How come sails aren't making a comeback? Seems like an ideal complement to electric ships. Use the wind to recharge the batteries using generators or to propel the ship forward. When there is no wind, run on the energy stored in the batteries.
edit: I can't find it offhand, but remember also seeing a video of a startup in SF, that's experimenting with an innovative sail system for the purpose of outfitting on ferries. These sails look more like vertical wings than the usual sail (which on many points of sail is actually a vertical wing) ... and the "flight controller" would basically trim them via rotation to the ideal position when they can eke out any knots to help them preserve diesel. And if they get caught in a squall, they simple head the sails into the wind to reduce windage. So it should be a very safe system to reduce the ferry system's usage of fossil fuels. Looked like a really interesting idea.
What do you mean by recharging batteries using generators and using wind? If you mean turbines, keep in mind most turbines are hundreds of feet tall and their blades are extremely long. Overall, wind turbine technology is far, far too large for ships to utilize.
NB i was on board coming around the tip of Manhattan soon after 9/11. US coast guard came up on us pretty quick. They thought they were misled too!
I recall reading about one suggestion for using high altitude "kites", and i could have sworn i have also seen one where the sails would be more similar to what you find on a Junk.
In both instances the operations would be largely computer controlled, and reserved for the open seas.