Never mind the sharks or the swirling ocean debris that await him, Benoit Lecomte is counting the days until his long-distance swim from Tokyo to San Francisco -- to raise awareness of environmental threats in the Pacific.

In the Canadian port city of Vancouver, he watches the loading of the Rolano, an 80-foot (24-meter) fishing vessel bristling with cameras on her masts, and stocked with six months of curry dinners.

The old ship is making final preparations before sailing from Canada to Tokyo next month, to serve as the support platform and science deck for Lecomte's project, dubbed "The Longest Swim."

In 1998, the French-born architect and environmentalist became the first person to swim across the Atlantic without a kick board.

Now aged 48, the naturalized American says he is so worried about the future of his two children, eight and 14, that he's returning to the water to raise awareness of the dire problems in the Pacific, hoping to become the first person to cross the ocean without a flotation device.

Lecomte's team includes six crew members on the Rolano, publicists and managers on land, and scientists at several American institutions, including the Woods Hole Oceanographic Institute, who will collect data, including plankton species and radiation levels.

He and the Rolano's six-person crew aim to leave Tokyo by the end of the year, covering the 8,850 kilometers (5,500 miles) to the US West Coast at a rate of 2.5 nautical miles per hour.

They expect the journey to San Francisco will take six months, aided by the Pacific Kuroshio Current.

Lecomte said his speed and strength may have waned since his Atlantic crossing, but his endurance has increased.

"It's mind over matter," he said.

- Sharks, radiation and debris -

In addition to the ardors of a grueling six-month swim, expected hazards on the journey include sharks and other predators, radiation from Japan's Fukushima nuclear plant, and debris in the Pacific Garbage Patch, where the ocean's gyre has funneled plastics from around the world.

Repeatedly delayed, this Pacific swim was originally planned for spring 2012 with the assistance of a catamaran.

Instead, Lecomte will be accompanied by a boat with a rich history of its own.

The wooden fishing vessel was seized in World War II by the Germans, fitted with a massive U-boat submarine engine, and has since been pressed into jobs from fishing to hosting a sushi restaurant.

The Rolano will play a key role in the swim, to publicize environmental issues and conduct ocean and medical research.

"We'll probably experience a hurricane out there," said ship captain Richard Idiens with a shrug and a grin.

The old ship has seen better days, and Idiens keeps rolls of duct tape on hand to patch it up where needed.

Its guts, however, still include the massive, fuel-efficient U-Boat engine. Its hold can sleep 12 and has locker room for science gear and food for six months on blue water.

On Thursday, the ship and crew will make the six-hour trip from Vancouver to Vancouver Island for final repairs and upgrades, then set sail to Japan.

Lecomte returns next week to Texas for some family time before heading next month to Tokyo, to start the long slog back across the Pacific, with the Rolano at his side for every stroke.