Maximise propulsive efficiency, reducing fuel consumption and emissions
Three DFDS Seaways ferries are to be upgraded with Rolls-Royce Promas Lite systems to maximise their propulsive efficiency, reducing fuel consumption and emissions.
Dover Seaways, Dunkerque Seaways and Delft Seaways serve the Dover- Dunkerque route across the English Channel. The three sisterships were originally designed for a speed of 26.5 knots, and have propellers optimised for that speed. The requirements for the current route are a service speed of 18-19.5 knots, with a few knots more available to recover delays, and responsive manoeuvrability in port. The ferries are equipped with twin screws and two engines per shaft. Normal sailing on the current route can be maintained on one engine per shaft (1+1), with 1+2 and 2+2 available if more power is needed.
Rolls-Royce says that under these circumstances a substantial improvement in efficiency could be won by just fitting new blades to the propellers; blades designed to match the present operating profile. But it was decided to go a step further and adopt a Promas Lite solution, so gaining the advantages of new blades plus the additional efficiency improvement from hydrodynamic integration of the propellers and the existing rudders.
The conversion work for each vessel involves, for each shaftline, welding a bulb on to the existing rudder, bolting a stainless steel hubcap to the existing propeller hub, which is a Kamewa CPP size 144, and fitting four blades of the new design to the hub. The settings of the existing control combinator will be revised to ensure that optimal engine load and propeller pitch are combined so that the propulsion system functions with maximum efficiency.
DFDS Seaways had already used Promas Lite to upgrade Pearl Seaways, and since the vessel returned to service earlier this year it has shown fuel savings of more than 13%, and similar results are expected for the vessels now to be upgraded.
The three ferries are due to be fitted with the Promas Lite systems in France during the first quarter of 2012, and the work contributes to DFDS’s goal of reducing its CO2 emissions by 10% over a five year period.
Source: The Motorship