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Different Sonar...Different Transducers

Garmin makes several different types of sonar and each requires a different type of transducer to work most efficently. Matching the transducer to your device’s sonar is very important.

HD-ID Sonar

Traditional sonar that is available on Garmin fishfinders. Dual-beam, HD-ID sonar transmits two frequencies, generally either 77/200 kHz or 50/200 kHz combos.

CHIRP Sonar Technology

CHIRP sonar transmits a sweep of many frequencies within a long duration pulse. The equivalent sound energy is hundreds of times greater, resulting in more energy on target. This provides huge advantages in detail, resolution and accuracy at much greater depths.

CHIRP Sonar Technology

Garmin DownVü and SideVü Scanning Sonar

DownVü scanning sonar gives you an ultra clear sonar picture of objects, structure and fish that pass below your boat while SideVü scanning sonar shows fish and structure that is off to the sides of your boat. DownVü/SideVü scanning sonar with CHIRP technology is also available for some compatible chartplotter/sonar combos.

DownVu and SideVu Scanning Sonar

Choose the Right Mounting Style

Transducers are typically mounted in one of 3 ways: through the hull, inside the hull or on the transom.


An in-hull transducer is installed inside a boat hull against the bottom and sends its signal through the hull.

In-Hull Transducer Mount
  • No need to drill through the boat; no drag
  • Boat can be trailered without damaging the transducer
  • No exposure to marine growth
  • Can be installed and serviced with the boat in still in the water
  • Give great high-speed performance as long as water flow below the transducer is “clean” (no turbulence)
  • Work with any engine type: inboard, outboard, and I/O when installed over solid fiberglass
  • Perform well on both power and sailboats
  • Not recommended for metal, wood and cored fiberglass hulls
  • Lose signal by transmitting through hull


These are attached to the back (transom) of a boat hull.

Transom Transducer Mount
  • Good for trailered boats, out of the way of the rollers
  • Easy-to-install and remove —especially if a kick-up bracket is used
  • Good performance at boat speeds below 30 knots (34 mph)
  • Can be used with any hull material
  • Will not work on a boat with an inboard engine due to the turbulence forward of the sensor
  • Not recommended for sailboats because of excessive heeling
  • Will not work on stepped hull


Thru-hull transducers, as their name implies, are installed in a hole drilled thru the hull.

Thru-Hull Transducer Mount
  • Work with any engine type: inboard, outboard or I/O
  • Work for power and sailboats
  • There are thru-hull transducers for every hull material
  • Do not use plastic thru-hull housings in a wooden boat. Wood swells as it absorbs water, so it may crack the housing.
  • Do not use bronze thru-hull housings in aluminum and stainless steel boats. The interaction between the metal hull and the bronze transducer, especially in the presence of salt water, will corrode the metal hull and/or the bronze housing.

Thru-hull transducers come in two styles: Flush and External

Flush mounts sit flush or nearly flush with the boat hull and are recommended for smaller boats with a minimum deadrise angle.

External mounts extend beyond the hull surface and usually require a fairing to aim the sound beam vertically and are for larger un-trailered boats.

To obtain the best possible performance, install all transducers according to the included installation instructions. If you experience difficulty during the installation, contact Product Support, or seek the advice of a professional installer.