The National Transportation Safety Board has issued its report on the investigation into the listing of an elevated liftboat caused by a November 2022 storm with gale-force winds and high waves in the Gulf of Mexico.
The incident occurred at 12:55 pm and involved the L/B Robert, which was stationed alongside an oil platform near South Marsh Island Block 137, about 80 miles southeast of Lake Charles, La.
The crew had evacuated the liftboat two days prior to the incident due to forecasted adverse weather conditions, leaving the vessel unattended and elevated out of the water. Fortunately, no injuries or pollution were reported, but the estimated damage to the vessel and cargo amounted to $6.9 million.
The L/B Robert, a three-legged liftboat owned by Falcon Global Robert and operated by SEACOR Marine, “faced challenging weather conditions that exceeded its operational limits and the decision was made to evacuate the rig personnel and liftboat crewmembers to mitigate the risks,” the NTSB said.
The 185-foot liftboat was constructed of welded steel and built by Gulf Island Marine Fabricators in Houma, La., in 2012.
The vessel furnishes up to 132 offshore workers with accommodations, and, according to its Certificate of Inspection, is required to have at least 10 crewmembers.
According to the report, the crew “followed guidance from shoreside management personnel during the evacuation and left an air gap of approximately 25 feet above the water’s surface, providing maximum resistance against overturning caused by the combined forces of wind and waves.”
However, subsequent analysis revealed that the vessel likely encountered waves as high as 30 feet, surpassing both the air gap and the initial forecasts.
The agency investigation found that the wind and waves “transferred significant forces down the vessel’s legs, resulting in the deterioration of the seabed foundation around them. Ultimately, it is believed that the deteriorated foundation under the port leg gave way, causing the vessel to tilt to port and submerge its deck edge.”
The incident, the NTSB said, “draws attention to the potential risks faced by liftboats operating in adverse weather conditions and serves as a reminder of the importance of accurate weather forecasts and adherence to operational limits to ensure the safety of vessel crews.”
The Texas-based Apache Corp., the owners of the platform, had contracted the vessel to support plug and abandonment operations on several decommissioned oil wells that were accessible from the platform.
SEACOR Marine also operated the SEACOR Power which capsized in 2021 off the coast of Port Fourchon, La., while underway in a severe thunderstorm, claiming the lives of 13 people.
As a result of that accident, the NTSB issued three safety recommendations to the company focusing on timely and accurate weather forecasts, adherence to operational limits, and revisions to operation manuals to enhance safety protocols during severe weather conditions.
By March 2023, the NTSB said, SEACOR Marine had implemented all three safety recommendations.