Garmin GPSMAP 392, 398, 492, 498 Owner's Manual

Also see for GPSMAP 392, 398, 492, 498: Quick reference guide Specifications

Contents

GPSMAP 392/398/492/498 Owner’s Manual 81U SING SONAR > U NDERSTANDING SONARTo calibrate the water speed:1. Use the ROCKER to highlight Calibrate Water Speed, andpress ENTER.2. Bring the boat to a cruising speed. Both the top GPS groundspeed and uncalibrated water speed appear at the bottomof the calibration window. Note your top speed, stop theboat, and press ENTER.3. By default, the top speed automatically appears in the Whatwas your top water speed? field. If a ground speed is notavailable, the top uncalibrated water speed is used instead.If the new speed is correct, highlight OK, and press ENTER.If you want to manually enter a calibration, press ENTER onthe speed field, enter a new speed, and press ENTER.NOTE: If the boat is not moving fast enough or the speedsensor is not registering a speed, a “Boat Is Not Moving FastEnough To Calibrate” message appears at the bottom of thescreen. Check that the speed sensor wheel is moving or safelyincrease boat speed. If there is a problem with the speed sensor,or if a speed senor is not installed, a “Water Speed Sensor IsNot Working” message appears at the bottom of the screen.Check the connections of the speed sensor cables.Graph Sub TabThe available Graph sub tab options are:• Fish Symbols—sets how the Sonar Page interpretssuspended targets and background information. If you selecta fish symbol, the GPSMAP 392/398/492/498 identifiessome returns for you by replacing them with fish symbols(in large, medium, and small sizes based on the size of thesonar return). If you are using dual beam, fish symbols fromthe narrow beam (directly underneath your boat) are solid,and the returns from the wide beam (out to the sides of yourboat) are hollow.The Sonar Page does not interpret the sonar return data.Suspended targets appear as symbols. No backgroundinformation appearsSame as previous with the target depth shown.Suspended targets appear as symbols. Backgroundinformation appears, making the distinction betweenfish and structure easier.Same as previous with target depth shown.