Ride along with Nautilus expedition's search for Mendocino and Sonoma shipwrecks

Famed undersea explorer Robert Ballard plans to go looking for a 78-year-old shipwreck off the Mendocino County coast Saturday night, and the images captured by an unmanned vehicle will be streamed live online.

Ocean conditions permitting, Ballard’s 211-foot research vessel Nautilus will deploy a remotely operated vehicle about 8 p.m. on a four-hour survey of the remains of the Dorothy Wintermote, a cargo freighter that sunk in 1938 after running aground near Fish Rock, 11 miles south of Point Arena.

Ballard, an oceanographer and marine geologist best known for discovering the Titanic, has hunted for shipwrecks around the world and explored hydrothermal vents on the ocean floor.

The Nautilus’s current voyage, which started Thursday and runs through Aug. 28, will survey the deep-water zone of the Greater Farallones National Marine Sanctuary, including the Sonoma and Mendocino coasts, and part of the Monterey Bay sanctuary.

The Dorothy Wintermote, a 261-foot steel-hulled, steam-powered cargo freighter, was captured in a colorful sonar image in 2007 showing the vessel lying on a flat, featureless ocean floor.

Video from the ROV Hercules, which can operate down to 13,000 feet, will offer the first time the Wintermote has been seen since it was lost at sea, said Robert Schwemmer of the Office of National Marine Sanctuaries.

The ship, with a crew of 29, was heading north from San Francisco to Portland, Oregon with a load of cargo valued at $115,000 on Sept. 17, 1938..

Running into offshore fog, Capt. O.J. Olsen cut the ship’s speed and was about to take depth soundings when the Wintermote ran aground off Fish Rock, a marine hazard that had claimed numerous vessels.

A Coast Guard cutter responded to the freighter’s SOS radio call and picked up the crew in lifeboats, with help from a fishing boat. Photographs showed the Wintermote grounded off Fish Rock, submerged from the bow up to the pilot house.

Three days later, the Wintermote was refloated after heavy seas broke it loose from the rocks and it was taken in tow by a tugboat. The freighter began to list as water poured in through a 15-foot hole in the hull and it sank in deep water while under tow.

The 3,295-square-mile Greater Farallones sanctuary contains more than 400 shipwrecks and is largely unexplored in its deepest areas.

Working around the clock, the Nautilus expedition scientists will conduct exploratory dives with the remotely operated vehicle and sonar mapping of deep coral reefs in areas west of Point Arena, the Farallon Escarpment and in Pioneer Canyon.

On Monday and Tuesday, the expedition also plans to survey the wreck of the USS Independence, a scuttled aircraft carrier used in World War II that served as a target in the first U.S. atomic weapons test at Bikini Atoll in 1946. Shattered above the water line by two nuclear blasts, the Independence was towed to San Francisco in 1947.

Four years later, it was towed out through the Golden Gate and sunk with explosives in what is now the Monterey Bay marine sanctuary.

When the Hercules vehicle is in the water, video feeds will be streamed at www.nautiluslive.org.