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TSB: 'Unidentified risks' led to rapid sinking of Montreal tugboat

Oct 13, 2017 04:29 PM

Three tugs were repositioning an excavation barge when a spud jammed

This TSB illustration depicts the moment of capsizing of Ocean Uannaq, lower left, showing the clockwise rotation of the excavation barge and the locations of personnel.

This TSB illustration depicts the moment of capsizing of Ocean Uannaq, lower left, showing the clockwise rotation of the excavation barge and the locations of personnel.

The following is the text of a news release from the Transportation Safety Board of Canada (TSB):

(GATINEAU, Quebec) — In its investigation report (M16C0036) released Thursday, the Transportation Safety Board of Canada found that the capsizing and sinking of the Ocean Uannaq tug off Montreal, Quebec in 2016 was due to a lack of formalized operating procedures and inadequate assessment of the safety risks associated with complex marine operations.

On April 1, 2016, three tugs, including Ocean Uannaq, were involved in repositioning an excavation barge on the St. Lawrence River as part of the new Champlain Bridge construction project. Ocean Uannaq and another tug were assisting Ocean Catatug 1, which was attached to the barge. In preparation for the move, the barge's upstream spuds, used for mooring, were raised before the downstream spuds. When one of the downstream spuds jammed as it was being raised, the barge and attached tug pivoted with the strong current around the jammed spud. Catatug 1's port wire made contact with Ocean Uannaq, which combined with the opposing current, created a hydrodynamic effect that led to the rapid capsizing of the tug. The two crewmembers managed to board the attached tug, and Ocean Uannaq later sank at 1850. There were no injuries or pollution.

The investigation found that neither the tug's owner nor the operator had assessed the risks of the complex marine operations. Therefore, no operating procedures had been developed to guide masters in the best practices for directing operations, and masters were left to make ad hoc decisions. Safety management and oversight is a TSB Watchlist issue. The need for effective safety management has been demonstrated in a number of other occurrences.

Following the occurrence, the operator invited those involved in the occurrence, along with other key individuals from the construction site, the tug and barge owners, to conduct an internal accident investigation. Following that investigation, the existing shoreside procedures were extended to the marine construction operations and the operator implemented procedures to help workers identify and mitigate risks on the work site. The operator also hired an assistant marine superintendent to specifically oversee the marine safety aspects of its operations.

Click here to read the complete report.

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