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Fishing Rod - Sensitivity Calculation

  1. Sep 14, 2007 #1
    Can one correlate the effects of a change in weight to the transmission of vibrations (fish strike) through a fishing rod?

    I'm not an engineer. I don't know what equations may apply. I'm not even certain I'm describing the question correctly. I'd appretiate any assistance.

    I've attempted to gather what I could through the Internet and understand that human physical sensitivity is measured as a matter of degree change that can be detected. The few articles I could find on fish strikes show measurements in grams force. I am guessing that this would equate to the rod in how much grams force is required to effect a physical movement of X degrees on the fisherman's grip. A change in the weight of the rod would then change the force required to affect the grip. I'm sure that there are many variables that would need to be considered; angle of the rod to the force being applied, distance from grip to tip top, etc.
  2. jcsd
  3. Sep 14, 2007 #2


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    Staff: Mentor

    I would think that the deflection of the rod's tip would be a more sensitive measure of a fish strike. Of course, the indicator mechanism (whatever it was) would go off while you were casting, and other times when you were moving the rod around to where the tip was deflecting.
  4. Sep 14, 2007 #3
    Movement of the rod tip is a visual clue but there is water movement, wind, hand shake, etc. that will also cause tip movement. Night fishing also eliminates that visual clue. Most strikes are a short "bump" you would feel through the rod that is more easily differentiated from the other factors. Besides, if you stare at the tip long enough it will do all sorts of funny things :)
  5. Sep 15, 2007 #4


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    Staff: Mentor

    No, sorry, I didn't mean to look at the tip. I go the impression that you wanted to make some device to help detect a fish strike, so I was just saying that the device should work by detecting deflections of the tip of the rod. There would be several potential ways to do that sort of detection.
  6. Sep 15, 2007 #5
    Oh. Nope, not building a device. Just trying to build better rods. There is an ongoing argument within the custom rod building community as to whether it's advantageous to add weight to the butt of a tip heavy rod in order to balance it. The opponents say any weight added will increase the rods mass and decrease its sensitivity (transmission of force from a fish strike). The proponents say that an off balance rod already has a decreased sensitivity due to the extra effort required to hold the rod in position. I guess I coulda' explained this better in my first post, sorry about that. Would there be a way to determine the effect to a rods transmission of fish strikes if weight is added to the butt in order to balance it? I guess we'd also have to determine the effect of an unbalanced rod.

    My unscientific guess at how to work it out:

    Case 1) If we presume the reel to be the c.o.g. on a balanced fishing rod that weighs 12 oz, the extended forefinger simply rests on the blank 3" from the reel toward the tip, the end of the butt is 12" back from the reel. Then x grams of force on the tip (perpendicular to the rod axis) would generate x degrees rotation and y inches of lateral movement. This displacement could perhaps be translated to x degrees rotation/movement on the forefinger.

    Case 2) Same rod as above but the c.o.g. is now 3" above the reel and located where the forefinger was resting in case 1. With the same X grams force on the tip how much rotation/movement would there be on the forefinger?

    Case 3) Same rod as in case 2 except that weight is added to the butt to bring the c.o.g. back to the reel. With the same x grams force on the tip how much rotation/movement would there be on the forefinger now?
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