Revision A Part Number GM494 Northstar a unit of Brunswick New Technologies Marine Electronics 30 Sudbury Road Service: 978/897-6600 Acton, Massachusetts 01720 Sales: 800/628-4487 Contents 1 Welcome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Welcome to the Northstar 491. . . . . . . . . . . . 2 Using this manual. . . . . . . . . . . . . . . . . . . . . . 2 Technical support. . . . . . . . . . . . . . . . . . . . . . 4 How echo sounding works. . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1-1 Autopilot Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Using this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1-1-1 Operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1-1-2 Steering modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1-1-3 Power

Important The choice, location, angle and installation Sonar fishfinder: The accuracy of the sonar of the instrument & transducers are critical to depth display can be limited by many factors, performance of the system as intended. Follow including the type of the transducers, the location instructions in this manual carefully. If in doubt, of the transducers and water conditions. It is the consult your Northstar dealer. user’s responsibility to ensure the 657 transducers are installed and used

4-6 DSC Functionality (DSC FUNC) DSC functionality can be disabled but this is not recommended. DSC SETUPDSC FUNC GROUP SETUP > ON INDIV REPLY OFF > DSC FUNC 1. Select DSC SETUP, then DSC FUNC. 2. The cursor is at ON. Press ENT or push the rotary knob to enable the DSC functionality and automatically disable ATIS functionality. The DSC annunciator appears on the screen. It’s not possible to have both ATIS ON and DSC ON simultaneously. When you enable one, the other will turn OFF. If DSC and ATIS

LOW POWER (1 W) only. 2. Receive Only. 3. LOW POWER (1 W) initially. Override to HIGH POWER by holding down H/L key before transmitting. Used normally in bridge-to-bridge communications. 4. Lightly Shaded Simplex channels 03A, 21A, 23A, 61A, 64A, 81A, 82A, and 83A cannot be lawfully used in U.S. waters unless special authorization is obtained from the U.S. Coast Guard. Not for use by the general public. 5. The letter “A” illuminated by the channel number indicates the USA channel is simplex. Thi