Patent attributes
A marine drive is engaged with and is driven by a vessel's engine drive shaft. The drive includes: a universal joint secured to the vessel's hull; a first screw shaft supporting a first screw; a first gear set driven by the first screw shaft; a second screw shaft driven by the first gear set; a second gear set driven by the second screw shaft; a third screw shaft driven by the second gear set and supporting a second screw; and a third screw supported by the second screw shaft at its terminal end. The first and second gear sets are enclosed within a water-tight enclosure enabling rotational speed differentiation between the first and second screw shafts and enabling rotational sense reversal between the second and third screw shafts. An actuator provides changes in angle of attack of the second and third screws.
