Aircraft carrier to set sail from Portsmouth
HMS Prince of Wales will lead Nato's biggest exercise since the Cold War
Royal Navy aircraft carrier HMS Prince of Wales is due to set sail from Portsmouth this lunchtime, a week after its sister ship was forced to cancel its deployment because of an "issue" with its propeller shaft.
The fleet flagship HMS Queen Elizabeth had been expected to depart from Portsmouth Naval Base last Sunday to lead the largest Nato exercise since the Cold War, involving more than 40 vessels.
But the sailing of the £3 billion warship was called off at the last minute after the problem was found in final checks with the starboard propeller coupling.
The setback came 18 months after HMS Prince of Wales broke down off the Isle of Wight, when it also suffered a malfunction with a coupling on its starboard propeller.
Since the cancellation was announced, the crew and base workers have been busily preparing the HMS Prince of Wales to take over its sister ship's role in Exercise Steadfast Defender - which will take place off Norway.
As part of the preparations, scaffolding which was seen on the carrier's flight deck has been removed ready for the sailing which is listed to take place at lunchtime on Sunday.
Having HMS Queen Elizabeth out of action could affect the ability of the Royal Navy to deploy an aircraft carrier to the Red Sea amid the continuing threat by Iran-backed Houthi rebels - which armed forces minister James Heappey has suggested was being considered.
Announcing the change of plans, Fleet Commander Vice Admiral Andrew Burns said: "Routine pre-sailing checks identified an issue with a coupling on HMS Queen Elizabeth's starboard propeller shaft. As such, the ship will not sail on Sunday.
"HMS Prince of Wales will take her place on Nato duties and will set sail for Exercise Steadfast Defender as soon as possible."
A Royal Navy spokesman said: "The aircraft carrier HMS Prince of Wales is due to sail from Portsmouth to take the place of HMS Queen Elizabeth to join the Nato Exercise Steadfast Defender.
"As ever, sailing will be subject to suitable tide and weather conditions.
"On completion of initial investigations, HMS Queen Elizabeth will sail for Rosyth in Scotland so any necessary repairs can be carried out in due course.
"The cause of the issue with HMS Queen Elizabeth is wear and tear of her starboard propeller shaft coupling."
The MoD has not confirmed if HMS Prince of Wales will take over all of its sister ship's scheduled duties, including taking part in the annual Joint Warrior exercise off northern Scotland.
HMS Prince of Wales broke down as it was heading to a diplomatic mission to carry out exercises with the US Navy, Royal Canadian Navy and the US Marine Corps.
The carrier came to a halt off the Isle of Wight and was brought under tow back into harbour for the problem to be identified.
Inspections by divers and engineers found the carrier's 33-ton starboard propeller - the same weight as 30 Ford Fiesta cars - had malfunctioned, with a coupling holding it in place breaking.
A Ministry of Defence spokesman said the issue on HMS Queen Elizabeth was "separate and not linked" to the earlier defect on its sister ship.
He said: "The issue identified is with the ship's shaft couplings. The ship's propeller shafts are too big to be made from a single piece of metal, so each shaft is made from three sections, which are connected using shaft couplings, which bind the shaft sections together."
HMS Prince of Wales was taken to the Babcock shipyard where it was built in Rosyth, Fife, to undergo repairs to a propeller shaft, which took nine months to complete.
On that occasion, HMS Queen Elizabeth acted as the replacement for its sister ship on the US deployment.
You can see the expected timings of today's departure here.