The New Zealand Transport Accident Investigation Commission (TAIC) has released its interim report on the investigation into the grounding incident involving the Ro-Pax ferry Aratere near South Island earlier this year.
The TAIC said Aratere had been in service for about 26 years. In May 2024, operator KiwiRail installed a new steering control system in four of the five command consoles on the bridge. However, it was not installed on the autopilot console, which was part of the original track pilot integrated bridge navigation system by a different manufacturer.
In the three weeks following wet docking, Aratere completed 83 Cook Strait crossings.
At 21:19 local time on June 21, 2024, Aratere left its berth at Picton. The re-familiarisation master, piloting and controlling the engines, asked the helmsman to steer for the first waypoint off Mabel Island.
At 21:26, the autopilot was engaged on the current heading of 028 degrees in course mode. The helmsman was released from the wheel to stand by in the bridge.
The re-familiarisation master then pressed the execute button to initiate the Mabel Island waypoint turn, but Aratere had passed Mabel Island 36 seconds earlier, so the next waypoint was Snout. Pushing "execute" tells the autopilot to execute the next turn, so the autopilot executed the Snout turn, not the Mabel island turn, and set nine-degree starboard rudder for a course of 73.8 degrees.
At about 21:27, the night master realised from ECDIS that Aratere was turning towards shore and called the helmsman back to the central steering console. The helmsman pressed the "takeover" button and turned the wheel hard to port, to no effect.
Both the officer of the watch (OOW) and the night master repeated the helmsman’s action at the central helm, again, to no effect. Aratere instead remained under autopilot control and continued its turn to starboard.
The bridge team did not know that the new steering system gave them two ways to transfer steering control between consoles: align the rudder command at each console to within two degrees (but the autopilot was at nine degrees starboard rudder and the helmsman wheel was set to zero degrees); or "force takeover" by pushing down and holding the takeover button for five seconds.
With Aratere heading towards shore at 13 knots and the helmsman lacking steering control, the night master put both engines at full astern. It took 21 seconds for the port propeller and 38 seconds for the starboard propeller to begin turning astern.
A manual steering mode was then engaged using independent tillers on the centre pilot console. The port rudder moved hard to port and the starboard rudder moved to port. Around this time, the night master instructed the OOW to start a bow thruster to assist manoeuvring.
Aratere crossed the 10-metre sounding at about seven knots. By 21:28, the vessel was aground on a heading of 76.5 degrees.
Aratere’s hull remained watertight, but the ship still sustained damage to the internal structure of the bulbous bow that required repair. There were no injuries.
In the following 48 hours, authorities worked to refloat Aratere using two Picton-based harbour tugs.
The commission is continuing to collate and verify evidence directly related to the grounding, across multiple lines of inquiry.
Upon the completion of the full investigation, the commission will issue a final report that report will include analysis of the facts, identification of safety issues, and – if necessary – recommendations.