Rod damping

[Merlin]

Paul

Where do you see MCF2? To me Graeme damps at RSP2. If you can capture the MCF2 moment on the video, many thanks to post it.

Merlin

[Graeme H]

Daniel,

If I was effectively damping at RSP2, the hump that's visible in the rod leg would not occur. That hump is there because the rod tip rose above RSP2.

Cheers,
Graeme

[Merlin]

If I was effectively damping at RSP2, the hump that's visible in the rod leg would not occur. That hump is there because the rod tip rose above RSP2.

Graeme

I think confusion comes from the fact that the rod is not a simple SHO with one degree of freedom, but it is a multimodal system. For sake of simplicity let’s say that there is one higher mode only (between CF2 = death grip and FF1 = no grip). To bring the rod to a standstill you have to damp the fundamental mode (CF1) and the higher mode as well. This higher mode does not appear clearly before the rod is close to a RSP state. When one speaks of MCF1, one speaks of the fundamental mode of the rod.
Below one can see the damped situation (RSP1, MCF1, RSP2)

GH damped.JPG (18.5 KiB) Viewed 151 times

And the undamped situation (RSP1, MCF1, RSP2)

GH undamped.JPG (19.27 KiB) Viewed 151 times

At RSP1 and in both cases, the rod exhibits an S shape meaning that a higher mode affects the rod. MCF1 situations look similar, the amplitude of higher mode being small it is hard to see it in the rod bending shape. For RSP2 the higher mode has larger amplitude in the undamped case.

It is fairly common to critically damp the first mode, but it is more difficult to achieve the same for the higher mode at the same time. If one speaks of counterflex close to RSP2, it corresponds to the higher mode, not the fundamental one. Since the rod vibrates around RSP2, I consider that the hump which can be seen in the rod leg does not correspond to what we would call MCF2 if the rod was effectively undamped and free to vibrate along its first mode. The MCF2 you mention belongs to the higher mode, not to the fundamental one. I’m splitting hairs likely but I want to make my point clear.

Merlin

[Paul Arden]

Paul

Where do you see MCF2? To me Graeme damps at RSP2. If you can capture the MCF2 moment on the video, many thanks to post it.

Merlin

Too hard for me on my phone to pick it. If would interesting to see no pull-back for comparison. Also trying to get rod of the MCF2 wave.

Cheers, Paul

[Lasse Karlsson]

Difficult to hear you above the wind there Lasse. Which direction was it blowing?

I'm speaking Danish, you wouldn't understand it even with less noise. Luckily the important parts I wrote in the clip

And it was blowing from that direction, and that one.

Have you tried one of those Norwegian rods that has taken away caster dampening?

Cheers
Lasse

[Paul Arden]

Have you tried one of those Norwegian rods that has taken away caster dampening?

No I’ve never heard of them. Are they waterproof?

[Graeme H]

Too hard for me on my phone to pick it. If would interesting to see no pull-back for comparison. Also trying to get rod of the MCF2 wave.

Cheers, Paul

This one has just a little bit of pullback. Is that more helpful?

[Paul Arden]

Hi Graeme,

I’m not really sure. I don’t have a fibreglass rod here to play with. Can you damp MCF2? I’m guessing that’s what Chris is doing. I thought initially he was lengthening hover time, but it’s too early.

I can try overlining an HT4 in the daylight.

Cheers, Paul

[gordonjudd]

Graeme,
Thanks for taking these great videos. To bad this one has repeated frames to get a slow motion effect but that white rod against a black background is perfect for getting overlays of the rod bendforms as it recovers from MCF1 and goes to MCF2 using the ghost filter in Tracker.

As with other casters it appears the rod butt moves down while the tip moves up to produce a node in the bendform that is about 80% up the length of the rod.

The same pattern of tip and butt movements and a node bout 80% up the length of the rod are captured in the loose grip case, but it has a bit more counterflex at MCF2.

Gordy

[Lasse Karlsson]

Have you tried one of those Norwegian rods that has taken away caster dampening?

No I’ve never heard of them. Are they waterproof?

As much as other rods I would think

And I bet you have they just aren't marketed like that