Gordy,
I think this
statement highlights a concept that is sometimes forgotten when teaching
students:
?Good casters will start rotation at the "right
time", which they sense naturally?
All of the
scientific analysis is interesting and fun, but the ability to ?feel? the cast
comes only with thousands and thousands of repetitions, aka, development of
muscle memory. We overline a rod to help the student ?feel? the rod
load. We have the student stand sideways and cast with the rod in the
horizontal plane so they can see the line and get a ?feel? for the timing.
We have them cast too hard, then too soft, then somewhere in the middle??all to
help them develop the ?feel?. All of these tricks help, but only the student can
perfect the ?feel?. That?s why we harp on new instructors not to ?smother?
the student. Let the student experience ?The Joy of Self-Discovery?, which
is the only way to ever get the ?feel?.
?Constant
acceleration? is entirely ?feel?. That?s why it?s so challenging to
define, which makes it challenging to teach, and consequently, challenging to
master.
Tim
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Tim...
For me, your message is timely. This is exactly what
happened yesterday evening when I had my 8 yr. old grandson out tarpon
fishing . We had a spanking back wind. He had to change his
timing .... so I decided to let him work it out himself. Took some
steel nerves on my part, BUT HE DID IT ! Only after that did I add a
brief lesson on change of trajectory.
(He was
blind casting. No tarpon showed up.)
Gordy
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From Bill
Keister. (Bill has an engineering background) My comments in his text in
italics ....
G.:
Gordy,
First, I have to
put my two cents worth in on the definition of "stroke". I view the
stroke as starting when the rod makes the first movement in the direction of the
cast (not RSP for some subtle reasons having to do with counterflex during drift
which I consider to be outside of the stroke, and which occur after
RSP of the preceding stroke, if that makes sense).
The stroke
ends when the rod reaches RSP in the direction of the cast. This means
that the stroke encompasses creep (a fault), translation and rotation which are
both means of applying force to the fly line.
Many agree with your
definition of CASTING STROKE. Many don't. That is a problem as we
discuss these things. On our FFF Glossary Committee we debated that for
years. Some place the almost pure translation of DRAG in the stroke;
others don't. Most agree that the stroke ends at loop formation (which is
so close to RSP that it may be at that point.). Some place CREEP within
the stroke and many others don't.
I respect yours as a
good working definition, so let's proceed G.
:-
Now let us look at what is
happening with constant acceleration during the casting stroke. I am going
to use a casting stroke (my definition) of 16 feet for the discussion because
the numbers work out so well. If we break down the cast
into four time periods and look at the distance the rod tip travels during each
period it becomes apparent why we use translation and rotation the way we
do. During the first time period, using constant acceleration the rod
tip will reach 25% of its ultimate velocity. And, it will have
traveled 1 foot. During the second time period it will travel 3
feet. During the third time period it will travel 5 feet and during the
last time periods it will travel 7 feet. The percentage of the total
distance traveled in each succeeding time periods 6%, 19%, 31% and
44%. Prior to calculating this out I had always had the impression that we
were not putting enough emphases on the beginning of the cast. But, it was
still quite a surprise to me that we get half of the final velocity of any cast
using only 25% of the total casting stroke.
That doesn't
surprise me ... You've quantified.
G.
What does this mean for
translation and rotation? During the first half of the stroke from a
time standpoint we don't have to move the rod tip very far. We can
cover this distance primarily using translation, especially during the first
foot. As velocity builds up it becomes harder and harder meet
acceleration needs just with arm movement. We begin to take advantage of
the level aspect of the fly rod through the use of rotation. During
the last quarter of the cast the rod tip must move 7 times farther than it did
during the first quarter of the cast. Rotation is crucial at this phase of
the cast to meet that requirement. This need for speed and the end of the stroke has given
rise to teaching descriptions such as speedup and stop and power
snap.
Yes. That is
why, I think, that these word descriptions have had such long term teaching
success. Point is that the "speed-up-and-stop" is what
has to happen anyway without a separate and distinct effort on the part of
the caster. No "two stage stroke". G.
From a subjective standpoint I
use and emphasis a long Draw (Drag) even when casting fairly
slowly. Regardless of the speed of my casts the first half
is predominately translation and the second half is dominated by
rotation. I am predominately a sidearm or open stance caster, translation
is automatic. When I am casting for accuracy (really artificial targets) I
cast straight overhead and translation is held to a
minimum.
I do that as
well. That is what I meant when I said, a few messages back, that with
most efficient casts there is an ever changing mixture of translation and
rotation as the cast proceeds. Almost all rotation near the stop.
Why ? To use different words to say what you did : Pure translation
can only achieve the same acceleration as that of the hand. No more.
Rotation yields so much more because it magnifies hand motion as a function of
rod length. G.
Paradox: If I am casting
at targets square on and I have locked my wrist and am using only my elbow and
shoulder joints is this translation or rotation.
Gordy, there is lots more that
should be said about the speedup and stop and its effect on straight line path;
the effect of rod angle and its effect on the force being applied to the fly
line. But I think that is probably more effectively addressed as a piece
for the LOOP.
Agree. We'd
need to get into things like release angles and timing .... launch points,
variations, haul release, etc., etc.
G.
Bill
Keister
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Bill .... Your on !
We'd all appreciate your taking the time to do that.
These discussions have been going on
for years. I just finished a book in which all this is discussed with the
knowledge and "conventional wisdom" of the past, printed in 1960 and given to me
by Ally Gowans. *
* THE ANGLERS CAST by Captain T.
L. Edwards and E. Horsfall Turner, London: Herbert Jenkins,
1960.
(Edwards was one time holder of
British, French, Belgian and European Open Casting Championships. Turner
was holder of the British Trout Fly Distance Record and editor of THE ANGLER'S
ANNUAL.)
Gordy
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From Jerry Puckett
:
Gordy,
Would you consider acceleration and exponential
redundant-- exponential acceleration?
Jerry
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Jerry .... Now THAT one I'd bounce to our engineers and physicists
!
Gordy
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From Mark Surtees :
Hi
Gordy
I
wonder if anyone believes that it is possible to achieve slp and a tight loop
without constant or near constant acceleration or indeed a wide or non loop
with constant acceleration.
Personally
I think that it is entirely fair to suggest that smoothness is a highly
desirable condition in achieving a good loop but smoothness is not necessarily
precluded if the acceleration is non-linear. In fact, If we really want to throw
a spanner in the works here, it is my understanding that although the angular
acceleration at the butt may be constant or near constant, the angular
acceleration at the tip will not.
To make the cast
effectively, the caster will reposition the rod with a slow
rotation/translation, this isn't part of the casting stroke, simply a
reposition.... BR
I
agree with Bruce, by the way, that translation does not, in its self, delay
rotation. Translation in most casting strokes will be coexistent with rotation
and is a mechanism for increasing casting stroke length. Equally the rod
can be accelerated using either a linear force via translation or an
angular force via rotation and in most casts the total force will be a
combination of the two in varying degree.
A
casting stroke that uses translation at the start, as in the roll cast, is no
less a casting stroke for having translation and rotation in sequence rather
than simultaneous. From a standing start position I accelerate the rod using
translation and rotate late, in my opinion the slow start is not a simple
repositioning move it is an essential part of the casting stroke that
must occur before I feed in additional angular acceleration with the late
rotation.
It
isn?t creep either?.. J
Mark
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Mark ... Some
good thoughts . I like your discussion on sequence because of the changing
admixture of translation and rotation.
Some oft used, simple words for
the new casting student: "START SLOW AND END FAST".
Gordy
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