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Fire on dive vessel caused by chafed electrical cables, NTSB says

Apr 29, 2015 05:17 PM

A deep-sea diving support vessel needed $9.8 million in repairs following a fire started by electrical cables as it sailed the Louisiana Gulf in 2013. 

Tightly installed metal bands on one of Ocean Patriot’s cable trays chafed the cables’ protective layers, causing ignition, the National Transportation Safety Board (NTSB) said in a marine accident brief in January. The fire was fueled by cardboard, air filters and other items stored beneath the tray. 

The 240-foot Ocean Patriot, owned by Oceaneering International Inc. of Houston, left Port Fourchon, La., on the afternoon of Nov. 28, 2013. The vessel, with 42 people aboard, headed to Green Canyon 205 under clear skies and in seas of 1 to 3 feet. The boat was 50 miles southwest of the port when a fire erupted below its main deck. 

At 2215, alarms from fire-detection and oxygen-sensor systems alerted watch standers to a problem in the machinery space. The boat’s assistant engineer told the mate on the bridge that he was leaving the engine control room to investigate. He headed forward on the mezzanine deck and saw smoke, then continued to the galley where he reported the fire to the bridge, using the ship’s telephone system.

“According to the assistant engineer, the fire was located in a cable tray above an electrical motor control center,” the investigators wrote. “The area directly underneath the cable tray was used for storing sundry items. He was first on the scene and attempted to fight the fire with a portable extinguisher, emptied the unit, but was not able to extinguish the fire.” The assistant engineer escaped through an emergency hatch.

On the bridge, the chief mate called the captain, rang the general alarm, and made a public address announcement to the crew. The captain reached the bridge where he was briefed, and then alerted Oceaneering International by satellite phone. The captain sent a signal over the Global Maritime Distress and Safety System, ordered the ship’s heading to be put into the wind and told the crew to muster, the NTSB said.

The captain went below to assess the scene and, on his return above, ordered that mayday be called over the VHF radio. The vessel’s fire teams donned protective suits and breathing devices. At first they used portable extinguishers to combat the fire on the mezzanine deck. A fire team advancing from the forward direction had to retreat because of smoke and heat, the investigators wrote. A second team approached from the aft direction, only to encounter smoke. The crew began the process of boundary cooling, using hoses charged by the fire main. Engineers secured fuel systems, ventilation fans and dampers before activating the vessel’s FM-200 suppression system, which uses heptafluoropropane to extinguish fires. 

During the fire, the vessel’s electrical generators struggled to maintain power. Three engines had been running before the conflagration. A safety device tripped one engine offline, the NTSB said. The chief engineer secured the other two generators as their speeds and system voltages dropped. The assistant engineer secured a fuel-oil purifier to prevent fuel dumping to the bilge, and he tried to raise the fire pump pressure in the engine room by adjusting a bleeder valve. He couldn’t see the pump in the smoke, however. He inhaled smoke through his mask and began coughing. 

Once the main generators were secured, the emergency generator started and supplied power to the boat. The vessel had no main power for lighting and propulsion but it did have its Global Marine Distress and Safety System, radar and VHF radio systems. After securing equipment in the engine room, personnel there evacuated through a hatch to the stern while wearing breathing devices, the report said. 

The captain ordered that the FM-200 system be released at 2240. Everyone had been accounted for at that time. The crew heard a hissing roar when the system was activated. Fifteen minutes after the FM-200’s release, the chief engineer monitored the deck’s temperature. 

“The deck was smoking and had buckled due to the heat, and the steel deck appeared to be breached,” the investigators wrote. “(The chief engineer) used a fire ax to break cement above the steel deck to allow cooling water to be applied directly onto the steel.”

Consulting the FM-200 manual, the crew learned that the space where the chemical had been discharged was now off limits. The FM-200 agent extinguished the fire; areas above it began to cool and were monitored until the vessel reached port the next day.

The 207-foot OSV Lily Jane responded to the incident and was secured to Ocean Patriot’s port quarter. A Coast Guard helicopter, the cutter Razorbill and other vessels assisted. Twenty-seven people were transferred from Ocean Patriot to Lily Jane, including the assistant engineer who needed oxygen. They were then moved to the 210-foot Harvey Hurricane, an OSV nearby, and taken ashore. The tug Delta Faith towed Ocean Patriot for 12 hours to Port Fourchon, where local firefighters inspected the vessel.

The NTSB said the vessel’s fire caused no environmental damage. A forensic firm hired by Oceaneering International found that fire had harmed Ocean Patriot’s motor-control centers and associated cabling, helium storage bottles, a ventilation trunk and piping systems. The machinery space involved had considerable smoke and soot damage, and diving deck equipment there was harmed as well. A main generator and a frequency drive were water damaged, and the main deck in the changing area had buckled in the heat.

Oceaneering International didn’t respond to requests for comment about the fire. In 2011, the company acquired the vessel, which was built in 2002, renamed it Ocean Patriot and outfitted it for deep-sea or saturation diving.

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