How to read a fish finder

How to Read a Fish Finder

Written by Boatsetter Team
June 4, 2021

Gearing up for a fishing trip aboard a boat rental is about as good as it gets. Nothing beats rising at dawn and heading down to the water to get on the fish with your buddies. Whether you prefer freshwater or saltwater fishing, there is always a great challenge awaiting you. One of the great challenges of fishing throughout the years is being able to find the fish. Some of you will know all too well the days that you have spent out on a lake on a rainy day only to get back to the marina empty-handed.

Luckily, with the innovation of technology, you now can use a fish finder to help optimize your catch rate. If you’re a stickler for tradition, then there’s no need to worry as you don’t need to use one. However, we understand that some of you cannot truly enjoy a day out on the water without getting a bite, returning home disappointed, and longing for a fish to be on your plate. So, if you know this feeling, you may be inspired to start improving your fishing performance. The next step is purchasing a fishfinder or taking out a boat rental that includes a fishfinder on board. Here is a complete guide on how fish finders work and how to properly read one.

What is a Fish Finder?

fish finder is a sonar device that detects fish by picking out their location from their sound waves. A GPS-like system can read the bed of the water by picking up the shapes but cannot pick up the fish. Instead, chirp sonar can accurately find out where they are congregating by picking out the sound made from their movement. Modern fish finders incorporate sonar and GPS together to create a clear picture of the underwater environment. Popular fish finder brands include Garmin, Humminbird, and Lowrance.

Fish finders are built upon the same premises as fathometers which send down pulses to build a picture of the seabed. It does this by calculating the time it takes from the echo sound bouncing off the floor. This revolutionized boating by allowing boats not to take as deep a cation when traversing through unfamiliar waters as there were assurances that the boat would not run aground. It would build up a permanent picture of the seabed so that routes along waterways were better known to traverse the safest passage when used in the future.

By using the same technology, the fishfinder was created. The technology is now so accurate that not only does it pick up where the fish are, but it can pick out individual fish. From there, it can pick up the size, density, and shape of the fish. This allows for the breed of fish to be identified, which further enhances your fishing experience if you an angler targeting a particular species. The beams of a fishfinder can bounce down and back up again up to 40 times a second on the most advanced fishfinder platforms. This allows completely up-to-date and accurate readings, meaning that you can make your fishing the best that it can be.

Furthermore, fishfinder technology now has capabilities to read temperature and gauge pressure. This continues to improve the fishfinder’s ability to identify the precise location of the fish, thus helping you to improve your catch. The results that the fishfinder device picks up are displayed upon a screen for you to read.

Different types of fishfinders display different types of results and levels of detail. A trawler boat searching for prawns will use a lower frequency as they do not need to see the details of what the prawns look like. They need to know that there is a large group of them on the seabed to drop their nets and pick them up. Similarly, if you are out on the flats going after a tarpon, you’ll want to know the exact details of the fish nearby to get after the one you want so that you can fulfill the challenge you set out to complete that day.

What are the Benefits of Using a Fish Finder

Benefits of using a fish finder

There are various benefits to using a fishfinder. The foremost reason for using a fish finder is that it allows you to locate fish. However, it goes even further than this due to GPS technology being incorporated within it. By analyzing the floor of the water bed, you can build up a picture of its structure. This is great for working out the different environments that different types of fish like to gather so that you can target specific areas or keep in mind where to hit up next time you’re out fishing on that body of water. For example, reef fishing is a great method of fishing in saltwater. Various species of fish dwell around these reefs, and a fish finder will help you to identify where these reefs are so that you can return to shore with full bags!

One of the other great benefits of using a fish finder is that it is excellent for fishing in waters that you are not familiar with. If you are out fishing in water that you know well, you may opt not to use a fishfinder and instead try to hunt them by using your experience of the area to sense where they are, giving you a greater challenge. However, when you are in unfamiliar water, you may have no idea where you can catch some fish. This is what makes them so great; you won’t be making that long drive back home with nothing to show for it.

How to Identify the Fish

Now, when you first use the fish finder, you may suffer from a lot of initial confusion as to how it works and how you can read it. After you have booted it up, the first thing that you’ll want to know is how to identify a fish. Depending on the type of fish finder, fish may be displayed differently, but in general, they tend to be displayed either as archers or as icons.

Icon display screens set out what the fishfinder has identified on the display screen. The interface of the icon display is designed to help the user by showing what the fishfinder has discovered transparently. It identifies as tags the different things it sees and labels them as fish, plants, rocks, etc. Each object will have a different picture shown next to it to identify what is what quickly. So you merely need to identify what is on the fish finder screen and the depth that it is at so that you can target the area effectively. The drawback of this way of displaying information is that sometimes items are mislabeled, so at times, what is displayed a fish may actually be a plant or a rock.

The other way that fishfinder is displayed is through arches. Fish are displayed as arches instead of fish icons. They vary in size depending on how big the sonar wave has registered them. Although the screen is not as transparent as the icon fishfinder, the arch-based fishfinder displays the size of fish more accurately. They are a little bit more complicated to use, but once you get the gist of how it works, you’ll be able to read it quickly and catch fish quickly. This is because the arch-based fish finder can work out what is worth registering quicker and more accurately than the icon-based fishfinder. They are not as clear when picking up images of rocks and plants at the bottom of the water, but with time you’ll be able to work out the structures that this type of fishfinder creates.

Working out the Size of a Fish

You also need to be able to identify the size of a fish when reading your fishfinder. If you’re trying to catch a sailfish out in the sea, then you don’t want to be targeting mackerel by mistake. The general rule of thumb is that the bigger the arch, the bigger the fish. However, this is not always the case, and there are sometimes some issues surrounding this.

The length of the fish cannot be displayed on the arch system. However, you can work out a rough estimate of the fish’s size depending on how big the arch is. When looking at the arches, you shall notice that some of these complete full arches, and some are half arches. The thicker the fish arch, the more likelihood there is that the fish is bigger. Although this is the general rule of thumb, remember to bear in mind that even if an arch isn’t as thick, it can still be a big fish. This is because it may not be swimming directly underneath the sonar signal; thus, it cannot register its full size.

Some of you won’t be looking for the big trophy fish from the get-go; however, you may want to pick up some live bait fish or small fish beforehand to help you land the one you’ve got on your mind. Baitfish are tiny, so they won’t show up as a normal arch as the bigger fish do. Instead, they show up as small lines or dots. You may see these figures floating in the middle of the water. If you do, drop down your net to see if you can scoop up a bunch to help you to pull in a really big one that pops up on your fishfinder screen later in the trip.

Other Things to Note When Reading Your Fishfinder

Plants, reefs, and rock structures offer great places to target some species of fish. Due to some fish hiding within them, the fish finder is unlikely to register them on the screen. But if you learn to identify the structures that they may be hiding in, you can target them to lure them out. The fish finder will display vertical lines near the bottom to indicate these underlying structures and vegetation.

Final Verdict:

Reading a fish finder is something that anyone can read. It may take you a couple of fishing trips to get used to, but you’re bound to improve your haul and the size of your catch once you are used to it.


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