I've studied Dr. Hanneman's Common Cents System in detail.I like the systematic approach to define and compare the characteristics of fly rods.
There are still a few "black boxes" in the article. Can anybody help?

1.
Relating Rod Deflection to AFTMA Line weight (common cents system, page 8/9)
Intrinsic Power(IP) = (10)(line weight)+(60)(AFTMA Line No)
Q: What is the rational behind the formula?

2.
Conversion of Cents to Effective Rod Number (ERN) (common cents system page 8, table B)
Q:What is the formula used to create the conversion tables?

3.
Matching Weight of Line (WL) to the Intrinsic Power (IP) of a rod (common cents system the rosetta stone, pages 3 and 5)
Weight of Line (WL) = 3.33(number of cents)-10 (for floating lines)
and
Weight of Line (WL) = 4.44 (number of cents)-10 (sinking lines)
Q: what is the rational behind the two formulas?

Any clue/clarification/further reading suggestions would be highly appreciated.

This was the original article and it contains most of the nuts and bolts, although they're not necessary in order to use the system.

[www.common-cents.info]

Following is a brief Q&A which Dr. Hanneman prepared for the most common questions asked concerning the CCS.

[www.common-cents.info]

Additionally, there have been numerous articles in RodMaker in which Dr. Hanneman has gone into more detail on various aspects of the system.

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Thank you Tom
Yes, www.common-cents.info is actually where I've got the articles from. I downloaded all the pdf's but still couldn't find the answers.
I know that I could just accept the formulas and tables to use the system. But I would prefer to understand what those formulas and tables are based on.
Cheers, Peter

I forwarded your comments to Dr. Hanneman. It's possible he may chime in within a day or so. Check back.

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That's fantastic! Thank you very much Tom.
Peter

Peter,
Answers to your questions:

1. The thought there should be a simple relationship between the weights of fly lines and the strength of fly rods which cast them. Plus, fifty years of practice looking at data and trying to develop some simple relationship between the two factors which would be useful for future predictions.

2. The ERN scale is nonlinear so the conversion was done by hand calculation, point by point.

3. Experience (not mine). The formulas are merely an expression of the slopes of the curves.

After you digest all this, there is more—things like, Delta and PPF—if you can talk Tom into publishing them.

Thank you very much for your comments Dr.Hanneman (and thank you Tom Kirkman for forwarding my questions) - what a great forum!

Although I was hoping to get some easy answers to my questions, I'm quite happy to accept the fact that some aspects of determining the characteristics of fly rods are a matter of extensive experience and observation and therefore the outcome has to be a combination of science and empirical findings. Thank you very much for sharing your insight with us.

I hope to read a lot more about the concept and related themes. As Tom Kirkman wrote in his editor's note: "I highly recommend that all serious rod builders carefully read this article several times."
Thank you again,
Peter (New Zealand)