Gordy,
We can keep this between the two of us or
just drop it if you prefer. Just let me know.
I kind of hate to drop it because I don't have very many other forums to discuss some
of this stuff
but I understand you don't want discussions
to get too confusing.
On the idea of using translation only to pick
up line:
Unfortunately, I have lent out my copy of
Jason's book and it's the only reference I can think of
that has information on hand casting but I'll
try to muddle through.
Jason tells the story about his mother and
another person going fishing but, due to circumstances,
they didn't have rods with them - only reels
with line on them yet they were able to fish by hand
casting.
When I'm hand casting I start with the line
laid out on the ground with no slack between
myself and
the fly and I face
perpendicular to the line. I have both hands near the center line of my body. I pinch
the line in my "line" hand (the hand closest to the
fly), form an O-ring around the line with my "rod"
hand near the "line" hand but between the
line hand and fly. I then slide the
O-ring in the direction
opposite the fly while holding the line hand still. Once I run out of arm with the rod
hand I pinch the line with my rod hand and
bring it back to the center line of my body
while the loop
is unrolling. I then switch hand functions by
forming an O-ring around the line between the rod hand
and the fly with what was my line hand and
sliding that O-ring in the opposite direction.
I'm not very good at hand casting but I can
keep 40+ feet of line aerialized this way. There is
no rotation - it is strictly
translation.
I believe that what some (note that I
said "some" and not "all" ) people refer to as a "water haul"
is basically the same thing but with a rod
in hand. Start with both hands in front of
you with the
line hand pinching the line and with enough
slack between the line hand and reel to allow for a
haul. It is important that there is no slack
between the line hand and fly. Now, rotate the rod slowly
to a near vertical position. This would be
the lift - I know it's not what we teach as a proper lift
but it does work as a lift. Now smoothly
accelerate into the backcast with the rod hand but do
not rotate the rod. It takes a bit of practice because our muscle memory from casting
always wants
to rotate the rod but I think you will find you can make a pretty nice looking
loop for your back cast
this way and it will unroll fully leaving you in good position to make a forward cast.
Depending on
where you finished your lift you may need to
drift a bit to position for the forward cast.
I suppose it would be possible to switch the
rod to the other hand and make a forward cast with
pure translation at thid point but it
certainly would be awkward.
Cheers
Walter
----- Original Message -----
Sent: Thursday, September 04, 2008
6:05 AM
Subject: Translation/Rotation....
PHYSICS DETAILS
Walter & Group.....
From Walter Simberski. (Note his attachment You may need
to scroll down to see his new diagram ):-
Gordy,
At the risk of beating a dead
horse:
Bruce's diagrams are carefully drawn and
are 100% correct but I think it might be worth pointing
out again that he has
reduced the examples to rod motion only. As such, they are
conceptual
only and not necessarily a depiction of the
real world.
If we get into a mind set that says if the
butt end of the rod moves through space
we must have
translation taking place then we may be
mistaken.
If we hold the wrist rigid and rotate the
lower arm and rod combination about the
elbow we will get
something that looks very similar to
Bruce's drawing depicting a mixture of
translation and rotation,
i.e. the rod will rotate and the butt
of the rod will move through space, but the
motion will be rotation
only.
I've taken the liberty of attaching a
modified version of Bruce's spreadsheet showing what I hope
are some clarifications regarding rotation
and a mixture of translation and rotation. Bruce
was very careful to show that the axis of
rotation (the point that the rod is rotating around) is
the very butt end of the rod. As you can
see there will be a subtle difference when the axis
of rotation is moved to the elbow and we
take away translation - the butt of the rod will move
in a circular path, not a straight path -
but the outside observer could think they
are seeing a
combination of rotation and translation
when no translation exists.
I came across a fairly good discussion of
translation vs rotation at the following web site:
I'm curious - I haven't heard a response
from you regarding my question of whether it is
possible to pick up 30 feet of fly line
plus leader using translation only. Did you get my email?
I could make it more of a challenge and ask
whether it is possible to pick up 50 feet plus
leader using translation
only...
Again - I fully agree translation and
rotation are not subjects for most students. I do find them
helpful when discussing the difference
between arc and stroke.
Thanks
Walter
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Walter .....
You have taken the risk.... and the
poor horse remains dead !
There is no disputing your
conclusions. This is one reason I looked at rotation as almost
always admixed with translation and vice-versa....
However, I didn't want to get into the
intricacies of physics which you understand in much greater depth than I
.....
In particular, I didn't want to
confuse the issue with our Group members, the vast majority of whom are
not scientists.
Just as you have exaggerated the axis of
rotation in your diagram by placing the, "handle" of the, "rod" half way
up the shaft, Bruce and I have exaggerated in the opposite direction
.... that of utter simplicity ..... to make a
point , realizing that from a strictly scientific view,
there are some inaccuracies.
In order to simplify things to make a
single issue as clear as possible my discussions and Bruce's along with
his depictions didn't consider rod bend, either.
I think the biggest problem we encounter in
trying to study fly casting is that it is an inextricable kaleidescopic
compendium of events involving flexible materials being manipulated by
different means and by different human beings. The variables are
almost beyond understanding. To teach it, we have had to reduce it
to easily understood segments ...... and then try to put it all together
so our students can actually cast.
In studying the material in the link which
you provide, I found some interesting things about TORQUE which I hadn't
known. One was the apparent attempt to depict torque as a straight
line vector ! The author apparently hadn't solved that problem in
his own mind, and passed it off as he continued with other
discourse.
Ally has asked questions of the Group on
TORQUE as it applies to fly rods and casting.
As we discuss this new topic, I'd like to
keep it at a level understandable to all and not get into the detailed
physics unless we are to be proven dead wrong
.........................
Now, to answer your question :
Is it possible to pick up 30' of
line plus leader using only translation ?
Short answer:
NO.
Long answer: I did get
your message. Before answering, however, I went out and tried to
do this on grass and on water.
Firstly: I couldn't convince
myself that my trials were with pure translation. Second: I
could pick up from grass, but not water to the extent that my fly/leader
did leave the ground.... however, no true cast resulted.
Gordy
Gordy