15m motor launch sunk off Motukorure Island in Mercury Bay not likely to be salvaged before weekend

The vessel, pictured as it was sinking near Motukorure Island.

A 15-metre motor launch that sunk off Motukorure Island in Mercury Bay likely will not be salvaged before the weekend, Waikato Regional Council says.

The vessel struck rocks near the island, also known as Centre Island, sometime before 3.45pm on Wednesday and sank fairly quickly with 1300 litres of diesel on board, the council said in a statement on Thursday afternoon.

The skipper and his passenger were uninjured.

The council previously described the launch as “new”, but council on-scene commander Cliff Gibson said it had determined the vessel was about 10 years old, but new to the owner.

He said the vessel was sitting upright in more than 20m of water.

“The conditions overnight have been favourable and the situation remains unchanged – the vessel has not moved, and there is no evidence of oil and no smell of diesel,” he said.

“Responsibility for salvage of the vessel sits with the owner, and indications from the salvor are that it’s highly unlikely the vessel is able to be recovered prior to the weekend.”

He said a favourable forecast for at least the next week meant the vessel was likely to stay put and was at a “low risk of breaking up and impacting the environment”.

There was a contingency plan in place in the event those circumstances changed.

An image of the vessel taken just as it disappeared underwater off Motukorure Island (Centre Island) in Mercury Bay on Wednesday.

A regional council-led response team has been working through the day with iwi and the Department of Conservation to identify culturally significant sites and undertake wildlife assessments, the statement said.

“[We] remain confident there is minimal risk to the environment at this time,” Gibson said.

The council’s maritime officers would visit the site of the stricken vessel twice a day – including over the weekend – to assess the scene for changes.

In a previous statement, the council said maritime officers arrived just before the vessel sank completely.

“Based on the information we have, we believe the vessel’s fuel tanks will be intact at this stage, but the breathers will be open.”

A breather is a vent from the tank to relieve pressure. It stops fuel coming back out of the filler tube when the tanks are being filled.