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Old 02-24-2012, 01:13 PM
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Default Re: The devils advocate???

Quote:
Originally Posted by chuck s View Post
I was going to quote and comment but that would even be more confusing I'm a tad bit confused as it is!


Carry a tip heavy outfit from your car to the stream (realitively static) and you risk drooping that tip and snapping it off!
Simple solution is to carry the rod with the reel facing forward and hold it at the upper end of the handle. This will place the tip behind you and unless the tip end of the rod is very heavy, it will be tip up. Even if it is still tip heavy, just move up the rod until the tip is up. Rod balance when carrying a fly rod is a nonissue IMHO

You can wind your way through the trees and the rod will follow you. One caution is to put the line through the guides and put a fly on the end of the tippet. Then rotate the rod so the leader spirals down the rod and clip the fly to the lowest guide. This leader wrap prevents loops of fly line from getting caught on branches. If you don't do this, a twig could catch the rod and pull off the top section og your rod and you will lose it.

When prospecting and walking up the bank, alway carry the rod behind you in the hand that is away from the river. If you carry it forward in the hand closest to the river, it will wave over the river edge ahead of you and spook the fish upstream and these fish will spook other fish.


Quote:
Originally Posted by chuck s View Post


When speaking of line speed coupled with the line's weight we are speaking of momentum, not energy as it's simple momentum that will or will not carry line in the shoot phase of that cast and it's minute adjustments with your hand and wrist that keeps the entire casting plane where it should be. The minute that gets a bit out of kilter your casting distance suffers and accuracy suffers even more.

I disagree.

My apologies for being technical but, I think we need to be very exact when we use physics terms in describing the cast.

My second point takes issue with use of the physics term "momentum" when considering the distance of cast. Momentum (P) is often confused with Kinetic Energy (KE) because they both are the result of Velocity and Mass. In fact, KE is the calculus derivative of momentum. While momentum is MxV, KE is .5MxV^2. It is kinetic energy and not momentum that actually results in the distance of the cast.



Both mass and velocity affect the distance of a cast, but velocity is much more important than mass. The momentum equation states that they are equally important; but you do not need to be a physicist to know that a double haul shows that to be false.

We all know that a short tug or a "haul" on the fly line creates a much longer cast than one would expect from the small amount of velocity added to the cast. The reason is that KE varies by V^2 (Velocity Squared). It is that second power rather than linear relationship to velocity in KE that amplifies the effect of a relatively small velocity change.

If it were momentum that increased the distance, how would we explain how a haul that actually removes mass by pulling in line and decreases the momentum by removing mass, could result in more distance? It is the second power or V squared that not only compensates the the removal of mass, but allows us to shoot line adding even more mass. If it was momentum we could not shoot line because adding mass would have to decrease velocity linearly to keep the momentum constant after the haul. With KE, shooting line decreases velocity just a bit because of the V squared effect.

We also know that it is air friction or "drag" that limits the distance of our cast. Well there is symmetry in physics because Drag also varies by V^2. Click on Drag below and you will see that velocity in the formula for drag is noted by "u" and drag varies by u^2.


When we consider that drag is related to the surface area of an object, and that fly lines are tubular; therefore drag varies linearly with the circumference of the fly line. This explains why additional mass adds distance to the cast. The mass of a fly line varies with the cross sectional area of a fly line which is square function of the radius. So for an increasing mass of fly line, mass goes up faster than surface area, and adds more energy than drag can take away.

We also know that "momentum" cannot be stored in a bent fly rod, but a bent rod does have "potential" energy. When a rod unloads it does not release potential momentum but potential energy into kinetic energy. So the concept of energy in its kinetic and potential forms explains the distance of a the fly cast.

Momentum is has a directional component and energy does not. So momentum gives the cast it's direction but it does not determine how far the cast goes or how aerodynamic drag affects the cast.

The physics of fly casting has been discussed in the physics literature by G. A. Spolek (Am. J. Phys., 54, 832-836, 1986) and by J. M. Robson (Am. J. Phys, 58, 234-240, 1990). Momentum does not enter in their discussions. It is all about kinetic energy.
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