TSB Canada issued an investigation report on a crew fall overboard incident after a workboat, belonging to the bulk carrier Manitoulin, struck a mooring line on St. Clair River, near Sombra, Ontario, in May 2020.
The incident
The Manitoulin was moored 50m offshore at a facility that is not equipped with a dock, and so the vessel’s workboat was used to transfer crew members ashore.
On 12 May 2020, three of the Manitoulin’s crew members were crossing over a submerged mooring line in the vessel’s workboat while proceeding to shore near Sombra, Ontario, when tension came on the line and it struck the workboat.
The impact caused all of the crew members to fall overboard. One of the crew members swam to shore and the other 2 re‑boarded the workboat. There were no injuries.
Probable causes and contributing factors
- While the Manitoulin was moored, the aft spring line was left slack, which meant the line could submerge and then unexpectedly rise out of the water with the vessel’s natural movements, posing a risk to anyone crossing near or over it.
- Because of the way the vessel’s mooring lines were arranged, and the strong current on the port side, the route from the starboard gangway to the crew vehicle waiting ashore required the workboat to cross over the slack aft spring line, which was submerged.
- The vessel’s senior officers were focused on unloading operations and did not brief the workboat operator or supervise the crew transfer, which resulted in a missed opportunity to consider the risk posed by uncontrolled movement of the aft spring line.
- Given that the Manitoulin appeared to be stationary and that the aft spring line was submerged and not expected to rise up, the operator proceeded with crossing.
- As the workboat was crossing over the aft spring line, the Manitoulin shifted in the current and the line rose up, catching the workboat by the stern and throwing all 3 of the crew members into the water.
Findings as to risk
- If precautions are not taken to mitigate the hazards associated with the uncontrolled movement of mooring lines, there is a risk that workers in the vicinity of mooring lines will be injured or killed if they are in the path of a line that suddenly comes under tension.
- If hazards associated with the use of a workboat are not adequately addressed through risk mitigation measures and if compliance with these measures is not monitored, occurrences involving workboats will continue to happen.
- If procedures for the use of workboats do not contain key safety information regarding operations, hazards, and limitations, there is a risk that workboats will be unknowingly operated in a manner that compromises the safety of those onboard.
Actions taken
- Lower Lakes Towing Ltd.:
Following the occurrence, a due diligence report was completed by the master and crew. While completing the report, the master and crew discussed the incident, and the workboat operators on the Manitoulin were told to never cross slack mooring lines.
On 18 January 2021, Lower Lakes Towing Ltd. issued a policy on the prevention of falls overboard. The policy includes best practices and lessons learned to prevent falls overboard. It also includes descriptions of activities and hazards that may lead to falls overboard, critical activities for various crew members in the prevention of falls overboard, and a job hazards analysis. A memorandum was issued to all captains, engineers, and officers to inform them about the policy.
- Smoker Craft Inc.:
Following the occurrence, Smoker Craft Inc., the manufacturer of the workboat, performed a flotation test on a workboat of the same model. The test resulted in a change to the recommended safe limits for the power and weight of engines used with this model of workboat. The revised maximum power limit is 22 kW (30 hp), and the revised weight limit is 159 kg. Smoker Craft Inc. is in the process of notifying all relevant parties about these changes.
