There's a patent for a memory metal sail[1], telescopic sail mast[2], automatic retractable sail[3], and many others[4]. Also, there's the Oceanbird[5], a mode

There's a patent for a memory metal sail[1], telescopic sail mast[2], automatic retractable sail[3], and many others[4]. Also, there's the Oceanbird[5], a modern car-carrying ship with telescopically retractable metal sails. [1]- https://patents.google.com/patent/US9481432B2/en https://patents.google.com/patent/US9481432B2/en [2]- https://patents.google.com/patent/DE202011101489U1/en https://patents.google.com/patent/DE202011101489U1/en [3]- https://patents.google.com/patent/CN103086280B/en https://patents.google.com/patent/CN103086280B/en [4]- https://www.google.com/search?q=telescopic+sail+patents https://www.google.com/search?q=telescopic+sail+patents [5]- https://www.maritime-executive.com/article/swedish-collaboration-unveils-world-s-largest-sail-powered-car-carrier https://www.maritime-executive.com/article/swedish-collabora...