PROPULSION SYSTEM FOR SHIP, AND SHIP HAVING THE SAME

摘要

PURPOSE: A propulsion system and a ship with the same are provided to design an economical ship because a separate ballast water treatment facility and a ballast tank are not necessary. CONSTITUTION: A propulsion system for a ship(20) comprises a pair of propellers. The pair of propellers comprises a first propeller(43) and a second propeller(53). The second propeller is arranged above the first propeller. The top of the second propeller is positioned at a position same as or lower than the full draft line of a ship. The top of the first propeller is positioned at a position same as or lower than a stern draft line(A) when the ship linearly sails. The bottom of the second propeller is positioned at a position higher than the stern draft line when the ship linearly sails.