An economist estimates the Government's footing a more than a 1.7 billion dollar bill for the new Cook Strait ferries

The Council of Trade Unions' has crunched the numbers, adding up rumoured costs like the break fee of the previous contract and the reported 900-million allocated for new ships.

The Government won't release the official figures.

CTU economist Craig Renney says taxpayers are in for a significant cost, with nothing to show for it.

He says 1.7 billion is a conservative estimate, which he predicts will only clime higher.