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.

Key Features

- Dual-channel CHIRP – Supports high-power conventional fishfinding through compatible transducers.
- ClearVü and SideVü – Adds downward and side-looking scanning sonar.
- 1kW CHIRP and 500W scanning output – Provides separate power levels for traditional and imaging sonar.
- 40-210kHz CHIRP and 455/800kHz scanning – Covers a wide range of fishing applications.
- Garmin Marine Network RJ45 – Connects the module to compatible Garmin MFDs.

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.

Compatibility

Confirmed compatibility includes Garmin GPSMAP 8000, 7400, 7600, 10×2, and 12×2 series displays through Garmin Marine Network. The supplied information does not identify specific transducers, NMEA 2000, NMEA 0183, radar, autopilot, Raymarine, Simrad, or Lowrance compatibility. No named incompatible system was provided.

Technical Specifications

- Brand: Garmin
- Model: GSD 25, 010-01159-00
- Technology: Dual-channel CHIRP, ClearVü, SideVü
- Output: 1kW CHIRP and 500W scanning
- Frequency: 40-210kHz CHIRP; 455/800kHz scanning
- Networking: Garmin Marine Network RJ45
- Compatibility: GPSMAP 8000/7400/7600/10×2/12×2
- Transducers: Not listed as included
- Display: Not included
- Warranty: 1-year limited warranty

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.