Garmin GSD 25 Premium Sonar Module

The Garmin GSD 25 is an external sonar module for Garmin boats that need both high-power CHIRP and scanning sonar through one networked system. It adds dual-channel CHIRP, ClearVü, and SideVü to compatible GPSMAP displays, making it useful on fishing boats and cruisers where sonar hardware is installed separately from the screen. This is a module, not a complete fishfinder.

The GSD 25 delivers 1kW CHIRP and 500W scanning output, with CHIRP coverage from 40-210kHz and scanning at 455/800kHz. That combination gives the operator traditional fishfinding plus downward and side-looking views when compatible transducers are connected. The RJ45 Garmin Marine Network link handles the data path, and compatibility is listed with GPSMAP 8000, 7400, 7600, 10×2, and 12×2 series displays. Transducers are not listed, so they must be chosen separately.

Who Is This For?

This Garmin external sonar module suits fishing boats and cruisers that already use a compatible Garmin display and need both CHIRP and scanning sonar. It is not ideal for buyers seeking a complete fishfinder package because the transducers and display are separate.

Warranty & Support

Garmin provides a 1-year limited warranty. The supplied specifications do not state warranty exclusions or service procedures.

The GSD 25 is the practical Garmin expansion module when an existing display needs conventional CHIRP and ClearVü/SideVü capability. Its trade-off is the installation work: the display, network, transducers, and power plan must all match. Choose it for a planned Garmin sonar system, not as a standalone sounder.