Andrey Melnichenko enjoys shaking up the yachting world.

The 40-year-old Russian billionaire first made waves when he launched “A,” the 396-foot motor yacht that became one of the most famous in the world for its radical design.

That ship, styled by the architect and designer Philippe Starck, has a stealthy, knife-like design that many likened to a submarine or battleship. (I took a rare tour of the boat, including it's "Nookie Room," which you can see here ).

Now, Melnichenko is planning an even more revolutionary entry in the mega-yacht wars. According to industry executives, Melnichenko and his yacht team are in the early stages of building a ship that will likely become the largest sailing yacht in the world.

The ship follows news this summer that a Middle Eastern billionaire is building a yacht that will become the largest motor yacht in the world . While the broad yacht market remains weak, with lower prices and slack demand for sales and charter, a few of the mega-rich continue to fuel the battle for biggest and best on the seas. (See photos of Super-Yachts at a Discount .)

Melnichenko's boat will be somewhere in the 400-foot range. Currently, the largest sailing yacht in the world is the 305-foot Eos, once owned by Barry Diller. (Some say Maltese Falcon, built for Tom Perkins, is larger if you don't count Eos's long bowsprit.)

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