The oil tanker that crashed into the Mildred Long Bridge allegedly hadn’t replaced a crucial device.

The oil tanker Harbour Feature, which broke its mooring and crashed into the Mildred Long Bridge between Maine and New Hampshire two years ago, had failed to replace a component of its mooring system after its last inspection, according to a federal report on maritime accidents released Wednesday.

Seen in this aerial photograph, tugboats hold the Harbour Feature in place against the Sarah Mildred Long Bridge after it slipped off its mooring at the New Hampshire State Pier on April 1, 2013. A new federal report says the ship’s operator had failed to replace a component of the mooring system. 2013 Press Herald file photo/Gabe Souza

The National Transportation Safety Board issued its Safer Seas 2014 report on 23 major marine accident investigations that were concluded last year and the lessons that can be gleaned from them.

The Harbour Feature incident was the only one in the report that happened in waters off Maine, though another of the high-profile maritime disasters also had a Maine connection.

The 108-foot H.M.S. Bounty, a replica of the original 18th-century British tall ship, sank Oct. 29, 2012 after taking on water off Cape Hatteras, North Carolina. The NTSB investigation found that the primary cause of the sinking – in which a crew member died and the captain disappeared – was the captain’s decision to sail into Hurricane Sandy. However, the consequences of that decision were compounded, the investigation found, by the earlier decision not to repair portions of rotten wood in the ship’s hull, discovered while it was being serviced at Boothbay Harbor Shipyard in Maine.

The captain and boat’s owner opted to paint over the rotten wood rather than replace it, a decision which likely caused the boat to take on more water than it normally would have had it been in good repair, the report said. The Coast Guard did an inspection of the ship but did not check its hull because it was not due for a hull inspection for another three years, the NTSB report said.

The boat took on water faster because of the rotten wood and eventually the propulsion system and with it the bilge pumps stopped working.

The captain ultimately radioed for help when the engine room had 4 feet of water in it, the report said. Fourteen of the crew were rescued.

In the Harbour Feature incident, the ship had just been loaded with petroleum cargo on April 1, 2013, and had been moved to another pier for refueling.

Because the 473-foot vessel was 29 feet deep in the stern, and the depth alongside the pier is just 30 feet, the pilot positioned the ship so its bow extended 30 feet beyond the end of the pier. The boat was then moored with just 10 of its 23 mooring lines, according to the safety board report.

When the notoriously strong tides of the Piscataqua River started coming in, it created a cross current which pushed the ship away from the pier.

A crew members noticed smoke coming from the mooring line drums that the lines wind around. Two lines broke and the others pulled free as the mooring winch brakes – designed to control how much mooring line is let out or retracted – slipped.

A later investigation would determine that the asbestos linings on the winch brakes were checked a month earlier and found to be just 3 mm thick, the point at which they are supposed to be replaced, the report said. But they were not replaced and so probably had less ability to stop the mooring lines from releasing than they might have otherwise, the report said.

The report said the primary cause of the crash was inadequate mooring arrangements made by the ship’s master and the pilot.

The Harbour Feature crash caused $2.5 million in damage to the Mildred Long Bridge and $1 million to the ship itself, though the hull was not breached and there was no release of petroleum products.

The owners of the ship ultimately agreed to a settlement with Maine and New Hampshire, paying $1.3 million toward bridge repairs.

The report included all investigations that concluded during 2014. Investigations by NTSB occur when there is property damage of at least $500,000, six or more fatalities or the total loss of a ship weighing more than 100 tons.

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