How Does a Fish Finder Work

A fish finder is a fishing instrument used by anglers to detect fish underwater. The fish finders have a unique operating system that displays the activity beneath and around the boat. The modern-day fish finders come with the fish finder.

How does a fish finder work? Many traditional fishers don’t understand the basics of a fish finder. This comprehensive guide will help you know and how to read them. This article will help you to understand the working process of a fish finders and also helps you in reading them.

Kiyaotaka and Kiyokata Furuno invented the technology of detecting fish underwater in 1948. There are different models of fish finders like a flasher fish finder, ice fish finder, marine fish finders among others. Some models work on both deep waters and shallow waters. The fish finders manufactured by the fish finder, Lowrance, and Garmin are quite popular.

Parts of a Fish Finder

Before learning about the workings of a fish finder, you will have to learn about the integral components of a fish finder.

The Transducer

A transducer is the main component of the fish finder as it helps you to detect the fish. The transducer uses SONAR (Sound Navigation and Ranging) technology, which recognizes the object by emitting the signal. The signal then transmits the size, distance, and other data in the graphical form.

The primary function of transducers is to create an electrical wave and pass it through the water via a transmitter. The wave, when hit by an object, would bounce back and display the image through the display screen. The device calculates and provides information about the shape, size, and altitude of the object.

The accuracy of the length and weight depend upon the power and frequency of the fish finder. The fish finder transducer calculates the distance by reading the time interval between the wave and the received signal. The speed of seawater wave gets considered to be a constant of 1500 meter per second.

On the other hand, the constant of 1463 meter per second gets considered as the speed of the freshwater wave. Transducer comes in various sizes and technologies. Traditional 2D sonar uses round-shaped elements. The imaging elements are generally rectangular. The rectangular elements create the thin high-frequency signals that get used in imaging. The CHIRP sonars or the broadband sonar operate in a broader range of frequencies.

The work rate of the device depends upon how does a transducer work for a fish finder. The best fish finder is the one that has a powerful and advanced transducer.

The Display

The display is another integral part of a fish finder. The display screen provides all the information gathered by the transducer, including water depth, speed over water, temperature, and fish location and types, etc.

the fish finder come in different shapes and sizes. The bigger the screen, the more information is on display. However, smaller screen fish finders are more portable. Higher pixels and HD screen mean crystal clear display.

GPS and Chartplotters

The modern fish finders have an inbuilt GPS. The GPS enables you to track your location on waypoint maps and navigate around. Other features like the temperature, speed, depth of the water are also available. This feature makes fishing a pleasant and exciting experience.

The GPS on your fish finder can chart your position and point it out on a map. An internal GPS receiver gets commonly used. But an external receiver can show boat’s position and their direction even at slow speeds. A good the fish finder gets used for scouting, navigating, and making waypoints for future.


The modern-day fish finders come with connectivity options such as Wi-fi, Bluetooth, and others. These options enable you to connect with the device with smartphones, tablets, and other fish finders without the use of a cable.

How does a Fish Finder work – The Process

The basic working process of a fish finder is pretty simple. The transducer produces the sound wave or sonar signals and sends to the water. When this signal hits an object underwater, the sonar wave takes an estimate of the object’s size and the depth. It can be any object like a fish, a rock, or other debris. The sound wave then returns in the form of an echo. The information then gets fed back to the device. The device then creates an image of the activity beneath you in the water.

The higher frequencies give you a narrower Cone Angle that provides you with the image in great detail. On the other hand, lower frequencies provide greater depth penetration. The only downside is that the lower range has limited sensitivity. The corresponding image then gets displayed on the screen of the fish finder. You can interpret and execute the data on your own.

Multiple frequencies get used by the fish finder to give you a better view of the situation. Sonar waves are basically sound noises. This sonar wave can travel through water. The waves then bounce back once it hits an object. The object can be a fish, marine vegetation, or a rock. The word transducer means any device that converts energy from one form to another.

The transducer converts the DC(Direct Current) electricity into AC(Alternating Current) and then converts the ac into sound energy (sonar waves). The transducer converts power into sound energy with the help of tiny crystals grown in large labs. These piezoelectric crystals and are of specific shape and geometry.

The crystals get made up of barium titanate or lead zirconate titanate. These crystals are efficient at converting electricity into sound. The crystals grow or contract when exposed to electric currents. Alternating current gets used rather than direct current. The AC enables the crystals to expand, contract and vibrate rapidly.

This process ultimately produces sound. These crystals vibrate again creating sound waves in return. The transducer calculates the time taken by the sonar waves to travel to determine the distance. This information gets sent to the fish finder’s display, and the angler can interpret as visual data.

Detecting Fish through a Fish Finder

Reading a fish finder is not as hard as it sounds. The fish finder provides us with an approximate estimate of the depth of water and the shape of the bottom. Fishfinder helps us in choosing the best lure, weight, rods, and fishing equipment. You can also avoid snags.

While the average fish finders work entirely giving you proper information about the fish and water depths. The advanced models are incredibly accurate and regularly updated. These devices can differentiate between the type of fish, along with providing precise fishing information.

The fish symbol feature of a fish finder helps to distinguish between fish, rocks, vegetation and other debris. The distance between the boat and the fish are continuously changing as the fish swims around. In such cases, a fish id symbol on the fish finder lightens up. The fish id symbol is that of an arch. Hence, you can easily distinguish between fish and other objects through the help of a fish finder.