It looks like there would be a lot of snapped tippet and lost flies in the learning process
You only get a snapped tippets if you "crack" the whip by starting the forward cast BEFORE the backcast has unfurled. If you wait until the backcast has straightened, you are starting the forward cast against a tight leader and the tippet will not break.
how are they getting a straight line path when the rod tip is not traveling in a straight line on the forward cast ?
The rod tip is traveling in a straight line BEFORE the stop, then the caster tips the rod tip down to form the loop. The amount the rod is tipped, determines the size of the loop.
The cast does NOT break any of the rules of casting. The rod tip direction and path determines the direction and shape of the fly leg of the cast. The tip down of the rod AFTER the stop, starts loop formation and determines the loop size by separating the rod leg from the fly leg of the loop.
Since one end of the fly line (the trailing end) is attached to the fly (fly leg) and the other end (the leading end) to the rod (rod leg), the loop width has to be the distance the rod tip was tipped from the path of the fly leg! Physics dictates that this has to be so. Before the stop, the rod leg and fly leg are IDENTICAL. Once they are separated, one leg is moving (the fly leg) and has kinetic energy (KE) and momentum (P), and the other (rod leg) is stationary and therefore has no KE or P.
As the fly line goes around the loop (the fly leg become the rod leg), the KE and P of the just formed rod leg is transferred the the remaining fly leg. The fly leg is getting shorter, therefor it is losing mass. Since KE and P is being added to the fly leg, its velocity must increase as the mass goes down to conserve KE and P. Some of the KE and P of the fly leg is lost to aerodynamic drag of the line, leader, and fly as the loop and fly leg move through the air.
This balance of aerodynamic drag which is slowing the cast vs KE/M transfer whihc is speeding the cast determines whether the fly leg moves faster or slower as the fly line turns over.
Look at two casts in the video below.
The first cast is at about 1 min 50 sec and is an overhead cast. The stop and loop formation happens so fast that it may look like there is no stop, but there is. The fly leg is the path of the rod tip.
The physics of casting dictate that if you follow the fly get forward, it will lead to the level of casting rod stop. This is where the loop begins to form.
Similarly,
the physics of casting dictate that the level of the rod leg will be determined by the amount the rod tip was moved out of the way of the fly leg. Therefore the rod leg reveals the amount of the rod tip movement AFTER the stop.
EVEN IF WE CANNOT SEE THE ACTUAL ROD STOP, THE PHYSICS TELLS US WHERE IT OCCURRED!!!! This deductive reasoning is just as valid as seeing it.
The second cast is at 2 min 40 sec into the video and shows a very tight loop. The caster performs a thrust cast in which the rod is thrust forward at the very end of the cast much like you would thrust a sword forward. This automatically produces a very HARD stop. At end of a thrust, the arm cannot go forward anymore and the rod is forced to stop! The size of the loop is determined by the thrust of the rod tip, and this thrust can form a very tight loop depending on the direction of the final thrust vs the direction of the fly leg (the direction the rod tip was going before the thrust).
Roll the video back and forward to examine these two casts to see what I mean. Then run the 2nd cast at regular speed and watch the end of the fly line at the leader as the cast unfurls. Is the velocity increasing?
[ame]http://www.youtube.com/watch?v=w-Wgs6KftR0[/ame]
