correction
A previous version of this article said Norsepower's rotor sails typically help ships save 8 to 10 percent on fuel. Those numbers came from one trial onboard the Maersk Pelican; the company says a better estimate for typical fuel savings across all ships is 5 to 25 percent. The article has been corrected.
To cut costs and carbon emissions, cargo ships are putting a new spin on an ancient technology: the sail.
These aren’t the sailboats of yore. Modern sails look more like airplane wings, smokestacks or balloons, and they use artificial intelligence to catch the wind with little help from mariners who long ago forgot the art of hoisting a mainsail.
