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Going beyond the conventional in marine propulsion

ABB is a leading manufacturer of electric power and propulsion systems for marine needs, with over half a century of experience in the field. ABB’s reliable, safe, and environmentally friendly solutions – such as the Azipod® propulsion system – reduce operating costs and help ensure optimum life cycle performance.

Originally introduced in 1990, ABB’s Azipod® is the market leader in podded propulsion technology and powers a wide range of ships today, including luxury cruise vessels, ferries, drilling rigs, arctic tankers, offshore supply vessels, and icebreakers.

With over five million cumulative operating hours under its belt, the Azipod® propulsion concept has leveraged numerous improvements in ship design and operation. Azimuthing propulsion offers excellent manoeuvrability, saves space inside the hull, and gives ship designers a host of new opportunities. Perhaps the single biggest benefit of the system of the technology, however, is reduced fuel consumption and CO2 emissions – and the latest products in the range are the most energy-efficient electric propulsion systems anywhere.

Integrated ‘power packs’

Azipod® electric propulsion units, like those seen here fitted to the Freedon of the Seas, use a variable-speed electric motor to drive a fixed-pitch propeller in a submerged pod outside the hull. Pods can be rotated around their vertical axis to provide thrust in any direction, eliminating the need for rudders, stern transversal thrusters, or long shaft lines inside a ship.
Fitted oustide the hull, Azipod® propulsion modules can be rotated around their vertical axis and combine the functions of a propulsion motor, main propeller, rudder, and stern thruster. When used with cruise ships, for example, Azipod® systems have been shown to reduce fuel consumption by around 10% compared to diesel-electric propulsion systems employing a conventional shaft-line arrangement.

The CRP (contra-rotating propeller) Azipod® has taken the basic concept even further, by using two propellers facing each other and rotating in opposite directions. Replacing the rudder used in a conventional shaft-line arrangement, CRP Azipod® solutions are ideal for fast ferries and other fast ships that need very large propulsion power, and have been able to offer fuel savings in the order of 20%, while enabling more transportation capacity to be built into a design compared to similar-sized ships powered by conventional diesel engines.

Enter the next generation

ABB launched an extensive development project to develop the next generation of Azipod® propulsion units a couple of years ago to take the proven advantages of the technology to a higher level.

The new concept being developed will further improve operational efficiency and availability, and reduce the total life cycle costs of systems. This will enable maintenance of most vital components to be carried out without dry docking ships, and will reduce steering torque and improve hydrodynamic efficiency.

The even greater design flexibility of the new generation of Azipod® technology will allow units to be integrated into a wider range of ship types and/or hull forms.

The new generation will also feature electric steering controlled by variable-speed drives. The latter will offer greater overall efficiency and will be easier to install and maintain as well, as they will make it possible to eliminate hydraulic systems. Noise levels will also be lower.

The steering module is also being redesigned, with a special focus on reliability, maintenance, and ease of integration into the hull. A new propulsion control interface will provide crew with a better understanding of overall system status, helping minimise the risk of human error and reduce mechanical wear and stress by helping crews use the system as optimally as possible.

Inherently flexible

ABB’s Azipod® propulsion is an inherently flexible system that can be used in several configurations and with a broad spectrum of different types of vessel. A number of benchmark vessels have already been made possible by the technology and the use of Azipod® propulsion is growing, with ship designers and research laboratories working on new innovative vessel concepts based on the Azipod® system. Current Azipod® applications include:

  • Single Azipod® solutions for vessels such as tankers and cargo ships
  • Twin Azipod® installations provide greater manoeuvrability and full redundancy from power generation to propeller, and are most widely used in cruise ships
  • Triple Azipod® is an attractive solution for large vessels with high power and redundancy requirements
  • CRP Azipod® is a unique contra-rotating propulsion system designed specifically for high-speed, highpower vessels such as Ultra Large Container ships, LNG carriers, and RoPax ferries.

Powering the new giant of the seas

A new milestone was reached in shipbuilding – and the use of Azipod® technology – in 2009 with the delivery of the world’s largest cruise ship, the Oasis of the Seas, to Royal Caribbean International by STX Europe’s Turku shipyard in Finland. Her sister ship, the Allure of the Seas, is due to be delivered in 2010.

The largest ship of its type and the most valuable ship in the history of commercial shipbuilding, the 225,000 grt Oasis of the Seas is a giant in every sense and over 40% larger than the previous generation of cruise ship. 361 metres long, 66 metres wide at its widest point, and rising 72 metres above the waterline, the ship is capable of carrying up to 6,360 passengers. Ships of this calibre obviously need a propulsion system to match, which is why ABB was selected. The three Azipod® units supplied for main propulsion give the ship outstanding manoeuvrability and fuel economy despite the massive size of the vessel. With a total power plant capacity of 97,000 kW, the Oasis of the Seas will cruise at 22.6 knots.

ABB supplied a complete electric power plant and propulsion package for the ship, covering:

  • 3 x Azipod® propulsion units
  • 3 x ACS6000SD frequency converters
  • 6 x main generators
  • 11 kV main switchboards
  • 6 x propulsion transformers
  • 4 x thruster motors
  • Distribution and propulsion excitation transformers, and
  • Substation switchgear.
> Antti Lehtelä
(Published in HighTech Finland 2010)