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 Pod-mounted, fixed pitch propeller
In 1990, the Pod system for cruise ship propulsion was born with Azipod and the similar Mermaid systems. Instead of having shaft-mounted propellers, the propellers are carried on pods hanging below the ship. A powerful electric motor within the pod drives the fixed-pitch propeller at continuously variable speeds. The pod can either be fixed in position or, more commonly, rotating or azimuthing a full 360 degrees. With pods, a rudder is no longer necessary thus both simplifying the design and reducing drag. Pods also remove the need for stern thrusters since when rotated 90 degrees, they have the same effect as a powerful stern thruster.
 Queen Mary 2 fixed (forward and outboard) and rotating (aft, nearly amidships) pods
Some ships have a combination of rotating and fixed pods. Either 2 pods of each type as for the QM2 or with a single, amidships, fixed pod.
The propellers have the same Rotational Direction and Relative Thrust Effects as for classically mounted propellers and much, much more. As on the QM2 above, the propeller is on the forward facing end of the pod in normal cruising position. As the pods are rotated, the turning angle of the ship increases while the forward thrust decreases. When rotated past 90 degrees, more and more reverse thrust is applied until the pod has rotated 180 degrees into the "full astern" position. If the pods are facing each other, one at 90 degrees and the other at 270 degrees, their effect on each other is cancelled.
In the simulation you may find that, as you approach the dock, you want to cut the thrust of the pods to slow down. Cutting the thrust too far, however, results in an inability to steer. Having at least one fixed pod gives the possibility of using the fixed pod to accelerate or slow and the rotating pods for steering. You might also keep one of your 2 rotating pods in a fixed position to slow the ship and use the other pod for steering.
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