Azimuth Stern Drives Azimuthing drives use conventional propellers that can be rotated a full 360 degrees to provide thrust in any direction without a rudder. Such a configuration is commonly known as Z® drive. The name "Z-Drive" is derived from the drive shaft configuration which is horizontal off the engine, vertical through the hull, and horizontal at the propeller hub, thus forming a rough outline of a letter Z. These tugs combine certain advantages of conventional tug and reverse tractor tug. They can operate like conventional tug as well as reverse tractor type. ASD tugs have a towing winch forward as well as towing winch or hook aft.