Your argument is sound, when you consider salt water boats. I am into
building a house boat for inland waterways in Europe, and in this case
electric transmission makes sense, if you can afford a long investment
return time. Part of the energy will come from solar panels, and part
from a generator. The produced energy will be stored in lead-acid
batteries. This makes a complicated machine, yes, but it brings the
ability to save fuel when it becomes very expensive in the next ten
years, and the fun of quiet and smokeless operation most of the time
when on canals. On rivers, the generator is required full time, but this
is only part of the time we ride our boats.

Denny wrote:
Hydraulic drive not ready for prime time in personal boats... May never
be... Just a function of basic physics, pump a fluid hard enough to do
useful work and you get lots of wasted energy in pumping and heat
losses...

Electric drive not ready for prime time in cruising boats of our
sizes... I spent part of last week on the phone with STI, Siemens, and
a couple others in a desperate search for numbers that would convince
me to put it in my power cat... The numbers just are not there... For
putzing around the harbor in your electric launch it's fine... For
trolling with your bass boat it's fine.. For moving your 1000 foot
cruise liner, it's fine... For a 30-40-50-60 foot boat it's not fine...
As an auxillary for a sail boat, electric may be a workable solution,
but for the sailor who only uses the engine to get in and out of the
harbor or when the wind dies, a conventional inboard or outboard engine
is a better solution... In the years we kept our Pearson sailboat the
most gas I used in a summer was 10 gallons... Not enough to justify a
$30,000 installation...

denny