IMPROVEMENTS TO MARINE DRIVE APPARATUS

Abstract: A marine drive apparatus (1) including a shroud channel (7) selectively rotatable to direct the water produced by a rotatable propeller (4) so as to provide reversing and steering of a marine craft. The shroud channel (7) has spaced side walls (8, 9) joined by a roof portion (10), the side walls (8, 9) being used to deflect the water flow so as to produce a steering thrust and the roof portion (10) being movable aft of the propeller (4) to deflect the water flow and produce a reverse thrust.

Description: The present invention relates to marine drive apparatus and is directed to achieving reverse thrust as well as steerage. Conventionally, marine drive apparatus of the shaft and pitched propeller type achieve reversibility by complex mechanisms reversing the rotation of the propeller. A durable apparatus of this type may be of undesirable bulk and weight for certain applications. Steerage requires a separate rudder means. It is an object of the present invention to provide reversible, steerable thrust by a relatively simple, light weight and durable means. According to the invention there is provided a marine drive apparatus including a reversing and steering channel at least partly shrouding a rotatable propeller so as to direct the flow of water produced by said propeller, said channel in its forward configuration having spaced side walls joined by a roof portion and being selectively rotatable about a first substantially vertical axis to provide steerage and a second substantially horizontal axis to move said roof portion aft of said propeller such that said channel can intercept and deflect said flow, thereby to provide reverse thrust. Preferably said roof portion includes inwardly directed deflection means located at least at its aft end for providing increased reverse thrust. A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:- Figure 1 is a part sectioned side elevation of a marine drive apparatus according to the invention, showing the channel positioned for ahead propulsion. Figure 2 is a schematic view of the channel configuration shown in Figure 1. Figure 3 is a forward looking end view of the apparatus shown in Figure 2. Figure 4 is a view similar to Figures 1 and 2 but illustrating the channel rotated to its position for providing reverse thrust. Figure 5 is a plan view of the astern propulsion configuration illustrated in Figure 4. Referring to the drawings, the marine drive apparatus 1 is shown attached to a propeller shaft housing 2 by a wedge-shaped mounting bracket 3. The propeller 4 may be of the surface-piercing type such that the vessel operates between a low speed water level approximately at 5 and a high speed water level approximately at 6. The drive includes a channel 7 having spaced side walls 8 and 9 joined by a roof portion 10. The channel 7 is selectively rotatable about a first, substantially vertical axis 11 and a second substantially horizontal axis 12 in a manner to be described hereinafter. The channel 7 partly shrouds the propeller 4 so as to direct the flow of water and control the direction of motion. Rotation about the substantially vertical axis 11 provides steerage while rotation about the substantially horizontal axis provides reverse thrust by moving the channel from the forward configuration shown in Figures 1 to 3 to the reverse configuration shown in Figures 4 and 5. In the reverse configuration it can be seen that the roof portion 10 has been moved to a position aft of the propeller 4 such that the channel 7 can intercept and deflect the flow and provide the required reverse thrust. The provision of inwardly directed deflection vanes 12 assists in diverting the flow of water and increasing the reverse thrust. The desired channel rotation about the two axes can be achieved by any suitable means. One preferred form is illustrated somewhat schematically in Figure 1. In this embodiment, the drive is supported by a central bearing sleeve 16 rigidly secured to the mounting bracket 3 by a rearwardly cantilevered support arm 17. Rotatably mounted within the bearing sleeve 16 and coaxial with the s ubstantially vertical steering axis 11 is a cylindrical rudder post 18 rigidly connected at its top end with a transverse support beam 19. A steering arm 20 extends forwardly from the support beam 19. Conventional steering means attached to the steering arm will then rotate the transverse support beam about the axis 11. Each end of the transverse support beam 19 is rigidly connected to a downwardly extending channel pivot arm 21. The lower end of each pivot arm 21 is pivotably engaged with a pin 22 rigidly secured to the channel side wall 8 by bracket 23. It will be appreciated that Figure 1 illustrates the port pivot arm 21 engaging the port channel side wall 8. An unseen but symmetrically identical configuration appears on the starboard side of the support beam 19 such that the pair of coaxial pivot pins 22 define the substantially horizontal axis 12. Each channel side wall bracket 23 also carries a rigid crank arm 24. A port tilt link 25 and a starboard tilt link 26 are each pivotably engaged with their respective crank arms by coaxial pivot pins 27. The crank arms may be replaced with pivot pins 27 connected directly to the channel in the same manner as pivot pins 22. The upper end of each tilt link is connected to a cross bar 28 by hinge pins 29. The centre of the cross bar is connected with a piston rod 30 and piston 31 which slides in a cylinder 32 defined by the inner surface of the rotatable rudder post 18. Hydraulic fluid is supplied by conventional means to the required opposite sides of the piston 31 via valving ports (not shown) through the walls of the bearing sleeve 16 and rudder post 8. Three O-rings seals 14 are respectively located between the central bearing sleeve 16 and the cylindrical rudder post 18 at the centre and opposite ends of the rudder post as shown. The seals separate the flow of hydraulic fluid through the ports respectively located between the three seals. Actuation of the piston 31 raises or lowers the cross bar 28 which in turn moves the tilt links and rotates the channel as previously described about its substantially horizontal axis 12. This rotation is obtained without interference with the steering function achieved by rotation about the substantially vertical axis 11. This axis may be vertical or suitably inclined as shown. Although the invention has been described with reference to a specific example it will be appreciated that the invention may be embodied in other forms within the scope of the appended claims.

Claims: 1. A marine drive apparatus including a reversing and steering channel at least partly shrouding a rotatable propeller so as to direct the flow of water produced by said propeller, said channel in its forward configuration having spaced side walls joined by a roof portion and being selectively rotatable about a first, substantially vertical, axis to provide steerage and a second, substantially horizontal, axis to move said roof portion aft of said propeller such that said channel can intercept and deflect said flow, thereby to provide reverse thrust. 2. A marine drive apparatus according to Claim 1 wherein said roof portion includes inwardly directed deflection means located at least at its aft end for providing increased reverse thrust. 3. A marine drive apparatus according to Claim 2 wherein said deflection means comprises a pair of vanes respectively located at the forward and aft ends of said roof portion. 4. A marine drive apparatus according to Claim 1, 2 or 3 wherein said first axis is defined by a cylindrical rudder post rotatably mounted to a coaxial bearing adapted for rigid attachment to a vessel. 5. A marine drive apparatus according to Claim 4 wherein rotation about said second axis is achieved by an hydraulically actuatable piston coaxial with said rudder post. 6. A marine drive apparatus according to Claim 5 w herein said piston connects with a transverse cross bar pivotably connected at its opposite ends with respective links in turn pivotably connected at their opposite ends to coaxial pivot points on said channel spaced from said second axis. 7. A marine drive apparatus according to any preceding Claim wherein said first and second axes do not intersect. 8. A marine drive apparatus according to any preceding Claim wherein said first axis is vertical.

Inventors: DOUGLAS, GEOFFREY BRUCE
Applicants: DOUGLAS, GEOFFREY BRUCE
Application year: 1987
Main classification: B63H25
IPC codes: B63H25, B63H11