Changing the Temperature DisplayThe graph will adjust and show the temperatures changes accordingto the Temperature Scale and Time Duration settings.Temperature Scale—select a degree span from the list. Select Autoto have the unit automatically determine the best range, or select aspan of 2, 4, 6, 8, or 10 degrees.Time Duration—set how fast or slow the temperature log scrolls; ashorter time duration means a faster temperature log scroll. Select aduration from 1 minute to 2.5 hours.Resetting the Temperature GraphTo reset the scale range for the temperature graph, press MENU,highlight Reset Auto Scale, and press ENTER. This is usefulwhen the scale spans a large range due to extreme temperaturechanges. You can reset the scale only when you select Auto for theTemperature Scale.To restore the temperature graph to defaults, press MENU, highlightRestore Default, and press ENTER.Understanding SonarThe transducer mounted on your vessel transmits sound wavestoward the bottom of the water in a cone-shaped pattern. Whena transmitted sound wave strikes an underwater object—such asthe bottom, a structure, or a fish—sound is reflected back to thetransducer. The transducer collects the reflected sound waves andsends the data to the GSD 20 Sounder Module and then to theGPSMAP 276C to be processed and displayed. The underwater datais shown on the Sonar display in the order that it is returned; firstreturned is the first on the display.Sonar PageGPSMAP 276C Owner’s Manual 97SETTING UP AND USING SONAR > U NDERSTANDING SONAR
