PROPELLING DEVICE FOR SHIP

PURPOSE:To improve the efficiency of a propeller, by providing two communicating passage to connect the annular recess of the front of the boss of the propeller, the pressure side of each propeller vane and its back side to one another to reduce the pressure difference between the pressure side and the back side. CONSTITUTION:An annular recess 4 is provided on the front of the boss 2 of a propeller and on the peripheral part of a propeller shaft 3. Each vane 5 of the propeller is provided with a first communicating passage 6 opened at one end in the pressure side 5a of the vane and at the other end into the annular recess 4 and with a second communicating passage 7 opened at one end in the back side 5b of the vane and at the other end into the annular recess. As a result, the pressure difference caused between the pressure side 5a and back side 5b of the propeller vane 5 due to the flow thereon is diminished.