'It's my ship and I'm gutted': Former minister Ron Mark on Manawanui sinking

The Defence Minister is staying tight-lipped on what insurance coverage the ill-fated HMNZS Manawanui has.

The $100 million specialist survey ship hit a reef on Saturday night and sank Sunday morning off the southern coast of Upolu.

The 75 people who were on board were first evacuated onto life rafts, before being taken ashore by rescuers.

Naval ships don't have replacement insurance, Judith Collins told Morning Report.

"Never have had...There are some things around insurance but I cannot go into that for the very sensible reasons for anybody who has ever dealt with insurance companies, you have to be very careful and therefore I'm not going to go into it."

If they did, the minister said they would have massive premiums.

"They go into places that are uninsurable."

Collins said the government needed to look at whether the ship would be replaced.

Former defence minister Ron Mark says buying a commercial vessel comes with a risk.

"It's my ship and I'm gutted," he told Morning Report.

Mark said his ministerial team purchased the vessel from Norway, used for oil exploration, and refitted it, getting it into service in 11 months.

"It became the Swiss Army Knife of the navy and it 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."

"We bought Manawanui knowing she was not a war ship, she's a commercial operation... but with that comes a risk and the risk is that commercial vessels do not have the same level of redundancy in their systems or their design that warships do - you can't seal off compartments, create water tight compartments and keep the vessel afloat so that it can be towed, salvaged and repaired.

"Unfortunately with 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."

Collins said the government was now focused on the environmental effects of the Manawanui's sinking and its salvage operation.

New Zealand will have to front up financially if there's a serious oil spill, she said.

"There's obviously issues around commerical issues that I need to be very aware of and very sensitive around and the fact is, is that clearly New Zealand is going to do everything that we can."

• What we know about the sinking of the Manawanui

Samoa acting Prime Minister Tuala Iosefo Ponifasio said an oil spill from the ship was likely.

Samoan authorities were doing an environmental impact assessment, he said.

The salvage and assessing the environmental impacts of the sinking were now the big focus, Collins said.

"There's a lot of fuel on that ship, partly this (the environmental impact) is going to depend I'm told on what is the state of the bottom of the ocean at that point, whether it's sand or whether it's rocky or whatever.

"But clearly New Zealand is standing ready to work with Samoa on this and I know that there will be discussions going on with those that are operationally involved as to what we can do."

It was unclear if the ship could be taken off the reef, she said.

"That's because they were dealing with high seas, they were dealing with a reef that has changed, and people should also remember, this reef hasn't been surveyed since 1987 and since then there have been earthquakes, there's been tsunamis, there's been changes to that reef and that's why that survey was taking place."

Maritime New Zealand was ready to assist "but they do need to work with the Samoan government because after all this is Samoan territory, it's not ours".

"We're looking at salvage as opposed to saving...and it depends on what depth of water that the ship is in, and we haven't got that information yet."

"We need to make sure we do everything we can around the environmental side," she told Morning Report.

"We'll probably also be using drones as well because of course we have that sort of technology to get right in to see what we can see."

A spill kit had been sent over but Martime NZ has special spill equipment and NIWA has mapping capability, she said.

The air force sent its newest Hercules plane to Apia just after 7pm Sunday, carrying medical and welfare personnel, along with light clean-up equipment.

Passengers and crew would begin to head back to New Zealand Monday, she said.

"I think really they'll be pretty shocked.

"Yesterday I was told that they were in a feeling of almost relief and almost euphoria given what they had been through and that they had survived it."

Collins told First Up a Court of Inquiry was being arranged by the Chief of Navy and will start gathering evidence - of which she says there will be a tremendous amount.

"And they will work out how it is that this happened, how the ship ended up grounded on a reef outside, on Uplou and then what happened from then on."

Collins said she has been told it will take weeks to complete, but it could to months if it was particularly complex.

Labour's defence spokesperson Peeni Henare has questioned if cost savings were made regarding the insurance of the vessel.

"My look of the Budget documentation from earlier this year showed that in effort to make cost savings, that there were some decisions around insurance generally speaking in the NZDF, I can't speak specifically to the Manawanui, but that cost saving were made by not having insurance on some things from NZDF," Henare told Morning Report.

"It doesn't list what those things are but it's going to be important to find out."

Henare said a defence vessel could be insured and insurance was sought for significant assets during his time as a defence minister.

No issues were raised about the Manawanui's sea-going ability during his time as minister, but repairs were needed to the ship's crane, he said.

"There was never a question with regards to its sea-worthyness."

The Manawanui was an important vessel undertaking good work and the government would now need to make clear decisions regarding the navy, he said.