On March 28, 2024, about 0018 local time, while transiting upbound in the St. Marys River, about 25 miles south of Sault Ste. Marie, Michigan, the bulk carrier American Mariner experienced a steering failure and struck the Munuscong Channel Junction Light, a 31-foot-diameter cylindrical concrete structure with a navigation aid on top. The vessel began taking on water; pumps stabilized the flooding. None of the 18 crewmembers on board were injured, and no pollution was reported. Damage to the vessel was estimated at $800,750, and damage to the Munuscong Channel Junction Light was estimated at $1.25 million for repairs.

​​​We determined that the probable cause of the contact of the bulk carrier American Mariner with the Munuscong Channel Junction Light 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.