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