[Uhehner]

Are you asking about the prop shaft seal   If so just install GFO packing and your problem will be gone forever. Perhaps you just need to tighten the packing nut. The cost of the GFO packing is about $10 per shaft. The labor depends on how difficult it is to get to the packing gland. A good man should be able to do a shaft in 1 hour if it's accessible. GFO packing will last for years without any adjustments. Google the job on-line if you plan on doing it your self.  Capt. George