Hi Haig, seems to be a common mistake to get Schottel Drives (Z-Drives) and Voith - Schneider confused with one another!
First two pics show a twin Voith propeller
on a tug hull (as on the plan above) and the operating principle.
3rd pic is cross section of the Z-Drive as produced by the Schottel company. it is a 360° rotating 'pod'.
Newer versions have electric motor
into the pod and don't need the mechanical Z transmission from inside the hull.
With such pods under bow and stern
even bow and stern
side thrusters are redundant 😊 4th pic is the Graupner version, Mk II.
Cheers, Doug 😎