| It depends on what propulsuion system you are using as to what you use to fill the stern tubes. On my larger boats which use quite a bit of power I have grease in the stern tubes but in my modified Revel U-boat model which has two 12" shafts running in two 10" tubes driven by two very small servo motors when I filled one with grease it wouldn't even turn!!
Consequently that one is filled with a light oil, which works fine. There is a very small amount of oil leaks out when I first put it in the water but it seems to be fine after that.
The best stern tubes have ball bearings fitted at either end which reduces the clearances considerably and you should always have an oiling tube fitted at the top to enable you to be able to top up whatever lubricant you are using.
On my steamer I will use a syringe filled with grease to add a spot of grease every now and then through the oiling tube.
Rudder stocks also need to be thought about because even if the top of the tube is above the water a choppy sea can allow water to enter the hull. Some form of lubricant to prolong the life of the bearings and to seal the tube is usually a good idea.
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“Dirty British coaster with a salt-caked smoke stack, Butting through the Channel in the mad March days" |