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Accidents

Maersk Essen (2021)

Maersk Essen was crossing the Pacific from Xiamen to Los Angeles when the casualty occurred about 450 nautical miles north of Hawaii. The Danish-flagged container ship was proceeding at about 10 to 11 knots in long residual swells. At about 06:00 ship's local time on 16 January 2021, the vessel made several sudden rolls of approximately 15 degrees to each side before stabilising. At 08:04 a further rolling episode began. Three minutes later the vessel rolled again, with the cycles increasing until the estimated angle reached 25 to 30 degrees. The officer of the watch altered course, and the episode stopped after about two minutes. The master then made a larger alteration to starboard and increased speed. At 08:15, the master saw containers hanging over the side and floating astern. The crew activated the heavy-weather response procedure, notified the company and relevant authorities, and completed a head count. No crew member was injured or missing. The final assessment recorded 689 containers lost overboard and 258 damaged across eight bays. Collapsed stacks damaged cargo-deck structures, accommodation ladders and passageways, and equipment shifted in accommodation and machinery spaces. The ship continued on a more southerly course and was diverted to Lázaro Cárdenas, Mexico, for discharge and emergency repairs. DMAIB concluded that excessive rolling imposed loads beyond the intended limits of the cargo-securing equipment. It considered parametric resonance the most likely explanation, possibly combined with pure loss of stability on a wave crest, but retained that conclusion as probabilistic.

Classification

FieldValue
Incident TypeCargo Loss
SeverityMedium
Investigation BodyDMAIB

Vessel Details

FieldValue
Vessel NameMaersk Essen
Vessel NamesMaersk Essen
Vessel TypeContainer
Flag StateDenmark [DK]
IMO Number9456783
Gross Tonnage141716
LOA (m)366.45
Breadth (m)48.26

Incident Details

FieldValue
Date2021-01-16
RegionPacific Ocean
LocationPacific Ocean, about 450 nautical miles north of Hawaii
Coordinates28.562667, -154.012000
Fatalities0
Injuries0
Missing0
Direct Damage
Economic Damage
Cargo Loss689 containers lost overboard; 258 damaged

Key facts

  • Maersk Essen was crossing the Pacific from Xiamen to Los Angeles.
  • Two episodes of heavy rolling occurred shortly after 08:00 ship's local time, with estimated maximum roll angles of 25 to 30 degrees.
  • The final assessment recorded 689 containers lost overboard and 258 damaged across eight bays.
  • Container-stack collapses damaged cargo-deck structures, accommodation ladders and passageways, while equipment shifted in accommodation and machinery spaces.
  • DMAIB considered parametric resonance the most likely explanation for the rolling, possibly combined with pure loss of stability on a wave crest.

Narrative

Maersk Essen was crossing the Pacific from Xiamen to Los Angeles when the casualty occurred about 450 nautical miles north of Hawaii. The Danish-flagged container ship was proceeding at about 10 to 11 knots in long residual swells. At about 06:00 ship's local time on 16 January 2021, the vessel made several sudden rolls of approximately 15 degrees to each side before stabilising. At 08:04 a further rolling episode began. Three minutes later the vessel rolled again, with the cycles increasing until the estimated angle reached 25 to 30 degrees. The officer of the watch altered course, and the episode stopped after about two minutes. The master then made a larger alteration to starboard and increased speed. At 08:15, the master saw containers hanging over the side and floating astern. The crew activated the heavy-weather response procedure, notified the company and relevant authorities, and completed a head count. No crew member was injured or missing. The final assessment recorded 689 containers lost overboard and 258 damaged across eight bays. Collapsed stacks damaged cargo-deck structures, accommodation ladders and passageways, and equipment shifted in accommodation and machinery spaces. The ship continued on a more southerly course and was diverted to Lázaro Cárdenas, Mexico, for discharge and emergency repairs. DMAIB concluded that excessive rolling imposed loads beyond the intended limits of the cargo-securing equipment. It considered parametric resonance the most likely explanation, possibly combined with pure loss of stability on a wave crest, but retained that conclusion as probabilistic.

Sequence of events

Date/timeEvent
2021-01-16 06:00 localMaersk Essen made several sudden rolls of about 15 degrees and then stabilised.
2021-01-16 08:04 localA further episode of heavy rolling began.
2021-01-16 08:07 localThe second episode reached estimated roll angles of 25 to 30 degrees before stopping.
2021-01-16 08:15 localThe master observed containers over the side and the crew began the heavy-weather response.
2021-01-30Maersk Essen berthed at Lázaro Cárdenas for cargo discharge and emergency repairs.

Contributing factors

FactorEvidence statusDescription
Excessive roll anglesConfirmed findingRolling of approximately 25 to 30 degrees imposed loads beyond the intended limits of the cargo-securing equipment.
Parametric resonanceSuspectedDMAIB found parametric resonance the most likely explanation for the sudden rolling under the combined conditions.
Possible loss of stability on a wave crestSuspectedDMAIB found that pure loss of stability on a wave crest might have contributed to the onset of parametric resonance.
Limited prediction capabilityConfirmed findingWeather routing did not assess parametric-resonance risk and the crew lacked a reliable onboard prediction method.

Investigation

The Danish Maritime Accident Investigation Board investigated the casualty using interviews, voyage data recorder information, logbooks, photographs, weather analysis and simulations. It concluded that excessive rolling caused the cargo-securing failures and container loss. Parametric resonance was the most likely explanation for the rolling, but DMAIB did not present it as certain and also considered pure loss of stability on a wave crest. The report does not provide a normalized monetary damage estimate.

References

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