JACKSONVILLE, Fla. - Deep seas will likely hamper efforts to find the sunken U.S. cargo ship lost off the Bahamas during Hurricane Joaquin, a federal safety investigator said on Tuesday, as a search for 32 missing crew ran into a sixth fruitless day. National Transportation Safety Board member Bella Dinh-Zarr spoke before her arrival in Jacksonville, Florida, to help spearhead an NTSB investigation into what maritime experts have called the worst cargo shipping disaster involving a U.S.-flagged vessel in more than 30 years. She said the probe promised to be difficult given that the ship sank in an unknown location, possibly in 15,000-feet (4,750-meter) deep waters. Its last known location, after departing Jacksonville last week en route to San Juan, Puerto Rico, was off Crooked Island in the Bahamas. “It’s a big challenge when there’s such a large area of water and at such depth,” Dinh-Zarr said. Locating the wreckage of the ship is crucial as it would allow investigators to retrieve the vessel’s black box voyage data recorder, which preserves the last 12 hours of engine orders and communications from the bridge. “We hope for the best and that the ship will be recovered.” Dinh-Zarr said. On Monday, the ship’s owner, Tote Inc, said the New Jersey-based company would “cooperate fully” with the NTSB. “All the information that we have will be made available to them,” said Tote President and Chief Executive Officer Anthony Chiarello. “We will find out what happened.” The NTSB will also check the ship’s maintenance records and other paperwork, Dinh-Zarr told reporters. Chiarello and other company officials have yet to explain why the ship sailed into the same area where Hurricane Joaquin reached a potentially catastrophic Category Four on the five-step Saffir-Simpson scale of intensity. And there are other major, unanswered questions about what happened to El Faro before it sank. The ship was crewed by 28 U.S. citizens, as well as five Polish nationals who were contractors hired to perform repairs and maintenance. The NTSB will also check the ship’s maintenance records and other paperwork, Dinh-Zarr told reporters. She said investigators hope to find as much material as possible amid two large debris fields strewn with items from El Faro. So far the Coast Guard has reported seeing a battered life boat, life jackets, life rings, and cargo containers, amid white polystyrene packing foam bobbing in the ocean. The 790-foot (240-meter) ship was piled high with containers and also was weighed down with trailers and automobiles below deck, according to Coast Guard officials. The U.S. Coast Guard said late on Tuesday that it had three vessels in the area of the El Faro’s last known position and would continue searching through the night into Wednesday, after suspending an unproductive aerial search for the day. Officials have acknowledged there is scant chance of finding survivors given El Faro disappeared in ferocious winds and seas up to 50 feet (15 meters) high. Only the body of one presumed crew member has been found so far. The El Faro left Jacksonville on the night of Sept. 29, just after U.S. forecasters warned that then-Tropical Storm Joaquin was poised to strengthen into a hurricane. Its crew issued a distress call about 36 hours later, saying it had lost propulsion, was listing and had taken on water after sailing into the path of Joaquin. It was never heard from again. Tote told reporters in Jacksonville the vessel was undergoing engine room work before it sank. But company officials have said they do not believe the work was related to a propulsion problem reported by the captain before the El Faro sank. “The contractors were on board doing some work in the engine room space, they were not performing any work on the engines,” said Philip Greene, who heads the ship management subsidiary Tote Services. “They were doing preparatory work in order for the ship to be converted for service in the Alaska trade,” Greene said. He acknowledged at a news conference that engine failure sealed the fate of El Faro, however, making it impossible to steer in the face of a brutal storm. “I think what’s regrettable in this is the fact the vessel did become disabled in the path of the storm, and that is what lead to ultimately the tragedy, Greene said.