Hi Brian,
First I limited knowledge of the rim drives and zero personal experience so can offer no help in that area.
Regarding DE drives and generators can offer some semi-educated opinions.
Yes, with the proper controller, the right
generator and
power output you can drive a
motor directly off a
generator without
batteries but the main thing is matching the
motor and generator. DC or AC motor, DC or AC generator?
How many or how few
batteries? Totally depends on how much range you want without running a generator. The problem with batteries is that in a typical cruising
boat unless you fill the
bilge and make the batteries part of the ballast it's difficult to get more than 50-60 mile range under
power and that only at moderate speeds and moderate conditions. Adding a generator adds complexity and cost to the system. My
research came out to double or triple the cost of a new
diesel engine and
transmission. So DE only makes sense if you're looking at other benefits, potentially the ones you mention like steerable and retractable drive or in my case, a cleaner, more accessible
installation and elimination of a v-drive that is a real pain.