I don't claim to know all the math for coverting the AC to DC, etc. But I
have seen a similar set up using hydrualics.

This was on an old 45ft work tug converted for coastal cruising and family
dive boat..

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'..

I'm not sure of what type of reverse gear this engine had and it there ever
was any problem turning it in nuetral.

The owner claimed he did 300 miles in Baja on that arrangement when the 671
broke down.

Just something I remember seeing, FWIW.

Steve
s/v Good Intentions