Saab R5 SUPREME AIS, Operation & Installation Manual

Page: 38 / 156

R5
SUPREME - Navigation System
CONCEPTS AND TERMINOLOGY
7000 118-301, A3 Page 38
The navigation algorithm is the algorithm used for calculating the course to steer to reach the
next waypoint. It is also used for calculating the distance to the waypoint. The navigation
algorithm can be either great circle or rhumb line.
Great Circle Navigation
The great circle navigation algorithm calculates a course line that is the shortest path
between two points on the surface of the earth. The course to steer when navigating towards
a waypoint is not constant using this navigation algorithm. The resulting track of this
navigation algorithm will differ from the straight line drawn on a Mercator projected chart.
Rhumb Line Navigation
The rhumb line navigation algorithm calculates a course line that corresponds to a straight
line on a Mercator projected chart, and cuts across all meridians at the same angle.
Waypoint Pass Criterion
The criterion used to determine when a waypoint in the active route is considered passed.
The waypoint pass criterion can be any of Manual, Distance, Bisector Line and Perpendicular
Line.
Manual Waypoint Pass Criterion
Using this pass criterion, the waypoint is only considered passed when the operator skips the
waypoint.
Distance Waypoint Pass Criterion
Using this pass criterion, the waypoint is considered passed once
the ship has reached an imaginary circle around the waypoint. See
illustration to the right. The radius of the circle is configurable.
Bisector Line Waypoint Pass Criterion
Using this pass criterion, the waypoint is considered passed once
the ship has reached an imaginary bisector line of the angle
between current and next leg. See illustration to the right.
Perpendicular Line Waypoint Pass Criterion
Using this pass criterion, the waypoint is considered passed once
the ship has reached an imaginary line perpendicular to current leg.
See illustration to the right.