thrusters Wärtsilä overhauls thruster ranges
Driven by what Wärtsilä describes as changing market demands, the Finnish power and propulsion specialist has responded by developing new ranges of both azimuthing and tunnel thrusters. According to Wärtsilä, its next generation of thrusters has been developed by using the latest calculation tools from thousands of hours of model testing to ensure the products are at the cutting edge of hydrodynamics. On the propulsion front, the new Wärtsilä Steerable Thruster (WST) series is being introduced to replace the company's Modular Thruster and Compact Thruster ranges. The first models to become available are the WST- 45U and the WST-14. The new WST-45U represents the latest technological evolution of higher powered units exceeding 3MW. An underwater de-mountable thruster, it has been specifically designed for the drilling and offshore construction sectors but is equally suited to
other vessel types that require mounting or exchange of thrusters afloat. Compared with earlier models, the new
design provides the same amount of thrust from a lower power requirement, thereby reducing fuel cost. However, Wärtsilä also says that mechanical improvements such as optimising the hydrodynamic design of the lower gearbox and incorporating an 8 degree tilt results in a better performing, more reliable unit that does not just reduce fuel but overall operating costs. Based on the ABS Guide for Dynamic Positioning Systems, a correction factor of approximately 14 per cent on the performance will be applied in case the DP-requirement is based on conventional DP-capability calculations. Already 116 units have been sold with the maker claiming this places it at the forefront of 8 degree tilt technology. The second of the new models, the
WST-14, represents the latest evolution of Wärtsilä’s series of steerable thrusters of less than 3MW and is intended for tugs up to 45 tonne bollard pull, inland waterway vessels and river/sea going cargo ships. This thruster is compatible with both medium speed and high speed (1,800 rpm) diesel engines. By focusing on a more integrated design, Wärtsilä says the WST-14 is more compact than its predecessor, making it easier to install. By improving the design performance, extending engine compatibility to include high speed diesel engines, providing light class compliance and reducing the manufacturing costs of this unit, the WST-14 series now represents a much more competitive proposition to the market.
In the new tunnel thruster range the first
The WST-45U is one of the first models in the new Wärtsilä Steerable Thruster series (credit: Wärtsilä)
Wärtsilä’s new WTT-11 tunnel thrusters (creit: Wärtsilä)
68 I Marine Propulsion I April/May 2014
product to be introduced to the market is the WTT-11, which is a 1,100kW tunnel thruster designed mainly for merchant cargo vessels and used predominantly to manoeuvre the vessel when mooring. Thanks to the smaller size of the auxiliary equipment, Wärtsilä says it is able to offer a cost effective solution which also has a reduced footprint. With its new range, Wärtsila believes is can integrate both thrusters and propulsion through one control platform, streamlining bridge activities and optimising equipment use. Multiple control stations can be installed to ensure maximum flexibility. The control system can be incorporated with Wärtsilä 3C, which combines navigation, communication, propulsion control and automation into one platform with a common user interface giving the bridge team easy access to all relevant systems with a more simplified user interface.
Pushing through the ice Towards the end of this year, the new 12,000gt flagship of Canadian ferry operator Société des Traversiers du Québec (STQ) will be completed by Italian shipbuilder Fincantieri’s Castellammare di Stabia yard.
The new ro-pax ferry will be larger and faster than its predecessor in the STQ fleet but, despite its larger size, the vessel will also be more efficient and environmentally friendly thanks in part to the pair of Steerprop SP 120 ECO CRP propulsors that will drive the vessel. Each of the Z-drive thrusters with their contra-rotating propellers has a power rating of 7,000kW. Because year-round operation involves the vessel often working in severe ice conditions during winter, the thrusters will be type approved to Finnish-Swedish 1 A Super ice-class standards. Van Voorden Castings from the Netherlands was entrusted with producing the four stainless steel propellers. These have diameters of 2.9m and 3.5m and a combined weight of over 25 tonnes. Stainless steel rather than the more normal bronze was used for the propellers because it resulted in thinner blades and thus an increase in performance in ice and allowed for lower fuel consumption. Furthermore ››› ››› the stainless steel has a higher resistance to cavitation damage than bronze. .Van Voorden claims to be one of the very few foundries in the world which is able to cast stainless steel in the dimensions and quality needed for the propellers which were surveyed and approved by Lloyd’s Register.
The ECO CRP thrusters are not the only products intended for use in ice infested waters to be supplied by Steerprop. The company was also contracted to deliver main propulsion systems for three icebreakers of the Russian Federal Agency of Marine and River Transportation from United Shipbuilding Corp. Two of these icebreakers will be built in the Vyborg shipyard in Russia and one in the Arctech shipyard in Helsinki, Finland. Steerprop is delivering two SP 110 ARC
PULL units for each of the icebreakers. The units will have a power rating of 9,000kW each and each will be classified according to the Icebreaker 7 rating of the Russian Maritime ›››
A pair of Steerprop SP 120 ECO CRP will power STQ’s new ferry (credit: Steerprop)
www.mpropulsion.com
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