Raymarine 420D Marine GPS System User Manual


 
Chapter 3: Operation 3-21
CDI display
The CDI display shows Cross Track Error (XTE) and distance to waypoint
presented in a runway format:
D4700_1
The runway represents a 0.3nm width with the vessel symbol shown at the
bottom. Bearing to Waypoint, Distance to Waypoint, Time to Go (TTG),
Course Over Ground (COG) and Speed Over Ground (SOG) are also shown.
Time to Go is calculated on the basis of distance to destination and Speed Over
Ground (SOG) towards the destination.
At waypoint ranges greater than 4nm, the symbol remains at the top of the
screen. As the waypoint range falls below 4nm, the symbol moves down the
centre line.
The chequered pattern moves down the screen to simulate movement when
SOG is greater than 2 knots.
The steering instruction is STEER STARBOARD if the XTE is 0.01nm or
more to port, STEER PORT if the XTE is 0.01nm or more to starboard or ON
COURSE if the XTE is less than 0.01 on either side. If no GOTO or follow is in
progress, the steering instruction is NO TARGET.
The graphical XTE indication places arrows either side of the steering
instruction and pointing towards it, dependent on the value of XTE.
The first arrow is shown when the XTE reaches 0.01nm, the second at .05nm
and subsequently at 0.1nm intervals .