On September 27th of 2010, the world’s largest solar-powered boat – the TÛRANOR PlanetSolar – set out from Monaco on a quest to become the first boat to sail around the world using nothing put the power of the Sun. This afternoon it successfully completed that quest, arriving back in Monaco after 18 months spent circumnavigating the planet.

A crew of five piloted the 31-meter (102-ft) long, 15-meter (49-ft) wide vessel, which is covered in 537 square meters (5,780 sq ft) of solar panels. These provide power to four electric motors (two located in each hull), that have a maximum output of 120 kW and can propel the boat to a speed of 14 knots. It is constructed mainly of a light yet durable carbon fiber-sandwich material.

“For 8 years we have been working on achieving this world tour with solar energy,” expedition leader Raphaël Domjan wrote yesterday, in his most recently-posted logbook entry. “If everything goes according to plan, we should cross the last longitude line tomorrow and then reach Monaco, the departure point of our adventure. Friday May 4th, 2012, on this day early in the afternoon we shall succeed in this first journey around the world with solar energy.”

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