Disclosed are a propulsion device for a ship and a ship having same. The propulsion device, according to an embodiment of the present invention, comprises: a rear propeller fixed to a driveshaft; a front propeller positioned in front of the rear propeller, and supported rotably on the driveshaft; and a counter rotation device for reversing and transmitting the rotation of the driveshaft to the front propeller; a motor for rotating the driveshaft; and an housing, which extends from to the lower part of the hull, and which is installed so as to envelope the counter rotation device and the motor.

Propulsion devices that provide increased propeller efficiency when operating outside of an optimal advance ratio are described. In one example, a propulsion device includes a hub having a curved surface extending around and along a rotation axis of the hub. The propulsion device can further include two or more rows of blades extending radially outward from the curved surface and including a first row of blades having a first blade and a second row of blades having a second blade that is angularly and axially offset from the first blade on the curved surface. A first centerline of the first blade and a second centerline of the second blade each intersect with a helical line that extends along the rotation axis of the hub. The first blade and the second blade collectively form a helical pattern of blades that projects radially outward from the curved surface along the helical line.