Ferry's mayday call being investigated

Several investigations are underway after a ferry got into trouble in the Rangitoto Channel last night.

The 360 Discovery vessel was sailing from Auckland to Gulf Harbour when it made a mayday call just after six following suspected mechanical failure.

Spokeswoman Lucy Farrington says the 57 passengers on board were moved to muster spots in case they needed to be evacuated.

She says the issue was contained and the vessel proceeded to Gulf Harbour on one engine, escorted by the Navy ship HMNZS Manawanui.

"There will be our own full internal investigation, and Maritime New Zealand have also been notified."

She says the vessel will be out of action for some time.

"It depends on the nature of the mechanical issue as well, but yes it will be until the investigation's been carried out and it's deemed safe to operate again."