Using of Azipod Powerplants On a Cruise Liner
Table of Contents
Design Advantages 4
Design Changes 6
Azipod is a revolutionary electric propulsion system, designed by Masa-Yards and ABB, and currently produced by ABB Group. This concept involves an electric motor installed inside a pod, which can rotate 360-degrees about the vertical axis. Azipod-type units have proven their efficiency when installed on large vessels. The report is aimed to justify the adoption of such an innovative drivetrain on a cruise liner, regarding major design impacts on a ship.
The development of electric drivetrains, increasing of AC motors efficiency and reliability, as well as advanced computer-aided software, have led to the concept of versatile, fully rotating propulsion units. Introduced by the ABB Group, the Azipod trademark is now widely used for designation of such systems.
When the Azipod unit was first installed on the Uikku arctic tanker, the concept shown significant benefits in terms of manoeuvring and efficiency. Operators found that not only the system improves ship’s overall performance, but also brings many unique features, such as new operating modes. This experience led to the extensive adoption of this type of propulsion on large vessels, including cruise liners.
In order to stay in the technological forefront of the industry, today’s newest cruise ships are equipped with Azipod-like units instead of conventional ones. The podded propulsion system has the following advantages over the conventional drivetrain:
Excellent manoeuvring capability and increased safety. Fully steerable drivetrains increase the safety of the vessel, because there is no minimum speed required for steering. The Azipod provides excellent control of a vessel in any direction, no matter how low or high the speed is. In the case of a crash stop, a ship equipped with Azipod units can be steered towards a desired point, which comes from the nature of rotating pods and instant response of AC motors with fixed pitch propellers.
Dynamic performance. A ship equipped with turning pods powerplant is able to stay in a desired position even in severe weather conditions, such as strong wind from any direction. The second benefit comes from the fact that podded drivetrains contain fewer parts. This means that they have a smaller exposed area and can be better optimised from the hydrodynamic drag standpoint. Thus, given the same amount of power, Azipod systems provide higher operation speeds due to the lower drag and a smaller surface exposed to the flow.
Variable speed motors. This type of drivetrain guarantees efficient torque delivery at all rotating speeds, which is not the case for internal combustion engines. AC motors reach maximum efficiency from the very low rotation speed, and it stays high up to the full power mode. Therefore, the design does not require reduction gears or controllable pitch propellers that are used widely in conventional powerplants. The operation speed is continuously variable, which makes possible low-speed manoeuvring, as well as the precise speed control during cruise operations.
Redundancy. The pods have neither mechanical nor hydraulic connection to each other. This ensures the …