Garmin GPSMAP 188C Manual

The Garmin GPSMAP 188C is a high-resolution color chartplotter/fishfinder combo designed for marine navigation. It features a sunlight-readable 5-inch color TFT display, built-in GPS receiver, dual-frequency (50/200 kHz) sonar with 500 watts RMS power, preloaded BlueChart g2 coastal charts, support for optional GSD 20 sounder module, NMEA 0183 interface, waterproof construction (IPX7), and trackplotting capabilities. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

Features at a Glance

Key components: 5-inch Color TFT Display, GPS Receiver, Transducer, Power/Data Cable, Mounting Hardware, Remote Control (optional).

Installation

Unpack and inspect contents. Choose a mounting location with clear view of sky for GPS.

1. Mount the unit: Use included bracket to mount on dash or console. Ensure secure fit.
2. Install transducer: Mount transom mount or thru-hull transducer according to instructions.
3. Connect power: Route power/data cable to 10-40 VDC source. Connect red to positive, black to negative.
4. Connect transducer: Plug transducer cable into labeled port on back of unit.
5. Connect optional NMEA devices: Use NMEA 0183 wires for interfacing with autopilot or other instruments.

WARNING! Ensure all connections are waterproofed. Disconnect power before making connections.

First-Time Setup

Power on unit; follow initial prompts.

1. Acquire GPS signal: Place unit in open sky view; wait for "Ready to Navigate" message.
2. Set language: In Main Menu > System > Language, select ENGLISH (default).
3. Set units: In Main Menu > Units, select nautical/miles, feet/fathoms, etc.
4. Calibrate compass (if applicable): Follow on-screen prompts.
5. Adjust sonar settings: Set frequency, sensitivity, and range for local conditions.

CAUTION! Do not power unit without proper voltage (10-40 VDC).

Specifications

• Display: 5-inch TFT, 320 x 320 pixels, 256 colors.
• GPS: 12-channel, WAAS enabled, position accuracy < 10 meters.
• Sonar: Dual-frequency 50/200 kHz, 500W RMS, depth to 2500 ft.
• Chart Storage: Internal memory for preloaded charts; accepts optional data cards.
• Power: 10-40 VDC, 1.5A typical.
• Waterproof: IPX7 standard.
• Operating Temp: -15°C to 70°C.
• Dimensions: 6.3" W x 4.7" H x 2.9" D.

Controls and Settings

Access menus via PAGE or MENU keys. Front Panel: POWER, PAGE, ENTER, ROCKER key (up/down/left/right), ZOOM IN/OUT.

On-Screen Menus: Main Menu provides access to Chart, Sonar, Highway, Data Pages, and System Setup.

Chart Settings: Detail, Orientation (North Up, Course Up, Track Up), Waypoints, Routes. Sonar Settings: Frequency, Sensitivity, Range, Grayline, Noise Rejection. System Settings: Units, Language, Backlight, Alarms, NMEA Setup.

Connecting Devices

Power: Red/black wires to DC source. Transducer: Dedicated port. NMEA 0183: Connect to autopilot, AIS, etc. Optional GSD 20: For enhanced sounding.

1. Turn off power before connecting devices.
2. Match wire colors/ports (refer to wiring diagram).
3. Seal connections with waterproof sealant.
4. Configure NMEA input/output in System > NMEA Setup.

Tip: Use marine-grade wire and connectors for all installations.

Using GPS & Charts

Navigate using preloaded BlueChart g2 charts.

1. View Chart: Press PAGE until Chart page appears.
2. Create Waypoint: Move cursor to location, press ENTER > "Mark".
3. Navigate to Waypoint: From Waypoint list, select waypoint > "Go To".
4. Create Route: Main Menu > Routes > "New". Add waypoints in sequence.
5. Follow Route: Select route > "Navigate".
6. Trackplotting: Tracks are recorded automatically; view in Track Manager.
7. Zoom: Use ZOOM IN/OUT keys to change chart scale.

WARNING! GPS is an aid to navigation. Always use updated charts and prudent seamanship.

Using the Fishfinder

Switch to Sonar page to view bottom and fish arches.

1. Select Sonar Page: Press PAGE until Sonar page appears.
2. Adjust Frequency: Menu > Sonar Setup > Frequency (50 kHz for deep water, 200 kHz for detail).
3. Set Range: Auto or manual. Use ROCKER key to adjust.
4. Adjust Sensitivity: Increase to see weaker returns; decrease to reduce clutter.
5. Use Zoom: Zoom in on bottom or specific depth layer.
6. Interpret Display: Fish appear as arches; bottom as solid line.

Note: Sonar performance depends on transducer installation and water conditions.

Care & Cleaning

Disconnect power before cleaning. Use fresh water and mild soap with soft cloth. Do not use harsh chemicals or abrasives.

CAUTION! Ensure seals are intact. Do not submerge connectors. Store in dry place when not in use.

Regulatory Information

FCC Compliance: This device complies with part 15 of the FCC Rules. Operation is subject to conditions that device does not cause harmful interference. IC Compliance: Complies with Industry Canada licence-exempt RSS standard(s). Copyright © Garmin Ltd. or its subsidiaries. BlueChart and GPSMAP are trademarks of Garmin Ltd. For support, visit www.garmin.com/support or contact Garmin Product Support.

Troubleshooting

Reset: System > Reset to Factory Defaults (caution: erases all user data).

Service: Contact Garmin Product Support or authorized service center.