Abstract: A multi-bladed marine propeller designed for efficient operation in intermediate, partially cavitating flow regions between fully cavitating flow and noncavitating flow. Each of the blades has a radially inner subcavitating section and an outer section which is configured to have a higher angle of attack and tapered trailing and leading edges so that it supercavitates at high speeds either with or without ventilation and subcavitates at low speeds. Various other features of each blade include different length chords on the pressure and suction sides of the outer section and an inclined trailing surface area extending between the chord ends for improved off design, design point, and astern operation. A minimized transition area is included between the inner and outer sections, and narrow chord lengths are provided in the tip area to minimize and balance overall tip section drag.

Abstract: A marine propeller with unique blade geometry resistant to cavitation and ventilation at high speed operation. The face of the blade has a special convexly curved portion extending from the leading blade edge to a transition zone along the blade chord length toward the blade trailing edge, and a special concavely curved portion from this transition zone to the trailing blade edge, both defined herein.

Abstract: A marine propeller drive coupling bushing assembly with an annular rubber bushing between radially inner and outer elements forming an annular bushing cavity rectangular in cross section, the rubber bushing being distortionally forced thereinto from a free form of an annulus having a trapezoidal cross sectional configuration. The displacement from the free trapezoidal cross section to the distorted configuration is 40-60%.