The National Transportation Safety Board has released a Marine Accident Brief (MAB) on last year's overturning of the elevated liftboat Ram XVIII in the Gulf of Mexico about 15 miles south-southeast of Grand Isle, La.

Five crewmembers and 10 offshore workers abandoned the vessel and were rescued. Three personnel suffered minor injuries during the evacuation. An estimated 1,000 gals. of hydraulic oil were released. The vessel was declared a constructive total loss at an estimated cost of $1.14 million, according to the NTSB MAB.

The 215'-class liftboat was owned by Aries Marine Corp., Lafayette, La., and was built in 2015.

The NTSB determined that the probable cause of the Nov. 18, 2018, overturning of the Ram XVIII was the industry practice of not regularly providing liftboat operators with adequate information about the seafloor composition, which resulted in the instability of the port leg due to unidentified conditions/hazards in seabed composition near the port leg landing site.

The liftboat's master had extensive experience with liftboats, and the final positioning of the liftboat before jacking was at his discretion. Factors in the positioning included the reach of the crane and gangway to the client’s platform, seafloor composition, pipelines and other obstructions, proximity to can holes, and bathymetry. The lease holder provided high-precision Global Navigation Satellite System positioning and historical data showing location of previous landing impressions or can holes. However, the lease holder did not provide core samples, past penetration depths, or historical preloading times for this block to the Ram XVIII, the MAB said.

It is likely that the liftboat overturned because the port leg became unstable, but it is unknown whether the sea bottom washed away, the leg settled very quickly in what is known as a “punch-through” in the industry, or the edge of the nearest can hole collapsed. Over time, the number of can holes increases and creates a greater challenge for liftboats jacking up to service platforms.