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When you’re looking to boost the amount of fish that you’re able to catch in a day, one of the most effective items you can buy is a fish finder. Fishfinders work using sound waves to detect fish locations as well as shapes and sizes (sonar). These sounds waves are transmitted into the water through the fish finder’s transducer.

Many of us who are new to fish finders will find ourselves asking “What is a transducer on a fish finder?” Hence, we aim to provide a clear understanding of how they work, what they are, and how they can benefit you as a fishing enthusiast.

What Is a Transducer Exactly?

When answering the question “What is a transducer on a fish finder?” it can seem more complicated than it needs to be. Essentially, transducers convert electrical transmissions sent from your fish finder into sound waves that are then emitted into the water. This information is then picked up by the sensors and displayed on your fish finder in the form of varying charts and images that depict the size, depth, and location of the object.

What Is a Transducer Exactly

Five Main Types

Transom Mounted Transducers

These are mounted to the transom of your boat directly into the water. These are recommended for planning hulls of less than 27 feet like a personal watercraft but don’t suit boats with large or twin-screw inboard motors since the increase in aerated water from the propellers dampens its performance as well as lowers the reliability of results.

In-Hull Transducers

Most commonly referred to as shoot-through, these are glued onto the side of the hull. You’ll only find these on fiberglass hulls due to the manner in which they operate.

These transducers work by transmitting and receiving the signal through the hull of the ship itself. The main plus points to this are that its performance is speedy and it’s also extremely low maintenance; however, you will significantly reduce your maximum depth reading.

Through-Hull Transducers

These require a hole to be drilled through your hull and aims directly into the water. These commonly provide the best results when paired with any fish finder. They need to be positioned in front of any object that may cause turbulence for the best results.

Tilted Element Transducers

These work similarly to through-hull transducers except for the fact that they do not require a fairing block. These come in two configurations, 12º and 20º, the former for when the deadrise of your hull is between 8º and 15º, the latter when between 16º and 24º.

Portable Transducers

These are more commonly found for shore or lake fishing where the transducer is located at the end of a line that can typically be cast out, set a distance from shore, or trolled behind a kayak or small watercraft. This will then have a small flotation device attached, allowing the transducer to sit neatly on top of the water during operation.

What are the Types of Imaging Systems?

There are four ways in which information is typically displayed on the screen of your fish finder after it has been received from the transducer. While the quality and sophistication of the imaging will vary with the price of the unit, they share universal layouts.

Side Imaging

Side imaging will require two transducers, one positioned on each side of the boat’s transom, which sends out frequencies from 90º angles across the path of the boat.

The main benefit of side imaging over other types is that it creates a wider field of view. This makes it ideal for those fishing in shallow water where fish are more likely to be spread out rather than in larger schools.

CHIRP Technology

GPS and Maps

GPS and maps imaging are exactly what you expect and are crucial when it comes to chart plotting. While this feature is commonly found across fish finders, some models don’t offer it.

GPS and up-to-date maps will provide you with a clear route and often allow you to mark waypoints and save locations while being able to add a comment about the quality of the fishing spot. This will help you gain a clearer picture of your fishing environment and help you track the local fish population.

Down Imaging

When it comes to deeper sea fishing, you can’t beat the quality and clarity of down imaging. Designed with a superior quality when compared to traditional sonar, down imaging makes it significantly easier to differentiate between fish types and structures. You’ll also find it easier to assess the position in the water column underneath your boat.

Attaching the transducer to the bottom of your transom allows it to send a signal directly down in a conical shape. This directed burst of sound waves typically penetrates deeper than that of other imaging technologies.

CHIRP Technology

CHIRP (Compressed high-intensity radar pulse) isn’t exactly a new type of sonar but rather an improvement of processing and displaying the information that’s received via the transducer. Rather than using one or two frequencies, CHIRP generates a large array which allows it to display more detailed images of objects encountered.


A transducer is simply an item that is responsible for detecting the objects underneath the water so that images can be transmitted to the fishfinder monitor, helping the fisher identify whether the area is a good fishing spot or not as well as helping identify the possible kinds of fishes present in the area.