NTSB releases its findings on what caused dredge WB Wood to capsize

The National Transportation Safety Board has released its report into the January16, 2023 flooding and eventual capsizing of the Wood Resources LLC non-propelled dredge WB Wood during sand dredging operations near mile 85 on the Lower Mississippi River. An estimated 5,000 gallons of fuel were released and the 1983-built dredge was subsequently declared a $1.5 million total loss. Though there were no injuries, the vessel’s sole person on board as it started to capsize, the night leverman, had to be rescued by a good samaritan vessel after jumping into the river (more details on that in the full NTSB report).

In its summary of the report, the NTSB says that, before the capsizing, the WB Wood 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 night leverman noticed the dredge listing abnormally to starboard. The leverman 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 postsalvage examination, 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 comprised watertight bulkheads within the hull further increased the starboard list and aft trim which led to the capsizing of the vessel.

“Two days before the capsizing, the day leverman discovered water in the starboard storage space, but 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.”

PROBABLE CAUSE

The National Transportation Safety Board determined that the probable cause of the capsizing of the dredging vessel WB Wood was a lack of company requirements for crew to regularly check compartments below deck, which resulted in undetected flooding from a through-hull pipe that was missing its overboard check valve and subsequent progressive flooding from compromised watertight bulkheads.

LESSONS LEARNED

Conducting routine checks of voids and hull spaces: Vessel crews should regularly check tanks and voids that are adjacent to the vessel’s hull to identify hull integrity issues (such as potential corrosion and steel wastage, and watertight integrity deficiencies) that can lead to flooding. 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.

• Download the full NTSB report HERE