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Types of Sonar

Traditional HD-ID Sonar

Traditional sonar that is available on Garmin fishfinders. HD-ID sonar transmits two frequencies, generally either 77/200 kHz or 50/200 kHz. Our echoMAP and GPSMAP chartplotter/sonar combos have Traditional HD-ID sonar built in.


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 is built into our GPSMAP chartplotter/sonar combos. Learn more about Garmin CHIRP.


Panoptix all-seeing sonar is unlike anything you’ve ever seen on the water. Use the Panoptix Forward or Down transducer with a compatible Garmin GPSMAP unit to see all around your boat in real-time. You can see fish in the water column in 3-D. You can also see your bait cast into the water and watch it as you reel it in. You can see fish swimming in front of or below your boat. You can even see them chase your lure. But to truly appreciate Panoptix, you have to see it.

DownVü Scanning Sonar

This high-frequency sonar gives you a clearer picture of what's below your boat, by producing a more detailed representation of objects, structure and fish. DownVü with CHIRP technology takes it one step further, producing an ultra-clear page with even more detail. DownVü scanning sonar is built into our echoMAP combos, and DownVü scanning sonar with CHIRP technology is built into our GPSMAP combos. Learn more about DownVü scanning sonar.

SideVü Scanning Sonar

SideVü shows you what is happening to the sides of your boat. An excellent way of finding structures and fish. SideVü with CHIRP technology provides an even more detailed and higher resolution image of what is beneath the surface. SideVü scanning sonar is built into our echoMAP sv combos, and SideVü scanning sonar with CHIRP technology is built into our GPSMAP combos. Learn more about SideVü scanning sonar.

Mounting Styles


is installed inside a boat hull against the bottom and sends its signal through the hull.


  • 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


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


  • 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


is installed in a hole drilled thru the hull.


  • 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 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.

Kayak In-Hull

attaches to the inside of a kayak, against the bottom and sends its signal though the hull.

Kayak In-Hull

  • No need to drill into the vessel
  • No drag, protects transducer from rocks when launching
  • Will not catch on weeds or marine vegetation
  • Easily remove the transducer
  • Not recommended for metal or wooden vessels
  • Slight loss of signal by transmitting through hull
  • Recommends flat section for best sealing against boat

Additional Information

Stepped Hull

A stepped hull contains a notch (or step) that runs crosswise across the boat hull and helps the boat generate more lift at higher speeds. If transducer is mounted after the notch, the notch creates cavitation and will interfere with sonar returns. For this reason, the transducer should be mounted in front of the notch, closer to the front of the boat.

Cored Hull

A cored hull refers to a hull with a void between the 2 layers of hull material. Sonar cannot transmit through that void.

Deadrise Angle

The deadrise angle is the angle between the horizontal line of the water and your boat's hull


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.