Transducers for boats – Types, function, and mounting tips

Learn the difference between transom-mount, thru-hull, and in-hull transducers, and how to choose the right one for your boat.

A transducer is a device that converts energy from one form to another. In the marine Industry Terms, transducers are primarily used to measure depth, and some models also include temperature sensors to measure water temperature – invaluable information for fishermen. Data is usually sent to a fishfinder or via an NMEA 0183 converter.

What is a transducer?

Transducers are electrical sensors that measure depth and sometimes temperature. The information is used for navigation and safety on board. For correct function, it is important to choose the right type of transducer and mount it correctly.

Transom-mount transducers

These are mounted on the boat's transom and are popular due to easy installation. They work with all hull types but can be affected by drag at high speeds. For best results, they are placed on the starboard side with one engine or between the engines in a twin-engine installation.

Thru-Hull transducers

Mounted through the hull and provide the highest accuracy because the sensor has direct contact with the water. Perfect for high-speed boats and works with various hull materials. For angles over 5 degrees, fairing blocks are used to compensate and reduce drag.

In-Hull transducers

Installation takes place inside the hull, providing a neat solution without external parts. Advantages: no risk of damage and easy access for maintenance. Disadvantages: only works with fiberglass hulls and requires a fluid-filled tank to compensate for signal loss.

Important mounting principles

Regardless of type, the transducer should be mounted so that the beam is vertical to the bottom. Incorrect angle results in poor echoes and inaccurate readings.

Transducer vs Tri-Ducer

A transducer measures depth, while a Tri-Ducer combines depth, speed, and temperature measurement in one unit. Choose the right model depending on your needs.

Summary: For best results – choose the right transducer type for your hull, mount correctly, and ensure a vertical beam for accurate measurements.