Many thanks for all of the suggestions and hints. The oil leaks slower than I said and a drip every 4 hours or so also comes out when the engine is off. The total leak in 10 days is about a fifth of the way between the Max and Min marks in the reservoir. I identified the source of the leak: it is the junction of the part (coupling?) that you can rotate by hand when in neutral between the reverse gearbox and the upper C-drive, right against the C-drive.
Craig, it sounds like this is the upper shaft seal you mentioned. The procedure you described (scoot the engine back a bit) is beyond my capabilities, so I will have to get a mechanic. Can the procedure be done with the boat in the water? (I have a vacuum pump to suck the oil out.). Is the 60-90-10 seal easy to find? Any additional specifications for it (temperature etc)? It would have been cheaper to install a rope cutter....
I really appreciate all the help. This year the maintenance time has been high. I had 8 pumps fail, needing replacing or servicing, and 2 major problems with the generator, as well as preparing the boat for my first Ocean crossing ever (Atlantic early December), so I have been very busy ... like the rest of you I guess.
Eamonn Washington
Travel Bug
Super Maramu #151
Currently in Calasetta, Sardinia, Italy.