How do lips/bills work

[Vodkaman]

Pete - I put myself in isolation around mid January, as 5M Chinese visit Indonesia every year, so an infection was inevitable.

The government numbers I suspect are nonsense, they are trying to protect the economy. They don't tell us where the infections are. There is no mandatory isolation, just weak advisories which everyone ignores.

In recent weeks people seem to be taking it more seriously which probably means there are infections here in Bandung. I simply don't know the true numbers.

I just did a fresh search for Bandung - 1 case, 0 deaths. What a joke with a population of 2.58M!

Dave

Edited May 7, 2020 by Vodkaman

[mark poulson]

16 hours ago, Vodkaman said:

Pete - I put myself in isolation around mid January, as 5M Chinese visit Indonesia every year, so an infection was inevitable.

The government numbers I suspect are nonsense, they are trying to protect the economy. They don't tell us where the infections are. There is no mandatory isolation, just weak advisories which everyone ignores.

In recent weeks people seem to be taking it more seriously which probably means there are infections here in Bandung. I simply don't know the true numbers.

I just did a fresh search for Bandung - 1 case, 0 deaths. What a joke with a population of 2.58M!

Dave

Be well and stay safe. 

Isolation works here in NorCal, along with masks, gloves, and hand washing.  I have a spray bottle of denatured alcohol I use to disinfect anything that someone else has handled, like packages and mail.

I was thinking of you today.  I made a wake bait, and it blew out on the retrieve, so I did a Dave, and shortened the lip until it became stable.  Thanks again.

[Vodkaman]

@mark poulson - I too use alcohol in a spray bottle. I distill my own

Dave

[Big Epp]

What shape lips do you prefer to make/use?  I'm trying to make more lures with lips, but I struggle to make nicely curved lips.  So far I pretty much stick with square bills for simplicity...

[Vodkaman]

19 minutes ago, Big Epp said:

What shape lips do you prefer to make/use?  I'm trying to make more lures with lips, but I struggle to make nicely curved lips.  So far I pretty much stick with square bills for simplicity...

I did a video that compared lip shapes. The difference between square and round was very minimal, so I prefer square, they are easier to produce and alignment is easier to visualize.

Dave

[mark poulson]

I have found that, for me, rounded lips are more forgiving and easier to tune and fish on deeper diving lures than square bills.  I think maybe it's because deeper divers are more difficult to get right in general than shallow running square bill cranks, so I find rounding the lip makes that one less thing to worry about.  And I've found that a square bill will flip up a bait to vertical more consistently when it's burned into a piece of wood, so it's hooks are thrown up and over the wood,  where a rounded bill can roll the bait more to its side, allowing the hooks to snag.

[Vodkaman]

Mark - I will bow to experience never having built a deep diver. I have only shallow waters available to me.

Deep divers are a complex lure, all about balance above and below the tow eye, so tow eye proportional positioning is everything. Deep diver theory needs to be a different thread, and all I can contribute is hypotheses, ideas.

Dave

[mark poulson]

You are so right Dave.  That's why I do shallow divers almost all of the time now.

Deep divers are a real pain to get right.

[Big Epp]

I know a lot of people use polycarbonate lips, but does anyone use acrylic?  If not, why?

[Vodkaman]

Acrylic is brittle compared to poly.

Dave

[Ronje]

Just discovered this site.

Trying to get a handle on use of lateral lines.  Hope you can help.

Is it the vortices themselves that send out vibrations or is it that there are are vortex induced vibrations from the lure body that are emitted?

 

Edited August 8, 2021 by Ronje

[Vodkaman]

As I understand the subject, the lateral line is the fish's ears, a row of sensitive pressure sensors along each side of the fish's body. Just like with our hearing were not only can we hear sounds, but with an ear on each side of our head, we can tell roughly where the sound is coming from.

When a fish moves through the water, it is pushing and pulling at the water making pressure changes, just like when you shout, you set up pressure changes or waves in the air. those changes in pressure travel away from the source, gradually getting weaker until they dissolve away to nothing. it is the same in water except it is movement rather than sound.

The vortex disturbance that our lure sends out create an image of something moving rhythmically through the water. An inanimate object would not send out such a sound wave, thus creating an image of something alive and possibly edible. Of course, the image may be the equivalent of a Keystone Cops video, but real enough to warrant further investigation.

I hope this helps.

Dave

[Ronje]

Thanks Dave.

Lateral lines are designed to operate at very low frequencies eg 10 hz so are below the range of fish hearing.  Incoming sound waves pass through the fish's body and move the swim bladder.  Attached to the swim bladder is a anvil and hammer (similar to humans) which operates via the swim bladder to "magnify the sounds waves.  These are higher frequency noises (100hz - 1khz) than those to which the lateral lines are tuned ( 10khz).

For our lure to generate the low frequency pressure waves like a fish, the bib is pulled left and right like you've described.

What I'm hung up on is which part of the lure actually generates the low frequency pressure waves (the 10 hz) to stimulate a distant fish's lateral line.

Is it the vortices themselves or is it the body of the lure itself pulled pulled sideways rhythmically by the bib action pulling at the head of the lure that causes the pressure waves?

If its the lure body (via vortex induced vibration--VIV-- causing the lure to vibrate at the same rate), then damping of the vibration by the body would have to be occurring.  So do smaller lures produce less damping?

There has to be a way of pre-determining the lateral line vibration frequency in the lure design phase (maybe by bib dimensions or similar).

Have your investigations led you in that direction?

regards

Ronje

Edited August 8, 2021 by Ronje

[Vodkaman]

I used sound/ears as an analogy. The lateral line senses minute changes in water pressure. The lure's movement disturbs the water causing minute changes in pressure. The fish senses these pressure changes and I would guess creates a perception of what is causing the disturbance.

You have obviously read up on the subject, so I am mystified by your confusion. I could try and explain more but I would only be repeating myself.

To control the frequency of the lure movement, look into the Strouhal equation. I use this to select my lip width to achieve my required frequency.

Dave

Edited August 8, 2021 by Vodkaman

[Ronje]

Quote

A scientist I'm not, Dave. 

Just a fisherman trying to nut out what seems to be something that nobody is able to describe or even tell me much about (until now).  The designed vibration freq of a hard body bibbed lure.

I follow the pressure reduction at the bib edge and the shedding of vortices.  The bib width obviously has a role.

I've played around previously with bib width, length and shape without success and ended up with too many variables so gave up.

As I understand it, Strouhal is  S (Strouhal number) =  freq (in hz)  x  L (bib width in mm)  / velocity across the bib surface (in m per sec).

Do I have the ingredients correct?

Thanks for persevering with me.  You seem to have a gift of making complicated subjects sound simple.

regards

Ronje

 

[Vodkaman]

OK, I was starting to think that you were some scientist come here for amusement.

An easy mistake to make is to think of vortices as separate from the rest of the water. The water and all the disturbances like turbulence, vortices, displacement, laminar flow and static, all interact with each other, think of it as a complete system. A predator say one meter away is sensing all the disturbance coming from the lure; the result of the body movement, the disturbance caused by the vortices. Among all that chaotic noise is the pulse of something alive.

Place a mirror in a bath tub of water, and drag your finger or any object over, you will clearly see all the micro pressure changes. Run a knife blade and see the vortices, they are clearly visible but not as clear as the theoretical diagrams would have you believe.

Dave

[Vodkaman]

As for Strouhal number, you have to figure out the value of 'S' to apply to the equation. The value I came up with was S=0.12 but this was before video and so not accurate. Video is your friend as the cycles are too fast to count and operate a timer at the same time.

'S' is a function of lip width, distance and time.

Once you have a value for 'S', you can apply this to different widths to calculate the new frequency, or the retrieval speed to achieve a specific frequency.

If you do a TU search for Strouhal, I am sure I have posted about this before.

Dave

[Ronje]

Found quite a few references with a search. 

What a treasure trove of the information I've been seeking and enough to keep me occupied for yonks. 

Fascinating how nature has provided and refined (after thousands of years of evolution) tools that fish need to survive.

The equivalent of a fish lateral line sensory system to find the source of something has only been developed by man in the last 75 years of technological advancement.  (mobile Commutated Antenna Direction Finding Systems....CADF)

And man thinks he's clever.

Thank you.

 

Edited August 8, 2021 by Ronje

[t_man7]

Good example of Vortex Shedding, bite was slow so took this video.

 

[Vodkaman]

T_man7 - nailed it

Dave

[RiverSmallieGuy]

Not sure if all of you guys are familiar with this lure, but the Megabass Vision 110 jerkbait-- I believe that a big part of it's erratic action is because the lip flexes a little bit when you jerk it, making every twitch a little different. I am going to assume that you can incorporate that effect into a crankbait if you use a thin circuit board lip, which could be deadly for a super shallow running crankbait for pond bass where you aren't hitting any hard structure, but the bait has that erratic hunting action that triggers reaction strikes.

 

Braden

[RiverSmallieGuy]

On 2/15/2022 at 2:26 PM, RiverSmallieGuy said:

Not sure if all of you guys are familiar with this lure, but the Megabass Vision 110 jerkbait-- I believe that a big part of it's erratic action is because the lip flexes a little bit when you jerk it, making every twitch a little different. I am going to assume that you can incorporate that effect into a crankbait if you use a thin circuit board lip, which could be deadly for a super shallow running crankbait for pond bass where you aren't hitting any hard structure, but the bait has that erratic hunting action that triggers reaction strikes.

 

Braden

Forgot to mention a question. How would the vortices change when the lip flexes? Would that allow for more roll or waggle?

[punkinhead]

I've been trying to make a slightly larger copy of a jointed Rapala topwater bait that I really like but I've struggled with getting much action out of my attempts.  Based on this thread I took a closer look and, to my surprise, the bill is concave.  Not just bent concave, but actually shaped like a soup spoon with a hollowed out "bowl".  I can't believe I didn't notice it earlier.  This morning I 3D printed a prototype and, sure enough, it has perfect action.

I should note that despite my training in engineering and statistics I changed two things at once: I added the concave hollow to the lip and moved the cut line so that the head of the bait was about 45% of the length vs. my original 30% so I can't conclusively say the the concave lip was what created the improved swimming action.

Edited February 29 by punkinhead