Hello again :)

I've read very interesting articles by Harry Emory in two of the backissues of The Rodmaker Magazine I ordered, related to blank construction.

The message of those articles is clear: when we seek for the sensitive rod, we should make it as light as possible.

I've heard some opinions, that hook-keeper and foregrip add some weight to the rod while not really being necessary, and "absorb" some of the vibrations that goes through the blank to the reel seat as well. The second is the reason for which some of the top notch japanese "enthusiast" rods are made with no foregrip & hook-keeper.
Some of the clients, though, are really used to the look of the foregrip and use of the hook-keeper, even in light rods.

Now comes the question: how do you think foregrip and hook-keeper really affect rod efficiency? Are we going to obtain considerably better rod sensivity when we resign from them?

Would be grateful for sharing your thoughts, as always


Best regards,
Pavel



Edited 2 time(s). Last edit at 11/24/2006 04:43AM by Pawel Tymendorf.

Any weight you add to a rod will result in some loss of efficiency and performance. But, you can't fish a naked blank very well. You have to add components and therefore you will undermine the original efficiency of the blank to some degree. The trick is to undermine it to the least extent possible.

Weight is your enemy when seeking an efficient fishing rod. Where that weight is located can be as great or greater an enemy. Adding a hookkeeper or a decorative butt wrap down near the handle won't likely affect the rod nearly as much as say, using too many guides up near the tip, or adding long underwraps to all the guide wraps. The further up the rod that you add any weight, the more pronounced the effect on efficiency will be.

It's not likely a hookkeeper is going to change the rod in any way that you'd notice. Leaving off the foregrip is done more for the ability to drop a finger to the blank than it is for weight savings, although you'd gain some for sure. All in all, it's important to use some common sense in these matters. You won't ruin your rod's efficiency of sensitivity by the addition of extra thread on a butt wrap, or a lightweight hookkeeper mounted just ahead of the reel seat. Sure you'll change it some, but it would be very little, indeed.

By the way, it's worth mentioning that many of the current rods that feature split-grips and the "no-foregrip" style handles were not Japanese inventions. They came from the work of Rich Forhan who has probably had a greater impact than any other custom builder on modern day commercial bass fishing rods. You can talk to him in person at the 2007 International Custom Rod Building Exposition in February.


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Tom,

thank you, again, for this broad explanation. Sometimes, for the novice like me, it is hard to verify how much of the truth is in all this advertisements and so on. Luckily, I've found this site and can count on You and other wonderful people here.
Thank you for information regarding Rich Forhan. If I live in US, I would be the first in the queue to shake Your or Rich hand, unfortunatelly this great event is not for me.

One more thing, if I may trouble you a little bit: as regards weight and rod performance, what is your opinion about EVA grips vs. Cork or Hypolon? I've read somewhere, that EVA transmitt vibrations better than cork + it is lighter and therefore more suitable for sensitive rods. On the other hand, handle weight is an important factor for me as regards rod balancig so maybe it is better to use heavier material for the grip....




Best regards,
Pavel

Pawel,
As usual I think that Tom is right on the mark with his answer to your question. The effect of added weight on a blank increases approximately logarithmically as it is added closer and closer to the tip of the blank. A very small added weight at the tip can have a significant effect while the same weight added at the butt of the rod will have almost no effect. The effect of the added weight of a fore cork and hook keeper is going to be very small. I think that the reason that some rod builders leave the fore cork off is not so much to save weight but so that they can get a finger or two on the rod in front of the reel seat.
As far as the difference in sensitivity between cork and EVA is concerned the cork will be the more sensitive handle material but it will not normally be a large difference because any vibration or impulse that comes up the rod and line will reach your fingers at the reel seat before it even gets to the rest of the handle. The difference in the amplitude of any vibration or impulse being transmitted up the rod and line is mainly a function of the mass density and the elasticity of the materials and the cork will have a little higher mass density and higher elasticity than EVA. In actual fishing situations though I think that the line actually has more effect on sensitivity, the amplitude of the vibrations that get to your hand, than the rod does. Braided lines will have significantly higher mass density and elasticity than monofiliment and therefore higher amplitude vibrations or impulses.

The denser material should transmit vibtation better, want better feel through cork, add a 1/8" graphite sensor ring where your hand sits on the blank as you glue up the cork rings on your grip. Some ppl sand a finger slot in the cork down to the blank so they can touch it and feel vibration better. On a casting rod where a low profile baitcaster is used, palm the reel and touch the line before it enters the reel, everything that comes down the blank came up the line, so if your in contact with a tight line, touching the blank itself is a secondary indicator of a strike

@Emory, @Chris

thank you for joining the thread, I can only confirm your thoughts about braided line and reel palming, actually I started to wonder to what extend "all-metal" reel can enhance transmittion of the vibrations, but that is I guess not exactly a rod-building forum issue :)

thx again!

Best regards,
Pavel

Chris,
There are a lot of variables that can affect rod sensitivity, the rods resonant frequency, damping factor, Q, etc. in addition to mass density and elasticity and the issue can get very complex but I basically agree with your points. In actual fishing situations another variable that we normally do not think about that has a significant effect is the angle that the rod is held. If the rod is held at a low angle or so that it is pointing directly down the line almost all of the vibrations will travel relatively unobstructed straight up the line to the fisherman's fingers. On the other hand if the rod tip is held at a high angle, up in the air, then most of the vibrations will be transferred through the guides to the rod and down the rod to the fisherman's fingers and the sensitivity will be lower.

Pawel,
Your question about the effect of the material that the reel is made of is an interesting question that frankly I have never thought about but obviously you are right that the reel also has to be considered. Just off of the top of my bald head I would say that on the one hand metal is going to transmit vibrations much better than any plastic, much higher mass density and elasticity, but on the other hand metal is likely to weigh more than plastic. Maybe some of the newer reels that are constructed mainly from very light weight metals like titanium are the best compromise. The smaller and lighter weight the reel is the better.

I suspect a higher mass density will reduce vibration transmission. For that reason, and for whatever effect the reel might have, a lighter, rigid, reel frame made from any of the various nylon/plastics will be better.


...........

The degree to which a material will transmit the vibration will depend on both the mass and efficiency of the material. The mass will affect the amplitude of the vibration and the damping factor will affect the degree to which the signal is lost as it travels through the material. The key in rodbuilding is to employ both lightweight, and efficient (low damping) materials when sensitivity is important.

Here is a list of the damping factors of a few typical handle/rodbuilding materials that I measured a few years back. These give a rough idea on how some of these materials rank:

Damping ratios:

Stainless Steel = 0.006 -----> Most efficient

Graphite Composite = 0.01

Fiberglass Composite = 0.02

Thermally Cured Epoxy resin = 0.035

Rigid Urethane shim foam = 0.09

Cork from Struble ring: = 0.15

Hypalon foam from grip = 0.20

RT cured Threadfinish = 1.0 ( may be time dependent)----> Least efficient

Emory, I would make the distinction between rod sensitivity based on materials and design vs. the idea of strike detection. If you hold the rod so that the line is 90 degrees to the tip, you will maximize the effectiveness of the line to transmit a deflection to the rod. That means you need to change the rod angle depending on the location of the lure. Most people do this naturally, without even thinking about it. A rod held level if the lure is straight under as opposed to the tip held high if the lure is much further away, both tend to optimize the line to rod tip angle of 90 deg. The more you point directly at the lure, the more you depend on line properties and tension to transmit vibrations down to the hand.


mark

@Mark

thank you for this info.

Guys, if it is correct that stainless steel is the most efficient material as far as transmittion is concerned, then maybe it would be advisable to make SS arbors for the tube-type reel seats? They would need some special design of course so that not to "cut" the blank surface when the rod would be under heavy load, but such a design I guess would be possible... How do you think?

Best regards,
Pavel

Not saying the figures above aren't accurate, but this isn't quite how things work in regards to transmission vibrations in this area. In fact, tool makers go just the opposite route in order to deaden vibrations in their equipement. Steel will not come close to transmitting what say, most common nylons or plastics will. Cast iron absolutely deadens vibrations. The greater the mass density, the more functionally "dead" the material will be.

Stainless steel arbors will not transmit vibrations on a fishing rod as well as urethane bushings, or plastic bushings, etc. In fact, to get the most sensitive fishing rod, you'd almost need to read Mark's chart in reverse, flipping steel from "most efficient" to "least efficient."

But again, sensitivity is not necessarily about "vibrations."

...........

As a long time cyclist, I can tell you that the most comfortable ride comes on a bicycle with a steel frame precisely because it deadens vibrations. Aluminum gives a harsher ride and carbon is the absolute worst because it sends every bump and jolt right up your spine. If it were not for the frame designers being able to create some flexibility in the way the frame is made, I don't think any cyclist would be able to stand a carbon framed bicycle for long. Too much vibration transmission.

I also won't dispute Mark's figures but there is something backwards about how they are being interpreted. No way will a steel bushing under a reel seat be as sensitive as one of urethane or graphite. I just don't see how. It sure doesn't work that way in other areas of manufacturer.

Tom, Mark,
The amplitude of the vibrations or impulses that travel up the rod are primarily a function of the mass density and the elasticity but at the square root of the mass density times the elasticity which tends to compress the difference in materials,
The velocity of the vibrations or impulses traveling up the rod drop in direct proportion to the increase in amplitude but they travel up the rod and get to the fisherman's hand before the damping factor can have much effect. Plus any material that has a damping factor also has Q. And the higher the damping factor, which is a ratio of the amplitude of the initial oscillation to the amplitude of the oscillation, if I remember correctly, at 512 cycles later. The Q determines how wide a range of frequencies a material will transmit. The The damping factor of glass is lower than graphite but the Q is higher which means that glass will only transmit vibrations over a narrower range of frequencies than graphite.
However, having said all of that, again neither the damping factor nor the Q is going to have as significant an effect as the mass density and the elasticity. Most fish bites are impulses not frequencies and get to the fisherman's hand long before the rod can convert an impulse to a frequency. The rod, because of the Q, can only convert the impulse to a frequency at or very near to the resonant frequency of the rod which with most rods is only going to be on the order of a cycle or two per second. But it is only going to take on the order of a few milli seconds for the impulse to reach the fisherman's hand, long before the damping factor or the Q has had any effect, several hundreds of milli seconds.
Plus Mark, I do not know where you got your figures for the damping factor for glass and graphite but I have made some measurements on glass and graphite blanks and have found the difference to be much larger than your data suggest. I have found the difference to be on the order of 4 to 1 rather than 2 to 1.



Edited 1 time(s). Last edit at 11/25/2006 11:17AM by Emory Harry.

Exactly. In terms of fishing rod sensitivity, it's not the longevity of the vibration that's important, it's the strength of the vibration that we're interested in. I've covered this many times here and in the magazine. A rod (or part) made from steel will never be as "sensitive" as one made from carbon, even though the carbon rod will damp the vibrations much more quickly. The amplitude of the signal reaching the user will be greater in the carbon rod than the steel rod and this is what's going to be the important factor in terms of rod sensitivity.

I have always stopped short of stating that as the damping factor of a material drops, the amplitude of any introduced signal will always increase. Although it is certainly true of many materials, including many of those we use in making fishing rods. I still stop short of making that statement across the board, however, as I haven't researched enough materials to know for sure if there is always a direct ratio between the two. And long time ago I learned that the "Q" Emory mentions can tend to foul things up just when you think you have an across the board, perfect relationship.

.........

I should have explained a little better so I hope the damping factors don't confuse too much.

For effective vibration transmission, You have to consider both the efficiency of the material as well as the mass. Steel is very efficient in terms of low damping since it's a very elastic material (small deformations). BUT, it's also fairly heavy, so that mass hurts you from an inertial point of view...not the best choice for arbor materials.

Polymers have a property called viscoelasticity. You could look it up, but the basic idea is that they will tend to dissipate energy to a greater extent than metals and many composites.....they have a viscous component and the damping properties can vary widely. They do tend to be much lighter though so that’s a big plus. Material strength of course is always a factor depending on the application.

The some of the best materials from a sensitivity point of view, tend to be the lowest damping AND the lightest in weight, such as rigid urethane, or cork. Again, even these will vary depending on density.

mark

In the simplest of terms, any input is going to be dissipated. If it damps slowly, then the amplitude is going to be low. If you damp the input quickly, the amplitude is going to be high. You can't lose anything - in the end, things have to work out even. I feel sure there is some sort of inverse relationship between these, but I have no idea if it would be a strict ratio that would be the same for all materials.

With regard to what fishermen feel when they talk about sensitivity, and the length of most fishing rods, amplitude is going to translate into sensitivity moreso than the time to damp out any vibrations. Steel may allow those vibrations to continue, longer, but the amplitude may be so low that the fisherman would have trouble feeling anything. Graphite or similar, will damp the vibrations more quickly but while they remain they'll be much stronger in terms of amplitude. In both cases the signal will certainly reach the fisherman's hand, so the stronger of the two will translate into greater sensitivity. For that reason I can't see materials with low damping ability being condusive to greater "sensitivity" than materials with a higher or quicker damping ability.

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Okay, I think I got it. Thank you very much.

There is one more question I woldn't like miss a chance to ask:

is it possible to "amplify" the original vibrations somehow (by the use of specific materials or design) so that the fishermen feels bites or lure movements (e.g jighead contacts with bottom obstacles) stronger?


Best regards,
Pavel

Pawel
To simply just a little the amplitude of what you feel at the reel seat, the impulse or vibration, is a function of first the amount of the initial energy in the impulse or vibration and then the mechanical impedance of the materials that it travels through to get to your hand. The mechanical impedance is determined by the square root of the mass density times the elasticity of the materials. When the impulse or vibration passes from one material to another the amplitude increases and the velocity decreases if it is going from a material of a lower to a higher mechanical impedance and conversely decreases in amplitude and speeds up when going from a higher mechanical impedance material to a material with a lower mechanical impedance. If the rod is not damped by tension on the line or something else it will try to oscillate at its resonant frequency which for most rods will be in the area of a couple of cycles per second. However, by the time these oscillations get to your hand you will have already felt the initial motion in the rod or impulse.
The things that you can do that are practical to maximize sensitivity are: use braided line, it is much better than monofilament; use a blank that is as light weight for the stiffness or power as possible or affordable; keep the weight of guides thread and epoxy as low as practical; and there are a variety of options for handle material but cork is still probably the best for most applications plus the impulse or vibration will get to your hand via the reel seat before the handle material comes into play to any significant degree.
As far as amplifying the impulse or vibration is concerned the answer is no. There have been some conversations recently about resonant cavities in the handle that amplify vibrations but that is hog wash. For a cavity to resonate at the resonant frequency of the rod or at the frequency of a fishes bite it would have to be to be a couple of orders of magnitude larger than a rod handle. Think about how large the pipes are in a pipe organ that resonate at low frequencies.

With regard to the dissipation of the input signal, the amplitude is primarily a function of the mass, and the rate of decay is governed by both the frequency of the oscillation and the damping of the material. Tom, I’m not sure what you mean when you say that nothing is lost. The damping factor is a material function, and what is lost is a fraction of the input energy with every cycle of the oscillation. Energy is still conserved since the fraction of the mechanical energy lost is transformed to thermal energy through internal friction and dissipated with each cycle. In larger scale motions, there is also a contribution from external friction...air resistance or other drag effects. The concept of damping from internal friction is a little hard to get a handle on because you can't see or feel it, but if you put a high damping material in a load frame and cycle, you can measure the temperature increase.

The basic idea here is that you can reduce vibrations with a large amount of low damping material, such as a heavy steel part, or a small amount of high damping material. CF composites are strong, lightweight, low damping materials, so that's the advantage they offer in blanks. Make thin metal ribbon though and you see the low damping characteristics too. Interestingly, Magnesium is one of the higher damping metals.


Emory,

As far as the difference between the CF composite and the GlassFiber composite, those are going to be fairly specific to the material and the fiber/resin ratio will play a big role. Those numbers I gave were for an aerospace CF and GF composite just to give a ballpark. For another comparison, the material from a tip section of an IMX comes in at 0.016 and an ugly stick at 0.03. The fibers are very elastic so it depends highly on the amount and type of resin in the system. The numbers are fairly accurate and it is even possible to see the difference in a blank section with and without the finish.

mark