Mike,
You may very well be correct. I have worked through it yet to the point that I have convinced myself so I am not going to try to convince you.
But I am still having a bit of a problem with your thermodynamic argument. If I apply a force to a blank and deflect the blank I have now have potential energy stored up in the blank, when I release the blank it oscillates converting that potential energy to kinetic energy, over time the oscillations drop in amplitude and that kinetic energy is converted to energy in the form of heat. I do not see how this has violated the law of conservation of energy. You will have to explain what I am missing.

Mike,
We might be better off continuing this conversation via e-mails since we cannot do it over a couple of beers. This thread is getting very long and there are probably very few here that are still interested and following this. Plus it may save me some further embarrassment. My e-mail is [[email protected]]

Emory Harry Wrote:
-------------------------------------------------------
> Mike,
> You may very well be correct. I have worked
> through it yet to the point that I have convinced
> myself so I am not going to try to convince you.
> But I am still having a bit of a problem with your
> thermodynamic argument. If I apply a force to a
> blank and deflect the blank I have now have
> potential energy stored up in the blank, when I
> release the blank it oscillates converting that
> potential energy to kinetic energy, over time the
> oscillations drop in amplitude and that kinetic
> energy is converted to energy in the form of heat.
> I do not see how this has violated the law of
> conservation of energy. You will have to explain
> what I am missing.

I think what you are thinking of is "how much energy is getting absorbed by the rod." Your arguments have all been valid as they pertain to energy getting into the rod. BUT, higher energy into the rod is less energy left over for your hand to feel. This is thermodynamics at work. So the real sensitivity question to answer is "how much energy is getting through the rod to your hand," and that is inversely proportional to the energy absorbed by the rod.

I'm happy to e-mail if you would prefer. ChesapeakeCustomRods@ mail2fisherman.com (remove spaces to make that address work)

Yes, when I deflect the rod only part of the energy gets to the handle because part is stored in the rod and the more the rod deflects the more energy that is stored in the rod. That should have been obvious to me but I guess I just had brain block.
However, isn't it then true that how much energy is stored in the rod is a function of not only how much it is deflected but also how stiff the rod is. Careful now I am trying to set a trap for you.

I'm following it and hope you don't make it private.

C. Royce- judging by the number of thread views, you aren't the only one. It's a shame more people haven't joined the discussion.

Emory- Sure, a stiffer rod could be loaded with more energy, but I don't think there is any storage taking place in a fishing rod (except instantaneously). The energy coming to the rod is transferred right away.

There is a good article waiting to be written about this- we should team up Emory.

I think from the number of views on this subject that there is a tremendous amount of interest in how rod characteristics affect “sensitivity”. Although the arguments have been thought provoking and stimulating, they don’t seem to me to be conclusive. I’m hoping that someone will do some comprehensive testing and provide us with quantitive results.
It would be great to have the tests include as many variables as possible. “fast” vs. “slow”; “light” vs. “heavy”; “long” vs. “short”; mono vs. braid, handle materials, different guide types, etc.

Mike,
I think teaming up on an article is a great idea. Tom encouraged me to put together another article that included the results of a bunch of testing. But it appears that a second article on sensitivity before the one with the testing may be in order.

I do not understand what you mean by no storage taking place. If there is no storage taking place except instantaneously how do you explain damping factor. I think that the damping factor is actually a measure of the capacity of the rod to store energy. Once the rod is deflected and released the oscillations continue for a very long time, in fact theoretically forever. Kinetic energy is being converted to heat but over a long period of time. Damping factor is the difference between the initial amplitude and the amplitude after 535 cycles. If the resonant frequency is say 2 cycles per second that says that some of the input energy is still being released after about 4 minutes. In other words it has been stored in the rod for 4 minutes.




Edited 1 time(s). Last edit at 03/05/2007 10:10AM by Emory Harry.

I am following along also and hope it doesn't go private as well. In the end.....the butt end of course.....is going to be how an individual senses or feels in his own hand and that is what you will not be able to quantify. However, data is good and I am looking forward to it all. Unfortunately I had a break in my rod maker mag and also re-loocated. I do not know if I have the magazine with the initial article. Still, very interesting to read this. It may end up as a situation of "Mind over Matter" .....if you don't mind....it doesn't matter. Looking forward to more.

Jim,
I would agree with you that "feel" is subjective and may very well vary from person to person. But the "sensitivity" of a rod or how much of the input at the tip of the rod gets to the fisherman's hand is not subjective. We should be able to quantify it and measure it.

Emory, I don't know if this is really directly related to your statements on damping, but when I was doing my "dark ages" experiments with the vibrating reed meter, after a tip deflection/release, the meter would be registering vibration for long after the initiation. So long, that I never waited for it to stop before removing the meter. All that time, the magnitude was gradually decreasing, but still going on.

C. Royce,
Yes, what you were seeing is the rod damping out or converting the kinetic energy over time to energy in the form of heat. It is partly due to internal friction in the material that the rod is made of. The heat then gets radiated into space. All rods will be what is called "under damped" which simply means that it takes time for them to damp out. If the rod was "over damped" the oscillations would immediately damp out but no rod is going to be over damped. The amplitude of the oscillations in the rod will drop exponentially over time. As I mentioned earlier the damping factor number is the initially amplitude of the oscillations divided by the amplitude of the oscillations after 535 cycles but in theory the oscillations will continue at an ever decreasing amplitude forever. Don't ask me why it is 535 cycles instead of some other number. At one time I knew the source of this number but I have since forgotten.
There is another source of damping other than internal friction and that is air is slightly viscous so the air tends to act to dampen the oscillations over time. I am not sure how much is a function of internal friction and how much is a function of the air. I should look this up
I am not familiar with a vibrating reed meter. Can you describe it? Would it be useful to make the measurements that I have planned? I had planned to use strain gages but they are a pain in the backside because they are very small, difficult to solder leads to and they have to be epoxied to the rod and because they are epoxied to the rod are usually destroyed and cannot be reused for each measurement.



Edited 1 time(s). Last edit at 03/05/2007 12:06PM by Emory Harry.

Emory Harry Wrote:
-------------------------------------------------------
> Mike,
> I think teaming up on an article is a great idea.
> Tom encouraged me to put together another article
> that included the results of a bunch of testing.
> But it appears that a second article on
> sensitivity before the one with the testing may be
> in order.
Taken to e-mail- let's do it.
>
> I do not understand what you mean by no storage
> taking place. If there is no storage taking place
> except instantaneously how do you explain damping
> factor. I think that the damping factor is
> actually a measure of the capacity of the rod to
> store energy. Once the rod is deflected and
> released the oscillations continue for a very long
> time, in fact theoretically forever. Kinetic
> energy is being converted to heat but over a long
> period of time. Damping factor is the difference
> between the initial amplitude and the amplitude
> after 535 cycles. If the resonant frequency is
> say 2 cycles per second that says that some of the
> input energy is still being released after about 4
> minutes. In other words it has been stored in the
> rod for 4 minutes.
>

I should have been more clear when I said energy is stored only instantaneously. One could say that it's the ease of energy storage that makes a soft rod less sensitive. When the energy of the line gets to the tip of a soft rod, it's quickly changed from kinetic energy (of lateral motion) to potential energy (stored in the bent blank). In the stiffer rod, less energy is stored- instead it's transmitted directly to your hand. (note- the ability to quickly store energy is what makes soft rods so great at keeping fish from throwing lures).

When fishing, any oscillation dies extremely rapidly through several pathways including the "give" in your hand and absorption by the line at each guide. When you are fishing, you have fractions of a second to react following a strike. Whatever the rod does in your hand, it must do it fast or it's not going to help.

I should add here that while I've made a lot of lightning fast, uber-sensitive rods, I fish very slow spinning rods myself. My all time favorite spinning rod is a Lami. Perigee. In fly rods, my beloved Orvis F&F 5 wt is so slow I can grab a bite to eat while my backcast straightens out. So don't mistake my positions on this topic as advocacy for fast rods being better fishing tools. I think super-fast rods are good for one thing only- detecting strikes. Other than that they tend to work against you.

Emory, I am doubtful that they are as accurate as what you are after, but in case, the vib. reed tachs are basically a hand held meter that measure amplitude and freguency. It's readout is typically as RPM. They are used extensively in road construction to test vibrating compactors and paving machine vibrating screeds. Here are a couple of web definations and sites with more and better info.

Reed Tachometer - A mechanical device that uses reeds to indicate the frequency and magnitude of the vibration.

[www.britannica.com]

[www.dlwilliamscompany.com]

[www.stichtco.com]

" In other words it has been stored in the rod for 4 minutes. "

Maybe it is because I am an angler who also builds rods and not a rod builder who also fishes, but that last statement certainly made me smile. I don't know about anyone else, but 4 minutes after a strike, I am not still standing there holding onto my rod and worrying about sensitivity. A sec after the strike, the hook is set and 4 minutes later I've already released the fish and made a few more cast looking for the next. By then, a whole lot of other "energy" has already been introduced to the rod.




Edited 1 time(s). Last edit at 03/06/2007 08:10AM by Joe Hepp.

Only needed to be said once.



Edited 1 time(s). Last edit at 03/06/2007 08:08AM by Joe Hepp.

Joe,
I probably did not say that very clearly and I can see why you might chuckle. Yes, in theory the vibrations will last a long time, minutes, but they drop off exponentially which means that very quickly, seconds, they will be so low that they could not be detected by your hand. And this is just the case for the raw rod.
In actual use in a fishing situation Mike is absolutely correct that the amplitude of the initial vibrations will be further reduced very rapidly by the damping effect of the fisherman's hand and by the line.
You can see this effect by just mounting the butt of a rod to a bench or solid surface, deflecting the tip and then releasing it. You will see the oscillations continue for some time. But if you now mount a reel and line on the rod and cast with it while watching the tip movement you will see the tip movement damp out very quickly as Mike suggests.
Mike is also correct about how rapicdly a fisherman will feel any fish bite. Vibrations will travel through graphite at thousands of feet per second. However, how rapidly the amplitude of the vibrations will increase is limited. The mechanical impedance, resistance to movement, increases directly with velocity or how rapidly the rod attempts to move but then drops dramatically at the resonant frequency of the rod. This means that from a practical standpoint most of what the fisherman feels will be at a low frequency or velocity or close to the resonant frequency of the rod.




Edited 1 time(s). Last edit at 03/06/2007 09:56AM by Emory Harry.

I have read the rod maker article along with every word typed in the over 5 pages of this thread and I will continue to read what folks have to say, if for no other reason then I find it to be intellectually stimulating.

But I know without a doubt which rod I will pick up when sensitivity is my #1 concern. For me, that would be the lightest and stiffest rod I can afford which will handle the lures and line needed to get the job done. If the window of opportunity to set the hook is but a fraction of a sec, the various mod to slow action rods will remain strapped to the deck. When I want a rod that will let a fish take a bait without my being immediately aware of the strike (e.g. fast moving crankbait) chances are I'll be picking up the a mod or slow action rod. May or may not agree with all the various formulas that can be found in a physics textbook, but out on the water, it certainly works for me!

Still, I have enjoyed every bit of the discussion and look forward to any future RM articles.

Joe,
I am glad that you found it enjoyable. I did not find it very enjoyable to realize that I had made such a serious error both here and in the article. Your experience led you to the right conclusion about a stiffer rod being more sensitive than a less stiff one while my calculations led me to the opposite and the wrong conclusion. I am very glad that Mike stepped in and was able to finally straighten me out but it is embarrassing.

Emory,
Your revelation speaks volumes for your character!
KUDO’S to you.