Queen Mary 2 drifted in open sea for around an hour with no power after an explosion in a main electrical switchboard room, a marine report has found.
No-one was injured in the incident on board the Cunard flagship which happened near Barcelona in September 2010, according to the Marine Accident Investigation Branch report.
The blast was triggered by deterioration in the capacitors, which store energy, the report said. It said it was fortunate the 150,000-tonne vessel was clear of navigational hazards at the time.
The emergency generator started automatically following the explosion on the 2,620-passenger QM2. The main generators were restarted and the ship was able to resume sailing.
Action had been taken since the incident by Cunard’s parent company Carnival, the MAIB said.