A P&O ferry will have to be inspected before it can depart Larne Port again after spending hours adrift off the coast of Co Antrim.
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.
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."
Now, the Maritime and Coastguard Agency (MCA) has confirmed that, while the vessel has not been detained, it will have to pass another Port State Inspection before it sails again.
A MCA spokesperson said: “When any vessel reports an issue to the MCA, dependent on the nature of the issue, the MCA may undertake an inspection of that vessel.
"We generally follow up all issues reported on passenger vessels to ensure the safety of those onboard the vessel and that any issues are not so serious that they pose a threat to life or the environment.
"In the case of European Causeway we will be following up the incident with an inspection.”
It is the second time in a month after the vessel was detained on 26 March before being cleared to sail again on 8 April.
The previous inspection identified 22 deficiencies including “failures on crew familiarisation, vessel documentation and crews training.”
A P&O Ferry spokesperson also said that a "full independent investigation will be undertaken” following Tuesday's events.
It all comes weeks after 800 staff lost their jobs, after the company suddenly suspended sailings.