Total Loss: No Remote Control of Ventilation Inlets
The U.S. National Transportation Safety Board (NTSB) has released a Marine Accident Brief about the sinking of the fishing vessel Ariel in August 2019 when a fire broke out in the vessel’s engine room.
On August 26, 2019, about 1830 local time, the Ariel was transiting Sheep Bay, Prince William Sound, Alaska, when the fire broke out. The four crewmembers aboard the Ariel attempted to fight the fire, but they were unsuccessful and abandoned ship into the vessel’s skiff. The Ariel continued to burn and subsequently sank. The crew was rescued by Good Samaritan vessels and returned to port uninjured. About 500 gallons of diesel fuel was aboard the vessel when it sank. The Ariel, valued at an estimated $600,000, was a total loss.
The NTSB determined that the probable cause of the fire was the ignition of fuel leaking from the generator fuel supply line in the engine room. The fluctuating rpm of the diesel engine generator observed by the captain just after the fire was discovered was likely the result of fuel starvation, which suggests that the fuel line to the generator’s engine was breached.
The fuel hoses that ran between the manifold, fuel filter, and generator met Coast Guard material specifications. However, over time a hose could have become worn from contact, its connections could have loosened through vibration, or it could have otherwise failed, allowing fuel to leak into the engine room. Leaking fuel or fuel vapor may have then come into contact with a hot surface, igniting the fire.
Contributing to the severity of the fire and the eventual loss of the vessel were the fixed-open inlets for the engine room ventilation, which allowed fire-extinguishing agent to escape and air to enter the space. The vessel was fitted with manually operated fuel oil shut-offs in the lazarette and engine room; there were no remote emergency shut-offs.
The crew was not able to close the manual shutoff valves before abandoning the vessel. Based on crewmember accounts, the Halon fixed fire-extinguishing system on the Ariel activated and appeared to reduce the fire, but the fire rekindled and eventually consumed the vessel.
The report is available here.