Schottel’s simple hybrid propulsion solution

For tug designers and builders, fuel efficiency, low maintenance costs and environmental friendliness will be high on the must-have list in their sales pitch. It is recognised that around 90% of a shiphandling tug’s operating time involves low engine loads and the inclusion of various hybrid solutions to avoid main engines running inefficiently for long periods is gaining popularity in addressing this conundrum.

With the typical arrangement of two azimuth thrusters and based on its Y-Hybrid thruster technology, Schottel’s new Sydrive-M connects the two allowing them to be powered by either one of the main engines offering an alternative to the typical hybrid propulsion system of two independent power sources per propeller, normally configured with a main engine and smaller electric motor, an arrangement which Schottel state requires additional electric components making “such hybrid solutions more complex and more expensive.” This solution mechanically and variably connects two thrusters to one main engine for low-load operations with no need for any additional electronic components or additional gearbox.

The system comprises three main modes. For light operations one of the two main engines remains alternating off with a “noticeable reduction of operating hours” along with maintenance cost savings. The engine is better loaded in a more suitable specific fuel consumption range compared to two engines running (in light operation mode) at relatively low rpm ranges with positive fuel efficiency and emissions results.

For short periods when full propulsion power is required the connection between the two thrusters is disengaged, each engine connected independently to each thruster. The system is now identical to any other directly-driven propulsion arrangement. For firefighting operations the disengaged main engine is simply used to drive the fifi pump through its front PTO shaft avoiding requirements for components such as slipping clutches, CP propellers or dedicated engines to supply fifi pumps.

Sydrive-M can be integrated into any usual vessel design with direct propulsion with no need for design changes. It is available for Schottel’s Rudderpropeller and EcoPeller series of azimuth thrusters from 1,000kW up to 3,000kW. Retrofit is possible for specific Schottel azimuth thrusters and engine types and the system has been filed for patenting.

By Peter Barker