Translation / Rotation

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

On the function of TRANSLATION from Walter Simberski.  My comments in bold blue italics.  Gordy :-

Gordy -

 

Been thinking about this for a while. If rotation provides the "power" or speed in the

casting stroke then what does translation do?

 

So far I can think of two major contributions that translation provides to the stroke:

 

1. It helps maintain slp.

    To explain - If we rely on rotation alone then we have to have a

    perfect match of arc and power in order to maintain slp. As the amount

    of line carried increases it becomes more difficult to do this for the entire

    stroke. By adding translation I can do things like lower and or raise my

    hand to cause the rod tip to lower and raise and thus help it to maintain

    slp.

 

That makes sense to me.   G.

 

2. It contributes to the haul.

    To explain - If we pinch the line in the line hand and hold the line hand

    fixed in space then we can haul with the rod hand by pulling away from

    the line hand with the rod hand. Of course to complete the haul we

    need to follow through (the up in the down-up) with the line hand (or we

    could slide load...).

 

Probably true, but I think that is a minor addition.  G.

 

    If we unfix the line hand to do its thing then the combination of hauling

    with both hands makes for an extremely powerful haul.

 

    Another way to look at this is that if I haul with the line hand only then I

    run out of arm at about 3 feet. If I haul with both hands I can haul for the

    full span of both arms (6 feet, more if we include shoulder width).

 

Not sure what you mean by hauling, "with both hands"   G.

 

Do you know of other ways translation contributes to the cast?

 

Yes, indeed.  Bruce Richards' studies have lead him to the conclusion that a major effect of translation, especially when used as, "drag", is that it helps minimize or eliminate slack.

 

I have always figured that translation can contribute to rod load, too.  Some others agree with me on that point.  Bruce felt that this was a minor contribution if it existed at all.  To me, proof that it does add to rod load lies in video studies of super casters like Rick Hartman who is an inveterate, "translator".  As he starts with pure translation, not enough arc to even see it, the rod tip does begin to bend.....ergo, LOAD.

 

Of course, that addition to rod load can never be very great for the simple reason that with pure tranlation (unmixed with any rotation at all) the rod tip must necessarily move at exactly the same rate as the hand  except for the effect applied to the rod tip by the inertia of the fly line. 

 

Once translation is mixed with rotation, the effect of rotation is far greater since the, "lever effect" of the long fly rod yields far greater speed of the rod tip than that of the hand.  As the amount of rotation increases, we see significant rod load as well as rod tip speed.

 

 

As you know better than I, there isn't much acceleration of the rod during pure translation.  Almost all acceleration is the result of rotational application of force (Torque).

 

You and other physicists including Noel Perkins, who has worked with Bruce Richards, have pointed out the relationship between acceleration and rod load (bend).  Simply put, "no acceleration, no load"  "Increased acceleration, greater rod load."  The way I see it is that the very little rod bend I see on the videos demonstrating pure translation is likely load as the result of some acceleration, even if this is, "from zero to slow".

 

Most casters don't cast the way Rick Hartman does.  They use various combinations of translation and rotation even for their distance casts.  Very few casts have any truly pure translation.  Most efficient casters appear to have a decreasing amount of translation mixed with increasing rotation as the casting stroke progresses.

 

When Tom White and I tried to video a cast with lots of pure tranlation, we found it almost impossible to do this, because neither of us could maintain more than momentary translation with no rotation at all no matter how hard we tried.

 

When trying to demo pure translation with no rod arc (rotation) at one of our Conclave Workshops, I did the narration while Jim Valle did the demo with an unloaded fly rod (no line)  Even then he couldn't help but get a little rotation in the movement. 

 

Theorertically, one should be able to make a demo by having pure translation with the rod tip moving at exactly the same speed as the hand ...... or even with the rod tip lagging.  This, however, is very difficult to really accomplish.  I think it would be rare, indeed, in the real world of fly casting.  A, "cast" made with pure translation would result in a pile of line at the caster's feet or behind..... while one can certainly make an effective short cast with rotation alone.

 

 

Short answer:   1.) Translation helps remove slack.

 

                         2.)  It may contribute slightly to rod load.

 

                         3.)  I am uncertain as to its contribution, if any, to the haul.

 

Gordy

 

 

 

Thanks

 

Walter