Heavy weather and an improperly secured cargo of lithium-ion battery energy storage system (BESS) units led to two fires aboard the 410-foot (120-metre) cargo vessel Genius Star XI as it was transiting the North Pacific Ocean on Christmas Day 2023, causing US$3.8 million in damages, the US National Transportation Safety Board (NTSB) said earlier this week.
Investigators determined that improperly secured lashing belts failed, allowing 41 lithium-ion BESS units to shift in the cargo holds, leading to internal structural deformation.
This damage caused batteries in three of the units to enter thermal runaway, when a lithium-ion cell enters an uncontrollable, self-heating state that can exceed 300 degrees Celsius, causing the two fires within the holds.
After the first fire, the crew activated the vessel’s fixed CO2 fire-extinguishing system and diverted to the nearest port, Dutch Harbor in Alaska, for assistance. The fire was eventually extinguished.
While en route to Dutch Harbor, a second fire occurred in another cargo hold on December 28. The crew cooled the affected area externally with fire hoses.
The fire was confirmed extinguished when Genius Star XI arrived at Dutch Harbor on December 29. No injuries or pollution were reported.
The NTSB said the vessel had encountered gale-force northwest winds of about 26 knots, with gusts above 30 knots and combined seas and swells reaching 19 feet (5.8 metres). These conditions caused significant vessel rolling and seawater to wash over cargo hatches.
NTSB investigators emphasised the importance of ensuring that cargo aboard marine vessels—particularly large stationary lithium-ion BESS units—is properly secured.
Crews should: follow the vessel’s cargo securing manual and approved lashing plan; thoroughly inspect all cargo-securing arrangements during and after loading; and pay close attention to lashing belt hooks, wires, and chain falls to verify they are properly seated on D-rings and attachment points.
The NTSB said proper inspection and verification are critical to preventing cargo movement, structural damage to battery units, and potential thermal runaway events during heavy weather.
The full marine report is available on ntsb.gov.
