Warrior approaching the bridges at Memphis on an earlier tow.
Marquette Warrior was downbound on the Lower Mississippi River with 35 barges in tow when the interior lights started flickering. Five minutes later, at about 12:10 pm on November 21, 2021, the vessel lost its steering around a river bend near Greenville, Ms.
The pilot helming the 166-foot, 8,000-hp towboat backed on the engines to slow down in the fast-moving current, the National Transportation Safety Board (NTSB) said in its report. Still, the forward portside barges in the 1,000-foot-long tow grounded on the left descending bank at Mile 538.
The tow ultimately broke apart and a barge loaded with beans partially sank, ruining its cargo valued at more than $1 million.
The towboat, homeported in St. Louis and operated by the Marquette Transportation Co., was underway with nine crewmembers on board pushing 35 hopper barges loaded with beans and corn.
The voyage was uneventful until the lights started flickering as the tow entered a portion of the Mississippi known as Leland Dykes.
T
he engineer requested the pilot push up against the bank to troubleshoot the electrical issue. However, the nearest such location was roughly 30 minutes downriver. Moments later, lights within the vessel started flashing and the towboat lost its steering.
At the time, the tow was making about 10 mph, aided by a 4.5 mph current. The pilot backed down on the twin EMD engines as the tow approached the turn near Lagrange Towhead Light.
Meanwhile, the engineer successfully started the starboard generator at 12:08 pm, and the pilot tried to steer around the bend. But by then the tow was out of shape and unable to avoid pushing the forward portside barges onto the left bank.
“The tow then started to rotate in the current,” the report said. “The pilot, realizing that the section of navigable river was not wide enough for the tow to rotate around safely, maneuvered the vessel to purposely part the wires holding it to the tow.”
The maneuver, the report said, was intended to “prevent the vessel and tow from being broadside to the swift river current and potentially capsizing.”
The NTSB determined Marquette Warrior had lost 3-phase electrical power to its steering pump motors due to a problem with the portside generator – the only one running at the time.
The agency attributed that problem to a wiring harness inadvertently moved out of position during preventative maintenance conducted two weeks earlier.
“The electricians’ analysis of the alternator following the casualty indicated that the most likely cause of the failure was rubbing or chaffing of the sensing wiring harness, which led to arcing between terminal block posts, heat buildup, insulation failure, and eventual winding ring terminal failure,” the agency said in its report.
“While it is possible the wiring harness could have shifted onto the terminal posts due to vessel vibrations,” the report went on, “it is more likely that the wiring harness was inadvertently displaced during the vessel engineer’s preventive maintenance inspection on November 7 and went unnoticed during his reinstallation of the cover panel.”
Marquette Warrior was equipped with two 139 kW Marathon generators. Crews alternated use of the port and starboard generators, each of which supplied enough power for critical vessel systems, including navigation electronics, interior lights, and steering pumps.
The alternators on each genset were completely refurbished during a nine-month overhaul that began in early 2021. The portside genset had only about 675 total hours since the towboat reentered service. It had only about 72 hours of use following a relay failure on November 7 that required preventative maintenance.
“The November 7 preventive maintenance performed by the vessel’s engineer required the removal of the port genset alternator’s cover panel to inspect all wires/connections for wire fray, chaffing, and loose connections,” the report said.
“Because the onboard engineer did not notice any damage within the terminal box or to the sensing wiring harness during his inspection, it is likely the chaffing of the wiring harness took place over the 72 hours the genset ran between the [preventative] maintenance inspection and the casualty” two weeks later, the report continued.
Based on the condition of the alternator, it would not have been able to supply 3-phase power, according to an electrician interviewed by investigators. That would cause the vessel’s lights to flicker and render the electric motors that drive the steering pumps inoperable.
Several other towboats operating nearby helped gather the drifting barges.
Ultimately, the Marquette Warrior’s crew was able to rebuild the tow, with the exception of the single barge that partially sank.