The GSD 21 analog sounder adds detailed sonar data to your compatible Garmin chartplotter.

Connect with CANet™

This black-box sounder connects directly to your chartplotter with a serial cable. To take advantage of UltraScroll™, which provides lightning-fast refresh rates, connect the GSD 21 to your chartplotter with CANet, Garmin's 1-megabit proprietary network.

Get Great Shallow and Deep-Water Performance

The high-dynamic range sounder provides exceptional performance in water as shallow as one foot to depths as great as 1,500 feet. The GSD 21 can connect to dual-frequency transducer (50/200 kHz) for deep-water performance and 500 watts of transmit power, or a dual-beamwidth transducer (narrow/wide) for operation in shallow freshwater as well as deep water and a transmit power of 400 watts.

GSD 21: Puts eyes in the bottom of your boat

Please note: This product does not include a transducer. Garmin offers a complete selection of transducers that you can purchase separately as accessories.