What is ultimate fly line weight for your fly rod? Or what is the ultimate fly rod for your line? The goal is distance.

[RSalar]

Yup, and if you don't already understand the standard as a rod maker, I can't help you

Cheers
Lasse

Damn -- I thought I was about to be educated.

Cheers

Ron

[Lasse Karlsson]

We tried on page one

@edit Torsten: Lasse, see my pm.

Cheers
Lasse

[Merlin]

Gordy

Ok, I restart from the beginning. How can I compare a 7 foot #4 rod with a 9 foot #9 rod? What can I say of their respective “action”? The only way I found is to calculate equivalent rods characteristics as if those rods were both tuned at 8 feet for #5 line. This is possible using structural relationships which apply to blanks. A small shortcut is to assume that the influence of hardware is globally relatively the same and I can thus apply those relationships to finished rods.

The plot you see in post 145 is the representation of rods having the same stiffness and length. This curve is thus representing various rods of 8 feet designed for #5 line. In fact it is a representation of mo = function of fundamental frequency and rod stiffness:
mo =k/4/pi squared/Fo squared

The various dots indicate rods having various equivalent masses and the corresponding fundamental frequency in the chosen conditions. Now I can compare various rods in terms of equivalent mass. There is some uncertainty attached to dots location because the dynamic stiffness is not exactly the static one and because of the precision of the measurement methodology.

There is a link with their deflection shape, that’s why I derived “classes” named butt action, butt mid action, tip mid action and tip action, just to match the current habit to design 4 piece rods. One can imagine another kind of split using ranges of equivalent mass for example. Instead of a curve I could change frequencies for the reciprocal of their squared value and get a straight line as well. If I change my reference rod, the location of the curve changes by shifting up or down or left or right, but the position of the various dots relative to each other does not change.

By the way your KK rod is now a #10 because its tip was shortened. I know it is no more an 9 foot rod and to make calculations I need its actual length, but let’s imagine I want to take it as a new reference, then I will correct measured values for various rods (mo, Fo) of the dataset I have, to make them similar in length and stiffness as the KK one. The curve will contain the 2.72 Hz / 6.57 grams point in the new graphic. All dots representing various rods in my dataset would move upwards in that case.

Merlin

[gordonjudd]

By the way your KK rod is now a #10 because its tip was shortened. I know it is no more an 9 foot rod and to make calculations I need its actual length

Merlin,
The data in that plot was taken before the tip broke so that data was for a 9 foot rod. Here is the frequency vs tip mass curve after it broke. I lost the top 9 inches in the break so it is now 2.515 m [8' 3"] long.

kk_8wt_broken_k_mo.jpg (32.5 KiB) Viewed 919 times

The change in k and f0 are close to rule of thumb values for a uniform cantilever where the spring constant varies as the cube of the length ( gives k_expected=2.42 n/m) and the frequency varies as the square of the length (gives fo_expected=3.22 Hz). Closer than I would have thought because of the taper in the rod.

If a k of 1.87 n/m would classify the original rod in the 10wt category does its present value of 2.57 n/m but in the range of an 11-12 weight?

Gordy

[Mangrove Cuckoo]

I have a question...

If a fundamental frequency is determined by the mass of the weight hanging from the tip, can that be used to characterize a specific rod and line combination?

Let's say that I have found a particular rod and line combination that I *really* like. I then weigh the head of the line and determine the frequency by hanging an equivalent weight from the tip.

Could I then take a different (though generally similar) rod and test it with different weights to find which weight gives a similar frequency?

And then, would a line with that head weight "feel" somewhat like the rod /line combo that I really like?

I guess I'm also asking if I, the caster, have a complimentary frequency preference?

[Torsten]

@Ron

Here are some resources for you to read:

The Rod & The Cast
by Grunde Løvoll and Jason Borger
https://www.sexyloops.com/articles/rodcast.shtml

8 rods - 8 casters: Test of 5 line rods.
Measurements of casting distance and action - what's best?
https://www.sexyloops.com/articles/8rod.shtml

Experimental investigations on the fly rod deflection
http://www.passion-fliegenfischen.de/wp ... -128cp.pdf

An Initial Study on the Coordination of Rod and Line Hauling Movements in Distance Fly Casting
Ulrik Röijezon et. al.
https://www.researchgate.net/publicatio ... ly_Casting

A Comparison of Distance Fly Casting Performance Between Three 5- Weight Long-belly Floating Lines
Ulrik Röijezon
https://www.researchgate.net/publicatio ... ting_Lines

All documents for the common cents system:
https://www.common-cents.info/
* Frequency is covered in Part 5

Measuring Fly Rod "Swingweight"
by Grunde Løvoll and Magnus Angus, March 2008
https://www.sexyloops.com/articles/swingweight.shtml
(nice addition to the CCS system)
@Paul the calculator is down (!)

Rutenbau - Die 15Grad Power Messung

http://www.solitip.com/15grad-power-vermessung.html
* this measurement method is popular in the German speaking countries

I'll comment later, but I think you have with the above links enough to read.

Greetings,
Torsten

[RSalar]

@ Torsten

Thank you,

Ron

[Merlin]

Gordy

I would say the shortened KK can take a #12 line.

Merlin

[Merlin]

Gary

The principle is correct but reality might differ because there is MOI to consider.

That depends on the angler's taste as well. A friend of mine always fishes with the same rod and line bacause he thinks that a change would need practice to get the best of the new outfit and that he will loose some line control.

In my case I can fish with different type of rods depending on the river. If it is large I shall take a fast rod, if it is not I can take a medium fast rod. For small streams I use either a fast graphite rod if the river flows among trees and branches, or a soft glass rod if the river is free from trees. Just a question of line control.

Merlin

[gordonjudd]

* this measurement method is popular in the German speaking countries

Ron,
There is a thread on the details of the 15 degree system and how it compares to the CCS and Hoffman/Kyte line-rod matching systems that you might be interested in at http://sexyloops.co.uk/archivedboard/vi ... 86#p212479.

A related thread to this one is at http://sexyloops.co.uk/archivedboard/vi ... an#p247806

Gordy