Britain's new and only aircraft carrier -- the largest and most powerful ship ever built for the Royal Navy -- set off for its first sea trial in Scotland on Monday, along with questions on whether its naval and air muscle matches that of cyber-security.

HMS Queen Elizabeth, a 280-meter (919-foot), 65,000-ton vessel, left the dock at the port of Rosyth on the Firth of Forth estuary near Edinburgh.

The ship, which can move 500 miles a day, took 11 tugs to maneuver out into the River Forth and then must wait for low tide so as to pass under the Forth's famous bridges - weather and systems checks permitting.

The ship cost £3.0 billion (3.4 billion euros, $3.8 billion) to build in a project employing 10,000 people and will be the country's future flagship. It can operate with a crew of 1,000 and 40 aircraft.

It took eight years to build HMS Queen Elizabeth and along with its sister ship, HMS Prince of Wales, it is part of a defense program worth 6 billion pounds ($7.65 billion), with building and fitting spread over six different shipyards across Britain. It will now spend around two years in sea trials.

"Of course they are expensive, absolutely, it keeps us in the premier league among nations around the world," Commanding Officer Captain Jerry Kyd told Sky News.

"The fact is that they are not just ships, but sea bases able to do a whole range of functions and missions ... whether that's engaging with the enemy at long range or indeed supporting British industry abroad or perhaps even assisting with disaster relief or humanitarian aid."

The ship's navigator Jez Brettell compared handling the ship on its maiden voyage to taking out a brand new sports car before it had been road-tested.

"The first time we put those levers forward will be the first time that we will have been under our own power and moving," he told the BBC.

It was scheduled to be fully operational by 2020 but that date may now be as late as 2026, Britain's National Audit Office said earlier this year, because of technical difficulties.

And an article by British daily The Telegraph also pointed to the fact that the giant ship runs on Windows XP – which is no longer supported by Microsoft – and started a nationwide debate whether the ship is secure against cyber-attacks amid fears in Britain against Russia's increasing power in that field.

Last month's major cyber-attack called WannaCry ransomware mainly targeted computers running on XP, including various government agencies like Britain's National Healthcare Service (NHS) and giant companies such as American logistics giant FedEx, Spanish telecom operator Telefónica or Germany national railway operator Deutsche Bahn.

While several experts stated that the ship's systems running on XP is a security breach, officials assured that the ship is being protected and there will also be specialists on board, while a computer refit will also take place within a decade.

Britain has been without any carrier strike capability since the government scrapped previous vessels in 2010 as part of austerity measures to curb a huge deficit.

The giant ship left the dock at high tide but will have to wait for low tide to be able to pass under the road and rail bridges across the Firth of Forth.

Sea trials in the North Sea will continue through the summer and the ship will eventually be taken to the Royal Navy base in Portsmouth at the end of the year.

Queen Elizabeth II named the ship in 2014, smashing a bottle of whisky on its side.

The Prime Minister David Cameron said at the time that the ship "will be the spearhead of British sea power for the next half century".

The ship was built by a partnership comprising arms makers BAE Systems, Babcock, Thales and the Ministry of Defense.

The project was dogged by questions about the U.S.-built F-35 jets due to be deployed on the aircraft carrier and about the need for mammoth aircraft carriers when Britain's military role in the world has diminished.

The F-35 stealth fighter, which is being built by the US in conjunction with Britain and other countries, has been heavily criticized for its high price tag and a series of delays over air safety concerns.

A sister ship to the new aircraft carrier, the HMS Prince of Wales, is also being built at the Rosyth Dockyard.