Mount Sakura-Jima, like the weather, is grumpy on this rainy Monday morning. An active volcano, she's belching black smoke and ash 200-300 feet in the air – fortunately carried south by a favorable wind. Rising 4,000 feet above the harbor's eastern arm, Sakura-Jima had the most recent of her many violent eruptions 100 years ago – wiping out eight neighboring villages – but scientists say today she's relatively safe.

At 2:00 p.m. today, our expedition will be heading due south out of Kagoshima on the Ocean Voyager. In 16 hours, we'll reach our destination – the site of the sinking of Yamato, 150 miles away. For now, though, we're tossing uncomfortably on a churning, slapping sea that's behaving like the agitated surface of a top-loading washing machine. Waves outside the harbor are running at 10 to 12 feet, and the sky is battleship gray with streaks of black and light gray racing through it. The sun has not made an appearance in all of this mess, and it doesn't look like it will soon. Conditions probably won't be much better tomorrow, since meteorologists are predicting that we'll have 30 to 35 knot winds.

This isn't the peaceful environment in which we've always departed on our Titanic expeditions during the last two decades, from places like the Azores, Boston, Newfoundland, Brest, and New York. But after all, Yamato was a warship – the strongest ever built – so maybe this is fitting weather for such a violent ship and such a violent story.

Joining the expedition this morning is Kenji Aihara, director of the Yamato Project for the Maritime Museum in Kure, just north of Kagoshima. Kure is the port for the city of Hiroshima, and the objects we recover will be brought to its beautiful new museum celebrating the region's rich maritime and industrial heritage.

The people of Kure built Yamato, and the museum is constructing a 1:10 model of the great warship – 86.3 feet long and 12.8 feet wide – for an exhibit on Yamato and its fate. Also with us this morning are Sakutaro Nishihata, 78, one of the Yamato's designers, and Yukio Mizuno, a highly regarded expert on the battleship.

As we prepare to weigh anchor, I am reminded of the opening of Requiem for Battleship Yamato, a book written by Yoshida Mitsuru just six months after the ship's sinking. Just days after the Allies began their dramatic assault on Okinawa, close to the Japanese mainland, the immense Yamato was hurriedly readied for departure and imminent battle. "There has never been so sudden a sailing," Mitsuru wrote. "How we have awaited this moment! Ours is the signal honor of being the nation's bulwark."

But under unrelenting, fierce assault, Japan's naval defense failed. The Yamato sank, in a flash of flame and explosions that could be seen in Kagoshima, 150 miles away. "With the sinking of the great battleship Yamato," historian Paul S. Dunn wrote, "the once-formidable Japanese Navy ceased to exist."

Now, the Ocean Voyager, like Yamato a half century ago, is weighing anchor and heading out for the East China Sea. The words and preparations are over. The operation begins.