Does anyone here have any experience with hydraulic drives for boats?
My first boss out of college had a 60 ft paddle wheel
boat in St Paul, MN on the Mississippi
. It was powered by twin stern paddles driven by hydraulic torque hubs. The torque hubs were powered by two diesel engines that were used to run the refrigeration
in over the road trucks. The boat burned 1.5 gallons per hour and could carry a full USCG approved load of 90 persons but normally would carry 40 persons comfortably on two decks. The draft
was 2.5 ft and had 4 rudders that were about 4 to 6 ft long. The wheel
itself was a farm tractor wheel hub with steel
spokes and frame for each paddle board. Each wheel could be powered in opposite directions for tight turning. Should the boat strike a log and break a paddle you could bolt on new board(s) just like the old river boats did. In flat water
it did about 7 knots. It was pretty quiet and really a great party barge. The mechanical system held up quite well for the 6 years I worked for the company. The vacu flush heads were probably the one part of the boat that took the most work. The hull
was all steel
and they froze it in place in the winter.
The large diameter of the wheels with the low rpms of the hubs made the solution work quite well. I don't know how fast you could turn a screw with hydraulics. The boat also had keel
coolers for the fluid. That would be a concern for any hydraulic propulsion system. This was a totally home brewed system.