After a 13-month effort, investigators say they won't be able to determine the definitive cause of the dive boat fire that killed all 33 passengers and one crew member in September 2019. The National Transportation Safety Board was told at a virtual hearing on Tuesday that though the Conception was recovered from the seafloor off California's Santa Cruz Island, its poor condition rendered the investigators unable to identify whether the fire began by way of lithium-ion phone batteries that were being charged, the boat's electrical system, or an "unattended fire source," as the Los Angeles Times puts it. But the investigation did assign blame, faulting the lack of an overnight watch (known as a "roving patrol") as required. An investigator told the NTSB that this fact "directly led to the high number of fatalities," per CNN.
He continued, "Had a crew member been awake ... it is likely that he or she would likely have discovered the fire at an early stage, allowing time to fight the fire and give warning to passengers and crew to evacuate." The Washington Post reports there were also no smoke detectors in the boat's common salon area, where it's believed the fire started (regulations didn't require them). The salon is where passenger cellphones were being charged, and interviews with surviving crew and passengers who'd been on the boat previously indicate the fire likely started at the charging point. The Conception's sister vessel, the Vision, experienced a fire in that location due to chargers 11 months prior, reports CNN, but it was spotted and put out quickly. (The boat's victims all had the same cause of death.)