How Fish Finders Work and How to Use Them

By | July 23, 2017

Using an advanced fishfinder is quite easy. Using one to the max of its possibilities, however, takes some experience. The more advanced fish finders with big color screens and with all the imaginable possibilities are essentially small computers with specific software developed particularly to show the user what’s going on under the boat. Not all fishermen are technologically experienced, so it’s no wonder that many people don’t fully grasp the fish finder basics. I have met people who has a $1,000 fish locator but really doesn’t know how to use it appropriately.

If you have not used a fish finder before, you are going to be puzzled and perhaps annoyed discovering some strange waves and lines all over the display. Sure, you’re probably thinking what a waste of hard-earned money. Well don’t throw it into the water quite yet. Fish finders will call for some knowledge to genuinely learn how to read and understand these waves and curves on the screen.

First of all, fish finders function together with a transducer. They send out so called pings or sound waves and that creates an echo-effect when it hits obstructions and bottom unevenness below the water. The velocity, rate, length and such things are calculated and then translated into an image on the finder’s view screen. The impulses received are shown as thick colored lines on the display at various depths that offers the place of the fishes depending on where it shows up on the display. There really isn’t much to it. Go out to the river, turn the device on and see for yourself.

There are several types of fish finders and we realize that there may have some dissimilarities reading them since they have varied capabilities. Let’s proceed with the most common and well-known types of fish finders.

GPS & Chartplotters
If your fish finder has GPS functionality (some have, some don’t), it can chart your location and show that on the same screen. Many fish finder models have an internal GPS device, but an external GPS can also be used to show boat location and route. In fact, a GPS working together with a lake map is a more useful tool than one may believe at first. It is fantastic for easy navigation, searching for fishing spots, and for doing waypoints so you can return to these hot-spots next time.

How to Read a Fish Finder Using the Color and Echo Return Strength
A fish finder can come whether in color or black and white. Whichever choice you have, you ought to be capable to read it thoroughly. We have founded the point that the transducer obtains echo signals that are translated on to the screen. Usually, the more powerful the echo signals, the stronger color is showed.

See the picture on the left, you will see two different layers – a dense red wave line that signifies the bottom of the river or a lake.

Just right after the thick red line is a green part that signifies a soft area like clay. When echoes hit a tough bottom, it comes back as a strong signal and weak signal when it hits a soft region. A very hard base will have just a single dense line and nothing beneath it.

Usually, you can see the water temperature just below the depth reading on the screen. This is also practical for finding certain species of fish, as some favor warm water and others live off better in cooler environments. Working with just these two functions, you can already start looking for fish and learning about the various environments different types of fish like.

Another useful thing found on most fish finder displays is the speed sensor. The speed sensor displays how fast you are moving, kind of like a speedometer right there on your fish finder.

Essentially, most fish finder show the sonar waves it obtains from the transducer as lines and curves. Some of the most recent models are even able to transform this info into a more detailed visuals, with crisper graphics and detailed data. This means some more expensive models can even show actual fish on the screen and even their sizes. The disadvantage can be that the data is always not accurate, but it sure is easier to understand what is going on under the boat.

How to Read Arch Fish Finders
Another way of showing the information on the screen is to show the details it gets from the transducer are shown as arch and lines and its left for the fisherman to translate it, a good example of why having at least basic understanding of how to read a fish finder is necessary.

When it obtains the returned sonar waves from a moving thing, it is shown as a curve (arch). Because fish and other creatures move in water, a fish will certainly be displayed as a curve while other fixed things will be displayed as a line. Basically, the bigger the curve, the bigger the fish on the screen. Items such as plants and rocks may be quite a job to separate out, but arch fish finders are easily one of the most effective and precise fish finder you can have.
Once you start figuring out arches, you may even be able to identify the fish based on their size and position.

Fishfinder/Chartplotter Combos


The picture above is of a Simrad GO7 XSE display fishfinder and chartplotter in one device – a genuine state-of-the-art in marine technology. With the greater display area, you can break up the view into two – looking at sonar readings on the right and navigational charts on the left. You can even put together the two views by marking viewpoints at spots you want to come back to. This can certainly make it easier to find fish below the water.

And there’s more, some models come together with a chartplotter, Bluetooth, Wi-Fi and a GPS. With this sort of capabilities, you can never have a boring moment during your fishing routines.

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