Stern Gland Greaser Question

[crown22]

Hello My boat is on the water and is moved from it's berth only about once a month.Is it a good idea to rotate the propshaft by hand when using the greaser which I can do once a week when I visit? I've tried this and the drip that I had has gone away.I thought that the rotation had distributed the grease better?When I next lift out I might look for a better solution. Any other suggestions gratefully received.

 

[Tranona]

The grease is there to partly fill the tube to keep water out when the shaft is stationary. it does not perform any lubricating purpose. You should adjust the nut(s) so that the shaft still turns and there is perhaps a small odd drip when the engine is being used and the shaft turning. Too tight and it will run hot, too slack and it will drip. Applying more grease when you stop is to replace the grease washed out when you are running.

 

[Porthandbuoy]

The grease is there to partly fill the tube to keep water out when the shaft is stationary. it does not perform any lubricating purpose. You should adjust the nut(s) so that the shaft still turns and there is perhaps a small odd drip when the engine is being used and the shaft turning. Too tight and it will run hot, too slack and it will drip. Applying more grease when you stop is to replace the grease washed out when you are running.

It does on mine as the tube has inboard and outboard white metal bearings.

 

[Tranona]

It does on mine as the tube has inboard and outboard white metal bearings.

That's fine and correct, but expect the OP has a simple stuffing box and its "stuffing" is self lubricating.

 

[ghostlymoron]

What keeps the bearings cool?

It does on mine as the tube has inboard and outboard white metal bearings.

 

[Tranona]

If it is the usual Stuart Turner type the stern tube is full of water and there is a seal on the inboard end, usually a stuffing box and maybe a cutless or rubber water lubricated at the aft end. There are many variations on the themes and some just have a white metal bearing with a greaser at the aft end. The big advantage of this type of stern tube is that the shaft is supported at both ends so does not move. Essential when engines were solidly mounted but also useful for a moderns engine with a good flexible coupling.

 

[Porthandbuoy]

What keeps the bearings cool?

Presumably the grease eliminates friction, ergo no heat generated. The stern tube is buried in the deadwood without any means of cooling. The shaft passes through a conventional stuffing box. I give the greaser a turn every half hour or so, and when I finish with the engine.

As for the OP’s original question, turning the shaft by hand to help distribute the grease shouldn’t be necessary but won’t do any harm. Perhaps the stuffing gland needs nipped up a touch or repacked.

 

[Neil_Y]

Grease is a poor conductor of heat so the bearings will run hotter than with water, but you are more likely to find white metal on older slower turning shafts.

One thing to be aware of with greasers is that over use can result in the grease blocking the waterways of your water lubricated bearings which can cook them so they wear out quicker.

Water is still the best lubricant and coolant for marine shafts, a conventional gland should should be able to be adjusted so it doesn't drip with the shaft stationary but drips with the shaft turning, without grease. Fiddly and awkward to get to for many small yachts though.