Garmin GPSMAP 820 Owner's Manual - Page 32

2 Select Settings > My Vessel > Keel Offset. 3 Select or based on the location of the transducer. 4 Enter the distance measured in step 1. Setting the Water Temperature Offset Before you can set the water temperature offset, you must have a NMEA 0183 water-temperature sensor or a temperaturecapable transducer to measure water temperature. The temperature offset compensates for the temperature reading from a temperature sensor. 1 Measure the water temperature using the temperature sensor or temperature-capable transducer that is connected to the chartplotter. 2 Measure the water temperature using a different temperature sensor or a thermometer that is known to be accurate. 3 Subtract the water temperature measured in step 1 from the water temperature measured in step 2. This is the temperature offset. Enter this value in step 5 as a positive number if the sensor connected to the chartplotter measures the water temperature as being colder than it actually is. Enter this value in step 5 as a negative number if the sensor connected to the chartplotter measures the water temperature as being warmer than it actually is. 4 Select Settings > My Vessel > Temp. Offset. 5 Enter the temperature offset calculated in step 3. Calibrating a Water Speed Device If you have a speed-sensing transducer connected to the chartplotter, you can calibrate that speed-sensing device to improve the accuracy of water-speed data displayed by the chartplotter. 1 Select Settings > My Vessel > Calibrate Water Speed. 2 Follow the on-screen instructions. If the boat is not moving fast enough or the speed sensor is not registering a speed, a message appears. 3 Select OK, and safely increase the boat speed. 4 If the message appears again, stop the boat, and ensure the speed-sensor wheel is not stuck. 5 If the wheel turns freely, check the cable connections. 6 If you continue to get the message, contact Garmin product support. Communications Settings NOTE: Some settings and options require additional charts or hardware. Select Settings > Communications. Serial Port 1: Sets the input/output format for port 1 to use when connecting the chartplotter to external NMEA devices, computers, or other Garmin devices. Serial Port 2: Sets the input/output format for port 2 to use when connecting the chartplotter to external NMEA devices, computers, or other Garmin devices. NMEA 0183 Setup: Sets the NMEA 0183 sentences the chartplotter transmits, how many digits to the right of the decimal point are transmitted in a NMEA output, and how waypoints are identified (NMEA 0183 Settings). NMEA 2000 Setup: Allows you to view and label the devices on the NMEA 2000 network (Viewing a List of NMEA 2000 Network Devices). Marine Network: Allows you to view the devices with which you are sharing maps, sonar, or radar. Not available on all chartplotter models. NOTE: You can only view networked data on a model that supports that data. For example, you cannot view networked radar on model that does not support radar. Wi-Fi® Network: Allows you set up the Wi‑Fi® network (Setting Up the Wireless Network). NMEA 0183 The chartplotters support the NMEA 0183 standard, which is used to connect various NMEA 0183 devices, such as VHF radios, NMEA instruments, autopilots, wind sensors, and heading sensors. To connect the chartplotter to optional NMEA 0183 devices, see the chartplotter installation instructions. The approved NMEA 0183 sentences for the chartplotter are GPAPB, GPBOD, GPBWC, GPGGA, GPGLL, GPGSA, GPGSV, GPRMB, GPRMC, GPRTE, GPVTG, GPWPL, GPXTE, and Garmin proprietary sentences PGRME, PGRMM, and PGRMZ. This chartplotter also includes support for the WPL sentence, DSC, and sonar NMEA 0183 input with support for the DPT (depth) or DBT, MTW (water temperature), and VHW (water temperature, speed, and heading) sentences. NMEA 0183 Settings Select Settings > Communications > NMEA 0183 Setup. Sounder: Enables NMEA 0183 output sentences for the sounder (if applicable). Route: Enables NMEA 0183 output sentences for routes. System: Enables NMEA 0183 output sentences for system information. Garmin: Enables NMEA 0183 output sentences for Garmin proprietary sentences. Posn Precision: Adjusts the number of digits to the right of the decimal point for transmission of NMEA output. Waypoint IDs: Sets the device to transmit waypoint names or numbers via NMEA 0183 while navigating. Using numbers may resolve compatibility issues with older NMEA 0183 autopilots. Diagnostics: Displays NMEA 0183 diagnostic information. Defaults: Restores the NMEA 0183 settings to the original factory defaults. Viewing a List of NMEA 2000 Network Devices You can view the devices connected to the NMEA 2000 network. Select Settings > Communications > NMEA 2000 Setup > Device List. 26 Device Configuration