A ferry which runs between Gravesend and Tilbury is out of service after it was hit by a Royal Navy minesweeper in Kent.
The ferry's structure was seriously compromised
HMS Grimsby lost power and drifted into the Duchess M at 2am on Wednesday when the ferry was moored on the River Thames in Gravesend.
John Potter, owner of the Lower Thames and Medway Passenger Boat Company, said considerable damage had been caused.
The excursion boat Princess Pocahontas was also damaged. No-one was injured.
Mr Potter said he was waiting for surveyors from the Maritime and Coastguard Agency to examine the damaged vessels.
The minesweeper collided with the ferry while it was moored
He said the Gravesend to Tilbury ferry was hit mid-ship.
"It has pushed the framework in, smashed all the windows and damaged the handrails."
There was no leak of pollution in the incident, said the Port of London Authority.
A man on the minesweeper, which had been working in the area, fell overboard during the night, but was rescued by the Gravesend Lifeboat.
The ferry service, which takes half an hour to travel from Gravesend to Tilbury, has been suspended until a replacement vessel can be found.
"I looked out and the minesweeper that has been working on the river was right alongside the ferry and the Pocahontas," witness Bill Sutherland said.
"They had the tannoy going, there were people talking loudly, there were torches and searchlights - it was chaos."