Rotor Sail

A rotor sail, or Flettner rotor, is a tall spinning vertical cylinder that generates forward thrust from crosswind through the Magnus effect, the same lift mechanism that curves a spinning ball. Modern installations on bulkers, tankers, and ferries report fuel and CO2 savings on wind-favorable routes, with the rotor folding or stopping when wind is unfavorable. It is the most widely fitted form of wind-assisted propulsion and counts toward EEDI and EEXI through an innovative-technology credit.