How is the propeller of a motorboat flying at sea made?

As a kind of marine propeller, there are fixed-pitch propellers with multiple blades and hubs. In this fixed pitch propeller, the pitch (angle) of the propeller blades cannot be adjusted. Therefore, a combined marine propeller having a plurality of propeller blades separated from the propeller hub is sometimes used.

For example, the patent document 1 discloses a combined marine propeller 100 as shown in figures 13a and 13b. In this marine propeller 100, the blade flange 12 1 of propeller blade 120 is fastened to the hollow propeller hub1/kloc-0 by stud bolts 130 and tensioning nuts 140. Specifically, the propeller hub 1 10 is provided with a plurality of openings 1 1, through which the stud bolts 130 are inserted. Each opening 1 1 1 extends around the center of the blade flange 12 1, and the pitch of the propeller blade 120 can pass through the opening1/kloc-0.

The washer 150 is sandwiched between the tension nut 140 and the propeller hub 1 10 which is screwed with the stud 130. In addition, the tension nut 140 is pulled away from the washer 150 by a plurality of tension screws 160, thereby applying tension to the stud 130.