A Bluebridge Cook Strait ferry had to turn back after it hit a wharf as it was leaving Wellington.
Wellington Harbourmaster Grant Nalder said the ferry departed about 8.15am on Wednesday and hit the southern end of Glasgow wharf.
The Connemara was sailing towards the entrance to the channel when the operator StraitNZ made decided the vessel should turn back.
"The company made the decision that they wanted a closer look at the ship so they brought it back into the berth," Nalder told Midday Report.
Nalder said there was "a decent dent" on the hull and a "very small hole" above the waterline.
The risk was low given the size of the hole, its height above the water, and that it was going into a relatively small compartment, he said.
Passengers were able to safely disembark once the ferry returned to port.
Repairs to the vessel were likely to be carried out in the afternoon and the ferry was expected to be back in service on Wednesday evening, Nalder said.
A CentrePort spokesperson said following the incident involving Connemara, engineers were on site assessing damage to Glasgow Wharf.
Glasgow Wharf was the back-up wharf for StraitNZ Bluebridge ferries and would be unavailable until engineers provided clearance that it was safe to use, the spokesperson said.
Connemara is now berthed at the main ferry berth used by StraitNZ.
Passengers aboard the sailing said they had no idea the boat was being damaged as it left its berth.
Waiting at the terminal to board a later sailing Stella Thorpe said she was just beginning to feel the waves of Cook Strait before the boat was turned around.
Passengers sat for half an hour in port as the boat was inspected before they were told the sailing was cancelled and they would have to disembark, she said.
The crew had kept them informed and provided a free coffee and vegan slice but she was disappointed her group of 19 would be cancelling their dinner booking in Blenheim because of the delay, she said.
Heidi Meister was travelling to see family in Christchurch today.
She said she was frustrated to be told by staff that her 1.30pm sailing had been cancelled only to learn after a long time queuing that the boat was only delayed as passengers from the Connemara were added to her sailing.
"Just annoying. Poor communication that's all," she said.
Glenice Powell and John Pratchett had travelled to Wellington to pickup two new bikes they were planning to ride back to Blenheim this afternoon.
Powell said the delays to her sailing meant they would probably have to spend the night in Picton as she doubted they could reach Blenheim before nightfall.
She said the Cook Strait crossing had become hard to rely on in recent years and people could not afford to take their chances on whether they would get home on time.
"It's the extra expense that's difficult really, having to pay for extra accommodation and all that," she said.
Kevin Bridges said he did not mind a couple of extra hours in the capital. He was off to the bar across the road from the Bluebridge terminal.
"Its all good, we don't have to drive, we're being picked up. I'm just hoping I get back in time for indoor cricket tonight. I reckon I play better once I've had a few anyway," Bridges said.