Having introduced the Rudderpropeller over 65 years ago, German manufacturer Schottel continues to introduce innovations to the marketplace and at SMM this year presented scale models of its latest EcoPeller (SRE), a thruster design optimised for both coastal and open sea operation. The SRE is based on proven technology combined with the latest enhancements achieved through the use of CFD simulation work and model testing.
Based on the Schottel Combi Drive design principle, the SRE has its electric drive motor integrated into the unit’s vertical support tube. This is a space saving feature but also removes the need for angled gearing, saving cost and complexity. The result is a simple and robust design that has low vibration and noise level emissions. The integrated High-Torque-Gear (HTG) technology also improves the durability of the unit, reducing maintenance downtime.
SRE products are available with seven different propeller diameters from 2.15m up to 4.2m. Power rating begin at 1,050kW for continuous unrestricted operation of vessels such as ocean going freighters and tankers. The largest units can deliver 4,000kW in the same duties or up to 4,600kW offshore or similar duties.
The SRE is also available with the Schottel LEACON sealing system, which has just gained certification from classification society DNV-GL as a leak-free sealing system for the oil-to-sea interface. This means the products can be operated in US waters without the need to use bio-oils complying with current US EPA vessel general permits.
The LEACON system has been operating in service since November 2009, with separate seals on the seawater and gearbox side and a negative pressure central chamber to collect any liquids leaking from either side. This eliminates the risk of seawater contamination of the gearbox and leakage of any oil into the sea. The system also monitors the condition of the seals through measurement of collected fluids allowing better prediction and planning of maintenance needs. Regular approved mineral gear oils can therefore be used with safety but the system can also be used with bio-oil to ensure maximum environmental protection.
Schottel also featured its SRT rim thruster at SMM, this being a space saving design that minimises noise and vibration levels for vessels where high levels of operational comfort are required. These electric-driven units are available in four frame sizes with propeller diameters from 800mm to 1,600mm and powers from 200kW to 800kW. The electric drive motor is integrated into the thruster tunnel, which acts as the motor stator, with the thruster blades being fixed to the rotor. With no gearbox or transmission losses, electrical power is converted directly into propulsive force and vibration is kept to a minimum. Thruster blades are also optimised to reduce cavitation.
The electric motor itself is permanently cooled by the surrounding water, preventing it from overheating and increasing its reliability. With few moving parts, the SRT also has reduced maintenance requirements. When work is required, this can be carried out in situ with wear parts easily replaced by a diver. With water being used to lubricate the slide bearings, the unit is also environmentally friendly.