Where on the cork do you grip the rod?

[Carol]

I met Mac Brown at the Denver Fly Fishing show in January and he worked with me a bit. He (and independently my mentor) suggested I try holding the grip a little differently with the fatty part of the palm -- hypothenar eminence (looked it up) -- just below the cork on the reel seat. I can't recall exactly what he said it was supposed to do, but I think the idea is that it dampens ancillary vibration or oscillation from the reel? (Merlin might know.) I've been trying this for months now, and for some casts this now feels comfortable, but when it comes to accuracy, I find the normal position on the cork seems better for me (so far). Have you heard of this? What are your thoughts about it?

[Mangrove Cuckoo]

Hi Carol

Mac does love to crowd the reel! I listened to his explanation and what I heard was an intent to change the lever mechanics.

He seems to believe that most casters "push" the rod, mistakingly treating it like a first (?) class lever. While he believes by gripping low, and "pulling" the rod by closing the fingers he is changing the fulcrum point and using it more efficiently as a second (?) class lever.

Before some of the engineers jump up and down, please look up the three types of levers... I may have mixed up the numbers!

But... I always take what Mac says as probably being right...he puts a lot more thought into it than most.

BTW... I gave his grip a try and really like it.... for light trout size flyrods. Mac seems to use 3 wts. a lot.

[Merlin]

Hi Carol

First, thanks to Gary for giving information on Mac Brown’s approach. I hope I understand the explanation which should be slightly corrected.
A SH fly rod is a “third class” lever, le rotation point (fulcrum) being below the rod end (at elbow level or something). To become a “first class” lever the fulcrum should be above the hand which is impractical. So a caster uses a “push”, and not a “pull”.
I guess that Mac is influenced by the position of the center of mass of the rod fitted with a reel or by the reel itself, assumed to be close to the actual fulcrum point but the grip story is not linked to the type of lever, IMHO. It has something to do with the vibration characteristics and the position of the “butt node” of the first free-free mode of the rod and reel system as illustrated below (by my friend John Symonds, MCI). Maybe Mac Brown changed his mind but the following explanation is in line with your comment about vibrations.

free-free nodes.jpg (12.39 KiB) Viewed 4265 times

In that illustration the “butt node” is supposed to be just above the handle, but it is usually lower than that for actual tackle. Here is an example with a small glass rod of mine (7 foot for a #3 line). I located by experiment the nodes placement with and without a reel (a Hardy Featherweight, the lightest reel I have) with line.

glass rod nodes.JPG (53.11 KiB) Viewed 4265 times

The butt node is somewhere between the center of mass (balance point) and the reel seat. Holding the rod at the butt node level allows controlling the natural trend of the rod to vibrate along its first free-free mode (the rod is on its own) as it unloads. The rod does not adversely affect the caster’s motion with a small torque, and the feel must then be comfortable.
With short light rods it is very difficult to keep the center of mass above the handle because reels are “too heavy” for that and you usually have to hold the rod very close to the reel (look at the node location on the photo). This also explains the recommendation made by TLT aficionados for the grip, the hand partly covering the reel, as shown below (from TLT Academy).

TLT grip.JPG (21.02 KiB) Viewed 4265 times

I guess that when you cast for accuracy (I understand during competition events), you need a tight control of the rod and you hold it more firmly. In that case you use the first “clamped – free” mode of the rod and the butt node just disappears. There can be a node left in the tip (S curved rod) if your input is a bit too fast for the rod and line system.

Merlin

[Mangrove Cuckoo]

Merlin

Thanks... I always screw up the class numbers!

The curious thing about how I interpreted Mac's idea is that I could actually cast a long (10.5 or 11') 3 wt rod simply by closing my fingers? Just as he suggested.

In that cast I had no translation as my hand did not move. It feels like the fulcrum is the knuckle in the palm below the index finger. So a first class lever?

But I should probably shut up as I don't want to misrepresent Mac's ideas any more than I probably have!

Gary

[Carol]

As usual, I first needed to learn what is a butt node. I found a rudimentary definition of nodes for the non-rod builder. With that rudimentary understanding, I can begin to make sense (sort of) of the balance point discussion. But, I believe you are correct that Mac is talking about vibration dampening as opposed to moving the hand closer to the fulcrum. Guess I should email him. I'll let you know the response if I get one.

[Merlin]

Hi Gary

I also had to check the class number

The “fulcrum” location, in others words the instantaneous center of rotation, varies during the cast and it is possible that if you use your fingers as described (what Paul explained he does for his 170 cast), then you have a first class lever at the very end of the cast.

Merlin

[Merlin]

Carol

Here are some explanations about the vibrations of a rod. Under some circumstances (input frequency), the rod can take a stable shape (a mode) showing points on the rod which seem to be fixed, rod material rotating around. These are the “nodes”. Nodes are attracted by mass, meaning that if you put a reel at the butt end, all nodes will come closer to the reel, and there is one of interest for us, the node in the butt.

Main « modes » for a simple beam are illustrated below (higher modes are rarely seen), the butt being on the left hand side. The “free-free” modes are illustrated on the left hand side, and the “clamped-free” modes are illustrated on the right hand side (one speaks of the ends). The “clamp” is your hand. In reality the situation is something in between depending on how tight you squeeze the cork. The “clamped-free” situation is relevant of the driving motion and the “free-free” is something which is not that far from relaxing the grip at the end of the cast and would be the unloading mode of a rod if it was free to move by itself. In practice you can see that free-free modes are pretty close to higher clamped-free modes (numbers on the graphic are indicative of the corresponding frequencies for a beam of uniform stiffness, the actual situation for a rod is slightly different). This can explain that if the rod can somehow unload on its first free-free mode, then the “S” shape of the rod can appear because the corresponding frequencies are close to each other.

The rod mainly responds to the caster’s input with its fundamental mode, but this response can also contain higher modes of small amplitude, leading to instabilities sometimes (rod vibration at the end of the cast) and visible “S” shape. The first free-free” mode is the preferred mode for the rod as it unloads, although it is constrained by the grip. Theoretically, it corresponds to the “speed of recovery” of the rod.

Modes.JPG (32.34 KiB) Viewed 4188 times

Merlin

[gordonjudd]

The first free-free” mode is the preferred mode for the rod as it unloads, although it is constrained by the grip.

Merlin,

I don't think that the pressure from the grip can come anywhere near the constraint you get by clamping the rod.

Thus I think the rod will recover in the free-free mode regardless of how firm the grip might be. If you have ever tried to measure the fundamental frequency with someone just gripping the rod you will find the vibrations are so quickly damped out that it makes a measurement of the fundamental frequency impossible to do unless you clamp the butt.

The fact that the angular velocity rebound hump is positive and thus the butt angle increases while the rod goes through the rebound phase also indicates it returns from MCF in a free-free mode.

Measurement have shown that a baseball bat also vibrates in free-free modes even when it is gripped with both hands, and those vibrations "sting" the hands when the ball impact is away from the sweet spot. Russel has show it is the second free-free mode that causes bat sting, and considerable effort has gone into developing internal dampers to minimize it.

I wonder how similar the feel from gripping near the reel, is to the feel obtained with the "Abel Arm" that Mel Krieger helped to develop.

abel_arm.jpg (18.47 KiB) Viewed 4150 times

Gordy

[Carol]

First. Merlin, I really appreciate the education. It's making more sense the more I read and [think I] understand it. The free-free beam produces a different type of oscillation than the closed-free beam. We can control, to an extent, which type of beam we are working with by location and tightness of our grip. A death grip produces the closed-free beam, hence a difference oscillation. Thanks to everyone for the other posts too.

I wrote to Mac, and here's his response:

Question: ... I now find it second nature to place my hand there but am not clear of the intended purpose. Is it to move the hand closer to the fulcrum point or to dampen reel vibration?
Answer: It does shift it closer to the fulcrum and helps keep it closer to reel as well which prevents reel from acting as a teeter totter. You answered those in your original question. Other reasons, the rod is a longer lever so torque is greater. When we cast the rod as a first class lever using the pinky & ring finger to pull opposite on forward cast...it becomes much easier to create great[er] rod accelerations."

[gordonjudd]

A death grip produces the clamped-free beam, hence a difference oscillation.

Carol,
As noted above I don't think you can get a clamped constraint on the butt regardless of how firm you grip the rod.

The mechanical stiffness of the wrist is not sufficient to get the same constraint as provided by a clamp.
Gordy