From pg. 2 of this thread

"The first law of thermodynamics is clear on this point. When that rod tip flexes, it's absorbing and destroying the energy it was given by the line (unless that rod has a battery). The more it flexes, the more energy is destroyed and the less left over for your hand to feel. Conversely, the stiffer the rod, the more energy is passed down the blank (mass being equal, of course)."

C. Royce- that is the argument I made (above). I just described it in terms of general thermodynamics instead of as individual molecular interactions.

In an effort to prevent falling asleep while reading all the scientific dissertations, I figured I’d go out in the back yard and do some testing. Obviously the “test” that I performed was not in a lab environment nor was there any sophisticated equipment used. The results of my “tests”, which I’ll explain in greater detail in another post, have not proven any of you wrong, but they seem to indicate that Emory is more right than the rest of you.
Basically, my test consisted of anchoring the end of 60 feet of 20# Sufix braid with the subject rod and reel at the opposite end. Two jury rigged thumping devices was used to tap the line close to the anchor point. One of these provided a much lighter “tap” then the other.
Two of the six rods I tested were identical (Rainshadow RX8+C742) except that I removed 1 ¾” from the tip one of them. Each has an overall length of 5’8 ½”. The one with the “fast tip removed has a CCS rating (actual cents) of 235 with A/A of 65 degrees. The other has CCS of 200 with an A/A of 70 degrees.
The results are:
The “stiffer” tipped rod (CCS 235 A/A 65 degree) measured a 5 (out of 10) “feel” with the “heavy” tapping device”. It measured a 1 with the “light” device.
The “softer” rod (CCS 200 A/A 70 degree) measured a 7 with the heavy tapper and a 5 with the light tapper.
Interestingly, the "transverse" was more accentuated than the "longitudinal". The rod actually seemed to magnify the "signal".
I don’t consider this “test” all inclusive, but until more sophisticated testing can be done, it does seem to indicate that “stiffer” is less sensitive.

Looks like this thread may approach a record! Congrats E for the stimulation!

I am beginning to have some understanding of the physical sciences involved in this topic. I understand somewhat the physical things involved such as resonate frequency, amplitude, integrals and derivatives, etc.. Each of these factors involve finite units of measurement. You can quantatively determine, measure and record the input, loss and output of each of these variables.

The issue is complicated by the use of the word "sensitivity". I see no way to transfer/compare the physical units of measure to the hand of a human holding a rod. In the art world a statement is made that "beauty is in the eye of the beholder. If you record finite physical numbers then the issue becomes - does the rod display the same degree of sensitivity to in the hands of a wood chopper and a blind person person trained in feel and Braille. What kind of value would you assign to sensitivity?

Things happen to a rod - some are lost - some get through

You can measure and record all input and output -

There is no control unit of measure that can be applied or accepted to quantify sensitivity.

I think the variable in "sensitivity" is within the hand of the fisherman and not so much the blank or rod.

It may be prove to be interesting to find a way to link the physical sciences with the "feel" terminology.

Jim, a few weeks ago I also did some NOT SO SCIENTIFIC testing on a couple of blanks, These were not new blanks. They were both Diawa 7 foot spinning rods that I had stripped. One was a fast and one was a medium. What I was attempting to do was try to see the results using some different grip ideas that I have been playing with.

I clamped the butt of the blank in a vise (with padded jaws) and used a vibrating reed tachometer to do my tests. This is an instrument for testing RPM and VPM. What I was more intersted in was the magnitude and that can be seen by the distance of the arc that the main reed is traveling, but with no numerical value.

One of my methods was to have my son deflect the tip 12 inches and release it. A second method was to have him hold a piece of line, that was attached to the tip with a 3/4 oz egg sinker inline with the rod and drop it. I tested at the foregrip and the reel seat. All these were attached in a tempory fashion but really snug.

Each time the magnitude of the vibrations was greater with the fast action. It was also greater on the foregrip than the reel seat. Of the different grips, the greatest magnitude was with cork.

Did this prove anything? I don't know. Did it disprove anything? I don't know that either. I feel that it may have given me some ideas, but that could very well be wrong. I'll probably just go along with them until and if I find them to be incorrect.

Jim- such tests mean nothing without blank weights. Since softer blanks tend to be lighter than stiffer blanks, on average a softer rod will be more sensitive just because of this. The question is- for two rods *of equal weight*, will the softer or stiffer of the two transmit more motion.

It's not an abstract question. Consider two 9', 5 wt, 1.9 oz St. Croix fly rod blanks. The medium action $42 SCII (2F9052 sold as an Avid) and the very fast $163 SCV (5F9055 sold as Legend Elite). Emory would tell you the Avid is the more sensitive, I believe the stiffer Legend Elite better at transmitting vibration.

When Emory started on this article, I argued with him over the same points that Mike is now making. If you go back and read over past posts on this subject here you'll see that I nearly always mentioned that of any two rods, the rod with the higher stiffness to weight ratio is generally going to be more sensitive. So for the same weight, the rod with the greater stiffness would be the more sensitive of the two. At least within the confines of line movement being what we call "sensitivity."

Emory came back at me with an analogy that I hadn't thought of before and which also made sense. I relented a bit after that and hopefully he'll bring it back up here so the rest of you can chew on it as well and see what you think.

In the long run, these discussions are interesting, but until the testing apparatus is set up and actual tests done, it's going to be hard to make anyone in one camp move to the other. Data won't lie and that's what's needed now.


...................

My “test” was conducted by anchoring the end of 60 feet of Sufix braided line and having the subject rod/reel at the opposite end. Two “tapping devices” were used, located close to the anchor point. One of the devices was a plastic tie strip stapled to a board. It was located so as to tap the line when released from a vertical position. The second much lighter “tapper” was a red plastic tube taken from a can of WD40 and “hinged” with duct tape so that it also could be dropped on the line from a vertical position. Consistency was obviously my goal.
Each rod/reel was tested by holding the rod approximately 90 degrees from the line with my hand on the grip and thumb on the reel’s spool. My assistant (my tolerant wife) then proceeded with a series of “taps” which I then evaluated by “feel” on a scale of 1 to 10 (10 being the best). The rod was then held roughly parallel to the line for further evaluation. The first round of tests was done with the “heavier tapping device”. We then repeated the tests with the lighter “device”.
The six rods that were tested, in the order of highest sensitivity:
Hvy tap / light tap
7 5 Rainshadow RX8+C742 5’ 8” OAL CCS 200 A/A 70 deg. 3.3 oz tot wt.
5 1 Rainshadow RX8+C742 5’ 8” OAL CCS 235 A/A 65 deg 3.01 oz wt.
(1 ½” of “fast tip” removed)
5 3 Fenwick Boron 5’ 8” OAL CCS 170 A/A 65 deg 3.8 oz tot wt.
7 1 Fenwick Boron 5’ 7 ½ OAL CCS 150 A/A 67 deg 3.26 tot wt.
7 1 Loomis IMXC722 5’ 8 ½ “ OAL CCS 240 A/A 70 deg 3.23 tot wt.
6 1 Loomis IMXC722 5’ 8 ½” OAL CCS 276 A/A 68 deg 3.3 oz tot wt.
(2” of “fast tip” removed)
It was noted during “testing” that there wasn’t a great deal of discernable difference with the heavy tapping device. Also, even with slack (no load) in the line, the tap could be felt. I did make one test using monofilament and it required a load in order to be felt at all.
The “lighter tapping device” seemed to make a more discernable difference in each rod.
The first two rods (Rainshadows) seem to be the most indicative of the trend since they are the same blank/handle construction.
I certainly wouldn’t say this “test” was all inclusive, but hopefully some of you lab rats will do some comprehensive tests and share the results with us. I think there is a lot of interest that would warrant such tests.
I’ll conclude by saying that I’ll still continue to build “technique specific” rods by modifying the blanks characteristics, but it’s good to know where I might be gaining or losing sensitivity (however slight), which I recognize might have to be part of the trade off.

Sorry about the clarity of the "scores". The actual post doesn't translate exactly as typed. I added a slash between the "hvy" and "light" which might help.

7 /5 Rainshadow RX8+C742 5’ 8” OAL CCS 200 A/A 70 deg. 3.3 oz tot wt.
5 /1 Rainshadow RX8+C742 5’ 8” OAL CCS 235 A/A 65 deg 3.01 oz wt.
(1 ½” of “fast tip” removed)
5 /3 Fenwick Boron 5’ 8” OAL CCS 170 A/A 65 deg 3.8 oz tot wt.
7 /1 Fenwick Boron 5’ 7 ½ OAL CCS 150 A/A 67 deg 3.26 tot wt.
7 /1 Loomis IMXC722 5’ 8 ½ “ OAL CCS 240 A/A 70 deg 3.23 tot wt.
6 /1 Loomis IMXC722 5’ 8 ½” OAL CCS 276 A/A 68 deg 3.3 oz tot wt.
(2” of “fast tip” removed)

Mike,
While I tend to agree with your logic, my test seems to validate Emory’s argument. The two Rainshadow blanks are almost identical. The same blank, except one has the “fast tip” removed. The slight weight differential is probably the extra 1 ½” of butt length to compensate for the tip length that was cut off.
This has been a revelation for me because I’ve also believed that the “stiffer” of two rods of equal weight would be the more sensitive.
Probably because I was biased toward your argument, I retested the two Rainshadows to see if I’d get repeat “readings”, and I did.

Mike and others,
You have had me thinking about this all day long and I think that I have it sorted out and I think that it turns out that we are both partly right and both partly wrong. See what you think of the following.
Normally mass will increase as stiffness increases with any practical rod but at one point we were only talking about stiffness. And I now think that at a very low frequency or rate of change, if the fish's bit is a slow tug or a pull, you are right with your argument about the thermodynamic losses when the rod deflects. In other words the sensitivity will indeed increase, at a very low frequency or low rate, as stiffness increases or the higher the stiffness the higher the sensitivity if we ignore mass. On this point you are correct and I was wrong and I apologize for being so hard headed.
But the mechanical impedance, which is a function of both the mass and the stiffness, increases as we increase the input frequency or rate of change. It increases because the inertia that is the result of the mass increases as we try to accelerate the mass. The faster we attempt to make the mass move the higher the inertia and the higher the mechanical impedance. And as the mechanical impedance increases the sensitivity drops.
As the speed of the fish's bite increases, the bite is a fast yank or a pulsation or a slow pull but a rapid release, and attempts to make the rod move more rapidly the mechanical impedance will increase and the rods sensitivity drops but the mechanical impedance drops dramatically as the input frequency or rate approaches the rods resonant frequency. At the rods resonant frequency the mechanical impedance is very low and therefore the sensitivity high.
In other words as we increase the input frequency or rate the mass takes over from the stiffness as the dominant variable. And as the tip of the rod attempts to oscillate the lower the stiffness the better because the rods stiffness will resist any motion at the tip of the rod and the stiffer the rod is the more force it will take to move the rod a given distance.
What this all suggests is that at a very low frequency or rate the stiffness of the rod will be dominant in determining sensitivity and the stiffer the rod ,assuming the mass does not increase with the stiffness, the higher the sensitivity. But as the input frequency or rate increases the mass takes over and is the dominant variable in determining sensitivity and now the lower the stiffness the higher the sensitivity.
Did I explain that well and does it make sense?

If we now look at the formula for resonant frequency it is a function of not only the mass but also the distribution of the mass and the length and this gets even more interesting but I will save that for now.

jim spooner Wrote:
-------------------------------------------------------

>
> 7 /5 Rainshadow RX8+C742 5’ 8” OAL CCS 200 A/A 70 deg. 3.3 oz tot wt.
> 5 /1 Rainshadow RX8+C742 5’ 8” OAL CCS 235 A/A 65 deg 3.01 oz wt.
> (1 ½” of “fast tip” removed)
>

Cutting 1.5" off the rod tip dropped the weight by nearly 10%? That does not seem possible.

You are on the right track here, but I can tell you with great confidence that unless you did not know which rod you held each time, you could not be as objective as you think. It is human nature, which is why science does experimental work "blind." And even then, it will be fairly subjective. It really needs to be done using some device that physically measures movement.

Mike,
I apologize for the discrepancy, but the weight of the rod with the “fast tip” is 3.03, not 3.3. The other being 3.01 ounce makes it less than .007% difference. (.02 ounce) Also, the one that I cut off the tip was 1 ¾ ,not 1 ½, for what its worth.
Another error I’ve found when I checked my spec sheet is that one of the Loomis rods (Ref CCS 276) is a #C723 Med Hvy, but both the Loomis’s got close to the same readings, so I guess its moot.
As to my objectivity…I think I’ve already mentioned that I was biased toward your argument. My test results surprised me.
Although I’m glad to share the results with all you folks, my intent was to satisfy myself.
Even if my “tests” were flawed because my sense of “feel” was not, by any means, accurate, I think I was still able to get what I thought was “relative” values. There’s no doubt that a strain gage or accelerometer, magnetometer,etc, would be able to get more accurate readings. I would hope that they would be attached/mounted in such a way as to replicate the way we would actually “feel” what was happening at the end of a line, not necessarily the end of the rod.
Even though I would concede to a sizeable percentage of inaccuracy, worst case would be that my test was inconclusive. I would definitely stop short of saying that my findings were the opposite of what I got.
If nothing else, I must say that the “tapping devices” that I came up with, really did simulate the feel of a fish picking up a bait. Kind of a cheap thrill! Maybe I could market a kit for those who have an “off” season (snicker).
We all need to “get a life”!

Mike,
You said “You are on the right track here, but I can tell you with great confidence that unless you did not know which rod you held each time, you could not be as objective as you think.”

Actually, to some extent, I did NOT know which rods I tested each time because most of my rods look very similar. (The two Rainshadows look identical). Until I later (after testing) checked the rod numbers that I’ve etched on each reel seat to my spec sheets, I had little recollection how each rod was rated (CCS & A/A).
I understand your skeptism, but until more legitimate testing is done with better equipment, correctly set up to replicate "actual conditions", all we can do is hypothisize one another to death.

Agreed. I did not mean to be overly critical. I apologize.

Mike,
You have not commented on my last post suggesting that whether a stiffer rod or less stiff rod is more sensitive is somewhat a function of the input frequency or dv/dt. I would like to hear what you think or are you still thinking?

Emory,
What you said…. “whether a stiffer rod or less stiff rod is more sensitive is somewhat a function of the input frequency or dv/dt”…, makes sense to me. I think the higher frequencies such as a “strike” or a “pickup” would be slightly better transmitted through the lighter rod with less mechanical impedance. It would also hold true with “vibrating” type baits as well, although I suppose it would depend on how high or low the frequency range would be. I mention baits (lures) as they relate to sensitivity because there are many instances where an indication of a “strike” is when we “feel” the lure’s action change or stop.
I can see where the slower tugging or pulling on the line, being at a lower frequency, would translate slightly better with the “stiffer” rod as it would be less apt to be diminished by the “fast” (soft) tip of the rod.
I don’t think there is a very definitive point where the two situations occur. I suppose it could be said that if you were fishing with a “stiff” rod and you missed the initial strike because the rod was slightly less sensitive, than you’d have a slightly better chance of feeling the fish swimming off with your bait. I’m exaggerating of course…ha!
I think the “bottom line” of all this is that if we build a rod for the type of fishing we’re doing (first priority), by using a relatively high modulus blank and keeping the weight of all the components to a minimum, we’ll end up with a “sensitive rod”. And, I don’t think there would be a lot of discernable difference in sensitivity unless two different rods were drastically different in stiffness, which isn’t likely for a given type of fishing.
I think you’ve given us all a lot to think about on this sensitivity issue and we’ll be looking forward to seeing your test results. Just remember there is an old saying that “you can tell who the “pioneers” are because they’re the ones with the arrows sticking out of their backs”. (snicker)

Jim,
I am not sure where the crossover point is either between the stiffer and less stiff rod. I am going to have to try to work this out. My intuitive feeling is that it is at the resonant frequency of the rod, below the resonance the stiffness with dominate and above the resonance the mass will dominate but this is little more than a gut feeling at this point and I could be full of prunes.

At our age, prunes is a good thing.

Emory,
I’ve been doing some more thinking about the low/high frequency thing and it seems to me that in a “low” frequency situation, a “shorter” rod would have slight “sensitivity” advantages over a longer one. I.E. a 5’ 6” vs. a 7’ 6”. Of course rod length is dictated by the type of fishing it was built for, but the adherent sensitivity could be an advantageous by-product in a shorter rod.

Emory Harry Wrote:
-------------------------------------------------------
And I now think
> that at a very low frequency or rate of change, if
> the fish's bit is a slow tug or a pull, you are
> right with your argument about the thermodynamic
> losses when the rod deflects. In other words the
> sensitivity will indeed increase, at a very low
> frequency or low rate, as stiffness increases or
> the higher the stiffness the higher the
> sensitivity if we ignore mass. On this point you
> are correct and I was wrong and I apologize for
> being so hard headed.
Apologize? Hogwash. You need not apologize to anyone. We are all in your debt for getting this topic started. It takes a real man to admit to being wrong, my hat is off to you.


> What this all suggests is that at a very low
> frequency or rate the stiffness of the rod will be
> dominant in determining sensitivity and the
> stiffer the rod ,assuming the mass does not
> increase with the stiffness, the higher the
> sensitivity. But as the input frequency or rate
> increases the mass takes over and is the dominant
> variable in determining sensitivity and now the
> lower the stiffness the higher the sensitivity.
> Did I explain that well and does it make sense?
>
I understand what you are saying, but I don't believe that at equivalent mass softer rods are more sensitive at either high or low input frequency. I think a stiffer rod would transmit more energy in either case.