Deviation from the charted route to avoid another vessel and then failing to return to the original course led to the grounding of a tanker in the Canadian Arctic in 2012, investigators have determined.
The 363-foot oil and chemical tanker Nanny departed Baker Lake, Nunavut, on Oct. 25, 2012, bound for Lewisporte, Newfoundland. After anchoring and waiting for high tide, Nanny proceeded toward Chesterfield Narrows, a very shallow channel. While underway, Nanny proceeded off the charted course in order to pass another tanker, according to a February 2014 report by the Transportation Safety Board of Canada (TSB).
“Once clear of the other tanker, instead of returning to the planned route, the Nanny continued on a roughly parallel course that was off the charted route by distances of up to 0.12 nautical miles,” the TSB reported. “This deviation continued even as the vessel turned into Chesterfield Narrows, an area marked by unlit range beacons, that allows for little margin of error; the vessel then ran aground on a shoal.”
A forward section of the hull was damaged in the grounding shortly before midnight. The vessel came off the shoal during strong northwesterly winds Oct. 27 and later proceeded to St. John’s, Newfoundland, for repairs. There were no injuries or pollution reported.
Nanny was built in 1993 in Ulsan, South Korea. It has a 15-foot draft and is powered by one diesel engine generating 5,430 hp driving a controllable-pitch propeller. At the time of the grounding, it had a crew of 14 aboard. The ship is owned by Coastal Shipping Ltd. of Lewisporte, Newfoundland.
In the grounding, the hull bottom plating in the bow thruster compartment and the machinery space were indented, as was the forepeak water ballast tank. Port and starboard water ballast tanks Nos. 1 through 5 and starboard water ballast tank No. 6 were indented. Ballast tank No. 2C was holed when the vessel came off the shoal.
The bow thruster propeller was bent, and the crown and pinion gears were stripped. The driving-shaft seal and electric motor were set up approximately 60 mm, and the free-end cover was shattered into four pieces.
In its analysis, the TSB found that Nanny was initially required to proceed off the charted course in order to pass the tanker Dorsch, which was anchored within the charted route. However, this deviation was not discussed by the master and the officer of the watch, nor did they exchange other navigational information after the vessel weighed anchor.
Prior to the grounding, after the vessel turned into the narrows, the master focused his attention on operating the main engine controls and thrusters, rather than monitoring the navigation of the vessel.
Among its findings, TSB said that “due to insufficient monitoring of the vessel’s navigation and ineffective bridge resource management, the bridge team was unaware of the extent to which the vessel was off the charted course as it entered the narrows.”
In addition, available navigation aids were not adequately cross-referenced, nor were they optimally set up to facilitate navigation. Searchlights were not used to visually confirm that the vessel was lined up with the range beacons.
Since the accident, the vessel operator initiated a confined-waters policy. This policy includes improved procedures to mitigate the risks of entering and sailing through confined waterways. The operator enhanced and accelerated its personnel training plan for bridge resource management and vessel handling. The operator has implemented voyage data recorder training to ensure that available voyage data will be preserved after any incident.
A representative for Coastal Shipping declined an interview with Professional Mariner, stating only that the company has offered the TSB the changes it has implemented since the incident and those are reported in the TSB report.