The second mate of the tug Nathan E. Stewart fell asleep on watch when the tug grounded off Bella Bella, on October 13, 2016, according to an investigation report released by the United States National Transportation Safety Board.
The NTSB also said “Contributing to the grounding was the ineffective implementation of the company’s safety management system procedures for watchstanding.”
Both the NTSB and the Canadian Transportation Safety Board investigated the grounding. The tug was American owned and crewed while the accident happened in Canadian waters. The TSB investigation on the incident is continuing and no report has been released.
The Nathan E. Stewart was pushing, not towing the barge, as the NTSB report notes:
The tugboat Nathan E Stewart and the tank barge DBL 55 were connected through the JAK coupling system.1 Controlled from a panel on the tugboat’s bridge, this system uses a 16-inch-diameter, high-strength steel pin pneumatically actuated on each side of the vessel’s bow to lock the vessel into a fitted socket plate welded to each side of the barge’s inner notch. The plates have multiple sockets that run vertically, which allows the tugboat to position itself within the notch to accommodate changing barge drafts as well as to prevent, or minimize, the horizontal movement between the two units.
The NTSB says the grounding of the tug caused about $12 million US in estimated damage to the tug itself and the barge it was pushing.
The Nathan E Stewart spilled 29,000 gallons of fuel and lube oil, released into the ocean off Edge Reef, off Athlone Island in Seaforth Channel in the traditional territory of the Heiltsuk Nation.
Although no petroleum products were released from the empty fuel barge, a subsequent marine survey found that post accident survey of the DBL 55 found that the barge’s external double hull was significantly damaged from its bow completely aft to the skegs on the stern. There were multiple areas where the hull plating had been inset and penetrated. Some of the framing also had been damaged, but none of the inner steel plating comprising the bottom, sides,or top of the cargo tanks had been breached. The JAK socket plates on the inside of the barge’s notch showed slight damage,with the second recess(fromthe bottom up) on both socket plates indicating scarring and heavy contact. Repair costs for the barge were estimated at $5.6 million.
Prior to thegrounding, all the vessel’s vital systems were functional, and there were noindications of a mechanical failure thatmay haveled to the accident.
The NTSB says the tug was on autopilot when the second mate fall sleep on watch and it missed course correction near Ivory Island. The tug had a computerized electronic chart system (ECS) on board that should have sounded an alarm when the way point for the course correction was missed, but the mate told the NTSB, the tug was not using that navigation tool on the night of the accident. According to the second mate, it was
normal practice for the navigation team to not utilize that tool.
The NTSB report says had the ECS been utilized, the ECS would
have entered into an alarm mode after the second mate missed the port course change required near Ivory Island. Based on time, speed, and distance calculations, the alarm would have activated at approximately 0055 and thereby provided ample time for the second mate to take
corrective action to return the Nathan E Stewart to the intended track.
Download the complete NTSB report:
NTSB report MAB1738 NathanStewart (pdf)