Stranded Vic ferry passengers cleared

Passengers stranded after the Spirit of Tasmania broke nine of its moorings during a wild storm in Melbourne have set sail on their way to the Apple Isle.

A wind gust around 100km/h caused the Spirit of Tasmania II's moorings to snap on Wednesday night, swinging the ship 90 degrees from the side of Station Pier and buckling the "sky bridge" ramp between the shore and the ship's vehicle hold.

About 650 passengers and 65 of the cars that were loaded on to the ship before the storm struck stayed there overnight.

The cars were unloaded by 2.45pm on Thursday using a second vehicle ramp in the ship's bow.

Spirit of Tasmania I was anchored in Devonport during the storm, arriving in Melbourne around lunchtime on Thursday where it was being unloaded by 4pm.

TT Line says Spirit of Tasmania I will operate a double sailing schedule until further notice.

It is not known how long it will take to repair the damaged ship.

Some of the 650 passengers from the damaged ship who stayed on board overnight will travel on Spirit of Tasmania I, while others took advantage of an offer of a full refund to pay for flights.

Tracee Hutchison, who was at the passenger terminal when the freak winds hit, said she stayed overnight but opted for flying to Tasmania instead.

"It was pretty weird, waking up this morning after an overnight trip that you expect to be in Devonport and you are in Port Melbourne," she told 3AW on Thursday morning.

"It's like something out of the Twilight Zone."

TT Line acting chief executive Stuart McCall said it was pure chance that no passengers were hurt.

"Once the ropes broke it spun 90 degrees and hit the loading ramp," Mr McCall told reporters on Thursday.

The Australian Maritime Safety Authority has confirmed inspectors will investigate what caused the ship to snap its moorings.