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The Science of Bibbed Minnows

ONE of the most popular lure families is that which we generally call “bibbed minnows”. These lures are also known as “crankbaits” in the  US and come within  a broader group of lures known as “hard bodies”. Bibbed minnows can  be made of either timber or plastic. They can be hollow or solid and come in a huge range of shapes and sizes,  but are all governed by some common physical characteristics.

Bibbed minnows are so named because they have a plastic or metal “bib” or lip on the front end of the lure. This bib is critical in influencing two main characteristics of the lure: the type of action the lure will have and how deep it will run. 

Here’s an explanation of how bibs work. The lure’s bib creates resistance against the water when the lure is being retrieved or trolled. Through a combination of physics and design, the bib attempts to reduce the resistance. The shape of the bib is the main thing that influences the action of a lure. If you can imagine in slow motion, water pushing against the face of the bib with resistance building until it exceeds the capability of the bib to hold it, forcing the bib to angle out  to one side and the pressure then “sliding” sideways off the face of the bib.
With the pressure relieved the lure attempts to return to its original position. Again, through physics and design, the force of the returning bib slightly over corrects, forcing the building resistance to slide off the opposite side of the bib. This constant correct and counter-correct movement is the lure’s “action”. Generally, the narrower the bib profile, the “tighter” the lure action. A tight action is where the lure’s side to side or rolling action is quite rapid. This is because the narrow surface area of the bib sheds  the pressure quickly and counter corrects quickly. This tight action creates a “shimmy” effect that looks like a small fish swimming at speed. Because these bib shapes offer minimal resistance, the action allows for quite quick retrieve or trolling speeds. Wider bibs provide greater resistance and have to move further in order to shed the pressure. This creates a wider “wobbling” action, which some fish, like freshwater  natives, find irresistible. The downside of these wider bibs means they are less capable of handling higher speeds.
Depending on the quality of lure design, once the speed exceeds the bib’s capabilities to handle the pressure,  it is more efficient for the lure to spin  or come to the surface than it is to continue to correct and counter correct. This is often referred to as a “blow-out”. Lesser quality lures are often prone to this as they simply don’t have the design tolerances built into them. 

The angle and length of the bib are the main things that determine how deep the lure can dive. Lure bibs are generally angled anywhere between horizontal and vertical. The depth capability  of the lure increases as the lure bib  angle moves towards the horizontal.  Again, through physics and design, this happens because of the water pressure pushing on the bib. When the lure is stationary there is no pressure on the bib and the lure sits in its natural state. As the lure moves the water pressure increases; because the bib is putting  up the greatest resistance, it is forced downwards towards the vertical angle to try and relieve the pressure. The bib is actually trying to go beyond vertical to allow it to shed the pressure. The force of the line attached to the lure prevents this and as such a point of equilibrium is reached once the force  of the line pulling on the lure and  the pressure of the water on the bib counteract each other. This becomes the lure’s tracking depth.

It’s also worth noting that line diameter can also influence lure depth. The finer the line diameter, the less resistance and the more it allows the lure to dive before equilibrium is achieved.

The location of the attachment point for the line will also influence the  action and diving capability of a lure. The further down the bib the attaching point, the more the line pressure helps  to control excessive counter correction, preventing lures from blowing out. It also forces the lure to try and dive “harder” to overcome the line force, which can cause a lure to dive deeper.

Bibbed minnows are designed to either float, sink or suspend, regardless of their bib design. This means that in their non-retrieve state they will do  one of the previous, each with its own advantages and disadvantages. Floating lures allow you to “float” your lure through structure by stopping your retrieve. While retrieving, your lure is diving to its tracking depth. When confronted with a snag or obstacle that is shallower than the lure is swimming, you simply stop winding and allow  the lure to float over the obstacle before recommencing your retrieve. This upward floating action can often stimulate an attack response from fish.

Sinking bibbed minnows allow you  to “sink” your lure down to a desired depth before commencing your retrieve. You should note that sink rates are  often quite slow but good quality lures provide you with a rough indication of sink rates. For example, your lure may be labelled as having a sink rate of 5cm per second. You can use this knowledge to sink your lure down a vertical structure where you suspect fish are hanging deeper before starting your retrieve. A floating lure, even a deep diver, in the same situation may be too far away from the structure before it reaches the “strike zone”. Strikes will also often come as the lure is sinking before you start to retrieve. The “countdown” method allows you to calculate at what depth the fish are holding and feeding.

Suspending lures are intended to hold their depth when you stop retrieving. However, truly “suspending” lures are difficult to make and most either very slowly float or sink. They are still called suspenders as the rate is so slow that  it is almost negligible. Suspending lures allow you to “hang” a lure in front of a fish. This “hanging” action is often irresistible to a predatory fish.

The design work and technology that goes into lure design is significant. Good quality lures cost as much as they do because they are constructed for superior and consistent performance. As with all fishing equipment, buy the best that you can afford.

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