Transducer
Also called ducer, sonar transducer
The puck that sends and receives sonar pings. Without it a fish finder is a blank screen.
The transducer converts electrical signal into sound, fires it down through the water, then listens for the echo and converts that back into electrical signal. Everything the screen draws comes from timing those returns and reading their strength.
How it mounts decides most of what the unit can do. Transom mounts bolt to the back of the boat and are the common budget option. Trolling motor mounts point where you are looking. Castable units put the transducer inside a floating ball you throw from the bank and read on your phone.
Mounting angle and depth matter enormously. A transom transducer sitting in aerated water behind the hull will lose bottom the moment you go above idle, which is the single most common complaint about cheap installs.
Mount a transom transducer so its face sits level and just below the hull bottom, in clean water away from strakes and rivets.
Related terms
Where this comes up
The guides that use transducer and show it on real gear.
Transducer is one of 206 terms in the glossary.
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