TSB: Poor risk assessment led to St. Lawrence River tug capsizing


Lack of a documented process to assist masters in evaluating risk in operations, such as transiting a barge in current to a work quay, led to the capsizing of a tugboat in the St. Lawrence River near Montreal, Canada’s Transportation Safety Board (TSB) determined.

The incident occurred on April 1, 2016, when the 31-foot Ocean Uannaq was working with the 51-foot Ocean Catatug 1 and 37-foot Blizzard Polaire to move an excavation barge at the Champlain Bridge construction site. Ocean Uannaq capsized when the barge pivoted on a spud that failed to lift, swamping the vessel.

The 127-foot barge was equipped with spuds at each corner. To move the barge, the four spuds lift from the river bottom using four hydraulic winches. When the forward spuds and port aft spud were lifted, the starboard aft spud jammed in its housing. The barge and the attached Ocean Catatug 1 began pivoting clockwise around the jammed spud, exposing the port side of Ocean Uannaq to the 6-knot current.

The port wire securing Ocean Catatug 1 to the barge pushed against the starboard exhaust stack of Ocean Uannaq, and despite the effort of the master to put the throttles full ahead to escape, Ocean Uannaq heeled to port and water began flowing onto the vessel’s port quarter.

Less than one minute after the starboard aft spud jammed, Ocean Uannaq capsized to port just as both of the masters on the tug scrambled onto Ocean Catatug 1. There were no injuries or pollution, the TSB said. Ocean Uannaq was raised from the riverbed eight weeks later.

Ocean Uannaq capsized when a construction barge pivoted on a spud that had not been raised, resulting in the tug being caught on a wire securing Ocean Catatug 1. The wire caused Ocean Uannaq to heel to port and take on water.

Pat Rossi illustration

In its findings, the TSB determined that neither the owner of the vessels involved in the incident, Ocean Group, nor the charterer/operator, Signature sur le Saint Laurent, had assessed the risks of complex marine operations. Therefore, procedures to guide masters in best practices were not developed, and masters were left to make ad hoc decisions.

“In the absence of documented operating procedures or a process to share best practices, the master of Ocean Catatug 1, who was new to the role, made a series of decisions that increased the overall risk of moving the barge,” the TSB wrote.

The agency noted that the upstream spuds were raised before the downstream spuds, which increased the extent to which the barge could rotate in the current. Assist tugs were not in position to immediately stop the barge’s rotation.

Signature sur le Saint Laurent hosted a marine operations risk workshop two weeks later. Participants examined the incident to determine its cause, and implemented procedures to help workers identify and mitigate risks on the work site.

New procedures were developed by the operator that require workers to evaluate the level of risk that each job entails, rather than just performing an overall “step back” risk analysis at the beginning of each day. Marine operations are to be assessed and identified as low, medium, high or extreme risk. Once the risk level of each operation is assessed, a step-back assessment may be documented for each, depending on the risk.

By Professional Mariner Staff