After initially denying the sunken HMNZS Manawanui was leaking oil, the New Zealand Navy has now confirmed that it is, and will attempt to remove the fuel tanks from what’s left of the ship on the sea floor off the coast of a Samoan island where it went down.
Samoa’s Marine Pollution Advisory Committee (MPAC) said on the weekend that the vessel had leaked about 200,000 litres of diesel. About 900,000 litres of fuel was onboard the Manawanui when it sank.
Initially, the NZ Defence Force (NZDF) had said the ship was not leaking, but now that its divers have inspected the site, has admitted it was wrong.
However, it still maintains the 200,000 litre figure is incorrect.
“NZDF and Maritime NZ consider that the amount of fuel leaked from the ship is likely less than 200,000 litres,” it said in a statement. “So far, the main fuel tanks that are accessible for assessment are intact, and there is no evidence of any leaks from the main fuel tanks.
“The reality is that we cannot definitively state how much fuel has leaked at this time but do consider, based on a week’s worth of evidence, that it is probable that the amount of fuel leaked is less than 200,000 litres.
“A Royal New Zealand Air Force P-8A Poseidon flew over the site on Thursday, confirming a light slick stretches from away from the mainland out to sea, covering approximately 365 metres x 60 metres before dissipating. Maritime NZ has not seen any oil damage on shore,” it added in a separate update.
The Manawanui is lying on its side, 30 metres underwater on a reef off the south coast of Upolu.
Local conservationists want the entire wreck removed to preserve the delicate ecosystem in the area. They say there is already substantial damage to the reef from the Manawanui’s collision and friction from its anchor.
A tourism business operator says food from a container on the ship is polluting the water, attracting sharks to popular surf breaks and making the water unsafe for fishing, snorkelling, and surfing.
MPAC has warned people not to eat fish caught near where the Manawanui ran aground.
Deputy Chief of the Navy Commodore Andrew Brown said “a small quantity” of oil had escaped and it was being monitored.
“The advice from our experts and our specialist is that the very small quantities [have] come to the surface and they commence a natural evaporation process, and also waves and general tides dissipate that. We are also obviously continuing the monitoring of where that fuel goes. We’re monitoring the beaches, the environment, the wildlife,” he said.
He said the fuel was thought to be coming from pipes, and there had been no evidence it had come from the ship’s main tanks, but getting them off the ship as soon as possible would remain a priority.
What Happened?
With attention now turning to the cause of the incident, several facts are emerging.Internal reports to Defence Minister Judith Collins late last year revealed the Navy had “significant deficiencies in required experienced and qualified staff, predominantly in technical trades and in supervisory ranks.”
The $100 million Manawanui was in a “maintenance period” before it went to Samoa, but Chief of Navy, Rear Admiral Garin Golding, said, “They did trials post that maintenance period and the ship was determined safe to deploy for their operation.”
The vessel cost the New Zealand government $103 million (US$62.7 million).
Built in 2003 by Norway’s Myklebust Verft shipyard as a commercial offshore support vessel, it was overhauled and commissioned into the NZ Navy in 2019, replacing previous dive and survey ships. It served as a platform for both diving operations and seafloor surveying.
Its flexibility was one of its greatest assets, deploying remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs), and traditional dive teams for various maritime tasks—from explosive ordnance disposal to environmental monitoring and underwater repairs.
The ship underwent a significant upgrade last year. However, commercial ships don’t have the same degree of redundancy in their systems or design.
Unlike a purpose-built naval vessel, the crew can’t seal off sections, creating water-tight compartments to keep the vessel afloat so that it can be towed, salvaged, and repaired.
‘No One Anticipated That She’d Hit a Reef': Former Defence Minister
Former Defence Minister Ron Mark, who signed off on the purchase of HMNZS Manawanui, said the decision “astonished our partners, the audacity that we would buy a commercial vessel of that type and press it into military service. And it proved to be extremely valuable in the what is short time that we had her.“Unfortunately, with a commercial vessel of this type, you know that in a worst-case situation, you’re going to have an issue. But I guess no one anticipated that she'd hit a reef.”
Ironically, part of the Manawanui’s job was acting as a salvage vessel—recovering wreckage and performing underwater repairs on damaged warships. With no other salvage vessels in its naval fleet, New Zealand must now rely on outside help if it is to recover it from the sea floor.
Headed by a senior naval officer, the court will comprise senior military officials from various branches, including two senior New Zealand Air Force officers and a captain seconded from the Royal Australian Navy.
An external legal review to provide independent assurance of the COI’s procedures and conclusions will then be conducted by a King’s Counsel.
