Hunting Cranks - theory, design and build

[Vodkaman]

I have just received a PM message asking about hunting, so I decided to post my answer:

Hunting

In my early days on TU, I too found old threads on hunting, and I was very intrigued. The message then was that it was not a designable feature, but more pot-luck. There was even talk about harnesses made from brass wire produced more hunters. But, as an engineer, I knew all the above was nonsense, and so I set out to explain the cause of hunting and solve the riddle of building hunters with consistent success. This took many years and became an obsession.

All lipped crank-baits are capable of hunting. It is just a case of finding the speed at which this occurs. I am sure you have noticed when you rip the bait through the water, sometimes it deviates to one side. You would probably dismiss the anomaly as a quirk, a water current issue, a fault in your lure build or it must have struck a bit of weed or a leaf and was thrown out of kilt. All these explanation, although plausible, were unlikely. You probably touched the transition speed briefly were hunting occurs.

Hunting (zigzag motion) is a function of lip length, lip angle and retrieval speed.

Theory

1 - The angle at which a lure swims in the water at a constant speed is determined by a balance between the lip and the back of the lure, all pivoting around the tow eye. Forces above the pivot point (eye) balance the forces below the pivot point and result in a swim angle and balance.

2 – The forces over the sharp edges of a lip are stronger than over a blunt or round surface. As speed changes, the forces over the lip change at a different rate to those over the blunt back of the lure. This difference in forces changes the swim angle of the bait; as the lure moves faster, the lip forces increase more than the back forces, this results in a steeper swim angle.

3 – as the angle of the lure increases there comes a point where the lip is perpendicular to the tow direction. The forces on the lip are now at their maximum. Any further increase in speed would try to force the lip beyond perpendicular and the effective lip exposure would be reduced. The reduced lip force has to balance the back force and results in a smaller angle. And so the lure ‘nods’ or ‘porpoises’ up and down.

4 – as the lure approaches this critical angle it just does the occasional nod. This interferes with the waggle. Think of it as replacing a single waggle motion with a nod motion. When you lose one waggle say the left side, then the lure receives a double waggle on the right side. This forces the lure to change direction.

5 – Now the lure is now swimming at an angle to the tow direction in plan-view. The forces on the edge of the lip facing forward are stronger. When the lip once again reaches the critical angle, the strong side triggers the nod and so the weak side gets two waggles and so the lure changes in the opposite direction, hence the zigzag motion.

Design

1 - If the lip length is short, the transition speed will be high, and you may well never observe the hunting phenomena.

2 – If the lip angle is too shallow, the whole lure would be swimming perpendicular to the tow direction. The lure would likely blow out before the transition is reached. In any case, the swim angle would be beyond the optimum dive angle and the lure would swim shallow but with a large thump due to the large diving lip fighting against the water. And so, hunting lures are shallow to medium depth lures only.

The trick is to design the lure so that it hunts at the speed that you want to retrieve the lure.

Retrieval speed – I like 2-cranks of the handle per second as a comfortable speed. Keep in mind that the hunting is only going to occur at one speed. Slower and the lure will give the regular waggle, faster and the lure will porpoise continually and possibly blow out.

Lip angle – I design my hunters with a lip angle of between 45° and 60° to the horizontal. A steeper lip angle will reach the transition sooner than a shallower angle, but the depth of swim will be shallower. If you want a slow, sub surface hunter, then a 60° or even higher will do the job. If you want a little more depth, a 45° or even less will give you say 4’ – 6’ but you may have to retrieve faster.

Build

Obviously a test tank large and wide enough would be ideal for testing, but a battery powered Dremel at the lakeside will do the job.

Make the lip too long, so that there is no waggle. If you look closely enough you will observe the porpoising effect.

Gradually trim the lip length back until the hunting starts. There is a lip length tolerance for the hunting effect, the trick is to stop trimming at the maximum hunt, but the only way to know what is the maximum is by trimming more and losing the maximum.

I build my lures 10 at a time. I waste the first one to find the maximum hunt effect and then trim the rest accordingly.

The trim operation must be on the final assembly; with hooks and topcoat. I suggest one or two lures without the fancy paint job, but they must have hooks fitted and the same top coat.

Dave

Edited April 9, 2017 by Vodkaman

[mark poulson]

Thanks Dave.

[Anglinarcher]

Excellent post Dave. 

[RPM]

Thank you Dave, this is awesome information and really appreciated.

[uncustered]

Very cool explanation!!!

[BobP]

Nice work Dave!  I'm not sure it explains ALL design factors of how to build a crank that hunts but it clearly lays out a path for those working towards that result.

when KVD was designing the Strike King square bill series of baits, He said that he obtained the hunting action he wanted by moving  the bait's ballast upward in the bait body.  How does that fit into your scheme?  I don't have an engineering bone in my body!

Edited April 10, 2017 by BobP

[Anglinarcher]

On ‎4‎/‎8‎/‎2017 at 7:47 PM, Vodkaman said:

1 - The angle at which a lure swims in the water at a constant speed is determined by a balance between the lip and the back of the lure, all pivoting around the tow eye. Forces above the pivot point (eye) balance the forces below the pivot point and result in a swim angle and balance.

 

Dave can fill in the gaps on this explanation, but in reality, the pivot is around the center of pressure, which is a complex interaction between the two eye, the control surfaces (lure back and lip, etc.) and center of mass.  It is the center of mass that is altered by moving the ballast.  By moving the ballast up, you move the center of mass up, and the resulting pivot point moves up.  Move it down, you move the pivot down. 

Moving the center of mass impacts the motion less then the lip adjustments that Vodkaman (Dave) does, so as a result, it works, but is not the only way.

[Vodkaman]

Bob - As Anglinarcher explains; raising the ballast will change the swim geometry some, but dynamic (in motion) forces are far more powerful than static forces. If the lure design is close to the hunting transition then raising the ballast may just make the difference. Personally, I don't consider the ballast, and leave it low down for vertical stability. The lip trimming method works every time for me.

Dave

[Travis]

Sisson and other well known lure makers have long mentioned raising the ballast higher in the bait.  These are baits that they don't alter bill geometry or length on.  I honestly believe these hunters are different from some of the "hunters" I see now.   "Hunters" have also become tainted in regards to what I see as classical hunting action.   I see "hunters" today that in no way really resemble what I recall guys searching for when I started fishing cranks more in the  late 80's.   Companies and individuals started calling all sorts of stuff hunting action.  

 Hunters that most I knew sought were not a  repeatable pattern.  Many "hunters" today when viewed from the top have  a sinusoidal pattern and are not hunters.  They have a wiggle that is constant and then have that larger  sinusoidal tracking pattern the crank follows.    

Hunters were erratic and may kick out to the right  a few times, times then left, return to center, then kick left,, track straight for a few,  etc...  The bait always returned to center just was all over the place (not in a cadence) on the way back.   Hunters very much were about operating on the edge of instability.

Maybe what I have always considered hunters is incorrect.  I also ran into a few guys over the years that make a buck or two cranking and talked briefly with them.  They may have been dishing some BS but their definition also was more in line with what I believed.   I have seen some of these same guys however talk about their sponsors baits hunting and they don't in anyway "hunt" as they discussed at the time. 

I see a lot you tube videos of claimed hunters and know it has been common practice for some manufactures to slap "hunters" on their description onto baits that track about as tight and regular as you can get.  

Edited April 10, 2017 by Travis

[mark poulson]

I think Dave's theory and method are the most reliable, in terms of repeatable results.

For me, hunting is the abrupt change of track during a retrieve that causes a reaction strike.  I like it in an open water retrieve, where the fish is tracking the bait, and then triggered into striking by the sudden offset in the lure's path, as though it was trying to escape.

I have been able to achieve this most consistently by raising a portion of my ballast just above the centerline I draw between the line tie and the rear hook hanger, and just behind the location of the belly hanger.

I also make that raised ballast a moving rattle, so it adds to the erratic change in the  center of gravity, too.

It is not an exact science for me, and I struggle to reproduce it on a consistent basis.  

[BobP]

I agree with Travis in regard to "the edge of instability" and what hunting actually is.  Random momentary deviations left and right (6-8" or so) for a few beats from a straight retrieve path, with the lure returning to center path between the deviations. The best hunters I've seen will hunt at virtually any speed and will not blow out even when burned back.

I built a hunting crankbait by accident and got on the "hunting bandwagon" for awhile. I was able to make batches of lures in which 70% would hunt, 20% would just run straight, and 10% were uncontrollable duds.  That last 10% was what killed it for me, and I gave it up after awhile.  But confess I still keep the hunters in the box for those open water situations.   You can get a similar hunting effect by bumping your bait into as many obstructions as possible to impart deviations.  So there is something to be said for a bait that runs straight enough that you can use it to accurately hit cover.  Player's choice.

[Anglinarcher]

I agree with Travis on his definition of hunting.  BobP is dead on with bumping cover.

It is unfortunate that the term "Hunter" has been stolen and redefined.

[Vodkaman]

When I started the quest for the hunter, my first assumption was that the geometry was on the edge of stability, and the edge might well produce the zigzag of hunting.

Having failed searching the stability idea, I then theorized that the explanation was a transition between two axes of movement. Of the three axes of movement; roll, yaw (waggle) and pitch, the only motion that was not evident in a regular crank was pitch.

I then changed the lure geometry to find pitch (up and down movement) and it was then that everything started to fall into place. Hunting is the transition between yaw and pitch.

Regarding the definition of hunting; my opinion is that all the mentioned definitions are correct. The yaw/pitch transition is not just one point, as the name suggests; it is a transition that occurs over a small range of geometry variation.

At the start of the transition, the action is mostly waggle with the occasional nod. This gives rise to the erratic action of the lure suddenly changing direction and then changing back to neutral at irregular intervals.

Half way through the transition, the action settles down to a regular zigzag that some would argue is not hunting. At the end of the transition, The action is mostly nodding which appears as no action, with the occasional and erratic change in direction caused by the odd waggle kicking in.

The change from pure waggle to pure nod is a smooth transition with no discernable boundaries. To get the action that you desire, you must fine tune the lure to find the point in the transition that works for you. The ballast cannot be tuned without disturbing the paint and topcoat whereas the lip can be trimmed easily. You cannot tune the lure at an early stage because the topcoat will throw the geometry off and the effect will be lost.

As a final note; in one of my early prototype tests, I stumbled across a hunting action that was unbelievably wild and erratic, so much so that I could not imagine a fish catching the lure. I have never managed to recreate this crazy action, but I will continue searching. I made the HUGE mistake of butchering the lure to make the next test thinking that I was in control and would be able to recreate the action – lesson learned.

Dave

[MonteSS]

I have found more tail heavy hunts more and shorter baits.

 

[calden]

Dave: not sure I can catch all the details of the movements you describe (pitch, waggle, so on…my English not that good). But I’ve got your idea. For sure I will be making longer lips set at your suggested angles, and going with lures, and a long, long cable to power my Dremel to my brother`s pool.

 

I have 3 questions. 1. What kind of cranks –size, shape- would be preferable to start searching for the hunting action?. 2.  Preferable lip shape?, and 3. How large should be the trims when probing (1mm, less, more?)?.

 

Thanks very much for your contributions to this site, extensive to all the other members. I learnt every day from you.  Diego, from center Argentina.

[Anglinarcher]

On ‎4‎/‎9‎/‎2017 at 8:06 PM, Anglinarcher said:

 

Dave can fill in the gaps on this explanation, but in reality, the pivot is around the center of pressure, which is a complex interaction between the eye, the control surfaces (lure back and lip, etc.) and center of mass.  It is the center of mass that is altered by moving the ballast.  By moving the ballast up, you move the center of mass up, and the resulting pivot point moves up.  Move it down, you move the pivot down. 

Moving the center of mass impacts the motion less then the lip adjustments that Vodkaman (Dave) does, so as a result, it works, but is not the only way.

 

[clemmy]

Calder,

 

Just to to help you with terms:

 

Yaw - is the sideways direction, in lures normally back and forth, like the lure is shaking it's head "No"

Pitch - is the up and down version of Yaw. Like the lure in shaking it's head "Yes"

Roll - is well, "roll" , lol.  Like a dog rolls on it's back so you can rub his belly.

 

 

These are terms used in describing airplane movement.

 

I think you must speak Spanish, so found this for you on the web:

 

 

 

 

Edited April 11, 2017 by clemmy

[Vodkaman]

Clemmy - good post, thanks.

Calden - good questions;

1 - body style. Pretty standard, see pics below. The length is generally between 1.5" and 4" purely because of the mouth size of the local Bawal fish which looks like a piranha.

2 - lip shape. I generally work with flat-bottomed lips, purely because they are easier to trim and keep symmetry.

3 - trim length. 1mm trims are about right. When you find the start of the hunt transition; even less.

 image 1 - My basic shape. I would make these 50 at a time on my duplicator machine.

image 2 - The last lure that I worked on; Bawal-12. This is a small body 40mm long.

I have also included a complete set of plans for bawal-12 including templates (see PDF files), also a video of the build.

Dave

 

bawal lure 12_Sheet_1.pdf

bawal lure 12_Sheet_2.pdf

bawal lure 12_Sheet_3.pdf

bawal lure 12_Sheet_4.pdf

[uncustered]

Is that wood? If so, what type?

 

And where they circuit board lips?

[Vodkaman]

Here is a short video of the Bawal-12. Poor quality as I was evicted and lost all my tools and equipment, including my duplicator machines and test tank.

 

Here is an early video (2007), I had not cracked hunting at this time and so repeatability in production was not there. The lure was resin and so not much waggle. In the video I show retrieval at different speeds to show the effect. You can see constant hunt and erratic hunt actions.

 

Dave

[Vodkaman]

Uncustered - The wood was albesia, an Asian wood, just slightly denser than heavy balsa. Very cheap, easily available as it is used in cheap construction and cheap tourist carvings.

Dave

[BobP]

https://youtu.be/Jyz7C7nGH5E

While the above video from Littleriver (a TU member) is of his version of a specialized  japanese bait called the Wattlebat, it is the best example I could Google of what I consider to be hunting action.  You can find lot of crankbait videos that purport to show hunting but really don't.

[Vodkaman]

Bob - I agree; very nice action. I too have searched for vids but unsuccessful.

DAve

[Travis]

Hard to find good videos of hunters.  To many are short pulls next to a dock, swimming pool, etc... and don't show enough of the lure travel.

The real Waddle Bat video around 1 min 8 seconds shows a few good retrieves but they are having to work the crank at very high retrieve rate and I think most that have used this bait have come away disappointed when looking for a hunting crank.

The S wave video also has a very limited segment showing some potential hunting action but then most of the under water footage doesn't appear the bait they were using for that shot was a hunter.

 

I do believe a hunters is a very specific action/definition and anything deviating from this is not a hunter.   The action was defined a long time ago, way before many of us made a crank.  To make something that does not exhibit these traits and call it hunter just further complicates the scene .  Very hard to have discussions or give instructions if everyone is using a different definition of hunter.   Throw in companies tossing the description around becomes clear why one can buy a dozen "hunters" from guys and not have a bait that really doesn't hunt.   These discussions are helpful in moving towards everyone on the same page and information.  

Edited April 12, 2017 by Travis

[calden]

Clemmy. Thanks a lot. Spanish is my language. I studied in Florida –Go Gators¡¡- time ago, and keep great memories and friends from my stay there. Whenever I can, I visit US and come back with luggage full of lure making stuff.  I searched in google for: “lure movements”, with no luck. I was just looking for a graph like the one you posted but not at the right place.

Dave: thanks you for your kind and comprehensive answer. Lots of good information and ideas that I’ll carefully read and use.

Diego. (Calden, my nickname, is a native tree from this region of Argentina. Great shade, pea pods make good animal forage, but wood not good for carving :-).