By David Adams
MIAMI (Reuters) - The cargo ship El Faro broke up partially when it sank off the Bahamas in a hurricane last month and its bridge and voyage data recorder are missing, U.S. authorities said on Tuesday.
The data recorder, similar to an airplane's black box and affixed to the bridge, could provide investigators from the U.S. National Transportation Safety Board with vital clues as to what caused the worst cargo shipping disaster involving a U.S.-flagged vessel in more than three decades.
It should contain the last 12 hours of engine orders aboard El Faro and other communications from the bridge.
The 790-foot (241 meter) ship disappeared with 33 mostly American crew aboard on Oct. 1, on a regular weekly run between Florida and Puerto Rico, after the captain reported losing propulsion and taking on water.
Wreckage of the ship was initially detected by the salvage team over the weekend sitting on the ocean floor at a depth of nearly three miles (5 km).
The vessel was described as intact in a statement from the NTSB on Monday. But in an update on Tuesday, after a remotely operated submersible equipped with bright lights and a camera had surveyed both sides of the wreck, the agency said damage did occur.
"The navigation bridge and the deck below have separated from the vessel and have not been located," the NTSB said.
"The voyage data recorder has not been located."
A Navy salvage team now plans to use an underwater sonar device to try to locate the bridge. However, early efforts to examine the debris field using sonar had failed to identify any targets "that have a high probability of being the missing navigation bridge structure," the NTSB said.
El Faro's crew included 28 Americans and five Poles and there are no known survivors. The wreck is sitting in such deep water - 2,500 feet (760 meters) deeper than the Titanic - that it is beyond the reach of divers.
(Reporting by David Adams; Editing by Tom Brown)