The Arahura was back in normal service today after engine trouble caused the Interislander ferry to break down in mountainous seas in Cook Strait yesterday.
The Arahura, with 676 people on board, lost power near the rocky and narrow Tory Channel about midday yesterday.
It limped into Picton under tugescort more than three hours late just before 4pm, having been diverted through the northern entrance to Queen Charlotte Sound.
Emergency services -- including the Rescue Coordination Centre and the Westpac rescue helicopter -- were put on standby after the Arahura captain issued a "pan-pan", a call indicating a potentially serious situation, as it headed into the channel.
Maritime Safety Authority spokesman Lindsay Sturt said today Toll and MSA personnel boarded the ferry as soon as it docked in Picton, to investigate the source of the power failure.
The engine was repaired, and MSA personnel remained on board the ferry for its return trip to Wellington last night in stormy weather conditions.
Interislander spokeswoman Sue Foley told NZPA the Arahura arrived in Wellington without incident yesterday at 9.30pm.
"The propulsion system problem, caused by one engine, was sorted out quickly."
The MSA is launching an investigation into yesterday's emergency.
The latest incident comes days after it was revealed that jinxed ferry Aratere -- nicknamed El Lemon by its crew -- was under investigation for the 45th time after a close encounter with a chemical tanker in Wellington Harbour on April 10.
