WASHINGTON (May 13, 2025) — A steering system failure led to a bulk carrier’s contact with a navigational aid in the St. Marys River near Sault Ste. Marie, Michigan, the National Transportation Safety Board said Tuesday.
The bulk carrier American Mariner struck the Munuscong Channel Junction Light on March 28, 2024, as it was transiting upbound in the St. Marys River. The Munuscong Channel Junction Light is comprised of a navigational light and signal mounted on a concrete, fixed structure. After the contact the vessel began taking on water but was stabilized using pumps. None of the 18 crewmembers on board were injured and no pollution was reported. Damage to the vessel was approximately $800,750 and damage to the Munuscong Channel Junction Light was estimated at $1.25 million.
American Mariner was on its first voyage of the season following its winter layup period, during which annual preventative maintenance was performed and a new steering control system was installed. During the voyage leading up to the contact, alarms for the vessel’s steering system sounded intermittently, but the crew could not determine the cause, and the rudder appeared to properly respond to input commands.
Following the contact, electronic technicians recalibrated the steering control system and the steering alarms stopped, indicating likely issues with the newly installed control system’s calibration parameters.
Crewmembers inspected the steering system after the contact and determined that the no. 1 control motor, which controlled the stroke of the main hydraulic pump, had failed. The motor was dissembled, and a piece of black, pliable debris was found to be lodged in between the rotating gears of the control motor, preventing it from rotating properly. Once a replacement control motor was installed, the steering system responded properly to steering commands from the bridge.
The NTSB determined the probable cause of the contact was O-ring-type material debris in the steering gear system’s hydraulic oil becoming lodged within a control motor, which caused it to seize, resulting in the rudder locking at its last ordered position.
Marine Investigation Report 25-18 is available online.
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