GPSMAP® 188/188C Sounder

Part Number: 010-00239-00


The GPSMAP 188/188C Sounder install easily in open cockpit and overhead boxes, and feature a quick map redraw using a high-speed RISC processor. These units combine chartplotter and sounder capabilities in one unit, with split-screen capability so you can view your position and sounder information at the same time. For the GPSMAP 188 Sounder, detailed marine cartography is presented on a high-resolution (240 x 360 pixels), 10-level grayscale, liquid crystal display. For the GPSMAP 188C Sounder, the display is a high-resolution (234 x 320 pixels), 16-color TFT display.

Featuring a built-in worldwide basemap, the GPSMAP 188/188C Sounder is fully compatible with Garmin's new BlueChart® marine cartography and many MapSource® CD-ROM products, including Fishing Hot Spots. These units are designed to provide precise GPS positioning using correction data obtained from the Wide Area Augmentation System (WAAS). They also provide position accuracy to less than three meters when receiving WAAS corrections. The GPSMAP 188/188C Sounder also accept RTCM-104 differential corrections.

The GPSMAP 188C Sounder offers daylight-viewable color as an option to the monochrome display of the GPSMAP 188 Sounder.

WAAS enabled BlueChart compatible


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Physical & Performance

Physical dimensions 6.3" x 6.2" x 2.6" (16 x 15.8 x 6.6 cm) (188); 6.3" x 6.2" x 3.7" (16.0 x 15.8 x 9.4 cm) (188c)
Display size, WxH 5.5" diagonal (188); 5.0" diagonal (188c)
Display resolution, WxH 360 x 240 pixels (188); 234 x 320 pixels (188c)
Display type 10-level grayscale FSTN LCD (188); 16-color TFT (188c)
Weight 1.7 lbs. (188); 2.6 lbs. (188c)
Antenna External only
NMEA 0183 compatible
Power consumption 8 W max at 13.8 vDC (188); 14 W max at 13.8 vDC (188c)
Mounting options Bail or Flush
Garmin Marine Network™ ports None

Maps & Memory

Preloaded maps None
Accepts data cards 1 Garmin Data Card
Waypoints 3,000
Routes 50

Chartplotter Features

Garmin Sonar compatible
Supports DSC (displays position data from DSC-capable VHF radio)
Tide tables

Sonar Features & Specifications

Dual-frequency (50/200 kHz) sonar capable
Frequencies supported 50/200 kHz
Transmit power 500 W (RMS); 4,000 W (Peak to Peak)
Maximum depth 1,500 ft.
Bottom lock (shows return from the bottom up)
Water temperature log and graph


NMEA 0183 input ports 2
NMEA 0183 output ports 2
Video input ports None
Video output ports None

In the Box

  • GPSMAP 188 or 188C
  • Basemap: Worldwide Marine
  • Power/data cable
  • Bail mount
  • Protective front cover
  • Remote antenna
  • Owner's manual
  • Quick reference guide


Maps for New Regions

Need maps for other regions? See all maps that are compatible with this device.

Need a map update?

Update the maps that came with your device for the best navigation experience.

Check for Updates