Four new tugs being built for the US Navy will have the latest Rudderpropeller technology for high performance and extended life.
Schottel has confirmed it won a contract to supply its SRP 340 propulsion systems to four azimuthing stern drive (ASD) tugs under construction at Washington, US-based Dakota Creek Industries’ shipyard.
The manufacturer provided more details on the technology that will be incorporated with these eight SRP 340 Rudderpropellers.
Each ASD harbour tug being built for the US Navy will have two Schottel azimuth thrusters, with 2,100-mm diameter fixed pitch propellers and an input power of 1,330 kW.
They will each have Leacon sealing systems certified by class society DNV-GL and Schottel’s own ProAnode on the nozzles.
Leacon sealing ensures seawater entering the system and gear oil escaping from the system are collected in an intermediate chamber.
“This prevents water from entering the gearbox and oil from escaping into the seawater,” said Schottel.
The SRP 340 Rudderpropellers have SDV45 nozzles that combine high efficiency at open-water speeds with good bollard pull values. With ProAnode, Schottel moved the position of the anode from the outside surface into the cross-section of the nozzle.
Schottel senior sales manager Uwe Neddermeyer told Tug Technology & Business in September that this “extends the lifecycle of the thruster and protects the anodes against external impacts”.
ProAnode also contributes to the optimal hydrodynamic flow of the nozzle as its smooth overall surface reduces flow interference, which lowers fuel consumption and operating costs, said Mr Neddermeyer.
Dakota Creek Industries is building the four harbour tugs for the US Navy to a Robert Allan Z-Tech 4500 design. They will have a pair of Caterpillar CAT 3512E main engines, each rated at 1,350 kW at 1,600 rpm.
They are expected to enter operation in November 2019. They will have a bollard pull of around 43 tonnes and a free-running speed of approximately 12 knots.
The US Navy intends to deploy these tugs at US military bases in the Pacific Northwest region and at Yokosuka, Japan. They are designed to handle a full range of US Navy surface warships and submarines. Therefore, Dakota Creek Industries will include an array of underwater fendering and resilient upper hull fenders for handling surface ships.