Not so long ago, around the middle of the 19th century, it would seem that the glorious two thousand-year era of the sailing fleet ended forever. However, thanks to advances in science, wind energy again makes modern ships move.
We are talking about a modern version of sails - rotary sails. They are installed on the so-called Flettner ships, which are set in motion based on the Magnus effect. A typical example of its action is the flight of a "swirling" soccer or tennis ball.
How it works? The air flow blows on the rotating cylinder from opposite sides at different speeds, as a result of which a pressure difference arises and a force vector is formed perpendicular to the flow. It sets in motion the object on which the rotating cylinder is fixed. Lift force on the wing of an airplane is also created approximately.
So far, cargo ships with turbosails are a rarity, but it is obvious that they have serious prospects. An example of this is the Pelican tanker owned by the Danish shipping giant Maersk, on which rotors 30.5 meters high were installed.
According to the company's specialists, rotary sails will save up to 10% of fuel. It would seem not so much. In fact, Maersk spends $ 3 billion annually on fuel for its ships, so this is a savings of $ 300 million. If the experience with the Pelican turns out to be successful, then over time, hundreds of cargo ships will turn into hybrid sailboats.