Conventions

Coordinates

latitude: -90° - 90°
longitude: -180° - 180°
headings: 0° - 360°, angular difference between North and the ship’s direction, angles are going in the negative mathematical direction (clockwise)

Units

Apart from one exception, the WRT uses SI units for internal calculations. Only angles are handled in degrees as defined in the paragraph above. All input variables that carry a unit are converted according to these definitions. For the output – i.e. when a route is written to a json file – the engine power is converted to kW and the fuel rate to mt/h, where mt refers to metric ton.

The WRT uses the package astropy for the convenient handling of units.

Logging

The routing tool writes log output using the python package logging. Information about basic settings are written to a file which is specified by the environment variable INFO_LOG_FILE. Warnings and performance information are written to the file which is specified by the environment variable PERFORMANCE_LOG_FILE. Further debug information are written to stdout.