And Is It Accurate?
Those who are serious about catching fish use fish finders. But for anglers new to the sport, choosing the right fish finder can be overwhelming. And once purchased, newbies realize there’s a learning curve. There are a lot of controls and settings to master plus they must learn the nuances of the graphical display.
In other words, using a fish finder takes patience and practice—not unlike fishing itself.
That’s why it’s so important for those on the sales floor to understand how fish finders work. By providing accurate advice, they can steer the novice to the right device so there are no regrets once out on the water.
History of the Fish Finder
Sonar technology, which became more widely known during WWII, is what made the development of fish finders possible.
In 1948, the Furuno brothers commercialized the world’s first fish finder in Nagasaki, Japan. They were the owners of a small marine electrical company. It was a pen recorder that used special paper to record objects found underwater. It was easy to operate and a game changer for commercial fisherman. The company, by the way, still makes fish finders for fishing vessels plus ones for recreational boats.
In 1957, Carl Lowrance and his sons Arlen and Darrell invented the first consumer sonar device. The Fish Lo-K-Tor, more affectionately known as the Little Green Box, was designed to detect individual fish, making it ideal for sport fishing. It was compact, transistorized, and wildly successful. It was finally discontinued in 1984. Lowrance, of course, continues to be a leader in the field.
Fast forward to today and there are many companies that make fish finders. In addition to Furuno and Lowrance, notable brands include Humminbird, Garmin, Raymarine, NorCross Marine, and Deeper.
How Do Fish Finders Work?
At its essence, a fish finder consists of a transducer that sends and receives sonar signals (sound waves) and a head unit with a display. The head unit acts as a computer to interpret the bounced signals and convert them into a variety of graphics. Among other things, these can show fish, vegetation, and the bottom. Castable fish finders have a wireless transducer that rests on top of the water. They use Bluetooth to connect to an app on a tablet or smartphone instead of a separate head unit.
Learning how to interpret the displays and use the various kinds of sonar signals is up to the angler. Although there are similarities across all brands, each manufacturer has one or more proprietary technologies and terminologies.
What is a Fish Finder Transducer?
Transducers send and receive the sonar signals. The shape of the signal pattern is a cone, with the narrowest up by the transducer and the broadest when it hits bottom. The return time and strength of the received signal is what the head unit uses to create its images. But there are different kinds of signals sent at varying frequencies and cone angles. Cones can range from 9° up to 60°. For example, low frequencies have large cones, can go deep, yet have low resolution. Higher frequencies are narrower, work better in shallow water, and have high resolution. A single transducer may have just a single beam for a single cone, or multiple beams for multiple cones.
That’s why a fish finder with multiple imaging technologies is more expensive—more signals to send and receive plus more signals to decipher, knit together, and display.
Types of Fish Finder Sonar
The kinds of marine sonar technologies used in fish finders today is quite impressive. Small wonder new anglers feel overwhelmed when trying to decide which fish finder to purchase!
- 2D Sonar. This is the oldest, most basic one still being used. It is single frequency and has a circular beam.
- CHIRP (Compressed High Intensity Radar Pulse) Sonar. This upgrade to 2D uses both high and low frequencies for a more complete picture. It too has a circular beam.
- Down Imaging Sonar. This has a rectangular beam. It’s narrower and provides more detail.
- Side Imaging Sonar. Instead of pointing down, this points off to the side, on either side of the boat. The scan is fan-like and angled. It has a wider field of view than down imaging and requires the boat be in motion. It will pick up structures like weed beds, rocks, and trees. But it’s not the best at picking up smaller objects.
- 360° Imaging Sonar. Instead of pointing in a single direction, the transducer rotates 360°, scanning all around the boat. This is ideal for use in relatively shallow waters so anglers can see what’s around them in terms of structures and fish.
- Live Sonar. This is a hot technology known in some circles as “video game fishing.” It shows continuous, updated sonar returns in real time. This means anglers can see how fish react to the bait as it happens. As exciting as that is, live sonar is not ideal for scanning large areas to find fish.
- Front/Forward-Facing Sonar. This shows what is in front of the boat in a live view. A special transducer is usually mounted to a trolling motor.
Types of Fish Finders
Fish finders are available in different types and mounting styles.
- As mentioned earlier, the transducer of a castable fish finder sits on the water. They are app-based so the display is a user-provided smartphone or tablet. They are ideal for those who fish from the shore or from extremely stable boats.
- Boat-mounted fish finders are what many of us view as typical fish finders. The transducer is mounted to the transom while the control head is mounted by the helm.
- Hull-mounted fish finders place the transducer either in the hull or through the hull—a more permanent type of mounting.
- Portable fish finders are designed to be mounted and removed every fishing trip. They tend to be easier to master because they provide more basic information. They are far less expensive than typical boat-mounted ones. They’re also not quite as precise.
- 3D fish finders turn 2D sonar data collected from a side imaging transducer into a 3D image using a special software algorithm. It more clearly shows how fish relate to structure.
- Chartplotter fish finders, in addition to sonar, also have more advanced mapping that works with uploaded lake maps that cross-check with actual GPS positioning.
- Networked fish finders. These high-end devices are designed to handle multiple data sources. Many even have Bluetooth and WiFi capabilities.
- Ice fishing flashers work in real time with live sonar so anglers can see the interplay of lure and fish unfolding under the ice. And cone beam is straight down—ideal when fishing from a hole in the ice.
So, as you can see, additional features can include GPS, navigation software, charts, live mapping, and so on. Plus, there are even boat-specific fish finders for bass boats, utility boats, pontoons, kayaks, etc.
How Accurate are Fish Finders? Preconceptions and Mistakes
Fish finders are very accurate. Even the least expensive fish finder will provide helpful, basic information, just at slower processing speeds.
But first-time buyers can get frustrated. And it’s because they bought one without understanding the technology.
Problems include:
- Failing to understand which transducer cone beam angles are best for what the angler is trying to discover and therefore buying the wrong fish finder
- Mounting the transducer incorrectly
- Buying a unit with the wrong wattage. If the angler wants fast and deep readings, high wattage is paramount. If fishing will be in shallow water, a low wattage unit is better.
- Buying a too-small screen or one with poor resolution
- Failing to learn how to use and interpret what is show on the display
- Not tuning the fish finder’s sensitivity—it’s not necessarily set up right out of the box
- Assuming the preset settings are adequate. Just because something is preset, doesn’t mean it’s the best it can be. The new angler needs to take ownership of what the new fish finder can do.
- Buying the least expensive one only to discover it can’t address how the angler plans to fish
- Buying “the best” only to be too impatient to master all the bells and whistles
- Purchasing a unit that doesn’t have the needed water resistance. For example, JIS/IPX 4 should not be used in a kayak. Check out this blog for a deeper understanding of IP, JIS, and ATM waterproof ratings.
Be Proactive on the Floor to Prevent Problems
The above concerns must be addressed BEFORE a sale is made at the store. Floor staff must ask key questions about where it will be used, the type of boat the person has, and the style of fishing the angler prefers. They must also understand the different types of sonar, which cone angles are best for different kinds of tasks and depths, how the head unit displays work, and so on. They must be able to explain, in layman terms, the various brand-specific features. And, if the store carries more than one brand, they need to intelligently compare and contrast.
We suggest you also read our blog “Fish Finder Buying Guide” for a slightly different perspective.
Gone Fishing. Catch You Later!—Fishing is big business in the USA
Is it worth carrying fish finders? Absolutely!
According to Statista, “fishing is one of most popular outdoor recreational activities in the United States.”
In 2020:
- 52.4 million Americans (17% of the US population) fished in freshwater, saltwater, and engaged in fly-fishing activities—that’s the highest participation rate in over a decade
- 11.5-billion-dollar market size
- 17% took solo fishing trips
- 49% fished at the shoreline
- 39% fished 4 to 11 times a year
- 44% released what they caught
In addition, fish finder sales are on the rise. This 2023 report indicates sales in both the commercial and recreational markets are growing at a steady rate. It projects multimillion dollar sales by 2029.
If you’re interested in learning demographic information on those who fish, the American Sportfishing Association has a 2022 Special Report you can download.
Needing to source fish finders and boating accessories at wholesale prices? Check out Petra’s extensive lineup here.
And if you’re not yet a Petra customer, be sure to sign up!