Aratere potentially speeding in minutes before grounding, tracking data shows

Tuesday, 25 June 2024

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Tracking of the final minutes before the 17,000-tonne Aratere ferry ploughed into a beach off Picton shows it seemingly breaching a speed limit before accelerating to more than quadruple the speed KiwiRail has as the ship’s last reading.

The day after the Friday night grounding, KiwiRail chief executive Peter Reidy described the incident as a “slow grounding” with the ship travelling at three knots (5.5kph).

But marine tracking website Marinetraffic.com shows that at the time the ship took an unexpected right turn towards the shore it was travelling at 13.3 knots (24.6kph). That was at 9.27pm on Friday.

The next ping was two minutes later and about 400 metres on – just over twice the Aratere’s length. By then, it was on land and reading 0.2 knots, or virtually at a standstill. Soon after, it was down to zero.

The ship’s top reading from crossing Cook Strait earlier in the day was 18.9 knots while the highest through the Marlborough Sounds was 16 knots.

Interislander general manager Duncan Roy said its 3 knots reading came from “reports on board” the ship.

“We know Aratere had reverse thrusters engaged and was slowing prior to impact but these details will be part of the investigation,” Roy said.

Deputy Marlborough District Council harbour master James Oliver said vessels of 500 tonnes or more had to travel at 12 knots or fewer south of Mabel Island – just out of Picton.

The Aratere has a 17,816 gross tonnage.

Marinetraffic.com data records it going at 12.5 knots south of the island, before it sped up to 13.3 knots by the following ping, two minutes later, north of the island.

In trips through the week leading up the grounding, it stayed under the 12 knot limit south of the island.

But Oliver said data available to the council showed the Aratere “does not appear” to be exceeding 12 knots in the area. The council could not explain the anomaly.

The Marinetraffic.com data used a mixture of satellite and local speed readings. The most-accurate reading was held by KiwiRail, he said.

KiwiRail was asked if the ship was breaching the 12 knot speed limit and whether on-board instruments showed different speeds from the tracking. It was also asked to explain the difference between tracked speed and the 3 knots claimed by KiwiRail.

“A formal investigation into the incident is now under way,” a statement from KiwiRail said.

“The true and accurate record is the bridge data, which is forming part of the investigation. We have no further comment at this stage.”

Pete Beech, from Guardians of the Sounds, said the captain would have had “so little time to react” after the steering issue and it would have taken minutes to change the large engines to reverse thrust.

“With a big ship it is virtually impossible to stop [in a short space],” he said.