

Gordy

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Paul Arden
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Re: Loop morph & water tension

#12

Post by Paul Arden » Tue Sep 28, 2021 4:22 pm

I wonder if it’s the MED taper? I need to try this with a DT to eliminate that possibility. Interesting to find it inverted however, especially so because the dangling end S shape also comes from a similar angle change. Perhaps understanding the difference between the two would teach us something.

What I don’t understand – and I think this is the crux of it – is why the front of the wave starts to overtake… and then why this “loop” then “disappears”.

There is a lot I don’t understand actually :D But it also ties up into anchors and I think it’s very relevant.

Cheers, Paul
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gordonjudd
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Re: Loop morph & water tension

#13

Post by gordonjudd » Wed Sep 29, 2021 4:06 pm

What I don’t understand – and I think this is the crux of it – is why the front of the wave starts to overtake… and then why this “loop” then “disappears”
Paul,
What is it that that you see the transverse wave overtaking? That wave is traveling towards the fly end of the line with a relative velocity going towards the fly end of the line that is equal to:
\(V=sqrt(T/\rho_{l})\)
Thus its velocity tends to go to zero at the fly end of the line as the tension goes to near zero at the end of the fly leg. Its shape also changes but I don't know how the shape is affected by the line tension or the linear mass density changes associated with the taper in the line.

Rather than getting frozen at the end of the line as you typically see with a dangle, the end of the line gets pulled through the loop at the end of that sequence and thus that loop formed by the transverse wave seems to disappear. That "disappearance" probably also happens with a dangle as the loop rolls out at the end of a long cast.

Gordy

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Paul Arden
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Re: Loop morph & water tension

#14

Post by Paul Arden » Wed Sep 29, 2021 8:10 pm

Hi Gordy,

It’s this bit here that catches my eye…
5D519709-DF7A-4EF7-AB6C-F3C6C8C371FD.jpeg
5D519709-DF7A-4EF7-AB6C-F3C6C8C371FD.jpeg (23.27 KiB) Viewed 437 times
It initially starts from a direction change in the fly leg And yes it’s very similar to a dangling end on a distance cast where the line often travels through.

Thanks, Paul
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Re: Loop morph & water tension

#15

Post by gordonjudd » Thu Sep 30, 2021 2:04 am

It’s this bit here that catches my eye…
If you play the original video on a high resolution monitor can you see the shape of the leader in that frame? In that frame grab, that "dangle" looks somewhat like the tear shaped loop you see in high speed videos of cracking a whip.

It would be good if this video could be repeated at a 240 fps frame rate with a closer camera position (that would cover a smaller field of view) so you could see the shape of the line and leader when the transverse wave gets to the end of the line.

Gordy

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Paul Arden
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Re: Loop morph & water tension

#16

Post by Paul Arden » Thu Sep 30, 2021 6:37 am

Maybe it’s the compound front tapering of the MED. I’ll have to try it with a DT. If I shoot at 240fps it’s 1080 and not 4K. Just me in the boat this week however!

Cheers, Paul
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Lasse Karlsson
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Re: Loop morph & water tension

#17

Post by Lasse Karlsson » Thu Sep 30, 2021 8:34 pm

I have seen it with other lines too, but only have a good example with a MED 🤣



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Lasse
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Re: Loop morph & water tension

#18

Post by Dirk le Roux » Thu Sep 30, 2021 8:58 pm

Paul Arden wrote:
Thu Sep 30, 2021 6:37 am
Maybe it’s the compound front tapering of the MED. I’ll have to try it with a DT. If I shoot at 240fps it’s 1080 and not 4K. Just me in the boat this week however!

Cheers, Paul
Hi Paul

240fps is overkill on slomo. Better to go for maybe 120fps with higher resolution.

I doubt that specific taper plays much of a role, but let's see.

All the best,
Dirk

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Walter
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Re: Loop morph & water tension

#19

Post by Walter » Tue Nov 09, 2021 6:34 pm

It’s an interesting demo Paul. A bit off topic for the tension bit but I’ve changed how I teach beginner flycasting by having students lay out 30 feet of flyline and have the students make a forward cast only with concentration on stopping the rod so that a loop is formed. Usually within a few casts most students can do this quite well. My theory is that this is building on existing muscle memory (almost everyone knows how to cast a spinning rod it seems) rather than trying to start from scratch and build all new muscle memory. The stop is made at exactly the same place where a spin fisherman would release the line so it’s just one minor change in a skill most people already have. Teaching the backcast then becomes teaching people how to watch their backcast so they can see for themselves if they are forming a good loop (hopefully we don’t end up in a protracted discussion here of what is a good loop) and having them realize the forward and backward casting strokes are identical. So, again, building on existing muscle memory, I.e you’ve learned how to make a forward cast now do exactly the same for the backcast. Overall, I find this to be less frustrating for most students.

Cheers man. Jungle living seems to work well for you.
"There can be only one." - The Highlander. :pirate:

PS. I have a flying tank. Your argument is irrelevant.

PSS. How to generate a climbing loop through control of the casting stroke is left as a (considerable) exercise to the reader.

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Re: Loop morph & water tension

#20

Post by Paul Arden » Wed Nov 10, 2021 6:34 am

Hey Walter,

that’s a great way of doing it. I often break down forward/backcasts, it’s especially useful for identifying if a problem is a result of the stroke or the transition, but best of all it seems to get the message across that the caster has more time than they think. I always teach the 170 this way incidentally.

I’ve never tried it in this way with beginners however. That’s a great idea. Especially here where they are all spin fishermen. I’ll give that a go - thanks! What I usually do nowadays is start them off (a) with a very short line length and (b) with the “triangle method” — the disadvantage of that method however is there are several changes to go to get to a vertical forward cast, one is going from a horizontal to a vertical casting plane with a complete turn of the body through 90 degrees (which is a problem) and then there is a trajectory adjustment. The big advantage however, is because that’s where we started it then becomes relative easy to teach the Double Haul later on, and often in the first lesson. It’s for that reason that I began starting them this way in the first place.

I’ll definitely try it your way.

I was impressed with a technique Graeme Hird is using where he shakes the rod from side to side to send waves down the line and gradually makes the waves longer and longer until they become loops. This really creates a narrow loop. It’s particularly good if you are elevated for example standing on a boat roof :) I’ve seen Lee do something similar working his way towards the triangle, but the triangle can become obsolete if you just stick it out with the “waves”.

For me I don’t think it really matters which route exactly you take. But giving a variety of exercises seems to help develop the core technique. What I like about what you’re doing is that you can focus on the body movement and it would certainly be nice to start with that and then add control drills, instead of starting with control drills and then trying to mould them into body movement.


Jungle life is great. I’ve missed having guests but soon that will change I think. Still if you’re going to be locked down I can think of worse places :) The drive used to be so much more pleasant when there was no one else on the road… Now it’s bedlam again. If people could drive over the top of each other, here they would!

Cheers, Paul
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