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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
These are my thoughts, opinions and ideas on hunting lures, after six years of investigation and building hunters. All open for discussion, you can disagree and add your own ideas. If you don’t want to read the technical stuff, you can skip to the last paragraph, but don’t whinge about it, there are people who do like to read this stuff. What is hunting – a regular or irregular stepping away from the line of retrieval. The lure zigzags but the lure always returns to center and the retrieval is still basically a straight line. What is so good about hunting – I believe that it is change of direction that triggers the bite. How many times have we seen fish trail the lure all the way back to the rod tip, obviously interested, but not biting. When a fish changes direction, it cannot immediately change again. So immediately after a change in direction would be a good time to attack. I believe that the trailing predator is simply instinctively waiting for that change of direction. What causes hunting – hunting occurs at transitions. This can be at the edge of stability, just before the lure blows out or at the transition between two different actions. At the transition, the lure tries to do something different but reverts back to normal action. This disturbs the regular action pattern and results in a change of direction. Often hunting is seen on a lure when you increase the retrieval speed. Hunting I find is relative to retrieval speed. To explain this, I have to discuss with you my ideas on swim angle. Static angle – when the lure is static, sitting in the water, its angle is determined by its distribution of weight of the different components that are heavier than water; ballast, hooks, harness, lip, top coat, eyes, rings – all have an effect on the center of gravity (CoG), a single point in the lure that all the downward forces are acting. Then there is the center of flotation (CoF), the single point at which all the lighter than water components are acting, namely the bare body. When the lure is still, the CoG and the CoF are vertically aligned and this determines the angle that the lure sits. If you remove the rear hook, the CoG moves forward a tad, then, when the CoG and CoF vertically align, the angle of the lure becomes steeper. Dynamic angle – when the lure starts moving, everything changes. There are new forces on the lure. The static forces of weight and flotation are still there, but there are additional forces; the water passing the lip and the back of the body. As the speed of the lure increases, so these extra dynamic forces become stronger, to the point of making ballast location quite irrelevant in determining the angle that the lure swims. Don’t get me wrong now, ballast is still very important and controls the action, how the lure wobbles, but has very little effect on the swim angle. The forces on the lip below the tow eye are trying to make the lure swim steeper and the forces above the tow eye, on the back of the lure are trying to make the lure swim flatter. The lure swims at an angle were the two forces are equal. Keeping all else equal, if the body is fatter, the lure will swim flatter, if the lip is extended, the lure will swim steeper and so on. This is why the eye position on deep divers is so critical, there is an optimum swim angle for achieving maximum depth. The eye position controls the ration of lip forces to body forces, basically acting as a fulcrum or balance point. Effect of speed – if the dynamic effect on the lip and the body were the same, then the lure would always swim at the same angle and never blow out. But we all know that speed does have an effect on the lures that we build. The dynamic forces on the sharp edged lip build up faster than on the rounded shape of the back. So, as the lure increases in speed, the lure swims steeper in order to balance the two dynamic forces. when the lip reaches vertical, any additional speed will press on the lip and rotate the lure past the vertical. The effective area of the lip will be reduced and the force on the back of the lure will rotate it back again. The lure has now changed action and is porpoising or nodding up and down. The technical term would be pitching. What has this to do with hunting – Like I said earlier, hunting occurs at transitions. Here we have found the pitch/yaw transition. As the lure reaches this transition, the lure will occasionally ‘bob’. This disturbs the wobble action, replacing one of the side movements with a bob and this is what causes the change in direction. As the lure swims away from the line of retrieval, the angle on the inside edge of the lip become steeper. The steeper the edge of the lip, the more force is generated. The lure bobs and direction is changed back towards center. The lure always bobs on the steep side, so the lure always comes back to center. How do I build a hunter – simply build with a lip that is too long and no longer wobbles and has the porpoising action. Trim the lip back until the wobble action just starts and it should hunt. Dave