Fly rod line rating, power, and action - an explanation.

[chuck s]

Interesting but all this defining and explaining leaves my head swimming so how would you explain this then:

First some credentials: Macauley
Then an article by the writer: Fly Casting Tips | MidCurrent and lastly note his assessment of overlining about half way down page one.

"Over-Lining a Rod You can make a rod’s action “slower” by overlining the rod with a fly line rated one size higher. "

Also isn't power often used to describe the casting quality of a fly rod and for that matter the fighting power of a particular rod and in both of those cases it isn't just about the lifting power of the rod is it? The general definition that most rod makers use for power is - the force needed to flex the rod or the rod's resistance to flex. Some rod makers go on to define lifting power, casting power and fighting power.

About the simplest explanation that I've seen that seemingly incorporates all of the above is the Common Cents System and they use another power term, intrinsic power!

The Common Cents System

[overmywaders]

I see no mention here of anything but a progressive taper. Before the advent of fiber reinforced plastic (FRP) rods - glass, graphite, and boron - the split cane rods were created with many different casting tapers.

One of the favorite tapers among cane rodmakers today is what is known as a "parabolic taper" or "semi-parabolic taper". Many rodmakers of "the Golden Age" designed with a gentle version of the parabolic taper. The original parabolic was probably the Castleconnell Kick rod; which acted as described - the butt would start the cast, a more limber mid-section would cause delay, and then throw the relatively stiff tip section over quickly. Inelegant, but very good for heaving out lots of line for salmon.

With a cane rod you have a significant amount of mass that is lacking in an FRP rod. This allows for more varied casting strokes. For example, with a 10' "wet fly action" (straight taper) the tip has appreciable mass. [ many wet fly rods were lighter on the scales than a dry fly rod of the same length, but they felt tip-heavy.] So, it is possible to simply bend the wrist - no arm movement required - and watch the tip load to the mid. On the forward cast the tip will - depending on the rod - actually stay in line with the line as it shoots, before straightening. This allowed for fewer false casts (false casts dried the fly you wanted to sink). To perform an upstream mend when the line was already on the water, you could just roll your hand and the mass of the tip would flip the line over.

Just some thoughts. YMMV

[silver creek]

Fly Fisherman magazine has recently published a portion of Simon Gawesworth's book Single-Handed Spey Casting.

The Fly Cast - Fly Fisherman

I wanted to add a quote from his book because it illustrates another important difference between rod actions for identical line weight fly rods.

Before I can explain the difference, I need to explain that when a fly rod bends, the "effective rod length" or what Simon would call the "lever length" of the rod shortens. In the illustration #5 And #6 below, it is the dotted line. In geometry this line is called the chord. A chord is the line that joins any two points on circle or an arc. Since the rod bends in an arc as we cast, we can define the effective rod length as the length of the chord from the rod tip to our casting hand.

It is obvious that if we are to cast so that the rod tip moves in a straight line for a tight loop, we must compensate with our casting stroke for the rod shortening.

Given the facts above, we can see that substituting a heavier fly line to slow the timing of the cast, does not make a fast rod into a slow rod. The timing might slow but the degree of rod shortening of the fast rod over time (graphed during the rod stroke) will not duplicate the shortening of the slow rod over time. So the caster still must modify his casting stroke if there is to be tight loop formation. Going up in line weight does not make a fast action rod into a slow action rod.

For rods of identical length and identical line rating but different rod actions, the faster action rod shortens less for a given casting stroke. Because it shortens less, the faster action rod is a longer lever and can accelerate the line faster for a given rod stroke.

Simon writes:

"An aside note is that two rods of the same length don’t necessarily have the same leverage. If you took a nine-foot rod that was very fast and a nine-foot rod that was very soft and slow and you loaded them up with identical line weight and length, the fast rod would actually be a longer lever. My dad, who was a teacher of math and physics before he became a fly-fishing instructor, showed me this one day while trying to give me an understanding of fly casting. The easiest way to see this is through illustrations #5 and #6."

[jaybo41]

Another good addition to an outstanding topic Silver. Thanks for the update. BTW, that's a very good book that you referenced.