KiwiRail's Interislander ferry Aratere is out of drydock and is expected to be back in service by the end of June.
The ferry has been out of commission since it lost a propeller during a crossing last year.
Interislander general manager Thomas Davis said new rudders had been installed and the ferry was returned to the water in Singapore last Friday.
It will undergo tests and sea trials before leaving Singapore on a two-week voyage to Wellington.
Meanwhile, an Interislander ferry master has been reinstated after an investigation into what KiwiRail called a "near miss".
Staff are automatically stood down after an such incidents and are required to undertake drug and alcohol testing with any investigation.
An investigation into an incident involving a second ferry master was ongoing, KiwiRail said.
Maritime New Zealand would be give then results of both investigations, it said.