Rudder hydraulic nut protecting device, ship comprising same, and protecting method

The invention discloses a rudder hydraulic nut protecting device, a ship comprising the same, and a protecting method. The rudder hydraulic nut protecting device is located below a rudderstock and comprises a top cap, a plurality of flanges, a plurality of screws and nuts; one ends of the screws are fixed to rudder blades, and a plurality of through holes allowing the screws to penetrate through are formed in the top cap; the flanges are located between the top cap and the rudder blades, the screws penetrate through fixing holes in the flanges and the through holes in the top cap, and the topcap is fixed to the upper part of a hydraulic nut on the rudder blades through the nuts; and sealing pieces are arranged between the top cap and the flanges, between the adjacent flanges as well as between the flanges and the rudder blades correspondingly, and thus the top cap, the flanges and the rudder blades define a closed cavity containing the hydraulic nut. The rudder hydraulic nut protecting device is easy to mount