On my 12'' to the foot Dutch barge
tube is filled with gear oil. There is a conventional inboard stuffing gland and a face seal between outer bearing
and thrust face of the propeller
So far so conventional, however instead of pumping top up oil with a large grease gun there is a pipe connecting the tube to a small oil reservoir placed above the shaft just at static water level.
This arrangement works really well, no seepage of oil or water when moored up and only a small trace of oil at the water surface when I have to use a touch of reverse to stop her.
would work well on a model
boat using very thin oil. Oh yes, I restored a 1936 outboard motor
and lost the prop because I forgot to replace the split pin on the retaining nut!
Fair winds and smooth seas to you all Captain Lemmerhengst