From seasoned pros to greenhorn anglers, everyone goes through a learning curve when using their first fish finder. But don’t worry, I’m here to flatten that curve and get you on the fast track to understanding and using your fish finder effectively.
This guide will unravel the basics of fish finders, explaining how they work and how to read the screen. With this knowledge, you’ll be able to spot and reel in fish like a pro in no time.
How To Read A Fish Finder?
Firstly, we need to understand how a fish finder works. When you unpack your new fish finder, be it a Garmin or a Humminbird GPS combo, you’ll find a display unit with a screen, a transducer, and some cables.
The transducer, once connected to the power supply, sends sonar beams in the form of waves into the water. When these waves hit anything in the water column – be it underwater objects, the bottom, weeds, or fish, they bounce back to the transducer, which collects them.
The transducer continuously collects data about the return times of the sonar waves which are then sent to the fish finder screen unit. This data is transformed into a sonar image for you to interpret.
Understanding Sonar Wave Frequencies
It’s crucial to understand how a fish finder works. Many fish finders can send out different sonar wave frequencies ranging from 80 kHz to 1200 kHz. Low-frequency sonar waves don’t pick up as much detail as high-frequency sonar waves but they travel further and thus do not get absorbed by the water.
Higher frequency waves get absorbed by the water and thus cannot travel as deep but they provide a wealth of detail.
A top-notch fish finder will come with CHIRP sonar, which sends out high, low, and medium frequency sonar waves. This gives you a detailed image of every part of the water column.
Now that we’ve covered how a fish finder works, let’s dive into how to read a fish finder screen.
Understanding What You See On A Fish Finder Screen
This section will detail everything you’ll see on your fish finder’s screen when using CHIRP or traditional sonar.
Temperature, Depth & Speed
Modern fish finders come with a built-in GPS and temperature sensor. On the screen, you’ll see three different numbers – the depth of the water under your boat, your speed, and the water temperature. This information is crucial as fish behavior changes depending on these factors.
Identifying Fish On A Fish Finder Display
Chances are, you will be using an arch fish finder as most fish finders today are of this type. When you see an arch on your screen, it means there are fish under your boat. The size of the arch generally indicates the size of the fish – larger arches usually mean bigger fish and smaller arches usually mean small fish.
Judging Fish Size Based On Arches
Knowing whether you have just cruised over a big fish or a tiny fish is invaluable information. The way to determine fish size from an arch is by looking at the width and length of the arch. If the arch is deep along the vertical lines, it’s a solid mass that is reflecting the sonar waves, indicating a large fish worth trying to catch.
What Are Half Arches?
Sometimes, you will see a fish arch that looks like it’s been cut in half. This is still a fish but it means the fish only swam through part of the sonar cone. A half arch could even be a sizable catch, so don’t dismiss it.
Using Fish ID Technology
Some fish finders come with Fish ID technology. Fish ID takes arches and turns them into fish icons on the screen, marking each fish with a depth so you know how deep it is and its relative size. Using Fish ID is a great way to learn how to read arches.
Spotting Baitfish On Fish Finders
Baitfish are displayed as small dots, dashes, or lines, usually suspended in mid-water. Often, baitfish tend to hold very tightly together in a ball and you will see them doing so in your readings too, like a big ball of tiny dots on the fish finder screen.
Understanding Different Colors
The stronger and darker the color you see, the stronger the reflection of the sonar waves received by your fish finder. This gives you an indication of the size of the fish or the hardness of the bottom.
Judging Bottom Types & Hardness
If you’re fishing over a hard bottom, your fish finder will show the bottom as a bold line in a deep, dark color. If you’re fishing over softer material like clay, the return will be weaker and you’ll see a light line in a lighter color.
Weeds & Vegetation
Weeds and vegetation will be displayed as vertical colored lines coming off the bottom. They won’t be in the form of an arch, so you won’t mistake them for fish.
How Do Different Sonar Beams Affect What I’m Seeing?
The beam you choose to use will affect what you see on the screen. A wide beam covers a large area but in less detail, while a narrow beam scanning will penetrate to the same depth but won’t cast as wide a net, thus picking up more detail of what is below your boat.
Traditional, Down, and Side Imaging Sonar Explained
Depending on the fish finder you own, you might have these three sonar scanning features to help you find fish. Traditional or CHIRP always scans under your boat using a wide beam and multiple sonar wave frequencies, giving you a full picture of the water column.
Down Imaging uses a narrower beam stuffed with higher frequency sonar waves to give you all the detail possible, perfect for getting a better look at something fishy.
Side Imaging scans on both sides of your boat, allowing you to see fish and structures that would have been missed using down or CHIRP. The image you see on side imaging is a little different and it’s best to think of it as a bird’s-eye view.
With these tips and tricks in your arsenal, you’re well on your way to mastering the art of reading a fish finder. Now it’s time to put these skills into practice and reel in the big ones! Happy fishing!
