Garmin GPSMAP 188 Sounder Manual

The Garmin GPSMAP 188 Sounder is a combination GPS chartplotter and dual-frequency fishfinder designed for marine navigation. It features a high-resolution color display, built-in worldwide basemap, dual-frequency sonar (50/200 kHz), chartplotting capabilities, waypoint and route management, NMEA 0183 interface, and waterproof construction. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

Features at a Glance

Key components: High-resolution color LCD display, GPS antenna, dual-frequency transducer, power/data cable, mounting hardware, remote control (optional).

Installation

Unpack and inspect contents. Choose mounting location carefully.

1. Mount the display unit: Select location with clear view, use mounting bracket and hardware provided.
2. Install transducer: Mount on transom, through-hull, or in-hull following instructions.
3. Connect power: Route power cable to 12-24V DC source, install inline fuse (3A recommended).
4. Connect transducer cable to display unit.
5. Connect optional NMEA devices if needed.

WARNING! Ensure all connections are waterproofed. Route cables away from engine and moving parts.

First-Time Setup

Power on unit; follow initial setup prompts.

1. Acquire GPS signal: Place unit with clear view of sky, wait for satellite acquisition.
2. Set language: In SETUP menu, select ENGLISH (default).
3. Set units: Choose nautical, statute, or metric units for distance/speed.
4. Calibrate compass: Follow on-screen instructions if equipped.
5. Set time: Choose local time or UTC, set daylight saving if applicable.

CAUTION! Ensure proper ventilation around display unit. Do not mount near heat sources.

Specifications

• Display: 5-inch diagonal, 256-color TFT, 320 x 240 pixels.
• GPS: 12 parallel channels, WAAS enabled.
• Sonar: Dual-frequency 50/200 kHz, depth to 1500 ft (457 m).
• Waypoints: 3000 with name and symbol.
• Routes: 50 reversible routes with up to 50 waypoints each.
• Tracks: 10 saved tracks, 3000 points each.
• Power: 10-40 VDC, 1.5A typical at 12V.
• Waterproof: IPX7 standard.
• Operating Temp: -15° to 70°C (5° to 158°F).
• Dimensions: 6.3" W x 4.7" H x 2.5" D (160 x 119 x 64 mm).

Controls and Settings

Front panel: POWER, PAGES, ENTER, ROCKER key (up/down/left/right), QUIT, ZOOM IN/OUT.

Menu Navigation: Press PAGE to cycle through display pages (Map, Sonar, Highway, etc.). Press MENU to access options for current page.

Setup Menu: System (Units, Time, Alarms), Sonar (Frequency, Range, Sensitivity), GPS (Interface, WAAS), Map (Orientation, Detail), Tones (Key Beep).

Sonar Settings: Adjust frequency, range, sensitivity, noise rejection, surface clarity, chart speed.

Connecting Devices

Power: Red to positive, black to negative. Transducer: Plug into SONAR port. NMEA: Connect to NMEA 0183 port for autopilot/instruments.

1. Turn off power before making connections.
2. Use waterproof connectors for all external connections.
3. Connect NMEA devices following wiring diagram in manual.
4. Connect optional external GPS antenna if needed.

Tip: Apply dielectric grease to connectors to prevent corrosion.

Using GPS and Chartplotting

Basic GPS and navigation functions.

1. View position: Press PAGE to Map display, see current position on chart.
2. Mark waypoint: Press and hold ENTER at desired location, edit name/symbol.
3. Create route: MENU > Route > New Route, add waypoints in sequence.
4. Navigate: Select Go To (waypoint) or Follow (route).
5. View trip data: Press PAGE to Highway or Data pages.
6. Set alarms: MENU > Setup > Alarms for anchor drag, arrival, etc.
7. Use tracks: View track log, save/clear tracks as needed.

WARNING! GPS is aid to navigation only. Always use traditional navigation methods as backup.

Using the Fishfinder

Sonar operation and interpretation.

1. Select sonar page: Press PAGE to Sonar display.
2. Adjust frequency: MENU > Sonar Setup > Frequency (50 kHz for deep water, 200 kHz for detail).
3. Set range: Auto or manual depth range.
4. Adjust sensitivity: Increase to see weak returns, decrease to reduce clutter.
5. Use zoom: Press ZOOM IN to magnify bottom or specific depth range.
6. Interpret display: Fish arches, bottom composition, thermoclines.
7. Use A-scope: Real-time sonar returns on right side of screen.

Note: Sonar performance affected by water conditions, boat speed, transducer placement.

Care & Cleaning

Use fresh water and mild soap for cleaning. Do not use harsh chemicals or abrasives.

CAUTION! Do not spray water directly into connectors. Keep display out of direct sunlight when not in use to prolong life.

Regulatory Information

FCC Compliance: This device complies with Part 15 of FCC rules. Operation subject to conditions: (1) device may not cause harmful interference, (2) device must accept any interference received. NMEA 0183: Compliant with NMEA 0183 standard. Copyright © Garmin Ltd. or its subsidiaries. For support, visit www.garmin.com or contact Garmin Product Support.

Troubleshooting

Reset: Turn off, press and hold PAGE + POWER while turning on for system reset.

Service: Contact Garmin Product Support or authorized service center.