PURPOSE: To enable usage in a small vessel, by coupling a stern shaft having a motor case and a propeller shaft bendably then penetrating a variable node shaft bendably through a hollow hole to provide a variable pitch propeller through a differential machine.

CONSTITUTION: A stern shaft 4 coupled to an output shaft 2 has a motor case 6 then coupled to a propeller shaft 9 through an universal joint 8, and propeller vane 19 is provided rotatably to a propeller boss 11 at the end. While a motor 23 associated with a speed reduction gear 22 is fixed to the case 6, then its variable node shaft 20 is penetrated bendably through the hollow sections 5, 5' in the stern shaft 4 and the propeller shaft and coupled to a differential machine 18 comprised of bevel gears 12W17 in the propeller boss section 11 to make the propeller pitch variable through the rotation of the motor 23. When anchoring at the shallow place, the propeller 40 is salvaged by a salvaging rod 42 and protected. Consequently a variable pitch propeller can be used even in a small fishing vessel.