There are limitations, such as choke points like the Suez and Panama canals: “Neither of them allows vessels to operate under sail. The Panama Canal also has a bridge over it, with a height limitation of around 50 meters,” De Beukelaer says. And of course, not all ships adapt well to sails. Container ships, for example, have little space on deck to mount them, in contrast to car carriers or bulk carriers, which tuck away their load in the cargo hold—leaving plenty of available surface—and don’t require cranes for unloading.

According to…