NTSB report highlights danger of repairs on double-coated ship hulls

The use of double plating to repair the hull of an uninspected fishing vessel eventually led to the sinking off Gloucester, Massachusetts last year.

The NTSB this week released its report on the loss of the F/V Gracie Marie with seven crew members on board. The entire crew was rescued by a Good Samaritan after abandoning the ship as the ship was sinking. No casualties were reported, but total damage was estimated at $650,000.

The NTSB investigation focused on the failure of the doubled hull under the engine room as the probable cause of the incident and highlighted the potential danger of such repairs. Double plates are small pieces of sheet metal that are welded to the hull to provide reinforcement at a specific point.

The F/V Grace Marie was on her way to the fishing grounds on July 8, 2022 when the engine room began to flood. The ship’s bilge pumping system could not keep up with the ingress of water, so the crew had to abandon the ship in a life raft.

According to the NTSB, the outer section of the hull along the keel and under the engine room was fitted with steel doubling, which was installed 8 to 10 years before the damaged steel areas were covered and reinforced. Although a marine survey in 2018 found that Grace Maries In order to be “overall in good condition for a ship of its age”, the use of a double coating can make it difficult to assess the actual condition of the hull.

“The hull plating under the engine room cannot be visually inspected without draining the ship. “The bilge under the main engine and other equipment would not have been readily visible to the master and deckhand 2 during the survey due to the high tide,” the report reads.

The NTSB said that while this is common with uninspected commercial fishing vessels, as is the case Grace MarieWhen using double plate to repair and reinforce damaged or wasted sections of hull, double plate repairs can result in increased stress in the repair area and consequent failures.

Although the cause of the flooding ultimately could not be determined with certainty, the NTSB named the probable cause of the flooding and sinking Grace Marie It was uncontrolled flooding of the engine room, probably due to a failure of the doubled hull below the engine room.

“Although double plating can be used as a temporary repair solution, it is generally not suitable for permanent hull repair,” the report states. “Ship owners should remove the excess steel on the hull and replace it with the installation of new plating rather than covering it with double plating.”

Marine survey report 23-13 see the NTSB website.

Related Articles

Back to top button