Podded drives are currently finding growing success in the marine industry. The Azipod system from Finlands ABB Industry and the Mermaid system from Kamewa/Alstom have both made inroads in the cruise industry and find that other markets are now opening up. Meantime, the Siemens-Schottel SSP has been specified not only in a cruise ship, but also in a chemical carrier, two RO/RO ferries and two heavy lift carriers. The latest entrant into the arena, the Dolphin, jointly developed by STN Atlas Marine Electronics of Hamburg and John Crane-Lips of Drunen, the Netherlands, has been selected for Seven Seas Voyager, the new 50,000gt cruiseliner under construction by T. Mariotti at its Genoa yard for delivery to Radisson Seven Seas in 2003.
AZIPODS CRUISE TO SUCCESS
The use of the Azipod propulsion system onboard cruise vessels has been developing dramatically with the number of Azipod-equipped ships operated by various cruise ship owners continuing to climb. Finlands ABB Industry, a division of ABB Process Industries, developers of the Azipod unit, has delivered some 70 systems to cruise ship operators since its inception during 1990.
The largest customer has been Carnival Corporation. It has three Carnival spirit class ships utilizing the Azipod propulsion system, with another three on order, while its Holland America unit has also ordered Azipod systems for five new cruise vessels. Carnivals Costa Cruises also has Azipod units onboard the Costa Atlantica, with plans for a similar unit onboard a further vessel.
The latest application is the Royal Caribbean Voyager Class 3,840 passenger-capacity Adventure of the Seas, the third in the series of this Class (Project Eagle), which is due for delivery during October this year. The builder is Finlands Kvaerner Masa-Yards.
The diesel electric propulsion plant comprises six Wärtsilä diesel engines type 12V46C, with a combined out put of 75,600 kW (42,000 kW for propulsion purposes). This plant drives three 14 MW Azipod propulsion units, one fixed and two azimuthing.
As has been well publicized, not all has been smooth running for the Azipod. Last July there was a malfunction in the propeller bearing system of one of the Azipod propulsion system onboard Carnivals 1998-built Paradise. The ship, following the failure of the starboard Azipod unit, was drydocked immediately at Newport News Shipbuilding (NNS), where the first ever repair to a Azipod system in an United States repair yard was carried out.
ABB Industry has some 200,000 operating hours experience with this propulsion system and therefore a solution to the problem was found very quickly.
Following the problems with the Paradise, CCL then decided to cancel during August last year, two voyages of the sistership Elation, to allow preventative maintenance work to be carried out, again at Newport News.
At that time, the Paradise and the Elation were the only two Carnival ships to have Azipod propulsion units installed. Since then they have been joined by the third ship in the SpiritClass.
The nature of the Paradise malfunction resulted in both CCL and ABB putting out statements last December to clarify the relationships between the two companies.
Carnival Corporation very much appreciates ABB standing behind its product and working diligently to quickly address our concerns and resolve matters important to us. ABB is a major player in marine propulsion, and we feel we have a good customer-supplier relationship with them, said Stein Kruse, HALs Senior Vice President.
ABB looks forward to continuing its 15 year long relationship with Carnival and helping it to maintain its well-deserved reputation for quality in the cruise industry, added Andreas Fokkens, ABBs Senior Vice President in charge of Marine Business and Turbochargers.
Podded drives are now finding growing acceptance beyond the cruise sector. ABB has received a recent order for a Azipod propulsion system from the naval market in the form of electric power plants for two survey vessels building for the U.K. Royal Navy by Britains Vosper Thornycroft. Each vessel will have two PWM DTC-controlled compact Azipod units rated at 1,700 kW each. These two survey ships, which are due for delivery in 2002 and 2003, are the first Royal Navy ships to have Azipod propulsion units.
For the Far East market, two Aframax-Class crude-oil double acting tankers are being built for Finlands Fortum Oil & Gas at South Koreas Sumitomo Heavy Industries (SHI). Each tanker will be supplied with a 16 MW Azipod unit with cycloconverter propulsion system. The stern form is designed to break ice and the Azipod system creates a lubricating water stream between the ice and the hull. Therefore the tankers will be able to reach speeds of three knots in one-meter thick ice. The tankers are due for delivery during June and August 2002.
The Azipod system is also currently being considered for use onboard large lng carriers. According to Mika Laurilehto of Wärtsilä Corp, there are some 10-12 large LNG carrier newbuildings required each year over the next few years. Wärtsiläs basic case study involves a 138,000 m3 vessel with an operating speed of 20 knots and a corresponding power requirement of approximately 26 MW at the propeller and a further 6 MW for electrical requirements (if electric cargo pumps are utilized.
One of the scenarios for a twin screwed ship based on these factors is a single-screw low-speed main engine with a fixed pitch propeller complemented by a podded drive replacing the rudder. The main engine, which would operate on HFO, would supply approximately half of the power requirement, the podded drive the other half.