Since hunting is over, it's too cold to work outside, and golf is a long ways off, I find myself pouring over back issues of RodMaker magazines gleening information. I just read the "Blank Properties and Terms" article by Emory Harry and Jack Hurt, although technical, it becomes understandable after rereading it over and over what doesn't sink in the first time around. Since it's difficult to know a blank's particular modulas of elasticity, and effects of resin, scrim, and finish, actual blank taper, etc., and sifting through marketing buzz words, are there other suttle ways to indicated what a blank's action taper and sensitivety are?

If two different blanks have the same length and line rating, but one takes a size 4 tip top and the other takes a size 5, would the size 4 tipped blank indicate a faster action taper and more sensitivity than the size 5 blank?

And what are the different characterics of a blanks with larger diameter thin walls versus smaller diameter thick walls?

Since butt diameter, tip top size, and blank weight are usually listed by blank manufactures (although these can vary from blank to blank), can they be used as a tool in any way to help understand a blank's performance without having it in your hand? Thanks.

"If two different blanks have the same length and line rating, but one takes a size 4 tip top and the other takes a size 5, would the size 4 tipped blank indicate a faster action taper and more sensitivity than the size 5 blank? "

Maybe, maybe not. You also have wall thickness to consider, although diameter plays the greater role in adding stiffness. Small diameter, thick walled blanks are usually tougher and heavier than a rod with a larger diameter and thinner walls. The latter will be a little more "crisp" and for the same stiffness can be lighter. It also will be more prone to breakage from impacts and such. Most manufacturers try to arrive at a decent compromise between the two. There are so many different materials and designs out there that simply going by butt and tip diameters isn't really going to guarantee you of anything, although it's a starting point. This is another reason why the AA of the Common Cents System is so useful (if the manufacturers would use it). Because it has such great resolution, it's a lot easier to see which of two "fast action" blanks is actually faster than the other.

Sensitivity is a little harder to pin down. A faster action rod is not necessarily more sensitive than a medium or slow action rod. For the same stiffness, the lighter rod should be more sensitive, although that might be considered an over-simplification by some.


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Tim,
In response to your first question, the best way to measure a blanks action and power is probably to use the Common Sense System. Sensitivity is probably best measured by measuring the resonant frequency of the blank. If you want to know more about this send me an e-mail and I will try to tell you exactly how to measure it.

As far as the trade off between a blanks diameter and wall thickness is concerned, the power of a blank will go up at the 4th power of the diameter so a very small increase in diameter will result in a large increase in power. (doubling the diameter will increase the power by 16) Also because the same 4th power is at work most of the load on a blank is carried by the outer layers of material so decreasing the diameter quickly reaches the point where no more power is being added just weight is being added. In fact solid blanks make no sense, in my judgement, because at the center of the blank is what is called the neutral axis and there is no load on the neutral axis, in other words the material at the center is doing nothing except adding weight. Maybe a more direct answer is, thinner walled, larger diameter blanks will weight less than an equivalent blank with the same power with a smaller diameter but the thinner walled blank will be more fragile. Typically they will also have more pronounced spines. I hope that this answers the questions that you had.

Tom, you and I must have been typing at the same time.

I do not want to be argue about words. I know that we often use power and stiffness interchanably but they really are two different things. When we measure the power of a blank we are measuring what a mechanical engineer would call the spring constant. Spring constant is a ratio , so many inches of deflection for so many pounds of weight. When we measure the power using the Common Sense System the amount of deflection is chosen, 1/3 of the blanks length, so it can be a single number, so many pennies. On the other hand stiffness is not a number or a ratio it is a curve. When we deflect a rod it will get stiffer and stiffer as we deflect it more and more. If we plot it X,Y, with the amount of deflection being X and with the applied force being Y, as we apply more and more force the deflection will be more and more, but not linearly. The curve will curve upward and to the right. The scale and shape of the stiffness curve will depend upon both the power and the action of the blank.

Not being an enginner ,will a " fast rod" in the hands of the same caster feel that it is more tip oriented than a rod described as a medium fast rod or is this just marketing. I guess what I am saying is a rod of same length ,tip and butt diam. and described as both being fast going to feel the same to the same person or is this technical only.
I built 3 rods and own @ 8 and the rplx feels more tip or stiffer than a h& h im6. If one wants a rod of similar "feel"in rod of similar length but different weights can one rely on hype or should one get the techs onthe rod from one of you engineers

Not being an enginner ,will a " fast rod" in the hands of the same caster feel that it is more tip oriented than a rod described as a medium fast rod or is this just marketing. I guess what I am saying is a rod of same length ,tip and butt diam. and described as both being fast going to feel the same to the same person or is this technical only.
I built 3 rods and own @ 8 and the rplx feels more tip or stiffer than a h& h im6. If one wants a rod of similar "feel"in rod of similar length but different weights can one rely on hype or should one get the techs onthe rod from one of you engineers

Two identical rods will have the same "feel," but depending on the person and how they describe things, they may use different terms to describe that feel.

All fast action rods are tip oriented. That is to say, the tip is quick and most of the rod's initial flex will occur there. But the resolution of the standard "fast, medium and slow" is so poor, that to say "fast action" isn't really saying much more than that all rods with such an action will flex initially in the upper 1/3rd. That's a pretty broad range. This is where the Common Cents System can greatly aid you. Because of it's much greater resolution, you can easily tell which of two "fast action" rods is actually faster than the other.

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Bill,
I agree completely with Tom's point about the Common Sense System. But I would add that because a faster action, higher action angle, rod will have a higher resonant frequency than a rod of equal power that has a lower action angle, the faster action rod will feel more crisp. I think that this is part of the reason that many people prefer very fast action blanks like Hot Shot blanks for many applications.