From Newsroom yesterday:

$3b a small price to pay for future of Interislander ferries – The Cook Strait ferries debacle has focused on the cost blow-outs for the respective port upgrades but there has been little attention given to what is needed to ensure adequate connectivity between our two main islands.

It is obvious that a country split into two main islands needs reliable, efficient, modern rail-enabled ferry services. It’s hard to think of another transport requirement as important as this. Yet Government ministers have nickel-and-dimed the debate to the extent that the real question in play here is obscured by silly metaphors (for example Finance Minister Nicola Willis saying it was time for a Toyota Corolla rather than a Ferrari).

The Interislanders are about 3 800 tonnes compared to the Glen Sannox at only 1 200 tonnes, so three times as heavy.

The MV Sannox and Glen Rosa cost has risen to £360 million or 775 million New Zealand dollars compared to 3 billion NZ dollars for the two new Interislanders.

So, the New Zealand ferries will cost around 4 times as much but are only 3 times heavier.

The NZ ferries are, pro rata, nearly 1.33 times as costly.