Fish Finder Transducers – The Hows & Whats

What is a Transducer?
Fish finder? Check. Fish finder transducer? Nope. Now, you’re on a quest to match your fish finder with the appropriate fish finder transducer, but you’re not even sure what a transducer does. We’re here to help you with your basic fish finding needs. Fish finder transducers are arguably the most important part of a fish finder. The transducer is a little like a bat, it’s the heart of the echosounder system that changes electrical pulses into sound waves (or acoustic energy) and then back again, thus sending and receiving wave signals of echoes. Thus, a transducer can detect or interpret the water underneath your boat; it can detect water depth, location, fish, etc.

What Makes Up a Transducer?
The piezoceramic element is the main component of a depth transducer. It’s the part of the transducer that is able to convert electrical pulses into sound waves and then back again. The shape of the piezoceramic element is typically in the shape of a disk but may also be in the shape of a ring or bar. The typical transducer is made up of the following six parts: housing, piezoceramic element, acoustic window, sound absorbing components, encapsulating material, cable, and finally housing.

How Can it Detect Things?
– The fish can be detected via the air bladder, that part of the fish that fills up with gas so that the fish may easily adjust to the various water pressures under the water. The fish’s buoyancy can be reduced or increased based on its needs. Due to this gas being drastically less dense than the flesh and bone of the fish and the difference in the water that surrounds it, the sound waves that result from interaction with the air bladder create a disturbance that can be uniquely identified. The echosounder is programmed to identify these sound waves and then recreates the data for the mariner. Thankfully, fish cannot hear these high frequencies so having a fish finder does not alert them.

Depth – To measure the depth of the water the echosounder measures the time it takes to transmit the sound to receiving the echo. Sound travels through water at roughly 4,000 feet per second (1,463 m/s) and to calculate the distance to the floor of the body of water. The echosounder system interprets the data and the depth is then translated and displayed on the user’s screen.

What Things Look Like – The transducer knows what the bottom looks like based on the messages it receives back and at what time. It’s all about timing. If one sound wave returns more quickly than the other ones, that basically means there’s a bump or hump underwater. The fish finder transducer can also detect the type of surface (hard or soft) based on how the waves bounce off. Everything echoes differently and is read by the transducer.

What is Frequency – What Kind Do You Need?
Frequency is, at a basic level, is the number of regularly occurring events in a unit of time, typically one second. In this case its sound vibration frequency. To explain this easily, consider the human voice. A child has a higher pitched voice, which means their voice is high frequency while an adult male has a low-pitched voice and is low frequency. The frequency that you need will depend on the type of water you want to use the fish finder in. Refer to the table below:

Salt Water Fresh Water
Frequency High or Low Low High High or Low
Cone Angle Wide or Narrow Wide Wide or Narrow Narrow

A higher-frequency range is necessary for fishermen in shallow lakes who desire a clean, crisp picture of the lake bed. Low range will not give as clear a picture, but will have a greater range. With that being said, low range frequency is better in deep waters. Choose the appropriate fish finder transducer for the location you wish to frequent. If you have any questions about fish finding transducers please send us a message.


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