KiwiRail has some tough decisions to make over its ferry fleet, after a year plagued with problems made a large dent in its bank balance.

The state owned enterprise has reported a 28 percent drop in its operating surplus over the year.

The biggest expense has been the $25 million repair bill for the Aratere, and loss of customers while it was out of action.

Chief executive Peter Reidy says its other ships will be costly soon too.

He says the Arahura will need replacing next year and the lease for the Kaitaki also expires next year.