Britain's largest and post powerful warship set sail for the first time today, after its construction was marred by delays and cost overruns, in addition to doubts over whether the Royal Navy will be able to afford the full capacity of fighters.

Naval staff and contractors lined the deck of HMS Queen Elizabeth as the 280-metre, 65,000-tonne aircraft carrier moved from Rosyth out into the Firth of Forth on Monday in a three-hour operation.

The behemoth, which is set to be the nation's future flagship, and her 700-strong ship's company will undertake her maiden sea trials over the summer.

In pictures: construction of HMS Queen Elizabeth Show all 8 1 /8 In pictures: construction of HMS Queen Elizabeth In pictures: construction of HMS Queen Elizabeth HMS Queen Elizabeth Work continues on HMS Queen Elizabeth Aircraft Carrier at Rosyth Docks PA In pictures: construction of HMS Queen Elizabeth HMS Queen Elizabeth Workers pass scaffolding poles to each other on the flight deck of HMS Queen Elizabeth Reuters In pictures: construction of HMS Queen Elizabeth HMS Queen Elizabeth A worker sweeps in front of HMS Queen Elizabeth Reuters In pictures: construction of HMS Queen Elizabeth HMS Queen Elizabeth A view of the take off the ramp on the deck of HMS Queen Elizabeth Aircraft Carrier at Rosyth Docks PA In pictures: construction of HMS Queen Elizabeth HMS Queen Elizabeth Construction work in the hanger of HMS Queen Elizabeth Aircraft Carrier at Rosyth Docks PA In pictures: construction of HMS Queen Elizabeth HMS Queen Elizabeth Workmen carry out maintenance in a nearby dry dock as work continues on HMS Queen Elizabeth Aircraft Carrier at Rosyth Docks in Fife PA In pictures: construction of HMS Queen Elizabeth HMS Queen Elizabeth A welder works on HMS Queen Elizabeth Aircraft Carrier at Rosyth Docks PA In pictures: construction of HMS Queen Elizabeth HMS Queen Elizabeth Construction workers carry materials in the hanger of HMS Queen Elizabeth Aircraft Carrier at Rosyth Docks PA

The vast vessel's journey to sea was a major operation, where timing was key.

After waiting until high tide to leave the naval dockyard, the carrier then waited for the tide to drop so it could pass under the Firth's famous bridges.

Speaking before the maiden voyage, commanding officer Captain Jerry Kyd said: "We have to be very careful, but you practise it and drill it and rehearse it to make sure we could do it safely in a timely fashion because the tide waits for no man."

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For the next six weeks, the aircraft carrier will head to the North Sea for sea trials, with flight trials due to begin off the eastern coast of the United States in October 2018.

It is expected to be monitored by Russian submarines, ships and planes.

Captain Kyd said: "After that we're going back out for a further three weeks to test the ship on the more war-fighting capabilities - the radars, all the ship's sensors, radios and things like that.

"At the end of that period we know that all the basics work. She's done her test drive and after that we will go down to Portsmouth, the ship's home, and get her finally ready to join the Royal Navy fleet, hopefully at the end of the year."

She is scheduled to be operational by 2020.

The HMS Queen Elizabeth under construction in Rosyth dockyard in Scotland (AFP/Getty Images)

Royal Navy Leading Hand Claire Butler is presented with the first 'cap tally' for being the first crew member to board new aircraft carrier HMS Queen Elizabeth (PA)

But the HMS Queen Elizabeth has faced significant setbacks during its construction.

The ship has taken more than eight years to build at a cost of £3.5bn.

The Royal Navy's second new carrier, the Prince of Wales, will follow in two years' time, and together the ships will cost over £6bn - making them the most expensive project in the Navy's history.

Although each carrier can hold 36 F-35B stealth jets and four helicopters, there are concerns the defence budget won't allow the Navy to put a full complement of fighters on board.

To meet the shortfall, the Royal Navy will allow the US Marines to fly their own F-35Bs from the carriers, though the number is still under discussion.

Critics have also claimed the carriers are too vulnerable to new high-speed missiles, such as the Russian Zircon missile.