The National Transportation Safety Board (NTSB) has issued an investigation report on the fire that destroyed the towboat Mary Dupre while it was under way on the Intracoastal Waterway last year.
On June 26, 2022, about 0930 local time, a fire broke out in a stateroom on board the towing vessel Mary Dupre, which was pushing one barge of bio-diesel fuel (pyrolysis fuel oil) on the Gulf Intracoastal Waterway near Freeport, Texas.1 Nearby Good Samaritan towing vessels retrieved the barge from the Mary Dupre, extinguished the fire, and evacuated the four crewmembers. There were no injuries, and no pollution was reported. The towing vessel was deemed a total constructive loss estimated at $1 million.
The Mary Dupre was a 67.3-foot-long towing vessel constructed of welded steel and built in Larose, Louisiana, in 1974 as the Mary Delgrandile. The vessel had
several previous names and owners before it was acquired and renamed Mary Dupre by Dupre Marine Transportation in 2013. At the time of the fire, Dupre Marine Transportation operated 13 towing vessels from its facility in Houma, Louisiana.
While the towing vessel Mary Dupre was underway on the Gulf Intracoastal Waterway near Freeport, Texas, a fire started behind the wood-paneled bulkheads in
the pilot’s stateroom. The pilot’s stateroom was located between the vessel’s two stacks, which contained engine exhaust mufflers and piping. After the casualty,
investigators identified cracks in the welds on the upper section of the starboard muffler located inside the starboard stack.
Although the cause of the cracks is unknown, they may have been caused by a latent issue, such as a defect in the muffler during construction or the exhaust system design’s allowance for thermal expansion and contraction of exhaust piping above the muffler outlet. Vibration and movement during vessel operation over the years also may have caused or exacerbated the cracks.
The cracks in the exhaust muffler outlet allowed the hot exhaust gases from the operating starboard engine to escape into the stack area and increase the
temperature of the space and its bulkheads.
None of the crew were aware of the cracks or disconnected blanket. On the day of the casualty, they had inspected the vessel for fire hazards and completed a
daily inspection form, as was required by the company.
Probable Cause
The National Transportation Safety Board determines that the probable cause of the fire aboard the towing vessel Mary Dupre was undetected cracks in the starboard muffler that allowed exhaust gases from an operating engine to escape and ignite wooden structures affixed to the common bulkhead of an accommodation space.
Contributing to the extent of the fire damage was the substantial use of combustible materials in the joinery, outfitting, and furnishings in the accommodation spaces.
Engine and other machinery exhaust systems generate heat—which can radiate from exhaust components—and are potential ignition sources. These systems often
run through tight spaces that are difficult to access and inspect and are often located near materials or equipment that obstruct entry and direct observation. It is good practice to include these areas in periodic fire safety inspections. When conducting inspections of these systems, vessel owners and operators should consider using handheld equipment—such as inspection mirrors, video equipment, or thermal imaging equipment—to detect deficiencies.
