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The first Europe-built, LNG-powered, dual-fuel tug is also the first to feature two Schottel thrusters fitted with the company's new SDV45 nozzle.

The 40.2-metre-long vessel, named Dux, was built at the Astilleros Gondan S.A. shipyard in Spain for Norwegian shipowner Ostensjo Rederi. It is to be used to provide tug services to energy firm Statoil in the island of Melkoya, located west of Hammerfest.

The vessel is equipped with a pair of Schottel Rudderpropellers Type SRP 630 CP. The main thrusters are powered by two Wartsila 6L34DF main engines with a power rating of 3000 kW each. Additionally, the Dux is fitted with a Schottel Transverse Thruster Type STT 170 FP with 250 kW in the bow.

Market debut of SDV45 nozzle

After a period of computational fluid dynamics (CFD) analysis and trials, Schottel says the new VarioDuct SDV45 nozzle has been modified in shape to enable high-power applications along with reduced fuel consumption.

"The SDV45 nozzle marks a substantial progress in terms of a vessel's overall efficiency compared to other nozzle products. In combination with a compatible propulsion unit, fuel savings of up to 10% are possible at a certain speed, while maintaining a high rate of bollard pull," Schottel explained.

The Dux is not set to remain the only vessel equipped with the bunker-saving SDV45 nozzle for very long; France's Louis Dreyfus Armateurs has ordered a wind farm service operation vessel to be built in Turkey and feature three Schottel Rudderpropellers with the new nozzle.

LNG

The Dux has the ability to operate on either LNG or diesel. The vessel will be using LNG in most of its operations, with the option to switch to diesel when needed.

Built according to Robert Allan Ltd's RAstar 4000 DF design, the tug also incorporates Wartsila LNGPac fuel systems with 30-cubic-metre horizontally mounted Type C LNG fuel tanks. The tanks are said to allow for two weeks of operation between fuellings.

Image: Model test of Schottel's VarioDuct SDV45 nozzle in a towing tank.