Japanese sailor Kenichi Horie, who has sailed non-stop around the world and crossed the Pacific in a solar-powered boat made of recycled aluminium beer cans, is off on his next solo adventure at sea. He set sail for Japan on Sunday from the Hawaii Yacht Club on what he says will be the world's longest voyage in a wave-powered boat. The 69-year-old mariner will travel 6,400 km aboard a 3-tonne yacht called the Suntory Mermaid II at a speed of up to 5 knots. The journey is expected to take Mr. Horie two and a half months. The boat made of recycled aluminium relies on the energy of waves to move two fins at its bow and propel it forward. Mr. Horie has described it as a sturdy vessel, designed to right itself if it capsizes. It is also equipped with an engine and a 10.6-m sail mast for emergencies. "So many people came to see me... I can leave with a very good spirit,' he said through a translator. He had planned to carry microwaveable meals and beer. Solar panels on top of the catamaran will allow him to power a microwave. He will have a satellite phone and access to e-mail.