This function automatically redraws the chart according to the boat’s course, to maintain 2/3rds of the screen ahead of the boat, provided that the boat’s speed is greater than 3 knots. This function will be activated only if no waypoint has been previously inserted. Screen Marine amplifier The Overzoom function allows the chart scale to expand any- where up to 1/4 NM. The Overzoom does not provide any additional chart detail, but im- proves only the readability of the existing information, thus act- ing as a magnifying glass. When the Overzoom is activated, the unit will warn the user by Overzoom Functional Characteristics Without screen amplifier With screen amplifier ZOOM+ ZOOM until the“AUTOZOOM ? ENTER = YES” message is displayed. To deactivate the Autozoom function, press the key once.When the GEONAV is turned on, and if at least one waypointhas been previously entered, the Autozoom function is auto- matically activated. 26 By this function the user can enter local time instead of the Greenwich time (GMT) supplied by the BOAT GPS marine receiver. To enter local time, press Local time key. Press To cancel calibration, press NOTE: Most position sensors have intrinsic errors that make the boat’s position incorrect (from few meters to several hundred meters) with respect to the background display of the chart. This error is caused by the principle at the root of the satel- lite-derived position system.The position calibration allows the user to manually correctthe position error present in all GPS. Press Position calibration replacing RANGE with OVZ (blinking) within the navigationwindow.To activate/deactivate the Overzoom function, press When the calibration is activated, the coordinates will be marked by (*). ENTER to confirm the operation. cally the boat’s position and the target waypoint at the bestavailable chart range. As the boat approaches the target waypoint, the unit will automatically zoom in. Once the waypoint is passed, the unit will select the best range to display the boat’s position andthe following waypoint.To activate the Autozoom function, press CURSOR PAGE PAGE until the menu bar is dis-played, select SETUP, SET TIME and then LOCAL. A window will allow entering local time by using the until the menu bar is dis-played, select SETUP, CALIBRATION and then OFF. key. Press PAGE ENTER until themenu bar is displayed, select SETUP, CALIBRATION and then ON.A message will prompt the user to move the cursor to the boat’strue position by using the PAGE to movethe GPS boat’s position to the point indicated by the cursor. This operation will save the calibration for use in future cal- culations. CURSOR EnglishEnglish un-til the menu bar is displayed, then select SETUP, OVERZOOM and ON/OFF. 27