The Interislander's largest passenger ferry is expected to be out for six months after losing one of its propellers last week.
The KiwiRail-owned Cook Strait ferry service said it would be operating at nearly half its capacity over the peak summer period as repairs were carried out on its "workhorse'' Aratere ship.
The Aratere lost its propeller during a Cook Strait crossing last Tuesday.
"At this stage, we expect the ship will not be operating a passenger service for up to six months, a leased ship would not be in service until mid-January and we will have constrained capacity during this period,'' Interislander general manager Thomas Davis said.
"The Aratere is the workhorse of our fleet and carries out 38 crossings a week, which is 14 more crossings than the Kaitaki and the Arahura would normally carry out.