New Zealand’s Transport Accident Investigation Commission published its final report into the 2011 grounding of the MV Rena containership, the worst maritime disaster in the history of the country.
The Liberian-registered containership left the New Zealand port of Napier on Oct. 4, 2011, and was bound for the New Zealand port of Tauranga. The master calculated the estimated time of arrival by dividing the distance by the Rena's normal service speed. The calculation did not account for unfavorable currents that normally prevailed down that stretch of coastline, according to the report.
After he left Napier, the master learned of the unfavorable currents from notes on the chart. He authorized watchkeepers to deviate from the planned course lines on the chart to shorten the distance and to search for the least unfavorable currents.
Times for ships entering and leaving Tauranga Harbour are limited by the depth of the water and the strength of the tidal currents in the entrance channel. The planned course to the Tauranga pilot station was to pass 2 nautical miles north of Astrolabe Reef before making the final adjustment in course to the pilot station.
The second mate decided to reduce the 2 miles to 1 mile to save time, then made a series of small course adjustments toward Astrolabe Reef to make the shortcut. In doing so he altered the course 5 degrees past the required track and did not make an allowance for any compass error or sideways "drift," and as a consequence the Rena was making a ground track directly for Astrolabe Reef.
The master arrived on the bridge to prepare for arrival at the port, and he and the second mate discussed preparations for arrival at the pilot station. The master then assumed control of the ship, having received virtually no information on where the ship was, where it was heading and what immediate dangers to navigation he needed to consider.
During this period of handover no one was monitoring the position of the ship. At 2:14 a.m. the Rena ran aground at full speed on Astrolabe Reef. The ship remained stuck fast on the reef, and in the ensuing months it broke in two. The aft section moved off the reef and sank.
About 200 tons of heavy fuel oil were lost to the sea. A substantial amount of cargo in the containers was lost. The vessel became a total loss on Oct. 11, 2011.
The investigation commission concluded that the grounding was not attributable to the malfunction of any machinery or equipment, including on-board navigational equipment. Factors that directly contributed to the grounding included the crew:
• not following standard good practice for planning and executing the voyage.
• not following standard good practice for navigation watchkeeping.
• not following standard good practice when taking over control of the ship.