|Title: The Propulsion and Manoeuvering Concept of the BCF Double Ended Ferries|
|Written by: Stefan Krüger, Tobias Haack|
|in: PRADS, Houston, Texas, USA 2007|
Abstract: One important milestone of British Columbia Ferries (BC Ferries) during their Major Fleet Replacement Program was the development of a new Double Ended Ferry class to replace their existing C-Class vessels. The final design of the ships called the BCF Super Class Ferries, which are actually the worldâ€™s largest double end ferries, was finally carried out by Flensburger Schiffbau- Gesellschaft (FSG), Germany. Some of the Design requirements put forward by BCF had been very hard to fulfill in the final concept. Most challenging was the demand for extremely low fuel consumption, low wake wash, and very good steering performance that had to be combined with the require-ment for a diesel electric power plant. Furthermore, the operational profile of the vessel required a very short acceleration time of the vessel from zero up to full de-sign speed, which is quite high with 21 knots. These requirements lead to an unconventional propulsion con-cept with bow and stern CPP- Propellers which are operated in constant rpm mode where the bow propeller feathers with the trailing edge. This propulsion concept is embedded into a completely new hull form that was developed on the basis of numerical flow simulations. The concept was finally derived from the numerical and experimental evaluation of many alternative concepts. With respect to the maneuvering demands, most chal-lenging was the fulfillment of the Active Pass Route operation, which was demonstrated by a full mission maneuvering simulation carried out during the initial design phase. The harbor approach procedure requires a mode shift which includes the de-feathering of the bow propeller at full speed and the starting procedure of the bow drive motor into the constant shaft speed mode using a soft starter. To do so, the automation system of the propulsion plant was combined with the maneuver-ing model that allowed to determine all important inter-actions of the complex systems and finally lead to the design of the propulsion control system. The paper shows that the technological challenges of such a complex kind of ship can only be tackled in close cooperation between the owner, the shipyard, the main suppliers, and the research institutions, as many design tasks require scientific simulations on a high level.