NorthStar Navigation NorthStar 491 manual Echo Sounder Operations Manual

Models: NorthStar 491

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longitude Imaginary lines on the Earth's surface running North/South and expressed in degrees (0-180) east or west of the Prime Meridian (a line running from the North to South Pole, passing through Greenwich, England).

meter A unit of measurement (length) equal to 39.37 inches, slightly more than a standard yard.

nautical mile (nm) An international unit equal to 6,076.115 feet (1,852 meters) used officially in the U.S. since 1959. A nautical mile is about 800 feet more than a statute mile. One nm is equal to 1 minute of latitude.

ping A pulse transmitted from the 491 echo sounder. Also, the act of transmitting a pulse from the echo sounder ("pinging").

SOG Speed Over Ground. The actual speed of your vessel relative to the earth, not the water.

tide The vertical rise and fall of water caused by the gravitational pull of the moon and sun.

transducer The device mounted through the hull to send and receive ultrasonic beams that determine seabed conditions and locate fish.

waypoint A particular location, saved by marking fish on the echo sounder’s LIVE-DATAscreen, which is used as an intermediate or final destination.

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491 Echo Sounder Operations Manual

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NorthStar Navigation NorthStar 491 manual Echo Sounder Operations Manual