Loop size; different perspectives / Goh system

Mark Sedotti on the relationship between Lefty's "Speed-up-and-stop" to loop size :

Hi Gordy,

I understand Lefty's "speed up and stop" perfectly. To understand, just take it back from the stop. It's the point where the (rod tip's) accelleration speeds up noticibly right before the stop. This is a nice visual explanation. At least to me.

I explain it to my students a la Lefty too. I call it (as he used to) the "second stage of accelleration" ("which is faster - and shorter - than the first"), or the unloading stage.

Regards,
Mark

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Mark ... We both "understand" it .... but in different ways. I think Bill Keister came close to explaining this yesterday when he pointed out that he looked at it from a mechanical standpoint (Bill has an engineering background) while Lefty saw it from a different perspective. The phyicist may tell you something like this :

"Mark... When you "speed up noticibly right before the stop" it was nothing more than an extension of your smooth, constant acceleration that led to your nice tight loop".

As to your "second stage of acceleration". This would seem to fit with Joan Wulff's, "loading move" and "power snap". Now Joan will be the first to tell you that this only works if there is seamless transition from one to the other. Bruce Richards will likely say, ".... there is no such thing as a power snap." Both are eliminating the "seam" or "change" in different ways to achieve smooth acceleration. Whenever I watch Joan cast, I'm impressed that despite her words, her stroke is as smooth as melted butter !

It's sort of like the three blind men describing an elephant. Each description was totally different from the others, yet all three were correct.

Using the Casting Analyzer (CA) and video techniques, Bruce Richards and physicist Noel Perkins see it in even another way when they came up with the findings which show that an almost straight line path of the rod tip leading to a small loop is best achieved with CONSTANT acceleration ..... not a seperate phase of greater acceleration near the end of the stroke. Others have questioned this on the basis that the CA actually measures only one thing; rotational acceleration at the rod butt.

One is a physics analysis of what is probably close to what really happens. Others range from mechanical views to those derived from what the instructor or author feels or senses what is happening.

Speaks to the different ways in which we use our senses and our equipment as we launch into different ways of interpreting these things.

An example : Despite the scientific evidence to the contrary, I still feel that to achieve a tight loop I need to exert a burst of power to gain a greater level of acceleration prior to my "stop". That fits with the way Mel Krieger and Joan Wulff taught it for years. Lefty does it that way, too, hence his wording, "Speed-up-and-stop". They are joined by the instructors who use terms like, "Pop" and "Pop-stop".

Somehow, they were all doing something right when they taught as evidenced by the fact that their students did end up casting tight loops.

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In line with refreshingly different ways of looking at fly casting, we have this from Don Pendleton :

The other day on a parts run for work I went past Big Bob's Used Car Lot. Big Bill had just placed one of these giant fabric figures that has a fan blower in the bottom to make it stand up and attract attention to Big Bob's business. For some reason I'm always thinking about fly fishing and noticed the movement of the fabric figure. There would be an occasional "ripple" at the bottom of the fabric figure that would start at the bottom and proceed upwards to the top of the figure.

If you walk up to a tight clothes line for instance where the wire is anchored on both ends. Smack the wire lightly and a single ripple will travel down the length of the line and maybe even turn around and come part way back to you. Smack the line real hard the ripple will travel much faster and with greater defection hit the other end turn around and come back maybe even make one more return trip.

Mending is like putting that ripple in a fly line. The force and amount of defection travels down the rod leg until the line hits the water or the ripple runs out of the original tension and disappears. Make the mend early after the stop and the ripple ends up a long ways from the rod. Make the mend very late and the mend will not travel very far from the rod tip.

I have always wanted to sit in the back of a pick up truck and have someone drive down the road as I let out different lengths of fly line at different speeds of the truck and prove this ripple effect.

I am by no means a scientific person but somehow this has to be similar to some things we are doing to fly lines during various cast. Perhaps I'm way out there.

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Don .... Reminds me of my imagination taking me up so I could cast on the Moon .... and in outer space ! Someday, somebody will do that and we'll learn even more about casting. Way out ? yes. Off base ? NO. G.

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I had asked Bill Higashi if the Goh system was also used for tippet measurements. His answer :

Hello Gordy,

Yes, we use the Goh system for monofilaments (and silkworm strings) too. Some tippet spools made in Japan have descriptions of breaking strengths in kg and lb, of diameter in mm and inch, of thickness in Goh description and X. The labels get pretty crowded with numbers!

Goh only means "number" or "category" in our language, so the Goh systems for lines and hooks have nothing in common.

Thanks,

Tomonori ?Bill? Higashi
JAPAN

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