The Interislander ferry Aratere will arrive back in Wellington on Wednesday after lengthy repairs - with the total cost to taxpayers including lost revenue and a stand-in ferry totalling more than $25 million.
The ferry has been in Singapore since March, where it has undergone testing and repairs, after losing a starboard propeller in November.
At a media briefing this morning KiwiRail said the overall financial impact including lost revenue, charter of the replacement ferry Stena Alegra and cost of repairs is estimated to be between approximately $25 million and $30 million.
KiwiRail continue to maintain that there was no warning of the loss of the propeller, and said none of the ship's control system monitors were abnormal.
While in Singapore, a number of national and international experts looked at all potential factors that could have led to the tail shaft failure.
KiwiRail said from those expert opinions, and findings while in Singapore, they have concluded there were a number of factors that led to the loss of the starboard propeller.
As a result they were now reviewing their insurance, commercial and legal position, and because of this they were unable to say more as to what caused the malfunction without "prejudicing their position."
Details of work to be carried out over the next fortnight will include more sea trials and underwater inspections.
A leak down test to check for oil leakage and a crash stop to measure the stopping distance of the ship will also take place.
NZ First leader Winston Peters said KiwiRail should announce who will be fired for the Aratere debacle after the financial impact was announced.
"Incompetent management, on high salaries, should be paying for this with their jobs."
KiwiRail chief executive Peter Reidy acknowledged that people had lost trust in them, and said the company would now work to regain that trust.
"We're being transparent about what happens, and being transparent about what we're doing in the next two weeks to get this back into service."
The Aratere carries out 45 per cent of KiwiRail's capacity, alongside Interislander ferries Arahura and Kaitaki.
The Stena Alegra was replacing it's services, and had its last Cook Strait crossing last Saturday. The Aratere is tentatively scheduled to resume service from July 14.
* November 5, 2013 - Aratere loses a starboard propeller.
* December 2013 - Aratere is cleared to sail as freight only.
* January 2014 - Aratere is berthed in Wellington, and the Stena Alegra enters regular service.
* March / April 2014 - Aratere is drydocked in Singapore for the first time.
* April 2014 - Aratere is berthed, awaiting new rudder stocks, maintenance continues.
* May - Aratere's second drydock to replace rudder stocks.
* June 2014 - Aratere departs after undergoing shaft alignment, sea trials and repairs and the Stena Alegra finishes services.
* July 2, 2014 - The Aratere due to arrive back in Wellington.