Anglers have been pursuing fish for centuries. During that time, the sport has seen numerous changes in both equipment and tactics. Bamboo poles have been replaced with state-of-the-art graphite. Rudimentary reels have given way to those made from some of the same materials used in spacecraft. But without a doubt, one of the biggest advancements has come in the form of electronics used by many boat-owning anglers.
Depth finders used to consist of a string with a rock tied to the end. Anglers could find certain depths and relate to those areas. Still others had the notion that, “I’m on the bottom when my line quits going out.”
Yesterday and Today
But the use of sonar as a depth and fish finder began to take off in the 1950s after Carl Lowrance and his sons, Arlen and Darrell, began scuba diving to observe fish and how they relate to their surroundings. What they found was similar to other studies concluding that 90 percent of the fish could be found in 10 percent of the water on freshwater lakes.
Although primitive sonar units were in use at the time, they were large and cumbersome. They used vacuum tubes that required the use of car batteries for power. Lowrance and sons set out to build a better mousetrap that was more compact and that would detect individual fish.
The first “Little Green Box” was introduced in 1959 and quickly became the most popular, transistorized sonar in the world. More than a million of these were made and many older anglers remember them well, and likely owned one. They were discontinued in 1984 due to high production costs and outdated technology.
Over the years, the technology found in electronic fish-finding equipment has grown by leaps and bounds to the point where it’s almost hard to keep up – from global positioning systems (GPS) that use satellites to chart courses and find specific locations, to mapping instruments capable of guiding anglers around any body of water.
Choosing Your First Depth Finder
So where does a beginner start to look for a fish finder? After all, they’re now made by dozens of companies and they come in all shapes, sizes and price ranges depending on features offered.
First, it’s important to understand how sonar (an acronym for “SOund, NAvigation and Ranging”) works. The basic components include a transmitter, transducer, receiver and display. An electrical impulse is created by the transmitter and converted to a sound wave by the transducer and sent through the water. When the sound wave strikes an object, it rebounds and returns to the transducer, after which it is converted back to an electrical signal that is amplified by the receiver and sent to the display. The time it takes for the signal to return can be measured, since the speed of sound in water is constant at approximately 4,800 feet per second, and the distance to the object or bottom determined. This process is repeated many times per second.
Transducers come in many forms including ones that can be mounted on trolling motors, transoms or even inside certain boats in the bilge area to shoot through the hull. Trolling motor and transom mounts are likely the most popular, and provide the most consistent readings.
Each transducer is rated by the degree of cone angle. In general, a wide cone angle gives better results in shallow to medium depths while the narrow cone angle penetrates better to deeper depths but doesn’t show as many fish or as much structure due to its narrow beam.
Any sonar unit will send and receive signals and display the results on a variety of screens. Paper recorders used to be extremely popular but have been replaced by more advanced liquid crystal graph (LCG) versions that run a continuous reading without the need to change rolls of paper. While many of the early LCGs lacked the resolution and clarity of the paper graphs, today’s units now have that capability. Flashers (not the New York City kind), similar to the “Little Green Box,” were also popular as their display was instantaneous but showed only blips of red light and lacked the detail of the read-out friendly LCGs. Both paper recorders and flashers are still in use today but the liquid crystal versions are by far the most common.
Sonar units can cost anywhere from $100 or so on up to more than $1,000 – and everywhere in between. Options are available at additional cost including speed and temperature sensors. While it’s not absolutely necessary to buy the most expensive unit, in many instances you get what you pay for in quality.
Lowrance Electronics recommends that potential users consider four components in choosing a good sonar unit. They include a high-power transmitter, efficient transducer, sensitive receiver and a high resolution/contrast display. Each of these items is related to the others and must work together to achieve optimum results.
The higher the transmitter power the more likely a good signal will be returned to the unit. This is important in deep or poor water conditions. Additionally, the increased power allows the distinction of fine detail such as baitfish and structure.
Transducers should be matched to the units used, type and hull material of the boat and function in a reliable location. This is most likely from the trolling motor or transom area of the boat.
The receiver must be able to dampen extremely strong signals and amplify small signals in order to get an effective readout. It also has to have the capability to separate small targets that are close together into distinct, separate impulses for the display.
The end product as to what a fisherman sees must also be interpreted. The display must have a high resolution (vertical pixels) and good contrast to show all the detail crisply and clearly. Increased resolution allows small targets like fish and other fine detail to be accurately shown on the display.
In deciding on a unit best suited for your needs, visit with other anglers who have electronics and know how to use them. Ask what works for them and why they like a particular model or brand.
When it’s all said and done, a sonar unit will likely increase your fishing success if you learn how to use it and interpret what you see. That process may take some time, especially with the more advanced versions, but all the learning will be rewarded when you consistently feel the tug on the end of your line.