How Does a Fish Finder Work? – Complete Step by Step Guide

Every fishing hobbyist who uses either kayaks or boats must know this golden rule: A fishing rod isn’t the only thing you should focus on.

There is a vast range of essential gadgets, tools, and equipment that leads to a successful trip to the waters – one that yields tons of fish. One such gadget is the fish finder.

As the name itself reflects, it finds out the location of fish in the wide and deep water bodies. Along with making a fishing trip quick and fruitful, this device can be fun to use.

How Does a Fish Finder Work

If you’re also a fishing enthusiast, then you should definitely purchase one. It would save your precious time which is otherwise wasted when you pointlessly go around a river or lake in search of fish.

If you haven’t come across this device before, using it can be a bit tricky and confusing for you. So let’s find out what a fish finder is, How does a fish finder work, and learn how to use it.Contentsshow

What Is a Fish Finder?

Used to spot and locate fish beneath the surface, the fish finder isn’t exactly a new electronic gadget. It was first manufactured in the city of Nagasaki during the late 40s.

The early forms of the fish finder were quite heavy and huge. Also, they weren’t as advanced as they are today.

What is Fish finders

They did provide beneficial information like how deep the water body is or where big schools of fish could be found beneath them. Still, they could not spot each fish separately.

Modern versions of this device use various technologies. Some are equipped with a compass or radar.

Others may even use GPS, Bluetooth, and Wi-Fi facilities. But the basic technology which is found in all of them is SONAR.

With the help of this system, the fish finder delivers a graphical picture of the sea or lake. It shows what’s below the surface as well as underneath your kayak or boat.

This way you merely have to descend your line when you come across a fish without further ado.

How Does It Work?

As mentioned above, the foundation of a fish finder lies in SONAR technology – a contraction of Sound Navigation Ranging.

This system utilizes sound waves to locate fish and other marine animals living under the water. It also shows weeds or plants which may act as an obstacle in your way.

fish finder

When these sound pulses released through the device hit an object, they are bounced back to the surface. The sonar uses the phenomenon of echolocation which commonly occurs in nature too.

Animals like whales, bats, shrews, and dolphins use this magnificent ability to sense food and enemies. The sonar, however, utilizes it for a slightly different purpose.

It calculates the total amount of time that the sound wave took to travel to the object and back. This facilitates it to evaluate how deep the object lays under the water.

Components of a Fish Finder and Their Functions

Nowadays, the fish finder holds major significance for fishermen – regardless of whether they’re professionals with years of experience or amateurs who use fishing as a pass time.

As such, understanding its structure and components is essential to use it properly.

Two key components make up a fish finder: A display screen and a transducer. They work in collaboration with each other to display crucial details regarding both the fish and the surrounding areas.

1. Transducer

With the boat, kayak, or ship that you are aboard coming to a transmitter. It is usually kept underwater and utilizes the SONAR technology explained above. It releases sound waves (also known as pings in this case) across the lake or sea.


These sounds are created by the conversion of electrical signals. For this purpose, minute crystals are used, which vibrate at diverse frequencies according to their size and shape.

The width and depth of the resultant searching cones are decided by these frequency values as well.

Such sound waves are bounced back as a result of impact with a fish, plant, or the bottom of the water body itself. They are then received by this device.

The transducer then changes these echoed sounds into electrical impulses or signals again. These are then delivered to the next component which is the display.

But before that, it estimates the depth of that object beneath the water body. This is to find out how far is it from the fisherman and the boat or kayak they are riding.

Here you may wonder how the transducer differentiates between sound waves echoed from various objects. The answer lies in its working mechanism.

To get an idea of what kind of object it bounced back from, it calculates the strength of the reflected wave. If it is strong, that means the object is tough and sturdy.

2. Display

Also known as the head unit, the display could be considered as the mind of the whole device. The display receives electrical pulses relayed from the transducer.

With the aid of these, the points where the fish or whatever object the waves hit are shown on the screen.

display of fish finder

This unit contains all the electronic tools and software programs required to infer the received information. Most importantly, it has a screen where images are visualized.

What’s smart about the head unit is that it illustrates each wave differently, depending on what sort of object it reflected off of.

This is because waves take up shapes and sizes, each unique for the thing they hit. In this manner, the fisherman receives a clear idea which object (fish, plants, weeds, or stones) is where under the water.

Fish are represented as symbols similar to themselves, while for other obstacles, special signs are used. This is done to ensure there is no misperception at the fisherman’s end, and they don’t mistake an obstacle for a fish.

Moreover, when there is an abundance of fish in the area, the screen demonstrates arches. This brings the fisherman’s focus to the fact that now’s the right time to descend the line into the water.

The screen of the head unit can be of either Liquid Crystal or Cathode Ray Tube kind, depending on the model of the fish finder.

From super-compact and basic to massive and high-definition ones, modern displays can have a vast range of screen types.

Bigger ones have extensive characteristics like touchscreen and are therefore expensive, but little ones also perform fine.

How to Read a Fish Finder Display

To use your fish finder, you must know how to interpret what’s shown on the display. It may not be simple for you in the beginning, yet it’s not impossible either.

Fish Finder

Firstly, you should know that this device utilizes colors to represent the information it collected regarding the water body and the objects in it.

If the screen shows something dark, it means the wave has bounced off of a heavy and tough object, and vice versa.

This is because such objects make echoes with higher strengths. The end of the sea or lake would be represented using the darkest shade.

Installing a Fish Finder

Installing most versions of this equipment is an easy job. Even if you aren’t technologically sound, you can fix this device on your own.

fish finder install

You can find a wide array of fish finders in the market that is compact and portable. So you don’t need to put in extra time and effort to set it up – just switch it on and it’s ready to use.

You can even invest in handheld ones that are equipped with a basic suction cup. This cup eases the task of fastening the fish finder to your ship or kayak.

However, if you don’t have a smaller one, you don’t need to worry. You may simply set it up from the land. Larger versions of fish finders come with mounts that can be connected to your ship or kayak.

You can fix the device inside the mount easily. Just keep in mind that the power cords extend properly to the place where the main connection supply is located.

Types of Fish Finders

When it comes to types of this device, there are quite a few. Various brands release their own patented versions with distinctive features to stand out from their competitors.

Each of them uses advanced systems and technology to enhance the reach of their sound waves and to deliver the collected information in a better, more user-friendly manner.

The most famous manufacturers of this device are Lowrance, Humminbird, and Garmin. Their costs may differ depending upon what they offer. However, the cost of an average fish finder typically begins from 100 bucks.

Are Fish Finders Useful?

The most basic purpose of the fish finder is, as the name suggests, to aid the process of locating the fish. Fishing-specific sunglasses are also available in the market.

However, fish finders are a much better way to spot the fish – especially if you plan to catch plenty of them. They are suitable for water bodies of all depths.

They even sense the depth of the water body. This comes in handy to get an idea of what sorts of fish may be swimming at which level.

Some of these devices are power-packed with a GPS as well. It tracks your location and keeps a record of that, so it’s easy to visit the same area on your next trip. We would say these features are quite useful!


A fish finder should be a crucial part of your fishing equipment if you want to succeed in fishing, regardless of whether it’s your hobby or a profession. We hope that the in-depth information in this article about the workings of a fish finder helps you buy and use one!

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