How Does a Fish Finder Work? An overview of important features

By Wade Johnson

How Does a Fish Finder WorkBasically, a fish finder is an important electronic device that provides ease in maximizing the fun and efficiency of any fishing trip.

It is mainly used for either of these fishing activities, leisure fishing or commercial.

Whether you consider yourself as a seasoned fisherman or a novice, you would have probably heard about fish finders or maybe even used them.

Well, the interesting thing is that even most people that use these devices don’t really understand how they work.

The hard reality is that the fish finder manufacturers do not perform a better job in educating their customers, and to many out there, the internet is full of myths and bad info.

If you are curious to understand the basics of your new fish finder, this article will surely help you understand how a fish finder works.

Types of fish finders

Well as a matter of fact, In most cases, one fishfinder differs from another to a great extent. You would find a lot of various kinds of fish finders, with different features. The type of fishing you will be doing will help to determine which of these functions you will possibly be looking out for.

So, If you are fishing in the shallower water, you will definitely need a device with a higher frequency (around 200 kHz). The thing is that higher frequencies work best in shallower water, and they give you a high level of detail as well. Plus, they send out quite a number of waves and pick up smaller objects in the water around you.

Whereas, If you are fishing at a greater depth, you will want to look for a device with a relatively lower frequency. As lower frequencies can easily travel greater distances, so if you are fishing deep, this option would be much better.

How exactly does a fish finder work?

Let’s have a brief overview of what fish finders are and what exactly they do. So, these fancy fishing accessories are usually made up of two parts – a computer/display that is properly placed in the boat or an angler kayak if someone has a portable one, which then shows potential fish and their depths, and also a transducer, which further includes an underwater sensor that sends back information up to the display.

The display of a fishfinder is just like a normal screen display with basic computing power that takes the raw data from the transducer and converts it in an easily understandable way. The interesting thing is that transducer is the piece that does all the work.

Now, the transducer sends sonar waves or in simple terms sound waves down into the water. Whenever the wave hits something, it immediately estimates the depth and size of the object and then sends that information back to the display.

These machines are meant to locate fish to assist in sport fishing, but the problem is that sonar waves do not discriminate, so any object will be picked up and displayed on the computer unit. Hence, you would be able to locate fish using a fish finder but you’ll also be able to locate other stuff like rocks, logs, shallow waters, and other hazards.

An overview of some important features of a fish finder

Display Screen

Most of the fish finders come under sizes from 4 inches all the way up to 16 inches. If you can easily afford it, Considering a bigger screen would be the best way to go, so long as you have access to the sonar features you want.

The larger the screen size, you can just simply view more information at one time. Well, A 5-inch screen is generally considered hard to view both the sonar and Chartplotter side by side, but it looks perfect on an if it’s 9 inches or even larger screen. Also, some are Side Imaging fish finders and some are down imaging fish finder but both can be experienced with a screen on any fish finder, it’s just that some have one and others have the second one.

Chart plotters and GSP

If your fish finder has a GPS facility, it will chart your position and track on top of a map. Most well-reputed fish finders in the market today use an internal GPS receiver, whereas an external receiver can also be used to showboat position heading direction even if the speed is very low.

Most experienced fishers would know that a good GPS with a lake map is a very useful tool for fishing. It is great for purposes such as scouting for fishing areas, navigation, and for providing ease of waypoints which helps to return to those exact spots at a later time.

New models of fish finders have special software that enables an angler to create custom maps of unmapped waters by simply using whatever transducer is hooked up to the device. All it requires to do is idle over an area in a crisscross pattern, and the software automatically builds the map. It’s not less than magic watching the bottom contours come to life as you proceed.

Networking the fish finder

Experienced and serious fishermen will have more than one fish finder on the boat, one or two at the console (steering wheel), and another at the bow where casting takes place. Well, this is possible by networking with the fish finders.

It depends on the fish finder brand and whether units can be networked directly between themselves, or with a hub. Where Humminbird uses an Ethernet-based system, Lowrance and Garmin use NMEA2000 based system.


Before you start making use of this fishing device, it would be better to read the manual. It will provide you ease in understanding how it works and that will definitely make it easier for you to use, facilitating you with a successful fishing trip. Also, note that fish finder devices vary in size and description.

Wade Johnson
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