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News release

Associated links (M20C0101)

Unmitigated mooring line hazards led to three people falling overboard from a workboat

Québec, Quebec, 30 July 2021 — In its investigation report (M20C0101) released today, the Transportation Safety Board of Canada (TSB) found safety deficiencies associated with the use of workboats, including the unmitigated hazards associated with the uncontrolled movement of mooring lines.

On 12 May 2020, the Manitoulin, a River class self-unloading Great Lakes bulk carrier, was moored 50 m offshore near Sombra, Ontario, to unload stone. Because the shoreline facility was not equipped with a dock, the vessel’s workboat was used to transfer three of the Manitoulin’s crew members ashore. As they were crossing over a submerged mooring line, tension came on the line and it caught the workboat by the stern as it rose, which caused all of the crew members to be thrown into the water. One of the crew members swam to shore and the other two re-boarded the workboat. No injuries were reported.

The investigation determined that 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 submerged slack 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 the crossing.

The investigation identified that the Manitoulin is not subject to the International Convention for the Safety of Life at Sea, and was therefore not required to comply with the International Safety Management Code and have a safety management system (SMS). However, the operator had voluntarily implemented an SMS that contained a risk assessment on the operation of the workboats in the fleet, as well as a workboat operations procedure. The investigation found that, 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. For example, although the use of all personal protective equipment (PPE) was required, not everyone in the workboat was wearing a personal flotation device, and there were no controls in place, such as supervision and inspections, to ensure that this was being complied with.

Safety management is a Watchlist 2020 issue. As this occurrence demonstrates, even when formal processes are present, they are not always effective in identifying all hazards or managing the risks in every aspect of a vessel’s operations.

Following the occurrence, the operator issued a policy on the prevention of falls overboard and shared it with all captains, engineers, and officers through a memorandum. The policy includes best practices and lessons learned to prevent falls overboard.

See the investigation page for more information.


The TSB is an independent agency that investigates air, marine, pipeline, and rail transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.

For more information, contact:
Transportation Safety Board of Canada
Media Relations
Telephone: 819-994-8053
Email: media@tsb.gc.ca