Investigators board ship that was anchored near California oil pipeline

U.S. Coast Guard investigators have boarded a massive cargo ship as they probe what caused the rupture of an offshore oil pipeline that sent crude washing up on Southern California beaches.

The Coast Guard is investigating whether a ship anchor might have snagged and bent the pipeline owned by Amplify Energy, a Houston-based company that operates three offshore oil platforms south of Los Angeles. The Associated Press reported Wednesday that the Rotterdam Express appeared to make a series of unusual movements while anchored in the closest spot to where the break in the pipeline happened, according to data collected by a marine navigation service.

AP reviewed more than two weeks of data from MarineTraffic, a navigation service that tracks radio signals from transponders that broadcast the locations of ships and large boats every few minutes.

MarineTraffic spokesman Fotini Tseroni said in an email early Thursday that the questionable movements indicated for the Rotterdam Express on its website may have resulted from errors involving the ship's GPS system, rather than showing the ship's actual position. The company said it was removing the jumps in position to show that the ship stayed within its anchorage.

The Rotterdam Express, a German-flagged ship nearly 1,000 feet (305 metres) long, was assigned to anchorage SF-3, the closest to where the pipeline ruptured off Huntington Beach. Hapag-Lloyd, the shipping company that operates the Rotterdam Express, confirmed Thursday that investigators boarded the ship Wednesday while it was docked at the Port of Oakland. The company has said it played no role in the oil spill.