A fish finder is a device used to detect fish school, location, and other underwater objects using sonar technology. You might be wondering how this device works to detect fish underwater?
The device has a color screen that displays results from the sonar signals and converts them into various dots and arches, which indicates the object underwater.
The anglers can use these signals skillfully for fishing. Fish finder devices have many more features that will get thousands of benefits while fishing if you use them.
You will get to know many things through the fish finder like depth, water temperature, bottom consistency, the estimated size of fish, and a lot more.
This article will focus on how does a fish finder work. So, you will get to know the mechanism of your desired device.
How does a fish finder work?
A fish finder has two parts which are the transducer and the main processor and display. The processor receives information from the transducer and converts it into signals which are displayed on the screen.
The transducer comprises piezoelectric crystals. These crystals vibrate at a certain frequency to emit sonar pulses down into the water. These pulses come into contact with certain objects underwater and reflect the transducer.
With this process, the transducer receives signals and sends them back to the main unit. Thus, the main unit interprets the data.
The fish finder detects the location and the shape of the fish based on the power of the returning signal. This operation repeats dozens of times per second to upgrade the signal result and come by a real-time image of what is going on in the sonar cone.
Sonar signal details are interpreted, and the result is displayed on the fish finder screen. The result obtained from the sonar signal depends on the frequency of the pulses too. Hence, many fish finders use different frequencies at the same time to acquire additional data.
One question might come up in your mind if you can use your fish finder out of water.
No, you cannot use it without water. But, you can use it through the ice, which is an amazing feature of the fish finder.
Types of fish finders and how they work
In this article, we will have a detailed discussion on how fish finders work. Before that, you need to know the types of sonar technologies used in a fish finder.
We have 3 types of sonar technology which are:
- 2D sonar
- Down imaging sonar
- Side imaging sonar
Let’s take a tour of the details of the types of sonar technology.
2D sonar
2D sonar technology includes CHIRP sonar and is used in traditional fish finders. The conventional 2D sonar technology fish finders have a round shape transducer that emits the sonar signal expanding into a rounded cone. This expanding round cone signal collects data from a large circular area beneath the boat as it makes its way down through the water.
Down imaging sonar
The newest fish finders use mostly down imaging sonar technology. This technology has a thin rectangular transducer.
Besides, this narrow transducer emits a thin sonar beam straight down to the water to gather data. Down imaging sonar technology displays a bunch of information acquired from a short cross-section directly beneath the boat.
Side imaging sonar
From the name of the technology side imaging sonar, we already understand that this works from side to emit signals.
Side imaging sonar technology sends the signal in the direction of both left and right sides to gather more information about the boat’s surroundings.
2D vs. down imaging vs. side imaging sonar
Each type of sonar technology has its advantages and disadvantages. We will make some comparisons to each technology now to have a better idea of the mechanism of fish finders.
From the above section, we all know that 2D sonar has a round shape transducer, which is excellent for searching the area beneath your boat. But if the object’s outlines are blurred, undefined, and downy, then 2D sonar cannot define the thing in detail, confusing the angler.
As down imaging sonar pivots directly downwards of the boat in a narrow area, it helps get exact data of what is underneath your boat. Besides, it can easily spot structures such as game fish lying on the bottom.
2D sonar cannot detect such objects. But down imaging sonar has its disadvantage too, as it cannot detect objects of the broad picture. It will only obtain data on what is exactly beneath the boat. And it detects a very narrow area which is not enough for a general overview.
On the other hand, a side-imaging sonar will give an excellent overview of a large area around you, both the right and left sides of your boat. You will easily detect objects like weed beds, sunken trees.
But the drawback is it cannot detect small objects like fish which is the main objective of a fish finder. You can measure bottom consistency with side imaging.
So, with this comparison, we get that this no sonar technology is complete and perfect. The best way is to combine all the 3 technologies to have the best result in fishing. Now, many fish finders are including all the 3 technologies together in their device.
But it would be best if you learned how to use all the sonar technologies to shift your fish finder to any technology, get the required information, and improve your fishing.
What is CHIRP on a fish finder?
CHIRP stands for Compressed High-Intensity Radiated Pulse, which is a bit new in the sonar technology city.
Traditional 2D sonar transmits one frequency at a time. But CHIRP uses different frequencies range at a time to get more detail. It can send both low and high-frequency signals.
Fish finder batteries
Fish finders rely on batteries. It transforms electrical signals into sonar pulses sent to the water to detect fish and other underwater objects. So a suitable battery is a need for fish finders to charge them all the time and perform well in the long run.
Fish finders with GPS
GPS helps fish finders to perform well. Nowadays, many modern fish finder models thus use GPS in their devices. GPS will help you to navigate the locations on a map you want to sail.
Nevertheless, you can put GPS marking on specific locations to use as reference points so that you can detect fish schools easily. To identify particular fish schools, you can point to large underwater objects like wrecks or reefs with bottom consistency transition.
You can also create your customized water map using GPS. So, you can explore your locations more quickly.
Types of transducers & how they work
You can buy your fish finder with a transducer or without one. Transducers are of many kinds. So, you can buy it separately also.
Transducers are of many different frequencies. It would be best to choose which frequency you will need for your specific location and application. But you need to select the correct one. Because different water locations need different types of frequencies. Like freshwater fishing requires 50kHz to 300 kHz frequency for fishing.
In the above section, we already mentioned a difference between a traditional 2D sonar transducer and CHIRP. If you are to use CHIRP, buy one that covers your desired frequency for the specific location.
Transducer mounting style
As transducers are of different frequencies, so they have various mounting styles, too as follows:
In-hull
Some transducers can emit sonar through the hull. They do not need to keep in direct contact with water for that. The transducer is pasted inside the hull. Thus, double-check your transducer if it works or not with all types of a hull.
Transom-mount
Transom mount is the most common and typical method of transducer mounting. It works by fixing an adjustable bracket to the outside of the hull. It usually is near the back of the boat. This type of transducer works inside water.
Trolling motor mount
Trolling motor mount is attached to the side of a trolling motor. It can also be put into the propeller hub, allowing them to be inserted into the water.
Best Fish Finder Under $300 [Ultimate Buyer’s Guide & Review]
Overview of the fish finder’s operating system
The transducer positioned on the boat’s bottom sends ultrasonic waves to the fish finder. The transmitted ultrasonic waves move directly in the direction of the seafloor, but they will be reflected by any objects in their path, such as fish schools or stones. A portion of them will reflect back to the ship’s bottom, where the transducer will pick it up. The depth of the fish school will be determined by timing the duration between ultrasound transmission and reception.
Final words
The fish finder is gradually becoming popular with anglers and water lovers. Technology has been developing progressively over the past few decades.
So, choose your fish finder model carefully. Modern fish finder devices now combine all the sonar technology like CHIRP, down imaging, side imaging sonar. This helps detect the whole surrounding of your water map, including fish and underwater objects.
Thus, a fish finder helps identify fish locations easily, which decreases the fishing time of anglers.
You will get plenty of options from high-end models to mid-one. Choose the best that serves your purpose well.
How to Spool a Spinning Reel
Ugly Stik GX2 vs Elite Compared (Know The Differences)
Penn Fierce vs Battle
9 Best Flip-up Scope Covers in the Market 2025
Best Jigging Rod for Walleye 2025 (Buying Guide Included)