Hi Paul
There must be an immediate loss of tension at RSP because if you haul through RSP with a softer cast and less aggressive haul you can clearly feel the tension suddenly disappearing. So no line can be shot at this point as far as I can see. Tension reappears later as the loop propagates. At least that’s what the line hand is telling me.
It’s possible indeed: let’s take some picture to illustrate my comments. The first image corresponds approximately to the time when the tip is going to deviate from its initial trajectory. The second one is RSP (Lasse’s haul has ended) and the third one corresponds to some time near the end of loop shaping.
- Loop shaping 1.JPG (34.03 KiB) Viewed 2573 times
Between the two yellow arrows in the figure above, and in fact since MCL, the line is accelerating less and less until RSP where it reaches zero acceleration (maximum speed). After that point (below) the tip is decelerating the line until it reaches MCF.
- Loop shaping 2.JPG (23.06 KiB) Viewed 2573 times
If the timing of the haul is such that maximum haul speed has taken place before RSP, the line is being decelerated by the caster’s hand. A haul is made of four steps, approximately equal: at the end of the first quarter, positive acceleration is maximal which impacts rod bending. In the middle of the haul, speed is maximal and at ¾ of the haul, the deceleration is maximal. At RSP time, you may then cumulate two decelerations acting on the line, the one of the tip plus the one of the haul, which can also be at its maximal negative value if RSP is achieved at ¾ of the haul. The corresponding total maximal peak deceleration value appears just after RSP likely and before MCF.
This point is important since considering angular momentum allows estimating the difference in tension at both ends of the loop (completely shaped or not), and this difference strongly depends on the variation of speed of the line along the loop. It also depends on skin drag and loop mass distribution which act against each other, enhancing the importance of the variation of tangential speed along the loop on the difference in tension. If the line decelerates, then rod leg tension lowers by comparison to fly leg tension, which incidentally may be somehow weak if the cast is gentle, and there may well be circumstances when rod leg tension goes to zero or even beyond, meaning that the bottom of the loop is under compression. The line is stiff enough to handle that compression but a shooting or a running line can collapse. Such compression or zeroing delays any release effect at such period of time. The fly leg must accelerate to induce tension again at the bottom of the loop. For that the loop must be shaped first since an adequate variation of (horizontal or so) momentum of the loop is needed.
Merlin