Means for bearing a propulsion unit and a propulsion system for a waterbourne vessel
A propulsion system 2 for a waterborne vessel 4 having a hull structure 6, typically for a full or semi planing boat. The propulsion system 2 has a pod housing 8 having a front end 10 and a rear end 12 , a propeller 14 and a propeller shaft 16 . The propeller 14 is disposed externally at the front end 10 of the pod 8 and is rotatable about a longitudinal axis 18 of the propeller shaft 16 , the propeller shaft 16 being drivingly connected to a drive assembly. The drive assembly has a transmission unit 20 and a power unit 22 in the form of a diesel engine. In FIG. 1 the diesel engine is shown disconnected from the transmission unit 20 . The power unit 22 is disposed within the structure of the hull 6 and, in this particular embodiment; the transmission unit 20 is disposed substantially outside the structure of the hull 6 . The hull 6 is formed with a port 24 through which an interface unit 26 extends. The interface unit 26 provides structures for transmitting the torque of the power unit 22 to the transmission unit 20.
1. A bearing arrangement for a propulsion system for a waterborne vessel comprising a hull structure, the propulsion system comprising a rotatable outboard housing mounted to the hull structure; said housing comprising a bearing member, a turning assembly for turning the outboard housing about an axis; a propeller shaft rotatably supported on the housing; wherein the bearing arrangement comprises a first pair of plain bearing surfaces that are in slidable contact with each other, said first pair of surfaces extending in a plane substantially perpendicular to the axis of rotation, wherein one plain bearing surface of said first pair is part of the bearing member and the other plain bearing surface of the first pair is a part of the hull structure, and wherein the bearing arrangement further comprises a second pair of bearing surfaces arranged in the substantially longitudinal direction of the axis of rotation, one surface of said second pair being a part of the bearing member and the other surface of the second pair being a part of the hull structure, the arrangement being such that, in use, at least one of the pairs of plain bearing surfaces is in sliding contact with each other as the outboard housing rotates about the axis.
2. A bearing arrangement as claimed in claim 1 , wherein the plain bearing surfaces extend substantially around the axis of rotation of the outboard housing.
3. A beating arrangement as claimed in claim 1 , wherein the second pair of plain bearing surfaces extend substantially parallel with the axis of rotation of the outboard housing.
4. A bearing arrangement as claimed in claim 3 , wherein at least one of the plain bearing surfaces is a substantial annular shape.
5. A bearing arrangement as claimed in claim 1 , wherein the plain bearing arrangement comprises an annular element formed with the first and second pair of plain bearing surface.
6. A bearing arrangement as claimed in claim 1 , wherein the propulsion system comprises an azimuth unit.
7. A bearing arrangement as claimed in claim 6 , wherein the azimuth unit is a forward facing unit wherein the propeller is disposed at the front of the unit or a rearward facing unit wherein the propeller is disposed at the rear of the unit.