The National Transportation Safety Board (NTSB) has published its investigation report about the circumstances that led to the grounding of the Marshall Islands registered bulk carrier Nenita on the Columbia River. The incident, which occurred in November 2016 was as a result of an engine failure combined with inefficient communication on-board.
The incident
On November 19, 2016, the fully-laden bulk carrier Nenita was outbound on the Columbia River, when it suffered an engine failure impacting its ability to manoeuvre. The vessel subsequently ran aground at Three Tree Point on the Washington State side of the river, damaging its bulbous bow and hull. After the grounding, the Nenita was towed to Longview, Washington, for temporary repairs. Two weeks later, the vessel resumed the voyage to its original destination. There were no injuries or reported pollution as a result of the accident.
Probable cause
The NTSB determines that the probable cause of the grounding of the bulk carrier Nenita was the failure of a main engine cylinder cooling jacket that initiated an automatic reduction in engine speed, resulting in the eventual loss of steerageway. Contributing to the accident was the lack of information relayed from shipboard personnel to the pilot about the status of the main engine, which prevented him from taking effective corrective action following the engine casualty.
Recommendations
As a result from the incident investigation, NTSB highlighted the following points for consideration:
– Water Chemistry: Maintaining proper water chemistry in engine cooling water systems reduces corrosion, scale, and the formation of deposits, which ensures effective cooling (heat transfer) to satisfy the system’s operating requirements. Mariners should conduct testing per the manufacturer’s recommended schedule, ensure levels of treatment are correct, and maintain water quality within specified limits. Insufficient cooling water maintenance may result in increased corrosion, clogging of cooling water passages, or, ultimately, the failure of equipment.
– Tightening of Fasteners: Over the last two years, the NTSB has investigated three separate accidents that may have been caused by a failure to tighten fasteners on marine engines to the manufacturer’s recommended torque settings. Undertorqueing a fastener may cause excess vibration or allow the fastener to come loose, while overtorqueing may lead to failure of the fastener or the machinery component being secured. When installing fasteners, mariners should use a calibrated torque wrench and follow the manufacturer’s recommended tightening guide and torque values.
Click to read the full investigation report: NTSB-Grounding-of-Bulk-Carrier-Nenita
