PURPOSE: To prevent blades and a rudder plate from damage and to simplify a lifting work of them by providing a keel-like fender, a holding pin, a receiving seat, and a connector.

CONSTITUTION: The both ends of a connector are swingably fixed so as to permit any angle change of a suspended bearing when it is lifted. When a supporting bar 9 is lifted, a rudder shaft 18 and a rudder plate 13 are pushed from the bottom through a fender 12. Accordingly, when the rudder shaft 18 is not inclined at the angle unconvenient for the puhsing, the conventional structure can be used. However, at the lower portion of the rudder plate 13, a holding pin 24 for supporting axially it and a receiving seat 21 are provided. With reference to the holding pin 24, on which fixed one the seat 21 and inserted into a hole at the bottom of the rudder plate 13 or another one which, on the contrary, is fixed on the rudder plate 13 and extruded downwardly to fit into a hole of the seat 21 rotatably, or still another one which is used also as a shaft and a pin can be employed. In short, any device which supports the rudder plate 13 through its bottom without prevention of its rotation can be used.