HMNZS Aotearoa: New Navy ship already rusty – $9 million damage done

It was to be the jewel in the crown of the Navy, the $500-million, purpose-built supply ship that is the largest vessel ever to set sail under the white New Zealand ensign.

But
target=”_blank”>HMNZS Aotearoa has already hit troubled waters after less than four years in service.

Herald inquiries have revealed the Navy has launched an inquiry after contaminated diesel caused nearly $10m of damage to the ship, built in Korea by Hyundai Heavy Industries and delivered in 2020.

Meanwhile, the Navy has confirmed additional coating and corrosion issues have emerged in the ship.

A separate study is under way to identify the extent and cost of repairs to be carried out later this year.

Financial statements published in the Defence Force’s 2023 annual report include a provision for “fuel remediation” with a cost of $9.23 million.

“This provision represents the estimated cost of the HMNZS Aotearoa cargo fuel remediation,” a note attached to the financial statements said.

Approached for an explanation of the “cargo fuel remediation”, Assistant Chief of Navy Captain Simon Rooke – formerly the commanding officer of Aotearoa – said the culprit was fungi.

“The contamination was a type of fungi that can cause damage to equipment and machinery,” he said.

The microbiological contamination can cause damage to equipment and machinery, he said. It was first detected via routine sampling in April 2023.

Remediation work was carried out in Singapore during a deployment to Asia, Rooke said.

As for how the diesel became contaminated, that’s unclear.

“How the microbiological contamination was introduced will be clarified by an inquiry, which has been initiated to look into all the factors surrounding HMNZS Aotearoa’s fuel contamination issue,” Rooke said.

“What we do know is this is not an uncommon issue with diesel fuel and the Navy has a routine sampling regime in place to detect a range of impurities.”

Rooke said fuel tankers have management plans and cleaning processes in place, such as fuel polishing to filter out contaminants. The inquiry will look at whether any process failures were to blame, he said.

According to a paper published by Dow Chemical, the presence of water in a diesel tank fuels the growth of microbes.

The effects can include a change in the combustion point of diesel, degrading the performance of engines, and a degradation of the anti-corrosive elements of the fuel, the paper said.

Another study said bio diesels are more prone to contamination than petroleum diesel. However, the Defence Force said the cargo fuel carried by Aotearoa is F-76 military diesel, which is not a bio diesel.

The contamination on Aotearoa was mainly confined to its huge cargo tanks, used to carry fuel to replenish other vessels at sea.

A small amount of contamination made its way to the ship’s bunker tanks, used for its day-to-day operations, though there were no engine defects on the ship attributed to the contaminated fuel, Rooke said.

In addition to the damage to the cargo fuel tanks, rust has also caused other issues for the 173m ship.

“There have been some coating and corrosion issues identified since the ship was delivered in mid-2020 which are being systematically remediated during planned maintenance periods and other suitable windows of opportunity,” Rooke said.

“A study is under way to identify any further remediation work required. Once this is received, a repair plan and costing will be compiled. The scheduling of repair work is expected to be completed by mid-2024.”

As with the rest of the Defence Force, the Navy has battled a retention crisis as sailors left in droves.

Briefings show 57 per cent of the Navy’s marine propulsion technicians had set sail from the service.

BY THE NUMBERS – HMNZS AOTEAROA

George Block is an Auckland-based reporter with a focus on police, the courts, prisons and defence. He joined the Herald in 2022 and has previously worked at Stuff in Auckland and the Otago Daily Times in Dunedin.