Steve,
The low damping factor of cork is not mainly the result of what happens at a celular level but is primarily a function of what happens at a molecular level in the cork.

Emory,
I'm not questioning what you say on a scientific or theoretical, but on a practical level, any benefit of cork as far as sensitivity is concerned is totally lost on me. I just can't tell the difference, especially since I almost always have a finger on the blank or line.

Mike (Southgate, MI)
If I don't want to, I don't have to and nobody can make me (except my wife) cuz I'm RETIRED!!

Mike,
I understand your point that if you are not touching the cork when fishing then it is not really increasing your sensitivity. I would argue that you do not have to be touching the cork to realize part of the advantage of cork. You may not realize any of the advantage of cork having relatively high elasticity but you will realize increased sensitivity due to the low mass of cork over more dense materials. Here is a thought experiment for you to make my point. You have two identical rods. One has a handle made of cork and the other has the same size handle but made of lead. Which will have the better sensitivity?

Emory;
Lead is another dead material used to stop vibration so you are most likely correct in this incidence.
But if you used graphite as the other material you would have different results

On a practical level, it would be interesting to ask say the top 10 all-time money winners on the PWT circuit what they're thoughts are on various handle materials and sensitivity. That would be an interesting article...

I think that the walleye fishermen's rods push the envelope in this area pretty hard.

Putter
Williston, ND

Oh Boy!!!! If I were in trouble I sure wouldn't mind having one of you guy's as a lawyer. You all make good and valid points. IMO

Bill in WV

Steve,
Yes, lead has a low damping factor especially as compared to other metals but my point was the difference in the mass of lead and cork and the affect that this difference in mass would have on sensitivity.
Graphite is a better handle material than many others but it has much higher density than cork. Plus with the tubular graphite handles the material that is used as a shim between the rod blank and the tubular graphite is a problem.
Each material that vibrations travel through has a mechanical impedance determined by the mass density and the elasticity. (the mechanical impedance is the square root of the mass density times the elasticity) As the vibrations go from one material to another material with a different mechanical impedance several things happen. First there is what is called a discontinuity at the junction of the two materials and at that junction part of the energy in the vibration is reflected back, essentially lost. The bigger the difference in the mechanical impedance of the two materials the more of the energy that will reflected. Second the amplitude and the velocity of the vibrations increase or decrease depending upon whether there is an increase or decrease in the mechanical impedance.
The shim whether foam or masking tape or whatever will usually have a much different mechanical impedance than the tubular graphite so much of the energy in the vibration is lost at that point.

Randy,
That would be very interesting. But I suspect that most of them are just outstanding fishermen and it has less to do with the sensitivity of their rods than with their ability. At least the ones that I have watched on television were not using rods that I thought gave them any particular advantage.
Maybe they need to marbleize their rods, and boats and motors. Sorry, I could not resist giving you a hard time.




Edited 1 time(s). Last edit at 07/22/2007 08:44PM by Moderator.

So Emory, if you had a graphite rod and used a graphite handle, these being similar would have about the same “mechanical impedance” and therefore transmit vibration fairly efficiently

And you were able to use a “shim” with very similar “mechanical impedance”

Then that would give you a more sensitive rod then say using cork that has a vastly “different mechanical impedance”

Pretty much that is what I’ve have been saying. That; “There are a lot of materials and concepts out there that you are not aware of. Those do and will add up to rods being more sensitive.

Steve,
No, that is not necessarily true. When a vibration passes from graphite (blank) to cork (handle) there is a discontinuity at the junction of the two materials that results in a significant amount of the energy in the vibration being reflected. But when a vibration passes from a high mechanical impedance (blank) to a lower mechanical impedance (cork) the amplitude increases. It would be about a wash except a graphite handle will have higher mass than cork.
Do you have a copy of RodMaker Volume 10, Issue 1? There is an article in there that I wrote that will explain it. The explanations get a bit long for here. Ignore the part in the article about stiffness and sensitivity. That part has a serious error.
And, I guess I will ask one more time. Will you tell us about all of the materials and concepts that you know about that I am not aware of that will add up to more sensitive rods. I do not know how to say this except very directly, you have made this assertion twice but so far you have not supported it with one bit of evidence. Tell us something about these materials and concepts that we are unfamiliar with. Are you referring to physics and real materials or pipe dreams and magic fufu dust.

"When a vibration passes from graphite (blank) to cork (handle) there is a discontinuity at the junction of the two materials that results in a significant amount of the energy in the vibration being reflected. "


Meaning that the sensitivity is bounced back at the cause?



"But when a vibration passes from a high mechanical impedance (blank) to a lower mechanical impedance (cork) the amplitude increases"


Meaning the sensitivity gets greater when passing from graphite to cork?





Emory, these two sentances say the same thing and contradict each other. I dont "get it".

DR

I live and fish in an area that hosts at least one PWT event, an Flw Tour And an FLW league event, an MWC event (the championship will be held here in 2008) and dozens of "semi-Pro" circuits, every year, the mouth of the Detroit River and the western basin of Lake Erie. Every PWT record from big fish to single day basket to tournament weight was set here. The walleye club that I belong to, provides the support for these events and many of the pro's speak at our meetings and I have had the opportunity to meet and fish with some of them We recently had a previous PWT championship winner give a seminar at a meeting and his biggest piece of advice was don't waste your money on anything over IM7 and get a stiff rod He had his full arsenal of rods with him. Berkley Lightning rods!!! We previously had numerous well known pros and not one EVER mentioned rods, guide, etc other than to recommend length and power. One said it was ridiculus to spend over $100 dollars on a rod. We had one recommend cutting at least 3",s off the tip of every rod!

I agree with Emory, these guys a very sskilled fisherman but in many case their skill and luck compensate for their lack of knowledge of equipment! I haven't met a single one that had any idea what guide rings were made of

Mike (Southgate, MI)
If I don't want to, I don't have to and nobody can make me (except my wife) cuz I'm RETIRED!!



Edited 1 time(s). Last edit at 07/23/2007 12:12AM by Mike Barkley.

Duane,
I agree that it can be confusing because there are several things that are happening at the same time. A vibration introduced by the fish's bite travels down the rod and gets to the cork. At the junction of the blank and the cork the vibration sees a discontinuity because the cork is a lower mechanical impedance that the graphite. Part of the energy in the vibration is reflected back at any discontinuity. There will be a transmitted vibration that will continue into the second material and a reflected vibration that will travel back down the rod in the direction that it came from. How much is transmitted and how much is reflected is a function of the difference in the mechanical impedances of the two materials. The larger the difference in the mechanical impedances of the two materials the bigger the reflected vibration will be. In this case graphite and cork. But there is a second thing that happens. The second thing that happens is, any time a vibration passes from one material to a second material with a different mechanical impedance the velocity that it is traveling and also the amplitude change. If the vibration travels from a high mechanical impedance to a lower mechanical impedance, which is the case with graphite and cork, the velocity of the vibration will decrease but the amplitude of the vibration will increase. If the vibration traveled from a lower mechanical impedance to a higher mechanical impedance the4 affect would be the opposite, the velocity will increase but the amplitude will decrease.
In other words, part of the vibration will be reflected at the junction of the blank and cork which will reduce the amplitude and therefore the sensitivity BUT the vibration will pass from a high mechanical impedance to a low mechanical impedance resulting in the amplitude increasing and therefore the sensitivity increasing. I can send you the math that will let you work out how much the vibration will increase at the discontinuity and how much it will increase as a result of the two differing mechanical impedances but with cork and graphite it is about a wash.
I hope that I said all of that so that it is understandable. I know that it takes a little thought and I am not always the best in the world at explaining things. If it is still not clear come back at me again and I will try again.

Mike,
I sense that you and I are in complete agreement on this. I know a few Bass fishing pros but in this country there are a lot more Salmon and Steelhead guides, too many to suit me, and I know a lot of them. I think that most custom rod builders have forgotten more about what does and does not make a good rod than most pros and guides will ever know. Plus most abuse their equipment and they expect you to give it to them for nothing. In the past I have made rods for a number of them and every time it has turned out to have been a mistake. Now I just tell Bass pros and the Salmon and Steelhead guides, in a nice way, to get their rear ends on down the road.

Emory, you mentioned that the difference in cork and graphite may be a wash. Do you happen to know or have a feel as to how a PVC (3/4") tube mounted with PVC arbors would compare? Butt grip only.

I'm going to take a guess and say that PVC isn't going to make a very good handle or bushing material. I have no numbers in front of me but the higher mass density isn't going to allow it to be as sensitive as cork or graphite tubing.

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

Common PVC doesn't take to UV exposure very well, and it cracks/fractures easily. Take a piece and hit it with a big hammer..... you might want to wear eye protection.
Ever make a potato gun? Lots of folks used common PVC tubing to make them, and some found out the hard way by ABS was recommended. PVC can shatter nicely. People with PVC piping living in cold places often learn that characteristic too.

Besides building Rods I am also a Plumbing Contractor. So I can tell you with the most certainty. That PVC will not make a good product for rod handles or arbores. It will not hold up to the UV rays. Over time it will break down and become brittle.

When used during colder weather it will become brittle also. It won’t mater much if it is used in stationary situation like a rod holder. But during a cast it could and most likely will shatter sending out sharp fragments like a grenade causing bodily harm.
I have seen this several times over the years in plumbing situations.

Royce,
I agree with Tom I do not think that PVC will be a decent handle material. First as Tom points out it has relatively high mass. Second it is a plastic which means almost by definition that it will have poor elasticity. An elastic material will have a linear relationship between stress and strain while a plastic material will have a non-linear relationship. In other words a small increase in applied force will result in a large and non-linear deformation of the material. Almost all plastics are not going to make decent handle material mainly for these two reasons. The best handle materials are going to have low density (light weight) and high elasticity (stiffness).

Royce,
You might have also asked about the foam arbors. I think that they are made of a plastic but in looking at them they are obviously light weight (low mass) and stiff (elastic). I have looked at them closely and thought about it and do not really know what the answer is. The only thing that I can come up with is that while the material may be a plastic the structure itself is such that it is relatively elastic. That is my guess anyway.

Thanks Tom/Emory. That was what I was curious about regarding the transmission of the energy.

Dave, No I have never made a potato launcher. Have to walk too far to gather them back up for cooking. If I had made one, PVC would not have been my choice of material. Since it"s operation is dependant upon a rapid increase in pressure, and as you get up into larger diameters of tubing, the operating pressure and minimum burst pressures diminish rapidly. Yes, I agree that you can shatter it with a hammer, but it's unlikely that if I had PVC handle that I would take a hammer to it, unless it caused me to lose a fish. I'm not too sure that I couldn't shatter a hard wood handle with a hammer. Not as easily, but I think possible.

Steve, I have a rod that I made one as an experiment. It's only a couple of months old and so far no problem. Its a butt grip on a spinning rod, and I grip the reel seat when casting. It's coated with a textured paint. Don't know if that will afford any uv protection or not. I am in Florida, so maybe cold climate won't be an issue. It's an experiment, and I have had experiments fail before so we'll see.