Corrosion preventing device for a marine propeller

Abstract

A corrosion preventing device is disclosed for mounting in sea water on an electrically conductive propeller shaft supporting a marine propeller composed of a metal having a first galvanic potential. The propeller is fastened to the shaft by an electrically conductive propeller nut and is in electrical contact therewith. The device includes an annular washer having a generally circular periphery, composed of a metal having a second galvanic potential not greater than the first galvanic potential, with a central hole concentric with the circular axis thereof through which the shaft may fit to enable an electrical conductive mounting proximate to the propeller nut, for serving as an electrolytic cathode of the device. The device further includes a generally toroidal anode having a circular periphery concentric with the axis, composed of a metal having a third galvanic potential greater than the first galvanic potential, cast about the periphery of the annular washer and exposed to the sea water, for serving as an electrolytic, sacrificial anode of the device. In this manner, the galvanic cell formed by the washer cathode and the toroidal anode maintains the propeller at a relative cathodic potential, thereby preventing the corrosion thereof in the sea water. The resultant device is less expensive to make, use and replace than those in the prior art because its component parts require no machining in their manufacture and the device is fastened to the propeller shaft with a simple jam nut.

Dependencies are inferred from the claim text.