Grounding: Bridge Team Didn’t Know What They Didn’t Know

New Zealand’s Transport Accident Investigation Commission (TAIC) has released an interim report into the grounding of the passenger ferry Aratere in Titoki Bay, Picton, on June 21, 2024, citing lack of knowledge about the steering system.

The Aratere had been in service for about 26 years, and in May 2024, KiwiRail installed a new steering control system in four of the five command consoles on the bridge. It wasn’t 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.

For Aratere’s 2120 Picton to Wellington sailing on June 21, 2024, the bridge team comprised:

• Pilot: Master (the Refamiliarisation Master) re-acquainting themselves with the ship after some time commanding other vessels.

• Co-pilot: the Night Master, in command.

•Helmsman: a Deck Rating at the central helmsman steering console.

• Assisting as required: Officer Of the Watch (OOW) and a Deck Rating on lookout duty

Timeline:

2119: departure 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.

2126:01: autopilot engaged: the autopilot was engaged on the current heading of 028° in course mode. The helmsman was released from the wheel to stand by in the bridge.

2126:30: autopilot in control of steering: The re-familiarisation master 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 9° starboard rudder for a course of 73.8°.

About 21:27: off-course identified: the night master realised from ECDIS that Aratere was turning towards shore, called the helmsman back to the central steering console.

Remedy attempted: Helmsman pressed the ‘takeover’ button and turned the wheel hard to port. No effect. Both the officer of the watch and the night master repeated the helmsman’s action at the central helm, no effect. Aratere remained under autopilot control and continued its turn to starboard.

The bridge team didn’t know (and didn’t know that they didn’t 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 2°. (But the autopilot was at 9° starboard rudder and the helmsman wheel was set to 0°) or

• ‘Force takeover’: push down and hold the takeover button for five seconds.

2127:43: full astern: With Aratere heading towards shore at 13 knots and 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.

2128:06: autopilot disengaged. A manual steering mode was 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.

2128:34: Aratere crossed the 10-metre sounding at about 7 knots.

2128:46: speed about 3 knots.

By 2128:50 the vessel was aground on a heading of 76.5°.

Afterwards: Aratere’s hull remained watertight, but the ship did sustain 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.

TAIC 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.