@stavvers TBF this is a GOOD idea purely in engineering terms: kites can take advantage of wind speeds and directions that vary at different altitudes, aerofoils bolted to the deck on rigid masts are limited to surface winds. But it's still only a supplement for engine power: modern supply chains can't cope with VLCSs getting becalmed.
The real answer is marine nuclear propulsion. Or teleportation booths. Or sparkly unicorns. Or something.
@dr2chase @stavvers Here's the LARGEST diesel engine in the world, per wikipedia, the Wärtsilä-Sulzer RTA96-C. Two-stroke cycle, 14 cylinders, puts out 80MW (or about 107,000 horsepower), weighs over 2,300 tons. Used for powering 170,000 ton (and up) container ships.
It's hard to see how to replace a medium-sized city's power station with any kind of sail (or to abolish this scale of shipping in a century when climate change will cause frequent local crop failures).
https://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C