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NTSB: Lift Boat Toppled Due to Inadequate Preload Testing

lift boat
Courtesy NTSB / Sanare Energy Partners

By The Maritime Executive 11-17-2020 06:48:59

The National Transportation Safety Board has released the results of an inquiry into the capsizing of the liftboat Kristin Faye in the Mississippi River Delta in September 2019. While working in an elevated position with her hull out of the water, the Faye suddenly tilted over and fell onto her port side, coming to rest on the bottom. 

On September 8, the Kristin Faye completed work at a platform in the Main Pass area of the Delta. She got under way to another installation, Platform AQ, where she planned to pick up a 17,000 pound pressure vessel she had delivered a few days earlier. Her captain maneuvered to within about 10 feet of the platform in an area that had recently surveyed for hazards, obstructions and "can holes" - depressions in the bottom left by previous lift boats. Satisfied with the location, he lowered the boat's three legs and raised her about six feet out of the water for a preload test. During the hourlong test, he watched the vessel's inclinometers and monitored for any signs of listing or settling. None were observed, so he raised the boat to her working height of about 20-25 feet. Per procedure, he waited another hour to check for stability and signs of movement. Seeing no issues, he raised the crane boom and began to slew the crane to check whether it would clear the adjacent platform. The Kristin Faye immediately began tilting to port, and despite the master's efforts to counteract the motion by lowering her starboard and aft legs, she slowly toppled into the water. 

This evolution took about one minute, and the master abandoned ship into the water and swam to a nearby OSV. The other two crewmembers were rescued with a man-basket lowered by the crew on the platform. One of them, the cook, sustained a back injury when the vessel listed over. 

Salvage efforts got under way, but immediately encountered an obstacle. The salvage contractor found that her port side leg had penetrated 40 feet down into the mud, and her port side was stuck as well. The owner declared her a total constructive loss, and the vessel was salvaged for scrap. 

No signs of damage or failure were found in the Kristin Faye's legs or jacking gear, and the NTSB concluded that the accident was likely the result of a "punch through" - a condition in which the pad on the bottom of the leg penetrates a hard layer in the bottom, then sinks through softer mud underneath. The Main Pass area is notorious for shifting sediment deposition, shelves of harder and softer material, and "can holes" that have backfilled with soft sediment, according to the shipowner. 

NTSB recommended that lift boat operators in the region should undertake more thorough bottom testing prior to commencing operations, like checking soil resistence using at PSI loadbearing test. Alternatively, it suggested that small liftboats like the Kristin Faye should be fitted with preload tanks - ballast tanks used for adding excess weight to the elevated platform during preload testing, commonly fitted on larger jackup platforms but rarely on small working vessels like the Faye. Preload tanks would allow the operator to confirm whether the bottom could take the full weight of the liftboat and any load that it intends to pick up.