What if we put a large wind turbine on a ship? A sort of modern set of sails if you will.

A mid sized cargo ship has a 50_000Kw engine. A mid sized offshore wind turbine makes 1_000_000Kw. So depending on which way the wind is blowing it could work. Put a diesel electric drive and a full sized engine then use the wind turbine to see how much it could reduce fuel use. I was even having fun dreaming about the incidentals. how hard it would be to build a folding/quick assembly mechanism for the turbine to make harbor/bridge/crane access problems go away. could we duel purpose the wind turbine boom as a crane boom. Would a vertical turbine make sense?

While reading up on wind turbines I ran across the depressing story of the small ferry Hornblower Hybrid. A lot of hype on how environmentally friendly it was in 2008 when it was retrofitted with two vertical turbines. But my first though was "those turbines look awful small" and they are, the best they could do is power the lights not the boat itself. The boat itself was retro fitted in 2024 and lost it's electric drive. https://en.wikipedia.org/wiki/Hornblower_Hybrid

I bet even if it would work from an energy point of view, the extra complexity of the system would make it more expensive than a straight diesel ship from an operations and maintenance point of view.

There are several designs of kite propelled ships. Some commercially available.

A generator and a propeller would only add weight and complexity for a loss in efficiency.

There have also been ships with vertical turbines mechanically coupled to propellers. But you can't build them very tall, so you lose the best winds. Those haven't been good enough in the past.