The rollout of two new Spirit of Tasmania vessels has been plagued by scandal, mistakes, delays and cost blowouts.

There was an $81 million bailout to a Finnish shipbuilder two days before a state election .

Then there were revelations that a new wharf in Devonport had ballooned in cost from $90 million to $375 million , and now $493 million.

TT-Line sent wrong specs in 'human error', leading to $9m Spirit ferry fix

The head of Tasmania's state-owned ferry operator blames "human error" for a berth problem that needs a $9 million fix and modification to the hulls of the two new Spirit of Tasmania ships.

And the wharf itself was so delayed that the two new vessels — themselves delayed multiple times — would be finished in Finland without anywhere to berth in Tasmania.

This meant

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