Propellers and propulsion for high-powered container ships

摘要

The development of the high-powered, single-screw container ship requires a simultaneous effort to design the hull form and the propeller in combination with the selection of the main engine. Even if parameters are carefully chosen and a fully balanced design is made without serious vibration, no erosion damage being done to the propeller and the rudder, the limitations to the propulsive power are close by. Hence, a major step forward towards even greater powers is difficult to make for this single-screw concept. Nevertheless, because of the clear commercial advantages of the single-screw ship, the limitations of hydrodynamic origin are still being gradually pushed ahead. Alternative solutions in the form of twin-screw arrangements seem to be less attractive as gains in the propulsive power are small, if any, whereas additional costs are obvious. The use of a contra-rotating pod propeller could render a more feasible solution, since the service speed of the ship can be raised in combination with a certain efficiency gain, provided suitable rotating speeds can be offered by manufacturers of electric motors and diesel engines. A further exploration of this concept is needed to prove its feasibility.