The National Transportation Safety Board found that a tugboat sank, spilling diesel fuel off Locust Point last year, after a mate misjudged the location of a collapsed pier, according to a report released Tuesday.
The mate operating the harbor assist tug Kaleen McAllister first knew something was wrong on the evening of May 4, 2013, when he felt "a rumble under the hull" as he pulled away from the boat's berth at Pier 1, he told the NTSB, a federal agency that investigates transportation accidents.
The sunken pier — which collapsed in the late 1990s, leaving its pilings behind — was a "known and charted hazard," but one the mate mistakenly thought he'd cleared, according to the NTSB's accident brief.
Mike Reagoso, vice president of Mid-Atlantic operations for McAllister Towing, which owns the Kaleen, said the company was "really happy that no one was injured in the whole scenario," but declined to comment on the NTSB's findings.
The tug remains in the company's repair yard in New York, Reagoso said. The NTSB said the company estimated damages at $1.5 million, but Reagoso said he couldn't confirm that.
Tugs are the workhorses of the harbor, guiding larger boats and barges to berths — often around hazards above and below the water's surface.
The mate of the Kaleen, who was not named in the NTSB report, told investigators he had navigated the waters around Pier 1 about 500 times before the accident, and the boat's master told them he'd seen other masters and mates maneuver tugs through the same space where the 109-foot Kaleen ran into trouble.
When the mate first felt the rumble, the report says, he called the master to the wheelhouse and then went to the engine room with the deckhand, where they discovered "rapid flooding."
By the time the master had maneuvered the tug back to the pier, the flooding was "outpacing pumping" and the boat began to list. Emergency personnel, including the Coast Guard and Baltimore Fire Department, responded with more pumps.
"As the vessel continued to sink deeper and list, however, it became clear the pumping would fail," the NTSB report found. "The crew then worked to cover the diesel fuel tank vents with plastic and tape to minimize oil pollution."
Those efforts were hampered as the tug rapidly took on water, creating an electrocution risk, the NTSB found. About 40 minutes after the first sign of trouble, "the tug had sunk and an oil sheen was observed."
An oil spill response team arrived and placed booms around the boat, which was entirely submerged but for the top of its wheelhouse. A total of 2,400 gallons of diesel fuel leaked into the harbor.
The tug remained submerged for three weeks before being refloated on May 25, 2013. Divers found a 3-foot-by-1-inch hole in the tug's hull plating.
The master, mate and deckhand all tested negative for drugs and alcohol following the sinking. The NTSB did not include any recommendations with its brief.
Environmental groups recently called for a broad review of tug and barge transport of crude oil through Baltimore's waters — expressing concerns about leaks hurting the Chesapeake Bay's sensitive ecosystem — but declined to comment on the Kaleen's release of diesel fuel.