KiwiRail has cancelled passengers' sailing trips on the Kaiarahi, one of the Interislander ships, until the weekend.
A fault in the lifeboat reengagement system has been discovered, forcing KiwiRail to restrict trips to freight only until 1pm Saturday, March 16.
The ship is still mechanically sound.
The fault was discovered "during a scheduled asset maintenance survey", the Interislander announced in a service alert on their website.
"We apologise for any inconvenience, but safety is our top priority," they said.
Passengers impacted by the cancellations have been contacted and transferred to the next available option and if an option can't be found, refunds are being offered.
In January, KiwiRail was charged by Maritime NZ in relation to the breakdown of the Kaitaki ferry while it had hundreds of passengers on board.
A crucial, but ageing, rubber expansion joint was to blame an inquiry found.
