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Walter & Group....
[GH] Going further with Tim Lawson's question on stroke length and rod arc :
"I would like the answer(s) you would accept from a CI candidate during a certification exam if you asked for a definition/explanation of “stroke length” and “rod arc (angle)”.
From Mark Roberts :
Hi Gordy
I normally teach at CI/GAIC level that the stroke length is the travel of the rod from rod start to rod stop position during a cast and includes all elements of that cast including drift, arc and rod stop. The arc is the movement of the rod in rotation.
For a more detailed understanding I refer to translation i.e. the straight line rod tip travel during the cast (this can also be explained as pre-load for someone who gets confused with technical explanation) and rotation as the increase of rod speed to an abrupt stop which creates the line speed.
I go on to explain that only half of the power is created by this translation and that the essential second half of the power is created with the rotation and subsequent increased line speed.
Loop size is dictated by the amount of rotation at the end of the cast including counter flex. I.e. increase rotation then the loop is larger. (Provided this rotation occurs as part of the stop)
At a higher level I would also explain that the arc is the measurement of angle that the rod butt travels during the cast and that stroke is the linear measurement of the rod hand from rod start to rod stop position. this overall stroke length can also be increased with both body movement and hand/arm movement in the drift.
best wishes
mark
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[GH] Mark,
Re. ".....only half of the power is created by translation...."
I submit that with pure translation (no rotation whatsoever) far less than half the power is exerted and precious little if any rod bend (load) achieved.
With no rotation at all, the rod tip can travel no faster than the hand during pure translation. This results in insufficient acceleration to achieve much rod bend at all.
We tend to compartmentalize by looking at the cast as starting with translation and finishing with rotation, while what really happens, as I see it with most casts, is a changing admixture of translation and rotation. Progressively more rotation than translation as the cast continues to the stop sequence.
Almost all the rod load comes from acceleration produced by rotation even when it is mixed with translation.
When we actually went out and tried to make a cast with pure translation of the hand and rod (no rotation at all) we found it almost impossible to do. When we thought we were doing it with pure translation, the video clips proved that try as we did to prevent it, we were introducing some degree of angular change. When we got close to pure translation, the rod didn't load and we had no effective launch at all.
Some accomplished competition distance casters do use lots of translation at the start of the cast. They call that "drag" or "pull". Other champion casters such as the Rajeff's don't use it at all. Rick Hartman and others who do use it seem to accomplish 3 things which help them with their style: 1. Taking up any unwanted slack , 2. Achieving slight "preload" for early tension, 3. Delay of the start of rotation.
As Al Buhr said, the idea that loop size is determined strictly by rod tip path during the stroke is far from the whole story. You have pointed that out as well. I agree that what happens at the end of the cast is more important that what went on earlier in the stroke.
Gordy
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[GH] From Mark Surtees :
Hi Gordy
That would include things such as matching the rod load / rod bend to the casting arc along with a reasonable description of each.
I have long puzzled over this, not so much from a definitions point of view but from a purely practical point of view. We say the match bend to arc mantra a lot but how do we actually do it and more to the point how do we teach it ?
I blarped this out in a lesson a couple of months ago and was promptly asked “how do I do that then ?”
Still flummoxed, it’s not as easy to answer as it first looks…
Mark
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[GH] Mark,
Back in 1987 Mel Krieger published pictures which were the best I've seen depicting this match between rod bend and casting arc. *
If you can "beg, borrow, or steal" a copy of his THE ESSENCE OF FLY CASTING, First go to his drawings on pp. 8 - 13. They clearly depict the match as yielding a straight line path of the rod tip; the size of the loop small; yet widened (p.12) by stopping the rod farther below the path of the line.
On p13, shows the formation of narrow loops with either a narrow or a wide casting stroke (and narrow or wide casting arc, SO LONG AS THE BEND OF THE ROD MATCHES THE DIMENSION OF THE CASTING ARC.
On p.14, he drives this concept home by demonstrating in his drawings what happens when the rod bend and casting arc do not match :
.....Too little rod bend for the size of the casting arc = a wide loop.
.....Too much rod bend for the size of the casting arc = A tailing loop.
I find that the easiest way to have students understand this is to do what Mel did in print and demo a cast with a good match and then make casts with poor matches at both ends of the spectrum. Then have the students do it.
A few weeks ago, I taught a group of 11 native guides in Belize who spoke a little English and Spanish as well as Mayan with a Caribbean dialect. With the use of few words, and this demo. I had them understand this concept to the point that they were able to demonstrate as well as understand it.
Gordy
* The Essence of Flycasting by Mel Krieger,1987, ISBN 0-944169-02-3, pp. 8-14.
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