Improper Cargo Securing as Root Cause of Lithium-Ion Battery Fire on Genius Star XI

A catastrophic cargo fire onboard the general cargo vessel Genius Star XI in December 2023 has been conclusively linked to improper lashing hardware selection, according to a detailed investigation report released by the United States National Transportation Safety Board (NTSB). The incident resulted in approximately USD 3.8 million in cargo damage and highlighted critical vulnerabilities in the maritime transport of lithium-ion battery energy storage systems (BESS).

Vessel, Cargo, and Environmental Conditions

The Genius Star XI, chartered by Norden and operated by Wisdom Marine, was engaged in the trans-Pacific transport of battery energy storage system (BESS) units, each weighing approximately 9.5 tonnes and containing 840 lithium-ion battery cells. The voyage took the vessel through the North Pacific Ocean near the Bering Sea, an area known for severe winter weather conditions.

On 25 December 2023, the vessel encountered gale-force winds, significant wave heights of approximately 19 feet, and heavy swells averaging 13 feet. Green seas were reported to have washed over the hatch covers, subjecting the cargo and securing arrangements to extreme dynamic loading.

Technical Failure of Lashing Arrangements

The NTSB investigation determined that the primary causal factor of the incident was the use of incorrectly sized hooks on the lashing belts used to restrain the BESS units within the cargo holds.

• The lashing belt hooks were undersized relative to the D-rings welded to the deck structure.

• Instead of seating fully within the hook throat (as required for proper load transfer), the hooks engaged the D-rings only at their tips.

• This partial engagement significantly reduced the effective load-bearing capacity of the securing system and made the hooks highly susceptible to fatigue cracking and brittle fracture under cyclic loads.

As the vessel rolled and pitched in heavy seas, several hooks fractured progressively, resulting in:

• Load redistribution to remaining lashings

• Increased tensile stress on intact hooks and D-rings

• A cascading failure of the entire cargo restraint system

Ultimately, multiple BESS units broke free, shifting violently within the cargo holds.

Mechanical Damage and Initiation of Thermal Runaway

The uncontrolled movement of the BESS units caused severe mechanical deformation of the battery enclosures:

• Internal shelving rails were bent

• Structural bolts securing shelves to the chassis loosened

• Battery modules became displaced within the units

This deformation led to electrical arcing and internal short circuits, which are recognized triggers for thermal runaway in lithium-ion batteries. Thermal runaway is a self-sustaining exothermic reaction that rapidly elevates battery temperatures, releasing flammable gases and often resulting in fire or explosion.

Investigators also noted rail deformation in at least one BESS unit that had not broken free, suggesting a potential design vulnerability in the BESS structure itself when subjected to shipboard dynamic loads.

Fire Development and Crew Response

The first signs of fire were detected after the chief officer observed black smoke emanating from cargo hold number one during a post-storm inspection. The vessel’s fire alarm was activated, and the crew responded in accordance with established emergency procedures.

Key operational decisions included:

• Confirmation that only one cargo hold could be flooded with CO₂, due to system limitations

• Verification that hold number two showed no active fire

• Deployment of the CO₂ fixed fire-extinguishing system in hold number one, which successfully suppressed the initial fire

Following suppression, the crew attempted to re-secure shifted cargo in hold number two.

However, on 28 December, the vessel again encountered heavy weather. During severe rolling, fire alarms indicated a second outbreak in hold number two, with smoke visible from ventilation ducts. With the CO₂ system already expended, the master made the decision to:

• Alter course to calmer waters

• Conduct external boundary cooling using seawater fire hoses

After approximately four hours of continuous cooling, hold temperatures decreased and the fire was considered extinguished.

Post-Incident Actions and Damage Assessment

Upon arrival at Dutch Harbor on 29 December 2023, specialized marine firefighting teams from T&T Salvage and Resolve Marine boarded the vessel and confirmed that no active fires remained.

A lithium battery safety specialist was subsequently engaged to:

• Conduct a detailed damage assessment

• Safely manage and isolate damaged battery packs

• Arrange disposal of severely compromised battery modules in certified containment units

In total:

• 43 out of 160 BESS units were damaged

• 41 of the damaged units had broken free from their lashings

• Fires occurred in three separate BESS units across two cargo holds

No injuries were reported among the 19 crew members, and no environmental pollution occurred.

Corrective Measures and Industry Implications

Following the incident:

• Norden doubled the minimum breaking load requirement for lashing belts from 5 tonnes to 10 tonnes

• Stronger belts with properly sized hooks were introduced to ensure full seating within D-rings

• Vessel masters were instructed to adopt more southerly trans-Pacific routes during winter months to avoid extreme sea states

• Cargo was additionally secured using chain stays before the vessel resumed its voyage

After recharging the CO₂ system and securing approval from the U.S. Coast Guard, the Genius Star XI departed Dutch Harbor on 12 February 2024 and safely arrived in San Diego on 24 February.

Conclusion

The NTSB concluded that the incident was preventable and underscored the critical importance of:

• Proper compatibility between lashing hardware and securing points

• Conservative cargo-securing assumptions for high-risk cargoes such as lithium-ion batteries

• Recognizing the compounded hazards of heavy weather, mechanical shock, and battery thermal instability

The crew’s timely and disciplined response was credited with preventing a far more serious escalation, including potential loss of the vessel. This incident serves as a significant case study for the maritime industry as lithium battery shipments continue to increase globally.