The document posted by Angus describes how Ocean Star operated in SS2008 at the time I wrote it.
It still operates that way in the version that I have. If you have downloaded an “improved†version of OS, then good luck.
As explained, if you set one Az to 90 or 270 degrees, you can use it as a stern thruster.
If you balance it with the bowthruster, you can move OS crabwise.
With the second Az left at 180 degrees, you have control of forward movement.
You have the best control for that maneuver by using the mouse on the colored circles.
Yes, unlike Bug2, the screw rotation can be reversed on OS by moving into the red region of the controller. This makes more sense for a cruise liner.
The white triangle on the controller points in the direction that the screw faces. When it points aft, it behaves like the screw on a conventional ship: Forward (Green) rotation pushes the ship toward the pointy end.