The current status of electric propulsion in cargo, cruise, and navy ships, however, is quite different for each other.
Commercial Cargo Ships with Electric Propulsion
There is not much current interest for electric propulsion in cargo ships hauling freight over long sea routes at one constant speed, with no passengers to please or
weapons to launch with a high burst of power. Electric propulsion, however, is presently used almost exclusively in icebreakers and floating offshore oil platforms and is becoming more common in passenger and car ferries. Other kinds of commercial ships now being built with electric propulsion include shuttle tankers, pipe and cable-laying ships, and research ships.
Cruise Ships with Electric Propulsion
Electric propulsion with a podded motor is a norm at present for cruise ships. As discussed further in this chapter, this provides great benefits for the internal layout and ship maneuverability.
The pod propulsion motor is mounted in water beneath the ship. It is used extensively in cruise ships and is being considered for navy ships as well. Since the pod design is dominated by the motor and its cooling system, the newly developed compact motor technology is the main technology enabler for electric propulsion.
The electric propulsion systems used today in cruise ships and other commercial ships are generally made overseas, primarily in Europe. The two of the three primary European-based electric propulsion suppliers are Alstom and Asea Brown Boveri (ABB), which together account for most of the electric propulsion systems in operation today.
The primary electric propulsion facilities of ABB are in Finland and Italy. Siemens of Germany has a smaller market share but has a lead in the permanent magnet motors and the advance motor drives.
Navy Ships with Electric Propulsion
Electric propulsion technology is already in use on a few U.S. government ships. They include the U.S. Coast Guard icebreaker Healy, several TAGOS-type ocean surveillance ships for Military Sealift Command, and a few AGOR-type oceanographic research ships operated by academic institutions under the University National Oceanographic Laboratory System (UNOLS) of the navy.