May 9, 2003
Wartsila power for CRP Ropax ferries
The new ferries will each have a single controllable-pitch propeller driven mechanically by two Wartsila engines, while an azimuthing pod drive immediately aft of the main propeller will be electrically driven from two Wartsila-engined generating sets. The pod drive is in contra-rotation to the main propeller, thus contra-rotating propeller (CRP) pod propulsion.
The ferries are designed for a trial speed of 31.5 knots.
The twin Wartsila 12V46C main engines used for mechanical drive of the main propeller have a combined output of 25.2 MW. The electrical power for the 17.6 MW azimuthing pod drive and the hotel load is supplied in each ferry by two similar Waertsilae 12V46C engines in main generating sets and one smaller harbor generating set.
The CRP pod installation results in lower power demand than a conventional twin-shaft arrangement owing to the lower resistance of a single-skeg hull form and improved propulsion efficiency. The aft propeller takes advantage of the rotative energy left in the slipstream of the forward propeller when it turns in the opposite direction. The single-skeg hull also leads to a favorable wake field for the propellers.
The new CODED machinery with a CRP pod offers most of the benefits associated both with diesel-electric and diesel-mechanical machinery without their respective drawbacks. The result is a very competitive solution that provides outstanding technical and economical performance for fast RoPax vessels.