Schottel Rudderpropellers Offer Power, Maneuverability

New Installations In Catamarans, Tugs The first of a planned series of seven passenger catamarans for operation in Sydney Harbor, Australia, recently completed sea trials, surpassing the owner's expectations for strict minimal wave formation and low noise emissions.

A key element in complying with the strict environmental regulations that are in effect in Sydney waters is the vessel's propulsion system, which features two Schottel model SRP132/131 Rudderpropellers. The Rudderpropellers not only enabled the vessel to surpass the owner's specified speed of 22 knots—the catamaran achieved a trial speed of 23.7 knots—but also requirements for minimal wave formation.

Constructed for the State Transit Authority, Sydney, the Dawn Frazer, an extremely lightweight aluminum- hulled design, was developed and designed by Grahame Parker and built by the NQEA yard, Cairns Old. The catamaran has a length of 34 feet, draft of 4-1/2 feet and passenger capacity of 150. She will operate as a water bus in Sydney in waters where special environmental regulations apply. It is regarded as an extension of the existing range of high-speed catamarans equipped with conventional waterjet propulsion systems.

Specially designed by Schottel for t h i s application, the newly developed Rudderpropellers have streamlined housings and tractor propellers designed for high speeds.

Suspended between the two hulls, the resiliently mounted rudder- propellers are powered by two GM92TA 492-hp diesel engines.

Steering is effected with Schottel's Copilot 2000 system, while control of the engine speed is via Schottel's Speedtronic unit.

According to Schottel, the decision to select Rudderpropellers for the propulsion system was based on a concept that was developed by company experts at Spay and then successfully implemented in close cooperation with the designer and the owner. Schottel reports that because of their more favorable efficiency characteristics in comparison with waterjets, Rudderpropellers endow craft of this size not only with high speed but also with excellent maneuverability.

Besides being installed on a wide range of passenger vessels, Rudderpropellers have also found many applications in the workboat market.

One recent delivery was for the first of 12 tugs for an Italian owner.

The tug Liguria, built by the Hitzler Shipyard in Lauenburg for the Italian towing company Carmelo Noli in Savona, features sternmounted SRP1010 Rudderpropellers powered by two Wartsila-Nohab 6R25 diesel engines, each developing 1,250 kw (1,676 hp) at 950 rpm.

With a length between perpendiculars of 93.5 feet, a molded beam of 31 feet and draft of about 13 feet, the Liguria has an average bollard pull of 43 tons, with an open water speed of 12.6 knots.

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Other stories from April 1992 issue


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