Abstract: A marine propulsion system with counter-rotating propellers is provided with the capability of causing the propellers to rotate at different speeds. A first gear is attached to an inner propeller shaft and a second gear is attached to an outer propeller shaft. The inner and outer propeller shafts are arranged in coaxial and concentric relation for rotation about an axis of rotation. A driveshaft is connected to a pinion gear which engages the teeth of the fore and aft gears at different effective diameters. The pinion gear meshes with a first plurality of gear teeth on a beveled surface of the fore gear while a second set of gear teeth of the pinion gear mesh with a second plurality of gear teeth on a beveled surface of the aft gear. Because of the different effective diameters of the first and second pluralities of gear teeth, the inner and outer shafts rotate at different speeds.

Abstract: A shock absorbing drive sleeve (402, FIGS. 28+) mounts a marine drive propeller (12) to a propeller shaft (22) and has an asymmetric spring rate such that the sleeve has a higher spring rate and greater torque bearing capability for the forward boat direction, and a softer spring rate and greater shock absorption for the reverse boat direction, to protect the weaker reverse drive components of the gear train.

Abstract: In a marine drive having a tapered propeller shaft section (14) and a tapered propeller hub (20, 60) matching and fitting therearound in flush contact, a relief inner diameter section (28, 66) is provided in the hub, spaced from the propeller shaft, to prevent flush contact and facilitate removal of the propeller hub from the propeller shaft. In a further embodiment, a thrust collar (50) with a substantially steeper tapered section (56) further facilitates removal.

Abstract: In a marine drive having a tapered propeller shaft section (14) and a tapered propeller hub (20, 60) matching and fitting therearound in flush contact, a relief inner diameter section (28, 66) is provided in the hub, spaced from the propeller shaft, to prevent flush contact and facilitate removal of the propeller hub from the propeller shaft. In a further embodiment, a thrust collar (50) with a substantially steeper tapered section (56) further facilitates removal.

Abstract: A marine propeller (4) combines decreasing overall pitch from hub (6) to blade tip (20) and increasing progressiveness of pitch with increasing radii from hub to tip, and provides uniform loading from hub to tip. The balde has a maximum transverse dimension (36, 46, 48) between the high pressure surface (16) of the blade and a straight line chord (34, 34a, 34b) between the leading edge (22) and the trailing edge (24) of the blade. The ratio of this maximum transverse dimension to the length of the chord is ever increasing from hub to tip. A parabolic blade rake along the maximum radial dimension line (50) of the blade is provided in combination.