TOKYO (Reuters) - A Japanese sailor has set out from Hawaii for Japan, hoping to complete the 7,000 km (4,400 mile) journey using only the power of the waves beneath his boat.

Japanese yachtsman Kenichi Horie waves from the deck of the wave-powered boat Suntory Mermaid II in Honolulu Harbor, Hawaii in this handout photo taken on March 16, 2008. REUTERS/Shigeo Yamada/Handout.

Garlanded with flowers, 69-year-old adventurer Kenichi Horie waved from the deck of his catamaran-like boat as he set off on the latest of many challenges he has taken on since he became the first Japanese to sail solo across the Pacific in 1962, a video of his departure from Hawaii showed.

The vessel for his latest adventure, the Suntory Mermaid II, has two wings in front which convert the energy from waves into a movement similar to a dolphin’s kicks, making it the world’s first boat to be powered by the vertical motion of waves.

“Twenty years ago while sailing, an accident broke my main mast which actually fell in the sea,” the white-haired Horie said before setting sail on Sunday local time from Honolulu.

“The boat kept rocking and I thought how great it would be to actually harness the power of those waves to push the boat forward.”

He plans to reach his destination -- the port of Hino, about 450 km (280 miles) southwest of Tokyo -- at a leisurely pace.

“The speed of the boat is just faster than a human walking pace, perhaps not quite a jogging pace. At this rate, I plan to take two and a half months to get to Japan,” Horie said.

The trip is meant in part to promote the commercial viability of the invention, which Horie says will bring a new option to those seeking to travel in an environmentally friendly way.

“Wind and solar power have been well developed, but with our human intelligence, we should be able to harness wave energy for greater and wider applications and eventually sustainable energy should be able to solve all the world’s energy needs,” he said.

The boat was built by a team at Japan’s Tokai University, one member of which expressed concern about hazards Horie faces.

“I think he is the most able of solo sailors, so I am not worried for him at all as an adventurer,” said Yutaka Terao, a professor at Tokai University.

“However, there is still the unexpected to worry about -- I mean, he could bump into a whale or something -- so we still worry for him.”

Horie, who has sailed around the world solo, traveled the Pacific in a yacht made of recycled beer cans in 2002.