Lever / Fulcrum / counterbalance

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Please forgive my ignorance, math was never my strong suit. But I have a question that has been bugging me, and I can't seem to figure it out, and thought perhaps that someone here could easily answer my question.

I am a fly fisherman, and have been investigating certain claims regarding a reel balancing a rod. In essence the claim is that the actual weight of the rod and reel combined isn't the big issue in how heavy a rod feels (when casting), but rather how well it balances in your hand.

If we consider the hand grasping the rod as a fulcrum, there is a certain amount of weight above the hand (towards the tip of the rod) with considerable mechanical advantage over the weight below the hand (the reel). It's possible (and in fact fairly easy) to get these weights to balance since a reel is considerably heavier than the rod. Thus negating the mechanical advantage.

What I'm trying to figure out is if it takes more force (not sure if force is the right term) to "rotate" the rod (as in a casting motion) with this "balanced" set-up, or if it takes more force to do so without the "counterweight". In other words, if it had no reel weight to counterbalance the rod, would it feel heavier or lighter to cast (not carry). Think rotational force. (Torque?)

On the one hand you are rotating considerably more overall weight. But on the other hand the counterbalance weight would seem to make setting the weight in motion easier since there is less force required to upset the balance. (If that makes any sense.)

I'm sure I'm not using the right terms to effectively describe what I'm after, but hopefully you get the idea.

Perhaps this will help...

One camp of fishermen says, "A balanced set up requires less effort to cast, and will leave you less tired at the end of the day."

The other camp says, "That's baloney. The less weight you have to move, the better off you are. So just go as light as you can."

I just want to know from a scientific point of view who is right, and why. Numbers don't lie, and if it can be quantified, I think that's where I want to be.

Thanks for the help, and again please forgive my ignorance.

---David
 

Answers and Replies

  • #2
Cleonis
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What I'm trying to figure out is if it takes more force (not sure if force is the right term) to "rotate" the rod (as in a casting motion) with this "balanced" set-up, or if it takes more force to do so without the "counterweight". In other words, if it had no reel weight to counterbalance the rod, would it feel heavier or lighter to cast (not carry). Think rotational force. (Torque?)
Starting with your last question: yes, the correct term for force-configuration-for-rotation is torque.

The comparison is between two identical fishing rods, held in the same place, one with a reel, one without a reel. And the place where you hold the rod is the center of mass of the rod + reel.

Since the rod + reel is overall heavier than just the rod you need more torque to swing it with the same acceleration.

But that is not all.
Generally, if you hold a rod (any rod) in a place that is not its center of mass, and you move as when you cast a line, then the center of mass of the rod will tug at you.

I imagine that it's just sweeter to cast when you are holding the rod at the spot where the center of mass of rod + reel is. The motion is simpler then, all the more helpful for the accuracy of your cast.

With a reel the motion make take a bit more force, but as long as the required force is well within a comfortable range it makes no difference. So it seems to me that the sweetness of the motion is the main factor.

I call it 'sweetness' because I'm thinking of things like the 'sweet spot' of a tennis racket, or the 'sweet spot' of a baseball bat.
 
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Thank you Cleonis for your informative reply.

From that information, I now understand that a rod/reel combination will have a specific center of mass, and as such, it will require a specific amount of force to accelerate to a specific rotational velocity. Regardless of where it is held, and if it is balanced or not, the torque required is going to be the same. But the balanced set-up will not "tug" at you, and therefore would feel "sweeter". (If you don't like being tugged that is.)

Again, thanks for the assistance.

---David
 

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