translation vs rotation

Paul Arden · Post by **Paul Arden** » Sat Feb 19, 2011 10:30 am

In the old days, Frank, instructors used to teach that it was all in the wrist. This of course would be rotation only. Is this your current method of casting? The moment the elbow comes into play the rod begins translating. I think you see that as rotation, but your thinking elbow, not rod!

What are your thoughts on this subject?

Cheers, Paul

easterncaster · Post by **easterncaster** » Sat Feb 19, 2011 1:33 pm

http://www.googlefight.com/index.p....otation

andy_with_a_rod · Post by **andy_with_a_rod** » Sat Feb 19, 2011 2:56 pm

Guys,
I've attempted to create an accurate image of what the discussion centres around. I think you'll agree that it isn't only completely accurate, but also a little postmodern AND slightly inspired by the impressionists. I think it's a masterpiece. You do too.

anyway, thanks for thinking its great. i haven't spent 3 minutes drawing it for you to tell me i'm great. I think that the grey areas in the casts are the green areas, such as the questions over translational movement in a wrist only cast.

I've given you the tools, now you guys build the house of clarity, just remember, people in glass houses shouldn't throw stones. unless they're locked in the glass house, and its on fire, and the only other object in there is a stone. in which case throw it.

Frank LoPresti · Post by **Frank LoPresti** » Sat Feb 19, 2011 3:12 pm

Paul Arden wrote:The moment the elbow comes into play the rod begins translating. I think you see that as rotation, but your thinking elbow, not rod!

What are your thoughts on this subject?

Cheers, Paul

Actually no it doesn't. Something must be rotating in order to bring the elbow in play. That's simple biomechanics. The only way you can cause the elbow to translate on it's own is to walk forward in a straight line, as dumb or as obvious as that may sound, that is indeed the case.

As it goes to fly casting, translation lengthens the size of the arc. That is translation as a working "abstract" as it adds nothing of significance as to it's direct impact on actual loop formation. In a practical working sense it lengthens the ability of the caster to apply angular acceleration over a longer distance no more no less. I would also consider the contribution of translation as it goes to various casting planes. High to low, low to high or plane parallel to the water or ground.

This idea of translation as it might control the path of the rod tip would only come into play if the caster moved the rod hand off the translational path by a significant amount. But the ironic part is that in order to move the rod hand out of 180 plane you would have to curve the rod hand which is no longer translation but a rotary movement. You can't even move the rod straight up and down without rotating something.

So in a very real sense translation simply goes to applying force over a longer distance since translation in and of itself, as it applies to the rod tip, will move the rod tip the same distance as the rod butt, that is to say not at all, relative to one another. Both the rod butt and rod tip will move the same distance, and if they move the same distance, they cannot effect the path of the rod tip as it applies to loop formation, as the path of the rod tip remains unchanged, and if the path of the rod tip remains unchanged the the path the line that follows the rod tip as it trails the rod tip will remainunchanged also. Frank's # 1 rule of fly casting is that as the rod tip goes so to goes loop formation.

So relative to a cast that uses more translation rather than less, to lengthen the size of the CA, the only feasible tangible benefit or significance of translation, is that it increases the distance of hand travel that allows the caster to apply a smaller force over a longer distance.

Cheers,

Frank

Frank LoPresti · Post by **Frank LoPresti** » Sat Feb 19, 2011 3:16 pm

Hi Andy,

Nice diagrams but there is a number 4 if you begin with the elbow out like the letter L and the caster leads with the elbow but not by dropping the elbow as seen in # 3. Otherwise the rest seems to be spot on.

Frank

andy_with_a_rod · Post by **andy_with_a_rod** » Sat Feb 19, 2011 3:18 pm

frank, i've just tried that with a practice rod. i cant make a proper cast with it. am i supposed to move my shoulder?!

Magnus · Post by **Magnus** » Sat Feb 19, 2011 3:20 pm

New crayons Andy? Nice work

Thing I don't buy is the image that creates of distance casting or the difference between short and long casts by the same caster. I can't tell if those a long or short casts.

At the beginning of a long stroke the tip of my rod is well below the height it reaches at the portion of the tip-path we know is flat - SLP is just that portion - its is not the whole of the casting arc. Look at guys like Rajeff and on their delivery stroke they end up with the rod tip high - higher than it was at the start of the stroke.

I've been trying to find an article, I think it was Al Kyte and a co author, comparing long and shorter casts so see what the casters changed. If I recall right hand path lengthened for longer strokes and the angle of the path changed.

Paul Arden · Post by **Paul Arden** » Sat Feb 19, 2011 3:28 pm

I thought that's what you were looking at Frank. So I don't agree. I think for translation and rotation we are discussing the rod only. Not what it is connected to. If I rotate around the elbow the rod both translates and rotates.

Cheers Paul

andy_with_a_rod · Post by **andy_with_a_rod** » Sat Feb 19, 2011 3:29 pm

where on the rod paul? just for clarity.

Paul Arden · Post by **Paul Arden** » Sat Feb 19, 2011 3:42 pm

Generally speaking in the hand.

Frank LoPresti · Post by **Frank LoPresti** » Sat Feb 19, 2011 3:44 pm

Paul Arden wrote:I thought that's what you were looking at Frank. So I don't agree. I think for translation and rotation we are discussing the rod only. Not what it is connected to. If I rotate around the elbow the rod both translates and rotates.

Cheers Paul

I have no idea what your describing.....

Frank

Paul Arden · Post by **Paul Arden** » Sat Feb 19, 2011 3:55 pm

For stroke length there are a number of ways you can measure it. All of which give different results.

Frank LoPresti · Post by **Frank LoPresti** » Sat Feb 19, 2011 4:14 pm

The only result I'm aware of is is applying an angular force over a longer distance. Translational distance does not add angular force to the length of the stroke, only the caster can do that. It will always be the angular force that trumps the length of the stroke as far as I can tell. Nothing novel about that idea either.

Frank

Paul Arden · Post by **Paul Arden** » Sat Feb 19, 2011 4:25 pm

Just because angular force by way of leverage has the potential to do more work doesn't mean that you exclude translational force. Apart from which that's not how our bodies work most efficiently.

Cheers Paul

Frank LoPresti · Post by **Frank LoPresti** » Sat Feb 19, 2011 4:39 pm

Paul Arden wrote:Just because angular force by way of leverage has the potential to do more work doesn't mean that you exclude translational force. Apart from which that's not how our bodies work most efficiently.

Cheers Paul

Not that it just has the potential to do more work but that angular force is the dominate force that does the work that goes to loop formation, as Gordy pointed out. So what I'm left with is lengthening the stroke as a non dominate force and there is no way to measure that force that I know of as it goes to loop formation.

We've been about this for a long time and since then nothing about rotational force has changed nor to your point has anything changed about the translational forces as it goes to tip path and loop formation. It simply seems to me to be a case where the benefits of one outweigh the possible effects of the other to a large degree, a very large degree.

The main benefits of translation go to applying force over a longer distance and casting plane trajectory. Seeing as no change in tip path is a result of translation it would have to rank pretty low as to the other benefits that translation does indeed offer the caster. As Gordy pointed out this may have more to do with giving over to nuance more than anything else.

Frank

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