The midnight watch was uneventful as the tugboat Karen Koby sailed through the Gulf of Mexico with a crane barge in tow. That is, until the tug’s speed suddenly dropped at about 3:30 a.m. on June 15, 2022.
The mate at the helm checked the engines and the weather but saw nothing amiss. He trained the spotlight on the crane barge Ambition roughly 1,000 feet behind the tug and what he saw concerned him enough to rouse the captain.
“The captain and mate went to the wheelhouse and looked at Ambition with the spotlight. The captain said he couldn’t see anything at that time,” according to the National Transportation Safety Board in its incident report.
About 4 a.m., the mate saw the unmanned Ambition capsize, with the port corner of the bow dipping down before rolling over ‘quickly’ to port,” the report added.
The crane barge partially sank roughly 52 miles south of Cameron, La. with some 2,000 gallons of diesel escaping into the Gulf. The crane barge valued at about $6.3 million was a total loss.
Salvors eventually raised the barge, and NTSB investigators determined that wastage and other structural problems had allowed seawater to enter its compartments and move between holds.
The lack of hull inspection, maintenance, and permanent repairs by Ambition owner Rigid Constructors “resulted in the poor hull condition that caused the failure of the hull,” the agency said. “Flooding through an open hatch on the port barge’s rake void likely accelerated the rate of flooding, contributing to the capsizing,” the report continued.
Lafayette, La.-based Rigid Constructors did not respond to an inquiry about the NTSB findings. Neither did LA Carriers, the Larose, La. towing company that owned and operated Karen Koby.
The 195-by-70-foot Ambition was purpose-built to accommodate a large crane, the report said. Its deck consisted of two existing barges, each at least 24 years old, that were welded together. The vessel was laid up on the Gulf Intracoastal Waterway (ICW) near Sulphur, La., for about a month before the sinking.
The 2,800-hp Karen Koby reached Ambition on the morning of June 14, 2022, with a four-person crew. Their job was to tow the barge to the Mississippi River via the Calcasieu River and Gulf of Mexico, but the crane’s height made transit through the ICW impossible.
Five Rigid Constructors personnel secured the barge for transit with roughly 1,800 gallons of fuel in a tank on Ambition’s deck and 8,000 gallons of fresh water aboard after a Rigid supervisor noticed Ambition’s stern was riding higher than the bow. Rigid personnel did not check barge voids for water ingress before the tow began.
Meanwhile, a deckhand aboard Karen Koby inspected the barge before getting underway from a fuel dock near the mouth of the Calcasieu River. He noted a 1-by-2-inch rust hole on the deck of the port barge at the stern. He documented that multiple hatch covers were in poor condition and not physically locked down and that two hatch covers were missing altogether.
The captain summoned the Rigid personnel, and the tug’s deckhand watched as a Rigid employee covered an open hatch on the port barge rake with a dewatering pump and another on the port stern with a metal plate, the report said.
That was apparently good enough for Karen Koby’s captain, who got underway soon afterward, at about 5:30 p.m. and did not report the barge’s condition to his home office – despite a mandate to do so.
The voyage proceeded normally until the tow suddenly lost speed at about 3:30 a.m. the next day. The mate saw the tug’s speed drop from 5.2 knots to 4.5 knots and then to 3 knots nine minutes later, as he and the captain looked aft for the barge.
After attempting to see the Ambition in the pre-dawn darkness, the mate watched it roll over at about 4 a.m. The unmanned barge came to rest with its port bow stuck on the seafloor and its starboard quarter above the water.
NTSB investigators learned the barge had been towed offshore up to 12 times a year before the sinking, despite not having the required load line certificate. According to the report, Rigid Constructor’s president of marine operations reportedly was not aware that one was required.
After the salvage, investigators discovered that at least six hatches were not covered or fully secured, and that the barge showed signs of metal wastage and corrosion, along with the temporary repairs carried out to mitigate those issues.
“Post-casualty examination of the port barge found a 25-foot-long separation along the weld seam between the bottom plate and bilge knuckle plate with both plates exhibiting severely wasted steel,” the NTSB report said, noting that the damage likely did not occur during salvage.
“At some point,” the report continued, “a temporary repair, which consisted of steel plates welded to the floor and knuckle plating, forming a box inside compartment No. 1S, had been made to the area around the separation, to contain water ingress. Three soft patches with strongback-type bolts, typically used for temporary repairs, were found along the failed seam.”
Based on these findings, the NTSB believes the original water ingress occurred in compartment 1S, located forward on the inboard side of the port barge. They also believe wastage along the centerline watertight bulkhead allowed seawater to flow into adjacent compartments.
With only about a foot of residual freeboard in the 2-3-foot seas, investigators found that “any increase in draft forward would have likely exposed the open hatch at the port corner to seas reaching the main deck, and eventual down flooding in the rake void space below.”