Fracture of Propeller Shaft Leads to Flooding and Sinking


In August 2016, the fishing vessel ‘Lady Gertrude’ began flooding through its propulsion shaft stern tube, while preparing to dredge for scallops, in the Atlantic Ocean, southeast of Point Pleasant, US. The three crewmembers were forced to abandon the ship and were later rescued, but the vessel, valued at $400,000, sank, causing a light oil sheen. The NTSB issued an investigative report on the accident.

The Incident:

On 15 August 2016, about 01:50 local time, as the captain and one of the two deckhands began preparing the ship’s gear, the captain moved the throttle forward so that the dredges could be “flared” and lowered for scalloping. The engine’s rpm responded normally but the vessel did not accelerate. The captain then opened the fish hold and saw that the vessel’s propeller shaft had fractured in front of the stern tube stuffing box. He told investigators that “the shaft was turning in the forward part of the space and churning the water, but the shaft was about 2 feet short of the stern tube.” He said that there was water about 7 inches above the propeller shaft, and seawater was flooding through the 5-inch stern tube “like a fire hydrant.”

The captain then went to the wheelhouse to stop the engine and noticed that the fish hold bilge alarm had been activated. At 01:53, the captain made a distress call on VHF radio to the Coast Guard, activated the VHF distress button, and energized the emergency position-indicating radio beacon (EPIRB). Forces responded and converged on the Lady Gertrude’s position.

The Lady Gertrude crew members saw flood water entering the engine room. The captain energized the vessel’s two bilge pumps and a submersible bilge pump drawing water from the fish hold, in which flood water had risen to about 4 feet. Crew members entered the fish hold and attempted to plug the stern tube with debris but were unable to stop the flooding. The captain told investigators, he inserted his forearm into the stern tube and could not feel the shaft. He also said that after he was unable to plug the stern tube, it became apparent to him that the pumps were not keeping up with the flooding and the vessel was settling lower in the water. The captain was concerned that the vessel was becoming less stable, so he ordered the crew members to don their immersion suits and prepare to launch the liferaft.

At 02:34 pm, the flooding in the Lady Gertrude fish hold had increased to about 6 feet and the captain ordered the crew members to abandon the ship. All three crewmembers safely entered the liferaft and were subsequently picked up by a good Samaritan vessel at 02:46 pm.

Probable Cause:

NTSB determines that the probable cause of the sinking of the Lady Gertrude was the fracture of the propeller shaft forward of the stern tube stuffing box, resulting in uncontrollable flooding of the vessel’s fish hold and progressive flooding through non-watertight bulkheads of the engine room and lazarette.

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