Executive summary
At about 1930 on 21 June 2010, the bulk carrier Hanjin Bombay left the wharf at Mount Maunganui loaded with a full cargo of logs for the port of Kunsan in Korea. The vessel was under the control of a Port of Tauranga harbour pilot, with the master in command.
The vessel was manoeuvred off the berth and turned in the channel using the main engine and 2 tugs. Once the vessel was heading outward the vessel’s main engine was used to propel it seaward. The 2 tugs remained with the ship until it was about to enter the narrow entrance channel, at which point they were released to return to their berths, but remained in radio contact with the pilot.
As the Hanjin Bombay began to increase speed, a malfunctioning valve in the engine cooling system caused the engine cooling water to rise above normal temperature. The engine room crew did not alert the bridge to the problem, but instead began attempting to resolve the cooling-water issue.
Oblivious to the technical problem in the engine room, the bridge team took the Hanjin Bombay into the narrow entrance channel and continued to increase the engine speed to improve the steering performance.
The engine-cooling-water temperature continued to rise and reached the point where the engine safety control system automatically slowed the engine down, then shut it down completely to prevent it becoming permanently damaged.
The Hanjin Bombay was negotiating the turn from the Cutter Channel into No. 2 Reach when the engine shut down. The loss of propulsion reduced the steering performance of the vessel and the rudder was unable to arrest the turn before the ship left the Channel and grounded on the eastern shore of the channel.
The harbour pilot had radioed the tugs to return to the Hanjin Bombay, but they arrived at the vessel just after it had grounded. The Hanjin Bombay remained aground for about 2 hours until it refloated on a rising tide.
The vessel received a hole in one of its water-ballast tanks and indentations in the hull plating in the bow area. There was no pollution and the ship later re-entered the port, where it underwent temporary repairs before resuming its voyage. It later entered a dry-dock in China to effect permanent repairs.
The Commission made findings that the grounding could have been prevented if the automatic engine-shutdown condition had been overridden for long enough to stabilise the heading of the vessel, and/or if the tugs had been in attendance to help maintain directional control. Either option could have been achieved through better knowledge of the engine systems, better communication between the bridge and engine room crew, and if the bridge crew had informed the harbour pilot of the escalating engine problem.
Port of Tauranga Limited's risk assessment for its Port and Harbour Safety Management system did not fully address the risk of departing vessels experiencing failure of propulsion and manoeuvring systems at critical locations in the entrance channel.
The Commission made recommendations that the Director of Maritime New Zealand resolve the safety issue of adequate tug escorts for vessels in all New Zealand ports, and that he develop a national system that would allow port authority staff access to new and previous information on vessel and crew performance in the interests of preventing similar accidents and incidents in the immediate future.
The key lessons from the inquiry into this occurrence were:
- vessel crews must have a thorough knowledge of their vessels' operating systems if they are to deal effectively with abnormal situations
- the concept of crew resource management must extend to all operational areas on a vessel, and in particular must result in a common understanding of the voyage plan and good communication between bridge and engine room
- The level of tug assistance given to vessels when transiting narrow channels needs to be commensurate with the level of risk and should be decided on the basis of reducing the risk to as low as reasonably practicable
- shipboard operations must be conducted using an agreed common language that everyone can understand. Crew members lapsing into their native tongue during an emergency is a breakdown in communication that can seriously hinder any response to deal with the emergency.
Related Recommendations
Vessels' machinery installations and their control systems are complex, and regardless of how well maintained they are there will always remain the possibility that some part fails for some reason. For a vessel like the Hanjin Bombay that has only one propulsion system, the risk of losing control of the vessel caused by a single-point failure is higher than that for other vessels that have greater levels of redundancy built in to their propulsion and power-management systems. These types of vessel rely heavily on tug services when operating in confined pilotage waters.
The number of defects that are causing incidents and accidents in New Zealand pilotage waters is of concern. It is an indication that New Zealand port and harbour authorities cannot totally rely on the International Safety Management system to ensure that vessels transiting New Zealand ports are operated safely and efficiently. Minor technical defects and human performance issues are often lead indicators of deeper systemic safety issues on board a vessel.