The departure of Royal Navy aircraft carrier HMS Prince of Wales to head for repairs in Scotland is understood to have been delayed because engineers were unable to remove the damaged propeller in time.
The aircraft carrier has been due to sail to Rosyth where it will enter dry dock to fix damage that stopped her from deploying on US-based exercises.
The mechanical fault was discovered just 48 hours after she left Portsmouth for America.
Watch: HMS Prince of Wales returns to Portsmouth after suffering 'significant' shaft damage.
The £3bn warship broke down off the Isle of Wight in August after sailing from Portsmouth Naval Base to take part in flight trials and diplomatic visits in the US.
Inspections by divers and engineers found that the 33-ton starboard propeller – the same weight as 30 Ford Fiesta cars – had malfunctioned, with a coupling holding it in place breaking.
The 65,000-tonne ship was brought back to Portsmouth for further examination by engineers from Babcock before the decision was taken for it to travel to Rosyth, where it was built, to undergo the repairs in dry dock.
Divers surveyed the damage to the aircraft carrier's starboard propellor and shaft, following her breakdown.
A Royal Navy spokesperson said: "The full extent of the repairs will be known once the ship has entered dry dock. We are committed to getting HMS Prince of Wales back on operations, protecting the nation and our allies, as soon as possible.”
The propeller shaft is made up of a number of 'steel poles' joined together, with the engine on one end and the propeller on the other.
Each of the poles is joined together with a 'shaft coupling' which is where the fault has been identified on the Prince of Wales.
Work was continuing during the weekend to remove the giant propeller but it is understood that this was not completed in time for the planned sailing on Monday afternoon, according to the Press Association.
Divers are continuing to work on the ship but it is not expected to sail, assisted by a tug, until at least later this week because of a storm with heavy winds forecast on Wednesday. The Navy has not commented on how long the repairs are expected to take and how long HMS Prince of Wales will be absent from its role as NATO flagship, but it is understood to be months rather than weeks.
Its sister ship HMS Queen Elizabeth changed its autumn plans to travel to the US to take over some of the planned engagements, including hosting the Atlantic Future Forum in New York – a defence conference aimed at strengthening UK and US bonds.
Rear Admiral Steve Moorhouse, director of Force Generation, who is responsible for making sure Royal Navy ships are ready to deploy, previously explained the fault suffered by HMS Prince of Wales.
He said: "Royal Navy divers have inspected the starboard shaft of the ship and the adjacent areas and they have confirmed there is significant damage to the shaft on the propeller and some superficial damage to the rudder but no damage to the rest of the ship.
"Our initial assessment has shown that coupling that joins the final two sections of the shaft has failed.
"Now, this is an extremely unusual fault and we continue to pursue all repair options," he added.