Video report by UTV reporter Jordan Moates
P&O Ferries has said a full investigation will be carried out after a vessel travelling to Larne was left to drift off the coast of Co Antrim after losing power.
The 'European Causeway' - which operates between Larne and Cairnryan - had what the operator described as a "mechanical failure" on a sailing to Northern Ireland on Tuesday afternoon.
Emergency rescue crews from the coastguard and RNLI raced to the scene, however, P&O later said there were no injuries and the Maritime and Coastguard Agency said there were no concerns for safety.
One passenger told UTV the engine just stopped working and then it restarted and continued on for another 10 minutes or so.
"Then it just stopped and it completely blacked out, all the electrics and everything were just down."
A spokesperson for P&O Ferries confirmed that the vessel finished the journey "under its own propulsion".
They said: “Following a temporary mechanical issue, the European Causeway is now continuing on its scheduled journey to the Port of Larne under its own propulsion, with local tugs on standby, where it will discharge its passengers and cargo as planned.
"There are no reported injuries onboard and all the relevant authorities have been informed. Once in dock a full independent investigation will be undertaken.”
The ship has since docked in Larne.
Later services have been affected as the company also announced that a Tuesday evening Cairnryan service has been cancelled.
On social media, P&O Ferries said: "We regret that due to a technical difficulty the 20.00 sailing is cancelled. We have however secured you space on the 19:30 sailing with Stena.
"Please arrive at our port before 19:00 and we'll give you a transfer document to present to check in at Stena."
A spokesperson for the Maritime and Coastguard Agency (MCA) said: "At around 1.30pm today, HM Coastguard was alerted to a mechanical failure onboard the passenger ferry European Causeway off the coast of Larne."
Local Coastguard Rescue Teams from Larne and Portmuck are standing by and lifeboats from Larne and Redbay are also ready to assist in towing the vessel back to port.
The MCA spokesperson said: "A tug is currently on scene while the cruise ship Queen Victoria is standing by in case further support is needed.
"There are no concerns over the safety of passengers on board."
A RNLI spokesperson said that three lifeboats had been sent to the scene.
The spokesperson said: "Three RNLI lifeboats were requested to launch this afternoon to assist a passenger ferry in difficulty one mile south east of The Maidens."
According to a number of tracking websites, the European Causeway's automatic identification system (AIS) status was set to 'Not Under Command' for a time.
That means "through some exceptional circumstance [the vessel] is unable to manoeuvre as required by these rules and is therefore unable to keep out of the way of another vessel".
It comes just weeks after the European Causeway was detained at Larne Port over safety concerns by the MCA.
It failed an inspection on the 26 March before being cleared to sail again on 8 April.
Around 800 P&O staff lost their jobs earlier in March, after the company suddenly suspended sailings.
The European Highlander only resumed service on Sunday. That was the first time P&O was able to operate a full service between Scotland and Northern Ireland since the mass sacking.