ATSB published the report on the grounding of ‘Lauren Hansen’ off Melville Island, in the Northern Territory. The incident took place on 10 April 2018, with ATSB citing an error on the autopilot as the cause of the grounding.
The incident
On 10 April 2018, the 45.5 m landing craft Lauren Hansen was preparing for sea at Hudson’s Creek, Darwin, Northern Territory. The ship’s operator, Shorebarge, had chartered the ship for a voyage to Elcho Island.
As the ship exited the Darwin Harbour, the master encountered difficulties using the autopilot, which when engaged, applied port rudder regardless of the heading order set on the control panel.
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The master steered the ship manually until they left port limits, and the master tried to use the autopilot again with limited success. Shortly after departing the port, Lauren Hansen faced engine difficulties due to the starboard main engine’s gearbox cooling system.
A little later, the master passed the navigation watch to the chief mate and retired to his cabin, with the ship on autopilot and the chief mate the sole watchkeeper on the bridge. The weather was fine with partly cloudy skies.
The next day, on 11 April 2018, ‘Lauren Hansen’ approached a planned course alteration position (waypoint) laid about 0.9 NM off the coast of Cape Keith, Melville Island. At that time, the chief mate reported that he changed the ship’s heading by about 10° to port using the autopilot and that the ship appeared to settle on the new heading.
However, sometime later the ship started an unexpected turn to port, towards land, without any alarms or indications. The chief mate noticed that the ship had started to turn to port and reduced power on both main engines, while he attempted to call the master using the bridge telephone.
The master did not respond and the chief mate left the bridge and went down to the master’s cabin. He informed the master on the situation and they returned to the bridge. When they entered the bridge, they noticed that the ship no longer appeared to be turning but had steadied on a north-westerly heading.
The, ‘Lauren Hansen’ grounded on a shoal off Cape Keith, Melville Island. When the ship was refloated, it was found out that its tanks and bilges were safe and no breaches or water ingress were evident. Thus, the ship headed back to Darwin.
Probable cause
After conducting an investigation into the incident, ATSB concluded to the following as probable causes:
- The decision to execute the planned route, which passed close to land, instead of a route in more open waters similar to the chart’s recommended track through the Van Diemen Gulf, increased the risk of a grounding especially when the unreliability of the autopilot was a known factor.
- Lauren Hansen experienced an unexpected turn to port while on passage in autopilot steering mode. The ship’s manual or emergency steering modes were not engaged or used and the ship got grounded.
- The unexpected turn to port was the result of an intermittent fault in the ship’s autopilot unit or in the compass top sensor unit that fed heading information to the autopilot unit.
- There was no compass deviation book maintained on board Lauren Hansenas required by Australian Maritime Safety Authority regulations.
Recommendations
ATSB noted that relevant organisations may proactively initiate safety action in order to reduce their safety risk. For this reason, Shorebarge, the ship’s operator, will take the following safety actions:
Repairs and replacement
The autopilot unit and compass top sensor were both replaced with new units, with the autopilot now reported to be functioning normally. The ship has since been dry-docked and repairs and replacement of the damaged hull areas have been carried out as recommended by class.
Magnetic compass adjustment
Lauren Hansen’s magnetic compass was inspected by a qualified compass adjustor and an updated table of deviations compiled. The compass was operating satisfactorily with deviations on all headings less than 5º.
Shipboard safety meetings
Safety meetings were conducted on board Shorebarge vessels to review the grounding and to discuss the management of fatigue. The discussion included a review of AMSA’s legislative requirements and the company’s procedures for fatigue management.
Lessons learned
AMSA stated the following:
See more details in the PDF herebelow
