Effective Rod Length (ERL)

I interpret Marinaro's definition of effective length a little bit differently. I agree that he says the effective length

is at the point of maximum bend in the cast, i.e. there is an effective length for a given cast that does not change

during the specific cast, but different casts with the same rod could have a different effective length. The effective

length for a cast will depend on load and resistance which would vary with the amount of line outside the rod tip,

the use of a haul, and the magnitude of acceleration.

I've been using effective rod length as something that can vary throughout the cast.

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Until now, I've looked at EFFECTIVE ROD LENGTH (ERL) as a static thing. A way of comparing fly rods of different actual measured length and different flexibilities.

Aitor Coteron has already convinced me that we can see this as a dynamic entity. You join him in doing so.

I'm still not certain as to whether or not Vincent Marinaro and Don Phillips saw it in a dynamic way ..... but that is less important, I suppose, than the way in which we now choose to use the term.

I do think that the same cast (theoretically) with rods of differing flexibilities would demonstrate different ERL's. Would the same rod with different casts demonstrate different ERL's ??? I guess so, if we look at it from a dynamic standpoint.

Check out the detailed message from Aitor with comments by me in the attachment.

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This message from Walter Simberski on our comments to the Grunde Lovoll video casting clip :

Hi Gordy and Aitor -

Sorry, but when I look at the video here is what I see:

The rod is straight at the beginning of each stroke, monotonically decreases in effective length and then

monotonically increases in effective length until it is straight again. My perception is that during the time when the effective rod

length is decreasing that the rod butt is also being accelerated and during the time when the effective rod length is increasing

the rod butt is decelerating.

I don't see any point in the cast where the effective rod length appears to increase in length as the rod butt is accelerating.

Walter

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Walter....

I went back and studied this again. I think you are correct. Seeing those lines without graphic superimposition for me is sometimes not easy. The only way I can judge acceleration of the rod butt is by the apparent angular change at the handle and rod bend. Not sure how accurate that really is.

Gordy

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