They had a single 671 with a sprocket between the shaft coupling halves,
like you discribe.. The generater was a Westerbeke (unknown size) but but
had a medium size hydraulic pump driven off a PTO. This was normally used
for deck winches, windlass, etc. However, all they had to do was slip the
chain onto the sprocket and they had emergency 'get home power'..

Hmm, sounds good, maybe I could use hydr.instead of elec. The Petter 6 HP aux
diesel has a main shaft that runs at 3600 RPM and another shaft that runs at
1800. I could drive the AC gen off the main shaft and a hydr pump off the 1800
RPM shaft. When I needed to use the hydr for get home motive power I could just
run the AC gen with no load. I dont think an unloaded gen takes much parasitic
power from the engine. I guess I could use an orbit type hydr motor with roller
chain to drive the propshaft sprocket, those orbit motors have tremendous low
speed torque. Thanks to everyone for all the great suggestions.