- Vessel Collides with Navigational Aid in St. Mary’s River.
- Steering Alarms Overlooked Due to Apparent Rudder Response.
- Control Motor Obstructed by O-Ring-Type Material.
The National Transportation Safety Board (NTSB) concluded that a fragment of O-ring-type material led to a steering system failure on a bulk carrier that resulted in a collision with a navigational aid in Michigan’s St. Marys River, reports gCaptain.
Incident Overview
The accident happened on March 28, 2024, when the ship collided with the Munuscong Channel Junction Light off Sault Ste. Marie. The collision resulted in the ship taking in water, but the ship’s crews brought the situation under control through the use of pumps. The accident ended up causing around $800,750 worth of damage to the ship and $1.25 million worth of damage to the navigation structure.
Alarms Ignored Due to Apparent Rudder Response
The ship had sailed on its inaugural voyage of the year after winter overhaul, which involved the fitment of a new steering control system. Throughout the voyage, the crew observed occasional steering system alarms. Nevertheless, the rudder seemed to operate appropriately, and the cause of the alarms was not discovered then.
Investigation Findings
Post-incident inspection found that the No. 1 control motor, which controlled the stroke of the main hydraulic pump, had malfunctioned. Removal of the motor uncovered black, flexible debris—later determined to be O-ring-type material—stuck between rotating gears. This blockage inhibited the normal operation of the motor. Once the motor was replaced, the steering system returned to normal operation.
Calibration Issues Also Identified
Close examination by electronic engineers revealed that calibration settings in the recently installed control system were incorrectly configured. Upon recalibration, the system alarm issues were eliminated, which means physical blockage and calibration faults were responsible for the breakdown.
Damage to Critical Navigational Structure
The Munuscong Channel Junction Light, a critical navigation facility in the St. Marys River, is a navigational light and signal mounted on a fixed concrete pier. The pier was severely damaged by the collision.
Official Report Released
The NTSB has released its findings in Marine Investigation Report 25-18, which provides the causes and contributing factors of the accident.
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Source: gCaptain
