UPDATE: Spirit of Tasmania II passengers who were stranded in Melbourne overnight have set sail for Tasmania, after many of them spent the night on the damaged ferry.
The vessel broke free of its moorings during Wednesday's wild weather and crashed into Station Pier, scuppering the travel plans of 650 passengers.
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Spirit of Tasmania: extra sailings tonight
Hundreds of Spirit of Tasmania II passengers have had to wait overnight, with Spirit of Tasmania I sailing on a double schedule starting tonight. (Vision courtesy ABC New 24)
The Spirit of Tasmania I was anchored in Devonport during the storm and arrived in Melbourne about lunchtime on Thursday. It is already on its way back to Tasmania.
Acting Spirit of Tasmania chief executive Stewart McCall said earlier in the day that priority was to be given to Tasmanians trying to get home. He expected people booked into Thursday's scheduled service would still set sail.
"This is our peak period. It does cause us problems in regards to trying to accommodate displaced passengers, so it's going to be very difficult to accommodate those people quickly ... there will be some effect to passengers," he said.
Mr McCall said there would be a thorough investigation into Wednesday's incident, in which the ship's boarding ramp was badly damaged when winds wrenched the vessel away from its moorings.
"I was here when it happened; I saw the speed of it myself," he said. "I'd never seen anything like that in my life."
TT Line spokesman Nick Turner said the he vast majority of the damaged ship's passengers stayed on the vessel overnight and were provided with a complimentary dinner.
Sixty-five cars had been loaded onto the Spirit of Tasmania II before the storm broke. Those vehicles were to be unloaded from the back of the ship on Thursday morning.
All the affected passengers would receive a full refund, Mr Turner said.
Engineers were checking the damage to the vessel on Thursday and it would not sail until further notice, he said.
It is not known how long it will take to repair the damaged ship.
Writer and broadcaster Tracee Hutchison said on Wednesday that about half the passengers who were taking their cars to Tasmania had already boarded, while hundreds remained stranded in the departure terminal.
On Thursday, she told the ABC that she was among the passengers who spent the night on the ship.
"It was a bit like waking up in an odd RSL," Hutchison said. "It had a slight twilighty feel."
After receiving a refund, she opted to fly out to to Tasmania on Thursday morning.
But some passengers were not happy with the service. Scott, a teacher who did not want his surname published, said it felt as if he and his family had, in effect, been kept as prisoners on the vessel overnight.
"Their customer service was straight out of Guantanamo 101," he said.
Scott said his car was not on the ship when the storm struck and was one of the last to get to the three-lane loading bay, but Spirit of Tasmania staff would not let him drive away when it became apparent the ship would not be leaving Station Pier.
"We were some of the last in, so we could have just reversed out and left," he said. "We would have been out of there in two minutes but they wouldn't let us go."
"I was genuinely thinking of just putting the car into third gear and driving out. It might have been a logistical nightmare for a little while, but it was doable. There were three lanes and one was vacant and they could have had people ushered out."
Scott said he had cancelled the nine-day Tasmanian holiday he was planning with his pregnant wife and their two-year-old child.
"We're going to head down the Ocean Road instead," he said. "After the fires they can do with some tourism dollars."
French tourist Nicoles Nouchet was meant to board the Spirit of Tasmania II on Wednesday evening but was left in limbo, waiting at the waterfront.
"It was like a little tornado ... at about 6 o'clock, the wind was so strong you could feel the sand in your face, there were deck chairs flying around," he said.
"We heard a loud noise and it came really close to the shore."
Perry Tremewen, another passenger due to take the 7.30pm journey across Bass Strait, heard the loud crash all the way from Beaconsfield Parade and said the ship was at a right-angle to the pier when he arrived.
He said the incident risked disrupting his holiday plans of a week-long motorcycle tour across Tasmania.
Jetstar and QantasLink announced they would offer discounted airfares to stranded Spirit of Tasmania passengers in both states until Friday.
Affected ticketholders can book flights with Jetstar on 13 15 38 or with QantasLink on 13 13 13
With Nick Toscano, Patrick Hatch, AAP