The Transportation Safety Board of Canada (TSB) investigated a grounding incident involving a general cargo vessel in the South Shore Canal of the St. Lawrence Seaway, Quebec, on 22 August 2024. The purpose of the investigation was to identify safety deficiencies and improve marine transportation safety.
What Happened
While transiting the South Shore Canal, the vessel lost propulsion due to an automatic main-engine shutdown triggered by the oil mist detector (OMD). As propulsion was lost, the vessel sheered to both canal banks and subsequently grounded, blocking the waterway. Anchors were deployed, and no injuries or pollution were reported. The vessel sustained minor hull damage and was later refloated with tug assistance. The canal remained closed to navigation for 37 hours.
Why It Happened
During planned maintenance, the vessel received and installed a different model of OMD measuring head. This model required an external power source for its heater, which was not available, leaving the heater unpowered. Without heating, the OMD became vulnerable to false alarms caused by water vapour. Water vapour in the OMD triggered a false alarm during the voyage, shutting down the main engine and resulting in a loss of propulsion. Despite notification to the technical department that a different model was supplied, no corrective follow-up occurred. Performance tests and inspections did not identify the unpowered heater, as the OMD continued to pass functional checks.
Actions Taken
Following the occurrence, the operating company replaced the OMD measuring head with the correct model, under the supervision of a class surveyor. The replacement was installed, calibrated, and tested in line with manufacturer requirements.
Lessons Learned
- Ensure spare parts supplied to vessels are correct and fully compatible with existing systems, especially safety-critical equipment.
- Verify that all components of safety-critical devices, such as OMD heaters, are powered and functional during inspections and performance testing.
- Strengthen technical department follow-up when discrepancies in equipment models are reported.
- Incorporate checks into planned maintenance systems to confirm full functionality, not just alarm responses.
- Apply corrective actions across the fleet when similar incidents occur to reduce the risk of recurrence.
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Source: Transportation Safety Board of Canada
