The EcoPeller, which has been given the type reference SRE (Schottel Rudderpropeller high Efficiency), will be offered in both fixed and controllable-pitch versions, covering a power range of 1–5MW. Its high power reflects growing significance of manoeuvring and transit operations, compared with offshore support vessels’ traditional priorities of thrust and dynamic positioning capability, explained Paul Mertes, Schottel’s head of hydrodynamics and propeller design, when OSJ visited the company in September.
It is based on Schottel’s combi-drive (SCD) design principle, incorporating a vertical electric motor integrated into the Rudderpropeller assembly. This removes the need for an upper set of angle gears and shaft lines. Every gear represents a loss in efficiency, said Schottel’s chief executive Gerhard Jensen during OSJ’s visit.
The SCD is recommended for tugs, which require bollard pull, so features a duct, which is absent in the EcoPeller. The shape of the propeller’s support and the propeller arrangement itself were examined, with twin, contra-rotating and single-screw versions all tested in what the company calls its numerical towing tank.
This analysis indicated that a single propeller would be optimum, with a larger diameter than the SCD, mounted on a gondola that is longer and has a smaller diameter – all features that were found to improve its efficiency.
In its literature, Schottel emphasises those improvements, describing its new device as “a highly efficient thruster optimised for open sea and coastal operating conditions”. It provides course-keeping stability, reduced fuel consumption and thus low emissions, it said when it unveiled the design, along with “unbeatable comfort thanks to extremely low vibration and low noise levels”.
Despite it being designed for offshore vessels, the downturn in the oil industry has led to its first installation being destined for another sector. The company holds a letter of intent for its first order but declined to be more specific about its potential customer.