Q I’m finding conflicting advice on whether a tapered prop shaft should be lubricated prior to installing a propeller. Nigel Calder’s Boatowner’s Mechanical and Electrical Manual (2nd edition) recommends that a shaft be greased “to help in future removal,” but a few other reputable references I’ve found online do not mention this. What is the best practice?
Gerard Weatherby, Windsor Locks, Connecticut
A It is true that I recommend greasing the propeller shaft in my book, and it is something I have done myself. However, propeller experts disagree about this, and some claim that the grease may work its way out, leaving the propeller a loose fit. It is also important there be some friction between the shaft and propeller hub to minimize stresses on the keyway, so I no longer recommend the grease.
When installing a propeller, it is best to fit it first without its key and make a non-graphite mark (i.e., not with a pencil) on the shaft at the inboard end of the propeller hub. Putting a piece of tape around the shaft, with its edge flush with the propeller hub, works well. Then remove the propeller and refit it with its key in place, checking to see that the hub comes back up to the mark. This ensures that the key is not oversized or improperly seated. Lock the retaining nut securely. If there are two nuts, the thinner one goes next to the propeller, and the thicker one is the backup.
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