GPSMAP® 178 Sounder

Part Number: 010-00363-00


The GPSMAP 178 has everything you need in one space-saving package — GPS navigation, marine chartplotting, and powerful sonar. This combination chartplotter/sounder includes the same user-friendly interface as its color counterpart, the GPSMAP 178C, but sports a high-resolution monochrome display and a price that's within any mariner's budget.

The GPSMAP 178 packs a built-in worldwide marine basemap, state-of-the art processor with lightening-fast map redraw, and crisp, sunlight readable, 10-level grayscale display into a waterproof, space-saving console — perfect for large crafts and small runabouts alike. Boaters will love its convenient, intuitive design including:

  • simple keypad with backlighting for easy operation
  • one knob, adjustable tilt and swivel mount so you can quickly pop it in and out
  • front loading data cards for easy access

Users can enhance basemap detail on the GPSMAP 178 by simply plugging in data cards preprogrammed with BlueChart® or Fishing Hot Spots® detail or downloading data from optional MapSource CDs to an optional Garmin data card. BlueChart provides exceptional offshore marine coverage that includes shaded depth contours, navaids, shoreline, and more. For inland boating and fishing, the U.S. Recreational Lakes with Fishing Hot Spots CD & preprogrammed data cards are packed with inland lake maps, profiles, marinas, fishing areas and useful outdoor resources.

The GPSMAP 178 is available with either a single or dual-frequency transducer making it the perfect companion for offshore or inland lake fishing. Boaters can choose dedicated full-screen map, full-screen sonar, split-screen map/sonar, compass, and navigational screens — with customizable digital data fields for each page.

WAAS enabled BlueChart compatible Marine Updater


PDF Download detailed specs

Physical & Performance

Physical dimensions 6.3" x 4.9" x 2.8" (16.0 x 12.5 x 7.1 cm)
Display size, WxH 3.2" x 3.2" (8.1 x 8.1 cm)
Display resolution, WxH 320 x 320 pixels
Display type 10 level grayscale FSTN
Weight 1.2 lb (553 g)
Water rating IPX7
Antenna Internal with external connection
NMEA 0183 compatible
Power consumption 8 watts max at 13.8 vDC
Mounting options Bail with Swivel or Flush
Garmin Marine Network™ ports None

Maps & Memory

Accepts data cards 1 Garmin Data Card
Waypoints 3,000
Routes 50
Track log 10,000 trackpoints

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 900 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 178
  • Basemap: Worldwide Marine
  • Transom-mount transducer
  • Bail mount
  • Remote antenna
  • Power/data cable
  • Protective front cover
  • Flush mount kit
  • Owner's manual


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