Severe winds during a thunderstorm led to a loss of stability and then the capsizing of liftboat Seacor Power (IMO 8765682), the National Transportation Safety Board (NTSB) said at a public meeting on Tuesday October 18th.
There were 19 people aboard the vessel when the accident occurred on April 13th 2021; six people died, with seven more missing, presumed dead (see IMN April 20th 2021 and subsequent dates). Six people were rescued by the US Coast Guard and other vessels.
The $25m Seacor Power was a total loss. A liftboat supporting offshore work on oil-producing platforms, it capsized off the coast of Port Fourchon, Louisiana during heavy rain, winds exceeding 80 knots and 2ft to 4ft seas at the time of the capsizing.
The Seacor Power was heading for an oil and gas lease block in the Gulf of Mexico. It sailed shortly after midday. Sometime after 15:00 it was hit by a rain squall. The vessel’s mate said a second squall about 10 minutes later caused “white out” conditions.
A lift boat has extendable legs that can reach the sea bottom. The vessel is often used by energy companies for offshore construction projects or to service oil rigs.
The crew began to lower the vessel’s 265ft-long legs to the seafloor in an effort to ride out the storm. However, during the leg-lowering process, the mate turned the Seacor Power into the wind to slow its speed. As the vessel turned, it heeled over and capsized, a few minutes before 16:00.
A National Weather Service report concluded the area of the capsizing was affected by an “unusually intense thunderstorm wind event.”
The NTSB determined the probable cause of the capsizing of the Seacor Power was a loss of stability that occurred when the vessel was struck by severe thunderstorm winds, which exceeded the vessel’s operational wind speed limits.
Contributing to the loss of life on the vessel were the speed at which the vessel capsized and the angle at which it came to rest, which made egress difficult and the high winds and seas in the aftermath of the capsizing, which hampered rescue efforts.
NTSB investigators identified data gaps that prevented the National Weather Service from identifying and forecasting the surface wind magnitudes that the Seacor Power encountered. The localized wind conditions could not be detected by weather service radars due to their elevation angles.
The NTSB therefore recommended that the National Weather Service, Federal Aviation Administration, and the Air Force work together to assess coastal weather radar sites to determine if it was safe and appropriate to lower radar angles, which could improve the ability to accurately forecast weather conditions.
- The NTSB issued three safety recommendations to the US Coast Guard: develop procedures to inform mariners in affected areas whenever there is an outage at a navigational telex broadcasting site;
- modify restricted-service liftboat stability regulations to require greater stability for newly constructed restricted-service liftboats and;
- develop procedures to integrate commercial, municipal, and non-profit air rescue providers into Sectors’ and Districts’ mass rescue operations plans.
The NTSB also reiterated a recommendation to the USCG to require all personnel employed on vessels in coastal, Great Lakes and ocean services be provided with a personal locator beacon. The NTSB also recommended the Offshore Marine Service Association notify members of personal locator beacons’ availability and value.
“We’ve been waiting five years for the Coast Guard to implement our recommendation on personal locator beacons — a call to action we’re renewing today for the fourth time,” said NTSB Chair Jennifer Homendy, adding that “mariners’ safety can’t wait, which is why I’m urging employers to invest in personal locator beacons for their crew. As the Seacor Power tragedy shows, the lifesaving promise of these devices cannot be overstated.”
The final report will be published on the NTSB website later this year.
2002-built, USA-flagged, 2,276 gt Seacor Power is owned by Falcon Global Offshore II LLC care of manager Seacor Liftboats LLC of Louisiana, USA. ISM manager is Seacor Marine LLC of Morgan City, Louisiana, USA. It is entered with Skuld (Business Unit Skuld Offshore) on behalf of Falcon Global Holdings LLC.