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Azipod

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Closeup of one ofUSCGCMackinaw's 3.3MW Azipod units

Azipodis a trademarkedazimuth thrusterpod design, amarine propulsionunit consisting of a fixed pitchpropellermounted on asteerablegondola ( "pod" ) containing the electric motor driving the propeller, allowing ships to be more maneuverable. They were developed in Finland in the late 1980s jointly byWärtsilä Marine,Strömbergand the Finnish National Board of Navigation.[1]

Although "Azipod" is a registeredbrand name,it is sometimes used as ageneric trademarkfor podded propulsion units manufactured by other companies.[2][3][4][5]

Concept

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In the conventional azimuth thrusters such asZ-driveandL-drivethrusters, the propeller is driven by anelectric motoror adiesel engineinside the ship's hull. The propeller is coupled to the prime mover with shafts andbevel gearsthat allow rotating the propeller about a vertical axis. This type of propulsion system has a long tradition throughout the 1990s and today such propulsion units are produced by a number of companies around the world.[6]

In the Azipod unit, the electric motor is mounted inside the propulsion unit and the propeller is connected directly to the motor shaft.[7]Electric power for the propulsion motor is conducted throughslip ringsthat let the Azipod unit rotate 360 degrees about the vertical axis.[8]Because Azipod units utilize fixed-pitch propellers,[9]power is always fed through avariable-frequency driveorcycloconverterthat allows speed and direction control of the propulsion motors.[10]

The pod'spropellerusually faces forward because in this pulling (or tractor) configuration the propeller is more efficient due to operation in undisturbed flow. Because it can rotate around its mount axis, the pod can apply its thrust in any direction. Azimuth thrusters allow ships to be more maneuverable and enable them to travel backward nearly as efficiently as they can travel forward. In order for the full capabilities of podded propulsion units to be realized in commercial service, shiphandling training onsimulatorsandmanned modelsis required for the crew.[11]

The podded design typically achieved a 9% betterfuel efficiencythan the conventional propulsion system when it was first installed in the 1990s. In the meantime, improvements to the conventional designs have shrunk the gap to 6–8%, but on the other hand the hydrodynamic flow around the Azipod has been improved by fin retrofits and a dynamic computer optimization of the respective operating angles of the pods in multipod installations, thereby yielding overall efficiency improvements now in the range of 18%.[12]

History

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Development

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The first Azipod unit, installed on the Finnish fairway support vesselSeiliin 1990, is now displayed at theForum Marinummaritime museum inTurku,Finland.

In 1987, theFinnish National Board of Navigationmade a co-operation proposal to the electrical equipment companyStrömberg(laterABB) and the Finnish shipbuilderWärtsilä Marinefor the development of a new type of electric propulsion unit.[13]Prior to this, the companies had been working together for decades in the field of diesel-electric propulsion systems and in the 1980s produced the first icebreakers withalternating currentpropulsion motors andcycloconverters.[14]

The development of the prototype started in 1989 and the first unit was ready for installation in the following year.[15]The 1.5MW unit, dubbed "Azipod" (short for azimuthing electric podded drive[16]) was installed on the 1979-built Finnish fairway support vesselSeiliatHietalahti shipyardinHelsinki,Finland. After the refit, the vessel's icebreaking performance was considerably increased and she was also found out to be capable of breaking ice astern (backwards). This discovery of a new operating mode eventually led to the development of thedouble acting shipconcept in the early 1990s.[17][18]WhenSeiliwas refitted with new propulsion system in the 2000s, the prototype unit was donated toForum Marinumand put on display inTurku,Finland.

Following the encouraging experiences from the prototype installation, the development of the Azipod concept continued and the next units were retrofitted on two Finnish oil tankers,UikkuandLunni,in 1993 and 1994, respectively. Nearly eight times as powerful as the prototype, the 11.4MW Azipod units considerably increased the icegoing ability of the vessels that were already built with independent icebreaking capability in mind.[17]Since the 1990s, the vast majority of ships capable of operating in ice without icebreaker escort have been fitted with Azipod propulsion system.[19]

The first three Azipod units were of so-called "pushing" type in which the propeller is mounted behind the gondola. In the subsequent installations, ABB adopted the more efficient "pulling" configuration similar to propeller-driven airplanes.

The world's firstcruise shipfitted with Azipod propulsion units,Elation,was delivered by Kværner Masa-Yards Helsinki shipyard in the spring of 1998.[20]Even though the Azipod was initially developed for icebreaking vessels, cruise ships have become the largest group of ships by type to be fitted with Azipod propulsion system since the 1990s and the success of the electric podded propulsion units has paved the way for competitors such as theRolls-RoyceMermaid. Among the vessels fitted with Azipod units areRoyal Caribbean International'sVoyager-,Freedom-,Oasis-andIcon-classcruise ships, each of which held the title of thelargest cruise ship in the worldat the time of delivery.[19]

Another further development of the original electric podded propulsion concept is the Compact Azipod, a smaller Azipod unit introduced in the early 2000s. It is intended for smaller ships such as research vessels andyachtsas well asdynamically positioneddrilling rigsthat may utilize up to eight such propulsors.[19][21]The smaller Azipod Compact differs from the full-size unit by itspermanent magnet synchronous motorwhich is directly cooled by sea water. For drilling vessels, it is also available in "pushing" configuration and can be fitted with anozzleto increasebollard pullthrust in stationkeeping applications.[22]Unlike the full-sized Azipod units which are assembled in Finland, the Compact Azipod units are manufactured in China.[23]

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During the initial years in service, some widely publicisedcruise shipservice disruptions with the bigger Azipod V design have occurred.[24]

The latest design, the Azipod X, incorporates these improvements, with a view to a service interval of five years, and features bearings that can be taken apart and repaired from inside the pod while the ship is harbored normally.[25][26]

See also

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References

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  1. ^"ABB's Azipod® azimuth thruster system wins the Finnish Engineering Award and 30 000 euros".TEK.1 December 2021.Retrieved11 April2023.
  2. ^MAO:249/18.Markkinaoikeus, 8 May 2018.Retrieved 2019-02-18.
  3. ^Inside view: What makes QM2 goArchived2013-01-21 at theWayback Machine.Beyond Ships.Retrieved 2014-04-26.
  4. ^Marine Propulsion & Auxiliary Machinery: The Journal of Ships' Engineering Systems.Riviera Maritime Media. 2005.
  5. ^Brian J. Cudahy (2001).The Cruise Ship Phenomenon in North America.Cornell Maritime Press. pp. 53–.ISBN978-0-87033-529-7.
  6. ^Tammiaho, Erkki."Ruoripotkurilaitteiden liiketoiminta Suomessa, TEKES, 258/2009"(in Finnish). Archived fromthe original(PDF)on 2010-12-08.Retrieved2013-12-05.
  7. ^Pakaste, Risto; et al. (February 1999)."Experience with Azipod propulsion systems on board marine vessels"(PDF).Archived fromthe original(PDF)on 2014-03-27.Retrieved2012-12-25.
  8. ^Society of Naval Architects and Marine Engineers (U.S.) (1994).Transactions – The Society of Naval Architects and Marine Engineers.Society of Naval Architects and Marine Engineers.ISBN978-0939773152.
  9. ^Lakeside Publishing Co. (2002).Cruise Travel.Lakeside Publishing Co. pp. 42–.ISSN0199-5111.
  10. ^Mukund R. Patel (2012).Shipboard Propulsion, Power Electronics, and Ocean Energy.CRC Press. pp. 188–.ISBN978-1439888506.
  11. ^Port Revel Pod Shiphandling course
  12. ^"Azipod propulsion drives take the next step".Skipsrevyen. March 2011. Archived fromthe originalon 2013-10-02.Retrieved2013-09-24.
  13. ^Hepo-oja, Anssi; Mäki-Kuutti, Viktor (2012).Mekaanisen ja sähköisen propulsiojärjestelmän esittely(PDF).Satakunta University of Applied Sciences.
  14. ^Cycloconverters for the new icebreaker from Kymmene-Strömberg. Navigator 1985.
  15. ^1. Dynamosta Azipodiin – vuosikymmenien kokemukset jäänmurtajista.ABB Group.Retrieved 2013-10-05.
  16. ^ABB-teknologiat: Azipod®-propulsiojärjestelmät.ABB.Retrieved 2016-02-12.
  17. ^abJuurmaa, K et al.: The development of the new double acting ships for ice operation. Kvaerner Masa-Yards Arctic Technology,2001Archived2012-03-03 at theWayback Machineand2002Archived2012-09-04 at theWayback Machine.
  18. ^Juurmaa, K et al.:New ice breaking tanker concept for the arctic (DAT)Archived2012-03-03 at theWayback Machine.Kvaerner Masa-Yards Arctic Technology, 1995.
  19. ^abcReferences – Propulsion ProductsArchived2014-06-11 at theWayback Machine.ABB.Retrieved 2014-04-26.
  20. ^6.11. Azipod ® propulsionArchived2014-04-26 at theWayback Machine.ABB.Retrieved 2014-04-26.
  21. ^Compact AzipodArchived2014-04-26 at theWayback Machine.ABB.Retrieved 2014-04-26.
  22. ^Azipod CArchivedFebruary 24, 2014, at theWayback Machine.ABB.Retrieved 2014-04-26.
  23. ^ABB Propulsion Products for Main Propulsion and ThrustersArchivedFebruary 25, 2014, at theWayback Machine.ABB, June 2012.Retrieved 2014-04-26.
  24. ^Fredrickson, Tom (2000-07-22)."Carnival's Paradise Coming To Yard For Repairs".Newport News, Virginia:Daily Press.Retrieved2013-09-24.
  25. ^"Archived copy"(PDF).Archived fromthe original(PDF)on 2013-12-30.Retrieved2012-12-27.{{cite web}}:CS1 maint: archived copy as title (link)
  26. ^"Propulsion Systems by ABB Marine".Wplgroup.com. 2012-02-13. Archived fromthe originalon 2013-12-30.Retrieved2013-09-24.
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