Walter & Group..............
Ally Gowans answres the question on long belly lines and comments on the physics of fly casting:-
Hi
Gordy,
Re your question. It is
true that a perfectly executed cast with a long belly head (75ft +?) and running
line outside the tip ring should attain greater distance. The problem is that it
is not easy (or at least much less easy) to cast consistently well with as
little disturbance as possible at various wading depths whilst changing angles
by at least 45 degrees (ie during practical fishing). There are comfort limits
for all casts, they depend on tackle, weather conditions, physical situation and
angler skill and so they vary a lot as well we know! With Spey casts the Single
Spey can produce larger D loops than other methods but there are limits to this
loop and even in ankle depth water for a tall and highly skilled person it is
very difficult to support six times the rod length of fly line out of the water
with a taught “anchor”. Therefore a loop size of between 4 and 5 times the rod
length is more realistic in practice. I think that there are two reasons why
bringing the belly (or at least some of the thicker back taper) is helpful. The
stiffer line appears to offer more support and hence control for the loop (in
addition to reducing loop size) and rods appear to load more evenly when some of
the heavier line is in the guides. In practice the benefit of making a perfect D
loop far outweighs trying to make a larger but defective D loop with increased
water contact which robs the “shoot”.
I started to read the
paper on Physics of Fly Casting with an open mind but have some problem
translating it or more accurately trying to assimilate the authors thought
process. I will have another go at trying to make sense of it but it may be “If
you understand it – you didn’t read it correctly”!
Best
wishes,
Ally Gowans
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From Bruce Richards:
Hi Gordy, thanks for sending Servers piece. I've
had issues with things he
has written in the past, and do with this one also.
I've only had time to
read the first bit, some comments on it below. I'd like
to know what he
defines as a "hard stop", he must have a very different view
of it than I
do. To me, a "hard stop" is a rapid deceleration of the rod, and
I think
most others would agree. What he says below is that a caster
initiated stop
occurs after the rod has started to unload, which is a very
odd thing to
say. He is implying that the rod alone decides when to start
unloading,
which is pretty silly.
"Recall that the notion of
"hard stop" is that caster initiated stopping
occurs around peak rod load and
somehow then contributes to how the rod
unloads"
If "stopping" is
defined as rod deceleration, then yes, it occurs at peak
load, there is no
other way it can happen. And yes, how the rod decelerates
has a big impact on
how the rod unloads. If the deceleration is very slow,
the rod continues to
rotate all through the stop which causes a rounded tip
path and very rounded
loop, vs. a tight, top pointed loop.
Bruce
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From Troy Miller:
Agree greatly with
Bruce. Like him, I spent about 30 minutes trying to decipher Server's
First Law of Casting. And like Bruce, I take issue with the concept of
hard stop vs. negative acceleration, rod unloading and such. I am an
engineer, NOT a physicist. There's a HUGE difference. Engineers
concern themselves with the practical application of physical concepts.
Yes, we're familiar with general theoretical issues of macro and
microphysics - BUT WE DON'T OBSESS over them.
I believe that we can
actually see loop formation well before there's a pronounced stop - if we
accelerate the rod and flyline to a high speed midway through the stroke, and
then stop accelerating (constant velocity) for the remainder of the
stroke. Now I'm talking about the rod tip when I talk about acceleration
or velocity (not angular rotation of the butt, as Bruce describes). Not
that I disagree with him, but my video studies focused on the tip rather than
the butt. I don't feel qualified to try to speak with authority about the
butt's angular acceleration since I've not studied it like Bruce and Noel have
done so thoroughly. I didn't take physical measurements real-time, I
simply plotted points of stop frames with equal time intervals between. I
specifically attempted to make casts where I (the caster) accelerated different
ways and watched what happened to the way the rod loaded and what the tip did,
and then what the loops did. I changed the inputs and observed how the
outputs varied. I'm sure that my analysis was nowhere near complete (would
love to get a gov't grant to MAKE a complete
analysis.).
We've discussed many
times on Frank's and Guy's and Allen's and your lists how the rod can reach max
loading condition BEFORE the caster begins intentional negative acceleration.
He can do this by reducing his positive acceleration, or taking it to zero
acceleration. I commonly call this "soft stroking" the rod. I do
describe this to students if they're having problems with it, and have gotten
very good at demonstrating it. I explain using phrases like "you've done
good work in getting load into the rod up to about right HERE. From there,
seems that the load gets lost or wasted and ultimately doesn't contribute to
line speed. The rod needs to stay loaded all the way until you STOP the
rod." Even relative beginners understand it when you talk and show at the
same time.
There's one more thing
about hard stops. A long time ago, I learned the trick of reaching up and
stopping the student's rod where I want them to stop (either back or fore
casts). I used to let the rod hit my hand or forearm and the stop was
SOLID. Almost to the point that I'd even slightly reverse its direction
slightly. As you can guess, the shock induced by such a violent stop would
destroy all gracefulness in the loops and throw nasty shock waves through the
bottom leg. Gradually I learned that I should soften this stop slightly,
and even help them follow through a bit to encourage natural dampening.
Now I try to actually accurately "grab" the rod blank above the cork and
help them achieve a more controlled stop - as opposed to a "dead"
stop.
I think I disagree with
Bruce's statement that
If "stopping" is
defined as rod deceleration, then yes, it occurs at peak load, there is no other
way it can happen.
I think you can have a
fully loaded rod that then is taken through zero acceleration for an interval
(constant speed), during which the rod will try to unload. Later on in the
stroke, you will then decelerate the rod (reduce the velocity), but you would no
longer have a max loaded rod. A flyrod (which is a loaded spring full of
potential energy) will try to return to RSP as soon as the system reaches
steady-state (uniform) velocity. Maybe even
before.
Some of Server's ideas
sound VERY similar to Michael Montagne's. Montagne vehemently argued that
the rod unloading adds NO additional velocity to the flyline, beyond the speed
that the flyline followed the tip along at. The only way I can see that
being true is if the rod began unloading BEFORE the intended stop
(caster-induced deceleration). Anyways, better go to bed before my mind
starts unrolling at 200 mph! Thanks Gordy.
Regards,
Troy
Miller
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Followup message by Ally Gowans:
Hi
Gordy,
OK I have now read
Server Sadik’s paper. I agree with all the points made by
The paper rambles but
in parts it makes accurate observations of rod behaviour (eg the precise point
of loop formation relative to tip velocity). Unfortunately the language and
terminology used is confusing and unusual which probably makes it impossible to
understand for many readers and for that reason I do not commend it.
In places it is
confusing, for instance what he calls “kickback”. With modern materials its
effects are negligible during casting. When rods were made of greenheart and the
like a common test by intending purchasers was to hold the rod a few inches
above a horizontal surface such as a table and pantomime a back cast. The closer
the rod could be held to the table without the tip ring making contact with the
surface the better it was adjudged to be. Kickback is not a feature of the
direction reversing casts (Snap casts) that he describes made by Paul Arden.
We use the word “stop”
knowingly, somewhat liberally, conceptually and related to the rod handle but it
works very effectively during teaching which our purpose. I think that Server
uses the word “stop” in an absolute sense and of course that is not what happens
in practice so in his terms a “hard stop” is impossible. Unfortunately for the
less informed rejection of the “stop” word is bound to be simply confusing.
My response is far from
exhaustive, I suppose that if I had the heart I could go on and on with lots
more comments but I have no intention of “marking his paper”, wasting my time
and yours!
If he believes that his
“findings” are novel and illuminating then I suggest that he should be invited
to provide a factual précis with definitions and supporting sketches that will
allow these concepts to be easily understood and appreciated. Perhaps somewhere
in there a gem exists and we should know about it?
Hope that this is
helpful, have copied it also to Bruce.
Best
wishes,
Ally Gowans
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Dennis Grant helps bring us down to Earth with some comments which I appreciate and have taken out of context. I present them because I think they make good sense and avoid scientific argument.
Technical analysis belongs with the world of science and its appropriate forum is amongst the technical community. AND it is highly unlikely that that community would agree on very much.
In our ‘sport’ we very often answer a question with ‘it depends’
What type of line should I use – It depends
What weight of rod should I use - It depends
How wide should my loop be – It depends
How fast should I make the rod travel – It depends
When should I apply power to a cast – It depends
So on…. so on….
But we do need basic terms to have a student understand what is required to cast a fly rod.
We have taught fly casting to over 4000 individuals, one on one. I personally have privately coached close to 30 CCI’s and seen all but 1 of them pass on their first attempt. We have seen 8 year olds who 'catch on' to casting in a few short hours and do it well, LPGA golfers who pick it up in 20 minutes, and also we have attempted to teach retired, 200 pound plus, NFL players who couldn’t get a 40 foot line out if they shot it through a gun.
When we teach fly casting there are fundamental principles that we want the student to grasp quickly and clearly. Yes science can postulate all they want and mathematically prove that the many things we do are impossible or are inaccurately described. NASA can put a rocket into space by making mathematical calculations but can they do it any day of the week, well – it depends !!