Page 77: of Maritime Reporter Magazine (September 1999)

Podded Propulsors Gain Wider Acceptance

By David Tinsley, technical editor

The growing uptake of integral elec- tric-driven, podded propulsors in the most capital-intensive sector of the cruise shipping industry, has forever altered the established position of con- ventional propulsion systems in an

The Siemens-Schottel Propulsor (SSP) (also pic- tured far right) is due to make its operational debut next year, having been selected for Red- eri Donsotank's 19,500-dwt chemical product tanker booked with Shanghai Edward Shipyard in China. The contract for the newly-developed pod was actually awarded by the shipbuilder, which is partly German-owned. important segment of the market.

Having established a foothold in the offshore sector, the concept will no doubt find increasing application with the next upswing in investment by the offshore oil and gas industry. Once con- servatism has been overcome in various quarters of the shipping business, and once the net acquisition costs of such systems reach more acceptable levels for a broader band of the shipowning com- munity, usage of the technology will no doubt spread to other spheres.

The relative paucity of orders for pod- ded drives in areas where precision han- dling is paramount, as with icebreakers, cableships, ferries and specialized tankers, belies the extent to which such systems are being written into draft pro- posals or discussed at the project plan- ning stage. The concept is especially apposite to vessels with varying service profiles, particularly where high maneu- verability is required.

The long-term sales impact of the industrial commitment from the design engineering and manufacturing side cannot be understated. In each case, podded propulsors are the products of pairings entailing major players in propulsion and electrical engineering, entailing direct or indirect links with leading shipbuilders, in certain instances.

As a progression on thruster technolo- gy, the basic principle is that the con- ventional shafting, propeller and rudder system is replaced with a 360-degree rotatable thruster unit also encapsulating the electric motor. Space savings are thereby achieved within the hull, while the efficiency losses from reduction gearing, long shaftlines, rudders, stern thrusters and also brackets and bossings are eliminated.

The market is opening up not only because of the improved propulsion effi- ciency, design flexibility and also reduced noise and vibration conferred by the generic type, but also because of its virtues in generating high steering forces, and achieving extremely high levels of maneuverability, invariably at lower power cost than with conventional arrangements.

The first cruise ship application of podded electric drive was Carnival's 70,400-gt Elation, commissioned in (Continued on next page)

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