The GSD 21 replaces the GSD 20, and is a powerful analog sonar, along with the GSD 22 , Garmin's first digital sonar, are robust units designed to operate with stand-alone chartplotters or integrate with the Garmin CANetT and Marine Networks.

The GSD 21 is a black-box sounder that provides fast UltrascrollT displays and 500-watt (RMS) sounder capability to 2000 series and 292/392/492 series chartplotters featuring the Garmin CANetT bus. The GSD 21 will work with a serial connection to other Garmin plotters without the CANet connection, but will not offer UltrascrollT capability. The unit's all-new, high-dynamic range analog sonar receiver provides exceptional performance in water as shallow as one foot on down to depths of 1,500 feet. It connects to a dual frequency transducer (50/200 kHz) for deep-water performance or a single frequency, dual beam width transducer (narrow/wide) for operation in shallow freshwater as well as deeper water. Provides 500 W transmit power with dual frequency transducer or 400 W with dual beam width transducer.

The GSD 22 is a powerful remote sounder that plugs directly into the Garmin Marine Network for use with our network chartplotters — or into the new Garmin CANet™ for use with the 292/392/492 series chartplotters. Ultrascroll™ technology keeps the display scrolling at live-action speeds, while the unit’s digital design and up to 2 kW of transmit power (depending on transducer used) provide extraordinary target definition and deep water performance. Transmit power and receiver gain automatically adjust to produce excellent shallow water performance as well. The GSD 22 is dual frequency (200/50 kHz) and works with everything from a standard 500 W transom mount transducer to heavy-duty 2 kW thru-hull or in-hull transducers. Reaches depths to 5,000 feet.

Please Note: This product does not include a transducer. Garmin offers a complete selection of transducers to be purchased separately as accessories.