Westland Mineral Sands barge runs aground near Westport

A Westland Mineral Sands barge, owned by WMS Group, has run aground near Westport during a thunderstorm overnight.

WMS Group chief of corporate affairs Kate Lynch confirmed the barge Manahau came ashore on Carters Beach on Saturday.

She said all 11 crew on board were safe and there were no environmental concerns.

"Westland Mineral Sands is working closely with relevant maritime and coast guard authorities to understand how this incident occurred."

Buller District Mayor Jamie Cleine said the motorised barge carting mineral sands had been anchored since last Sunday, awaiting suitable weather for it to come into port.

"It's been anchored off Westport for the best part of a week ... and obviously last night's pretty severe thunderstorms and weather - something's happened and changed for them, and it's ended up coming ashore," he said.

He added Westland Mineral Sands would want to pull the boat back out into the water as soon as possible.

That job would require a tug boat from somewhere around New Zealand, but that resource was not available anywhere near Westport, he said.

Maritime Union national secretary Carl Findlay said not having a tug boat nearby was concerning.

"It is a real worry for us all. How are we going to get it off there?"

Westport resident Kevin Smith said he became aware the Manahau had run aground about 2am after seeing photographs posted on a Facebook group. He believed it happened between midnight and 1am.

"I went down this morning at 6.30am and just took some photographs."

The barge was resting between the beach and the sandbar, he said.

"If it was going to ground anywhere, it was probably the best place possible. It's a big, flat beach. It's a flat-bottomed boat."

However the barge did not appear to be firm aground, Smith said.

"It was evident that the stern, the rear of the ship, was afloat. So you could see it moving about."

He said there did not appear to be any damage.

Maritime NZ said it was aware that the barge had grounded at Carters Beach.

"We have received reports from the local on scene commander that the vessel is currently stable and there is no evidence of an oil spill.

"It is understood the vessel, which is used to move iron sand, grounded at about midnight. At the time, there were 11 people on-board, we have not been informed of any safety risks."

Union raises concerns about international crew

Findlay said concerns had been raised previously by New Zealand seafarers about the foreign crew and flag of the barge.

There had been no reports of injuries, which Findlay said was fortunate, as the West Coast was a notoriously treacherous maritime environment.

The 97.53-metre and 3706-GT self-powered barge Manahau had only just come into service in August, carrying mineral sands out of shallow draught port Westport to Nelson.

The Manahau did not have a New Zealand crew and the flag state was Niue, Findlay said.

"Vessels such as the Manahau operating in New Zealand's unique and challenging maritime environment should be crewed by experienced New Zealand seafarers."

It had been extremely disappointing to see substantial government funding go towards a vessel operating in our waters that was neither New Zealand flagged nor crewed, Findlay said.

"In the last several years, we saw an upsurge in New Zealand-crewed coastal shipping, but this is now going backwards with the loss of coastal shipping services, or in this case, failing to provide jobs for skilled local crews.

"New Zealand needs to build its coastal shipping capacity, and that means New Zealand-owned, operated and crewed ships.

"We're an island nation, so we've got highly skilled seafarers. We should be locally looking after our coast, because no one knows it better than us."