The Volitan, meaning "flying fish," is a pretty fantastic concept boat with impeccable green credentials, using sails, wind and solar power to get around, storing energy in its batteries. The secret to the Volitan — which can operate in 60-knot winds — is the way its four wings react to weather conditions.
A networked computer on board controls the boat's systems, including the wings, which track the sun and wind and adapt depending on whether it's sunny or windy. If the weather is absolutely atrocious, the upper wings, which are covered with solar panels and act as sails, fold up against the side of the boat. The lower wings help stabilize the boat, and contain a couple of DC motors. When the Volitan docks, these two stabilizer wings tuck away.
DesignNobis, the Turkish company behind the Volitan, claims that there were many factors behind the boat's design. "The objective was to create a new and alternative sailing vessel that would achieve a lightweight system, high sail performance, and all-weather navigation capacity with near zero emissions." [Yanko]