From: Grunde Løvoll <grunde@fiskekroken.org>
Date: August 16, 2010 2:04:33 AM EDT
To: Gordy Hill <MasterStudyGroup@comcast.net>
Subject: Re: Flycasting physics

Hi Gordy,

It's great to see that there are more people out there who are
interested in the physics of fly casting. I have not yet found the
time to fully read Server Sadiks paper but I'll like to bring up three
points.

1) There is _not_ a one-to-one relation between the strain measured by
a strain-gage at the rod butt and the overall deflection of the rod
during "the stop". This makes it very difficult to determine the RSP
time using a strain-gage and I believe this assumption is the root
cause for the erroneous "speed doubling due to flex" result published
by Perkins & Richards (the same curve is also in Sadiks paper). (My
high speed video data support this claim and I should probably discuss
this point with Server directly.)

2) Some years ago Jason Borger and I published a paper on what happens
during "the stop". The paper is available electronically on Jasons web
site: http://fishfliesandwater.com/casting-mending/the-rod-the-cast/
The paper is based on high speed video data (500 fps) and we are in
the process of releasing all the underlying videos in full resolution.
Currently one of the casts is available here:
http://fishfliesandwater.com/2010/08/11/500fps-fly-cast-m1-3-versions/
(more will follow shortly).

3) I agree 100% with Sadik that continued rotation during rod unload
is essential to good fly casting.

Best regards,
Grunde

On Sun, Aug 15, 2010 at 9:12 PM, Gordy Hill
<MasterStudyGroup@comcast.net> wrote:

Grunde & Group....
[GH]  Server Sadik and I have agreed to present his latest work on the
physics behind much of the phenomena which occur as we cast.
We do this realizing that not all if even many fly casting instructors are
interested in getting deep into the details.  Few fly casting instructors
have a background in physics.
We realize that some of the information presented in Server's document will
appear to fly in the face of conventional flycasting wisdom and teachings.
Most of us use statements, word pictures, actions and concepts which serve
us well as they get into the minds and actions of our fly casting students
to improve their casting ability.  We do this knowing full well that they
are often not in full accord with scientific principles despite the fact
that they work.
One example is our teaching students to make a "hard stop".  Almost all of
use that concept, because it works.  This despite the evidence that no
caster can make a true complete stop as defined as instant total cessation
of movement.  Further, that in the event of a full stop made by having the
butt section of the rod strike an immovable object, the rod vibrates causing
a ruined cast with erratic layout.  From a purely scientific point of view,
what then are we really doing as we "stop" ?
For those who seek to inquire more deeply into the science behind fly
casting, I offer his paper as a PDF attachment.
Server tells me he will be at the Conclave at W. Yellowstone.  He invites
any and all to seek him out to discuss his theories, findings and
conclusions.
Lastly, we have given some thought to hosting a future workshop on
flycasting physics to include informed instructors with similar as well as
opposing views.
Please bear with me as I request that we withhold Group discussion of this
paper until after the Conclave.

Gordy
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[GH]  Craig Buckbee offers an admittedly non-scientific teaching message
which might well be considered the antithesis of Server's paper.  It is,
nonetheless, in plain language which makes good sense to me and would
probably be well understood by his students :-
gordy,
as to the line following the tip, the "aerial pencil"...
to beginners i teach that the line follows the tip. works great, no
problems.

BUT
 if i have an advanced caster, a caster that wants more, i explain that the
line following the tip is a lil' white teaching lie, that in fact the line
goes where the momentum of the cast sends it. Al Buhr taught me this.  it
was one of those "ah ha" moments. it made sense to me, it hit home. now,
especially when casting distance i do not only think of the tip, now i
include putting my mind's eye (thanks to JimV for that term)  below the
tip where i feel the momentum is born. depending on the rod and distance
desired it may be about 2 -3 feet below the tip, maybe deeper.
i am NOT a scientist .... so, explaining it to myself, where the momentum
is, is "where the peak bend of the rod is when i release the it"
(... where the bend is when i stop.... where the bend is when i release my
grip on the cork)
crazy? make sense at all?
craig