NTSB Issues Report On 2023 Capsizing Of Dredge W.B. Wood
A company’s lack of requirements for crew to regularly check below-deck compartments led to undetected flooding and the eventual capsizing of a dredging vessel last year on the Mississippi River, the National Transportation Safety Board reported April 23.
The non-propelled dredging vessel W.B. Wood capsized in the early morning hours of January 16, 2023, during dredging operations. An estimated 5,500 gallons of oil was released, and the vessel was declared a total loss of $1.5 million. No injuries were reported.
Before the capsizing, the dredge had been in the same location for nine days, pumping sand from the riverbed to a pit on the west bank. About two hours before the capsizing, the dredge’s leverman noticed the dredge listing abnormally to starboard. He discovered a starboard storage space full of water and began using a portable pump to dewater the space. The onboard portable pump and a second pump later added could not keep up with the rate of flooding, and the starboard list continued to increase.
During a post-salvage examination, NTSB investigators found a through-hull pipe into the starboard storage space was open, and its overboard check valve was missing. Investigators determined the initial starboard list was likely caused by flooding through the unsecured through-hull pipe into the starboard storage space. Progressive flooding through compromised watertight bulkheads within the hull further increased the starboard list and aft trim, which led to the capsizing of the vessel, NTSB found.
Two days before the capsizing, the day leverman had discovered water in the starboard storage space, but he was not able to identify the source of the water. In the time leading up to the capsizing, the crew did not know if any hull compartments had leaks or water in them. The company did not have requirements for regularly checking compartments below deck, which resulted in the undetected flooding, NTSB said.
“Vessel crews should regularly check tanks and voids that are adjacent to the vessel’s hull to identify hull integrity issues,” the NTSB report said. “The presence of water can indicate an issue with watertight integrity or wastage and should be addressed. Vessel operators should ensure crews have procedures for anticipating, preventing and addressing the potential for water ingress and flooding, including establishing scheduled checks. Bilge alarms set to detect water at a low level in voids and other spaces are another means to ensure early detection.”
The NTSB’s Marine Investigation Report is available online here: www.ntsb.gov/investigations/AccidentReports/Reports/MIR2408.pdf.
