Uncontrolled Movement of Mooring Lines Poses A Risk of Injury or Death

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The Transportation Safety Board of Canada (TSB) published a report in which the crew of a bulk carrier fell overboard after a workboat struck by mooring line.

Incident 

On 12 May 2020, 3 of the bulk carrier 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. No injuries were reported.

Investigation 

During investigation, it was found that 

  • While the bulk carrier 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 bulk carrier 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.

Lesson learnt 

  • 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 on board.

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Source: tsb