A Cook Strait passenger ferry hit a rock, denting its hull, when its rudder was turned the wrong way, an inquiry has found.
The Strait Shipping ferry Monte Stello was able to continue on to Picton unaided and no one was harmed during the May 4, 2011, incident.
The Transport Accident Investigation Commission report said while making the left-hand turn into Tory Channel, the ferry's rudder was inadvertently placed in the wrong direction, causing the ship to deviate from the planned track.
"The error was soon realised and corrective action taken, but not soon enough to prevent the ship glancing off a rock on the northern side of the channel."
The ship's hull was dented but there was no puncture and one of its two rudders were damaged but it was able to continue on its journey.