In order for hydraulic systems to operate effectively at ‘zero speed’ extra-large fins protruding from the sides of the hull are used.
A large hydraulic pump moves the fins to create the desired effect. The pump speeds up and slows down upon demand creating a random load variance and may result in the need to install a larger generator.
On the other hand, the current demand for the ARG is even and steady, keeping your generator happy. Everything (gyro and driver) is contained inside the vessel which makes docking and maneuvering easier. It is possible to even run your ARG at the dock while plugged into shore power.