The incorrect installation of a single set screw led to the loss of propulsion control on the Canadian-flagged, 736-foot-long Atlantic Huron, causing the ship to strike a pier at 6.8 knots, the National Transportation Safety Board said Tuesday.
The NTSB issued Marine Accident Brief 21/10 on the July 5, 2020, contact between the self-unloading bulk carrier and a pier associated with the Soo Locks, in Sault Sainte Marie, Michigan, resulting in $2.2 million in damage. There were no injuries.
According to the NTSB, while on approach to the locks and attempting to slow, there was a propulsion problem involving the vessel’s controllable pitch propeller system that resulted in the ship moving forward with increasing speed instead of slowing or moving astern, as ordered by the captain. In a controllable pitch propeller, the blades are not fixed in position but are fastened to the hub in a way that allows them to rotate and thereby change pitch, the NTSB said. The blade pitch determines both the vessel’s speed and its direction.