prop shaft lubrication

[calloo]

My boat is conventially shaped long keel with transom hung rudder. The shaft from the propeller goes through a white metal bearing, I assume to be about 6 ins long. Then there is a cavity through the hull of approximately 14 inches, then the stuffing box which has a screw down grease cap. The stuffing has not been touched for 25 years but does not leak so I have left it alone. My question is - does the grease injected by the screw cap permiate from the stuffing box down the cavity to the white metal bearing or does it merely lubricate the stuffing box area leaving the white metal bearing to be lubricated by sea water? Further more can any body advise me on the best type of grease for the purpose please?

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[tillergirl]

The outer bearing will be water lubricated I guess. Some have water inlets to aid the flow of water in. My stuffing box is also water lubricated (off the engine) so I'm not the best to advise re grease but on my last boat I think I used a waterproof grease (Kneenol?)

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[Peterduck]

My 1917 ketch "swallow" has a bronze prop-shaft bearing and an inboard stuffing box which is fed by a grease line brought up to the front of the engine for ease of access. I feed it with graphite grease, but I don't doubt that automotive water pump grease would also be good for this application. I try to keep the whole stuffing box/stern tube/ propshaft bearing full of grease, thereby keeping the water out. [That's the theory anyway!]
Peter.

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[alanporter]

Just take care not to use lithium grease. Lithium is a metallic element and it will encourage galvanic corrosion.

<hr width=100% size=1>Alan Porter

 

[DMGibson]

Without seeing your arrangement it is difficult to be certain, but it is usual for the grease to lubricate the white-metal bearing. There are usually no water inlets on white-metal bearings - they are for the rubber bearings. On the white-metal ones there is sometimes a seal on the outside end to keep sand out of the bearing. As the water certainly gets in there as well, it is best to use a grease which works with water.I don't know about "Keenol" but the one which does work is "Neox" made by J D Vickers. I get mine from ship's chandlers, but you can probably get it direct from Vickers.

I took mine apart last winter (same arrangement as yours) and found the white metal bearing had only worn a few thou after some 16 years use.