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  • Energy input to the cast



    Walter & Group..........

    A good question from Bill Toone:

    Gordy, I am not sure if this one made it to you.  I am having a hard time wrapping my arms around there being no difference between physical effort on the caster’s part to move the rod/reel and the energy imparted to the rod/line during the casting stroke.

    Respectfully,

    Bill Toone

    Gordy, I am trying to understand this so forgive me if it appears I am beating a dead horse here.

    While I agree and understand that the heavier outfit (10’ 8 weight) will require more physical effort on the caster’s part to move the rod/reel I am not grasping how this would mean the line speed needing to be achieved so to transfer the required energy to the heavier line would be the same as the lighter line?  If two objects are moving at the same speed the heavier one is going to have more energy (velocity squared x weight in grains divided by 450240 = ft lbs of energy) or at least regarding bullets.  I assume this same law applies to fly lines or any other object. If this is true than less line speed or energy/power would need to be imparted to the heavier fly line?  If the definition of power or energy regarding fly casting is the loading of the rod than wouldn’t you not have to load the longer rod with heavier line as much as the shorter, lighter outfit to achieve the same results (I.E. less power being applied to the cast/rod)?   Not the same thing as energy required by the caster to move his/her arm/elbow – in my understanding. If you swing two hammers of different weights while you may need to exert more physical effort to swing the heavier hammer to hammer the same nail as the lighter hammer, you will not need to swing it as fast or hard (which is also an amount of effort or energy) to accomplish the same results. In other words less energy or power is required of the tool (in this case a fly rod) to accomplish the same task.  If equal or more energy was required of the hammer or the fly rod then what would be the advantage to using the heavier outfit to achieve the same result?  In our scenario it is a set distance we are trying to achieve and then comparing the mechanics of achieving it between the two outfits.

    Once again I am not trying to be argumentative.  Your knowledge is vastly greater than mine.  I am merely trying to understand where my thought process is in error.

     

    Respectfully

    Bill Toone

     

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    Bill :

    I see your point.

    With the set modest distance described, I don't think the heavier outfit would offer an advantage.  In fact, it would require a bit more energy expended by the caster simply to overcome gravity because of its additional weight.  The heavier outfit, however, would offer an advantage if maximum distance were to by achieved.

    In that event, the energy expended to move the heavier rod and line will have to be greater than that to move the lighter outfit.

    In your hammer analogy, with a single blow, one must use a lot more energy to employ the heavier hammer.  In trying to split a log, for example, he can do it with the expenditure of a lot of energy using the heavier hammer with one blow .... but he can't do it with the light hammer with a single effort... it may require several blows.  The energy expended with the multiple blows may add up to be the the same amount of energy used with the single application of the heavy hammer.

    As Bruce Richards has pointed out, one cannot accurately use the analogy of the bullet out of the gun.  Here there is no tapered line to unfurl to yield exponential transfer of mass to velocity as this taper unfurls.

    Yes... you would have to try to load the lighter outfit up to the point that the light rod would accept no more load.  To impart nearly the same energy to the fly line, then, you would have to put more energy in to the mechanics of the cast beyond that used to bend the rod.

    ALL the energy comes from the caster.  NONE from the fly rod.

    If the caster applies no energy at all, NOTHING HAPPENS.... NO CAST.....PERIOD.

    The fly rod can apply no energy at all.  The only transitive thing it can, "do" is to straighten.

    Having said that, there is a big difference in the effect of the use of that energy imparted by the caster in two different ways:

    1.) The energy the caster applies to bend the rod (load it) against the inertia of the fly line.  (The caster can apply a lot more energy to the heavier rod which can accept a much greater amount of stored energy than the light one.)

    2.) The additional application of energy by the caster to employ the other mechanics of the cast, ie. energy input to move the rod tip in the direction of the target added to that used to load the fly rod.

    Each is needed to make an efficient cast.

    Which of the two is more important ???????

    Two simple experiments can tell us.

    Many years ago, a chap named Robert Crompton did one in which he potted the handle of a fly rod in a stationary vise.  He, then, took the fly line and pulled it way back so as to bend the rod to the max. This action was obviously energy imparted by him. This loaded it as much as possible.  He let the fly leader go and observed that the, "cast" didn't go very far at all.  No where near as far as it did when he took the same outfit, loaded the rod by bending it as had been done with the vise, but added the additional energy of his own to move the rod tip in making a standard fly cast.

    An experiment which I demonstrate on occasion is this:  I have a, "fly rod" made from a broom stick, with guides and a tip top.  It won't bend.  Since I can't bend it, it won't load.

    With this unbendable, "rod" I make a fairly decent cast of reasonable distance.  Not a pretty cast, but it gets out there.

    These two demonstrations help tell us that the latent (potential) energy imparted by the caster to bend (load) the rod and to be released as the rod straightens is not quite as important as the additional energy imparted to the rod by the caster as he executes the mechanics of the cast in providing active stroke length (the distance moved by the hand) and rod arc (the angular change of the position of the rod butt from the start to the end of the cast .)

    ALL of this energy, in each instance was provided by the caster.  That which came from the release of kinetic energy from the bent rod had to come from the caster to bend it in the first place.

    Gordy