Water ingress on towing vessel caused by poor hull condition, NTSB report reveals

​​​National Transportation Safety Board (NTSB) investigators found holes in the hull of a towing vessel after it flooded and partially sank last year on the Lower Mississippi River near Ascension Paris, Louisiana.

The towing vessel Uncle Blue was towing one empty barge on March 26, 2023, when the vessel began flooding. When the vessel was lifted by crane during salvage, NTSB investigators noted water pouring from holes in the portside shell plating in its lazarette.

Investigators found the nearly 60-year-old vessel had numerous wastage holes in the hull and doubler plates installed near the wastage holes. Given the vessel’s age, the holes found in the hull, and the presence of the double plates, investigators determined that the hull was not adequately maintained.

"Although doubler plating can be used as a temporary repair solution, it is not generally suitable as a permanent repair for a vessel’s hull," investigators said. "Vessel owners should crop out wasted steel on the hull and replace it by inserting new plating instead of covering it up with doubler plating."

Investigators also found pipe runs inside the hull, which had previously been used to allow rods to run the length of the hull, were open on both ends in addition to being either corroded or missing where they passed through the voids. The openings allowed for progressive flooding forward into the voids and engine room.

"Steel hulls are susceptible to corrosion, erosion, and damage over time," investigators said. "To avoid flooding or weakening of the hull, it is good marine practice for owners to conduct regular oversight and maintenance of hulls, including between drydock periods.

"An effective maintenance and hull inspection program should proactively address potential steel wastage, identify hull and watertight integrity deficiencies, and ensure corrosion issues are repaired in a timely manner by permanent means."

Investigators also determined the lack of a high-water bilge sensor in the lazarette further contributed to the sinking by preventing early detection of flooding into the space. The only sensor was in the forward end of the engine room.

No injuries or pollution were reported. Damage to the vessel was estimated at $500,000.

Marine Investigation Report 24-23 is available online.