North Australian FISH FINDER TM forums

It ain't rocket science

Fish use ALL of their food-finding tools to survive and the most used tool of all is their lateral line.

Its works with no light, full light, night, day, dirty weather, dirty water, clear water.

The bottom line is that they MUST find food to survive.

We very cunning fishermen offer up lures instead of messy bait or the sometimes-backbreaking effort of live bait.

Lures aren't messy unless we insert one of the hooks in our (or someone else's) body parts and the blood gets messy.

So what does our lure need to do?

Well, the fundamental requirement is to attract the fish's attention that food is available by stimulating the fish's lateral line (its early warning and tracking sensor).

What stimulates the fish's lateral line? Vibrations in the water caused by food (a small fish like a mullet or other species).

To do that successfully we have to know a few things about that mullet so we can copy those characteristics into our lure.

The most obvious is to copy the vibrations.

The mullet has a vibration generator called a tail so our lure has to have a vibration generator as well that generates vibrations similar to a mullet.

ALL lures have such a vibration generator called a bib that needs to produce vibrations similar to a mullet's.

Understanding can be heavy if hit with a whole bunch of facts straight up so lets have a look step by step.

The fundamental role of a hardbody lure. Do we agree?

Step 2

So what is the vibration rate (tailbeat) of a 120mm mullet meandering around?

Luckily for us marine scientist have researched that topic to death over the years. We don't have to work that out.

Its 230 tailbeats per minute. When wagging their tails at 230 bpm, they are meandering around at .63 kmh. That's pretty lazy/slow covering 10m in 1 minute's meandering.

So step 3 is working out how to make our lure generate 230 (or so) beats per minute remembering that mullet don't spend all of their time meandering around waiting for a hungry barra to find them 'cos of the "here I am" signal put out by their tail.

So how do we work it out? Or even better, how do our knowledgeable lure makers design a lure that generates 230 (or so) bpm?

Ask 'em.

Well... how did we go asking luremakers? There are a few on here so you guys would know some of them personally.

Plenty of talk about action I'll bet ranging from tight, loose, open, slow, fast ... etc?

But bugger-all about the real info that we were after (how many beats per minute does your lure produce)?

However, before making any lure we need to know the target bpm that's needed which is how many beats per minute that a fish lateral line can respond to/ "hear".

"Hear" is a term that's probably easier to understand but "hearing" isn't what lateral lines do. They "feel" a vibration in the water with a special sensor on their skin.

Once we know that, we can start designing and building a lure. So...what vibration rate does a lateral line respond to?

Well, our scientist friends have researched lateral lines to death as well. Very nice of them and the answer is up to 600 beats/min. After 600 bpm the lateral line starts to go "deaf".
Look at the horizontal red line. Thats the response/"hearing" sensitivity.

Follow it from left to right until it starts to drop and at that point there's a green line that marks 600 beats per minute (bpm).

You know what? I can't see anywhere along the bottom line about fast, slow, tight .. or any other type of "action". So where did this word "action" come from?

Following any further along the dropping red line means that the lateral line is going "deaf". It can still "hear" but only if up close.

Bit like grandad with his hearing aid turned down/off.

So now we have the fundamental spec of our lure. It must produce up to 600 beats per minute.

Do we think its coincidence/chance that a fish lateral line has evolved over thousands of years to end up with the bpm/vibration rate of food smack bang in the middle of its sensitivity?

What happens next?

Maybe our luremaking friends can help us out again.

What is the most important job of a bib on a hard body lure?

Is it:
1. give us somewhere to tie our line?

2. set the swimming depth?

3. generate vibrations?

The most important job of the lure is to generate vibrations.

The surface area of the bib determines the depth to which it operates but that's a convenient secondary function.

I'm not going to go into how it does that in order to keep the thread on track. If somebody wants to know PM me and send u the info or I'll put up a separate thread.

If the bib's prime job is to generate vibrations, then how do we set the bib parameters to make the bib vibrate at the rate we want it to eg 230 beats/min?

Have a look at the attachment which gives us an idea of the width of the bib vs the vibration rate with the most important item being where the bib width is measured (and its not where most think it is).
Obviously the bib width in the image (7.5mm) is going to generate a higher rate than needed. 756 beats per minute.

Which is right around the very top of the response band of the barras lateral line and getting further way. It'd have to be in fairly close proximity to the fish to be "heard". I've used that type of lure in confined areas with great success but what we're actually dealing with is the lure finding the fish instead of the other way around.

The vibe rate is certainly quick on the rod/line feel but don't let the vibe rate get confused with the vibe strength.

So...is that it in respect of vibration rate of hardbody lures?

No. Its not.

All of this looks nice and tidy but there is one other variable that has a role in the vibration rate that a bib generates and that is the speed of the water flow across the bib surface.

The standard I've shown you is the vibration rate at a water flow of 1 kmh. If the water flow is faster, then the vibration rate is faster.

Like so Our target bpm is 600 or less and here's what happens with 3 different retrieve speeds of 1, 2 and 3 khr with bib widths ranging from 7.5mm to 24mm.

And what is the lesson for us here? Aim for 600 bpm or less.

Nine bibs and 3 different retrieve speeds gives us 27 different combinations. How many hit the target (in green)?

Only 11 out of 27 and what is the lesson for us? Use bigger bibs and slower retrieves to get combinations close to the "money lure".

What's that old, old advice about barra lures?

Slow down. Slow down.

I doubt that the guys giving that advice over the years knew the mechanics behind the success. Just that it worked.

Now you (and they) know why.

With our refreshed outlook on lure technical fundamentals, let's have a look at what hardbody lures are offered up to us to catch a barra.

Some are true works of art of which Rembrandt would have been proud. It's obvious by some of the workmanship, that there are some very talented lure makers in terms of workmanship out there in "lure land".

Yet many of these very talented people have no idea (even among big name manufacturers) of how lures and lateral lines interact.

On the lure packaging you'll find heaps of information such as depth, weight, length, action. "Action"?

There's that meaningless and useless word that has been used by lure makers and "experienced experts" for years. A substitute word for the most import piece of information that's missing. The lure vibration rate.

Knowing that a lure vibration rate needs to be around 600 beats/min, we buyers can then compare lures can't we.

That's not a bad thing (the ability to compare apples with apples) considering that some of these genuine masterpieces can be priced up to $40.

An example?

Say we're looking at 3 different 3m diving hardbody lures trying to decide which of these $30 offerings to buy.

One is described as having a "tight" action, the second as having a "wide" action and the third as having "sway". One has a further description of having a "harmonic profile". Geez, it's like a commentary associated with ballroom dancing.

What on earth does "harmonic profile" mean in english?

Some big words there and NO, it wasn't the Hydrology Engineer who claims to save lives worldwide with the medical knowledge and opportunity associated with Bureau of Met rainfall data.

So which one did we spend our $30 on? Or did we spend $90 because we didn't understand any of the "commentary" but didn't want to miss out in case one did actually work on barramundi.

What's missing? The most important bit of information of all. The vibration rate.

Why don't these whizzbang lure makers and expert advisers/commentators include vibration rates on the lure packaging?

There is a very good reason. They don't have sufficient knowledge about vibration rates or lateral lines and how to put the two interacting subjects together.

I frequently assert that most things associated with fishing ain't rocket science.

However, it was a physicist professor AND a NASA physicist, rocket scientist and mathematician who worked out the vibration rate calculations. Oddly, neither was a fisherman.

Maybe a few aspects of fishing ARE close to rocket science after all.