Walter & Group:
Comments by Walter Simbirski. (My answer follows, below this one.)
Gordy - Some great discussion here!
Ideally, the rod tip moves in a straight line during the power application phase.
Then all you need to do is dip the rod a bit at the end of the stroke to form the
desired loop and you get a great cast.
If the rod behaved exactly like a spring, i.e. if the change in the effective
rod length was directly proportional to the load on the rod, the path of the hand
required to maintain slp of the rod tip would be very complex. Fortunately, while
the change in effective length is proportional to the load it is not directly
proportional. This is because the rod has a progressive taper and the rod tip
is constrained to follow a curved path away from the rod axis. In order to maintain
slp of the rod tip through the majority of the casting stroke the hand follows
a nearly straight path as well. This is an approximation but the greater the load
on the rod the more accurate this approximation.
With repect to what Joan Wulff has to say about direction of line travel vs the
direction she uses the concept of point of impact.
Cheers
Walter
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Walter....
That makes good sense to me.
Your statement, ".....but the greater the load on the rod the more accurate this approximation". is interesting.
Looking at it crudely, if the rod had so much load that it bent all the way down to hand level, then the path of the rod tip would be exactly the same as that of the hand during the loading move. However that would dramatically change as the rod began to straighten and unload.
On the other hand, if the caster makes a very short cast requiring minimal rod load with a very short stroke and short casting arc, then the path taken by the hand would be very close to that of the rod tip as in so-called, "tip casting" to a very close target.
For most casts and most rods, it appears that there is some degree of adjustment of the path of the hand to match the changing bend of the rod in order to maintain a desirable near straight line path of the rod tip. As Bruce said, that is not easy. I don't have the faintest idea as to how one might go about quantifying this.
Gordy