New Zealand’s Transport Accident Investigation Commission (TAIC) has issued a report regarding the containership Shiling which suffered mechanical failures that were revealed to be related to several safety violations.
What happened
On 15 April 2023, the container ship Shiling was under pilotage outbound from the port of Wellington and had just initiated a turn into the Wellington Harbour entrance channel when it suffered a blackout that caused the main engine to stop. The momentum of the turn carried the ship into the shallow waters of Falcon Shoal, where the bridge team succeeded in using both the ship’s anchors to stop the ship from grounding. The ship was subsequently towed dead-ship by harbour tugs back to its berth to be repaired.
On 10 May 2023, the repairs having been made, the Shiling departed Wellington bound for Singapore. Because of forecast inclement weather for the Tasman Sea, the master decided to take shelter near the New Zealand coast and wait for about 36 hours for the weather to abate.
Because of the length of time spent at Wellington, the bilge water holding tanks and the engine-room bilges were full, and water had begun to accumulate on the engine-room tank-top . When the Shiling entered the Tasman Sea, it began to roll, and the free water on the tank-top entered the void under the main engine sump , where three rubber diaphragms were located.
The diaphragms linked the main engine sump to the main-engine lubricating oil tank (lube-oil tank) beneath. Their purpose was twofold: to compensate for the relative movement between the main engine and the solid structure of the tank; and to prevent water entering the lube-oil tank. However, all three rubber diaphragms were in a deteriorated state and allowed the bilge water to enter the lube-oil tank, causing the lube-oil pumps to lose pressure and the main engine to stop.
Without the main engine operating, the Shiling was unable to manoeuvre. The ship settled with its beam to the swell and began to roll heavily. With no option for recovering the main engine, the master made a Mayday call . A tow-capable vessel located in the nearby port of New Plymouth responded, initially taking the Shiling in tow to the sheltered waters of Golden Bay and eventually back to Wellington for further repairs.
Why it happened
The ship’s blackout in Wellington Harbour was caused by exhaust gases from a cracked cylinder liner in one of the generators entering the centralised cooling-water system that supplied cooling water to all generators and the main engine. The running generators tripped out because of high cooling-water temperature and caused the blackout, which subsequently caused the main engine to stop.
Although the ship held valid statutory and classification society certificates, the generators and several other safety-critical systems were found to be in a deteriorated condition.
It is very likely that the rubber diaphragms had not been inspected for many years, despite the issuing of several bulletins by insurance clubs and engine manufacturers warning of the critical importance of maintaining the diaphragms in good condition.
The Transport Accident Investigation Commission has identified several safety issues relating to the international and domestic systems for regulating international ships and the ability of ship owners to devolve their responsibilities for the safe operation of their ships to third parties without regulatory consequences. The Commission has made recommendations to Maritime New Zealand to address these matters through the International Maritime Organization (IMO).
Lessons learned
- Deferred ship maintenance, especially of critical equipment and systems, will significantly increase the risk of accidents and incidents.
- Failures involving critical equipment and systems must be fully investigated for their causes and resolved before the equipment or systems are placed back in service.
- The creators of risks are best placed to manage them (Committee on Safety and Health at Work, 1972). A ship owner who offers a ship for service must remain responsible for its safe operation, regardless of any other entities involved in operating, inspecting and auditing the ship and its systems.
