Trimmable pod drive

1. A trimmable pod drive assembly comprising:

a pod drive unit having a transmission assembly secured to a steering unit;

a gear case assembly coupled to and rotatable by the steering unit about a steering axis;

a propeller rotatable about a propeller driveshaft axis extending through the gear case assembly so as to generate thrust along a thrust vector; and

a trim assembly secured to the pod drive unit in a manner allowing for rotation of the pod drive unit about a trim axis,

wherein actuation of at least one component of the trim assembly causes movement of the pod drive unit and the thrust vector about the trim axis, and

wherein the pod drive unit is pivotably secured to an actuator that is positioned above a bottom of a vessel within the vessel.

2. The trimmable pod drive assembly of claim 1 , wherein the pod drive unit is at least indirectly secured to the vessel by way of the trim assembly, and wherein the movement of the thrust vector during operation of the vessel provides at least one of a negative trim adjustment or a positive trim adjustment that is capable of modifying a pitch of the bottom the vessel relative to a water surface.

3. The trimmable pod drive assembly of claim 2 , wherein the steering unit and gear case assembly are coupled via a gear case adapter that extends at least partially through a bottom passage of the vessel.

4. The trimmable pod drive assembly of claim 3 , wherein the at least one positive or negative trim adjustment is performable at all times or substantially all times during operation of the vessel.

5. The trimmable pod drive assembly of claim 3 , wherein the transmission assembly includes an input component directed towards a front of the vessel for receiving an input shaft from an engine positioned forward of the pod drive unit within the vessel, and wherein engine output is directed towards a rear of the vessel and the trim axis is substantially perpendicular to the steering axis.

6. The trimmable pod drive assembly of claim 1 , wherein the trim assembly includes a mounting plate secured adjacent to the bottom of the vessel and a pivot plate secured to the pod drive unit and the mounting plate, and wherein the trim axis is provided at a juncture of the pivot plate and mounting plate.

7. The trimmable pod drive assembly of claim 1 , wherein the trim assembly includes a mounting plate secured adjacent to the bottom of the vessel, and the pod drive unit is pivotably secured to the mounting plate to provide the trim axis for rotation of the pod drive unit.

8. The trimmable pod drive assembly of claim 1 , wherein the actuator is actuatable to provide rotation of the pod drive unit about the trim axis.

9. The trimmable pod drive assembly of claim 1 , wherein the trim assembly includes one or both of (a)a plurality of assembled components of an actuatable cylinder; and (b) a mounting plate secured to the pod drive unit, the mounting plate having a first mount end and a second mount end, with the first mount end and second mount end secured at least indirectly to the vessel by at least one of a trim cylinder, a link, a strut, and a mount.

10. The trimmable pod drive assembly of claim 9 , wherein the trim assembly includes (b), and wherein the first mount end and second mount end are each secured to the vessel and a variable trim axis for rotation of the pod drive unit is provided.

11. The trimmable pod drive assembly of claim 10 , wherein the first mount end and second mount end are each additionally secured to the vessel by mounts that are fastened to a stringer system adjacent the bottom.

12. The trimmable pod drive assembly of claim 11 , wherein the actuator is actuatable to provide rotation of the thrust vector about the trim axis.

13. The trimmable pod drive assembly of claim 2 , further including a compound active grommet seal positioned at least indirectly between the pod drive unit and the bottom to affect water sealing and transmit steering loads from the steering unit, while allowing rotation of the gear case assembly about the trim axis, wherein the seal includes a plurality of proximal stillness portions positioned for lateral stiffness during steering moments and longitudinal or vertical flexibility for accommodating thrust vector forces and trim adjustments.

14. The trimmable pod drive assembly of claim 9 , wherein the trim assembly includes (b) and wherein first mount end and second mount end are each secured to the vessel by links capable of supporting the mounting plate and the actuator is capable of moving the mounting plate about the constraints of the links to provide a variably positioned trim axis.

15. A marine vessel comprising the trimmable pod drive assembly of claim 1 , and further comprising an engine for supplying rotational power to the trimmable pod drive assembly and means for controlling the actuation of the at least one component of the trim assembly.

16. A trimmable pod drive assembly configured for use as part of a marine vessel having a vessel bottom, the trimmable pod drive assembly comprising:

a pod drive unit having a gear case assembly coupled to a steering unit, wherein the gear case assembly is positioned substantially below the vessel bottom and the steering unit is positioned substantially above the vessel bottom, and wherein the steering assembly includes a steering axis for rotation of the gear case assembly thereabout;

a propeller secured to a propeller driveshaft, the propeller driveshaft extending from the gear case assembly along a propeller centerline and providing a thrust vector that extends along the propeller centerline, wherein the propeller centerline is substantially perpendicular to the steering axis;

one or more actuators at least indirectly coupling the pod drive unit to the vessel in a manner such that actuation of the one or more actuators causes a rotation of the thrust vector about a trim axis; and

a compound active grommet seal positioned at least indirectly between the pod drive unit and the vessel bottom to affect water sealing and transmit steering loads from the steering unit, while allowing rotation of the gear case assembly about the trim axis, wherein the seal includes a plurality of proximal stiffness portions positioned for lateral stiffness during steering moments and longitudinal or vertical flexibility for accommodating thrust vector forces and trim adjustments.

17. The trimmable pod drive assembly of claim 16 wherein rotation of the thrust vector during operation of the vessel provides one of a negative trim or positive trim adjustment that modifies a pitch of the vessel bottom relative to the surface of the water, and wherein the one or more actuators includes a first actuator selected from the group consisting of a hydraulic cylinder and an electric motor.

18. A trimmable pod drive assembly configured for use as part of a marine vessel having a vessel bottom, the trimmable pod drive assembly comprising:

a pod drive unit having a gear case assembly coupled to a steering unit, wherein the gear case assembly is positioned substantially below the vessel bottom and the steering unit is positioned substantially above the vessel bottom, and wherein the steering assembly includes a steering axis for rotation of the gear case assembly thereabout;

a propeller secured to a propeller driveshaft, the propeller driveshaft extending from the gear case assembly along a propeller centerline and providing a thrust vector that extends along the propeller centerline, wherein the propeller centerline is substantially perpendicular to the steering axis; and

one or more actuators at least indirectly coupling the pod drive unit to the vessel in a manner such that actuation of the one or more actuators causes a rotation of the thrust vector about a trim axis, wherein the trim axis is positioned in a location that is substantially forward of or substantially aftward of the steering axis rather than substantially aligned with the steering axis.

19. The trimmable pod drive assembly of claim 18 , wherein the trim axis is positioned substantially forward of the steering axis in either a first quadrant or a fourth quadrant defined by the steering axis and the vessel bottom.

20. The trimmable pod drive assembly of claim 18 , wherein the trim axis is positioned substantially aftward of the steering axis in either a second quadrant or a third quadrant defined by the steering axis and the vessel bottom.