-The HMS Astute is the only new hunter-killer submarine on active patrol
-Four of the other submarines are still in production after numerous delays
-HMS Ambush is yet to complete a maiden voyage after 57 defects found
-Royal Navy is bolstering its resources by using older ships for defences

By Claire Carter for MailOnline
Published: 08:22 GMT, 3 May 2015 | Updated: 16:04 GMT, 3 May 2015

The Royal Navy has just one nuclear powered submarine in operation after the rest of the fleet has been left out of action due to defects and damage.
Four of the Royal Navy's new multi-billion hunter and killer submarines are still in dock at Barrow-in-Furness because of defects that have delayed their production - 15 years after the new ships were first ordered.
Only two of the boats have actively joined the fleet, and one has already had to return to the dock and can only be used for training after more than 50 defects were found.
The Royal Navy's HMS Astute is the only new hunter-killer submarine in active service after four were beset by delays and a fifth cannot be used yet after 57 defects were found

Just the HMS Astute is currently in active service.
The news comes as authorities in Finland had to fire after a submarine from Russia entered its waters. 
It also comes at a time of heightened tensions between Britain and Russia in the airspace over the North Sea and beneath the waves.
Delays in launching submarines from the new fleet, which cost around £1bn each, mean Britain's naval capabilities are having to be bolstered by older ships. 
A senior naval source told the Daily Express: 'The problem with having just one submarine on operations is, if it is deployed to Libya, or East of Suez, it leaves us unable to carry out patrols in the Northern Gap, that area of the North Sea prolific with Russian activity.'
Just two submarines in the Astute class -HMS Astute and HMS Ambush – have so far been handed over to the UK Royal Navy, while the remaining five are in various stages of construction.



But HMS Ambush has yet to launch after 57 operational defects were found. The HMS Astute has briefly returned to port for a short break. 
The Astute class submarines are armed with both Spearfish heavy torpedoes and Tomahawk cruise missiles. The boats have also been equipped with thousands of acoustic tiles to mask any noise as the huge ships plough through the water.
Each of the boats are also equipped with special fins to help them surface through ice caps.
HMS Talent is one of the ships being used to bolster the service but recently returned after being damaged

BAE Systems, the prime contractor in the Astute programme, is the UK's only designer and builder of nuclear powered submarines - one of the most complex engineering programmes in the world today.
To plug the gaps in the service the Royal Navy has been forced to retain four older Trafalgar-class boats.
Two of the 30-year-old ships, Trenchant and Triumph are being refitted while a third, Talent, was forced to return last month because it suffered damage after hitting ice.
The 5,300-ton HMS vessel limped back to port with a huge dent and will be out of action for several months. 
It suffered £500,000 worth of damage while tracking Russian vessels after a 6ft hole was made at the top of the conning tower.
Vanguard submarines are also in operation by the Royal Navy, but these are tasked with Britain's nuclear deterrent and are therefore not available for active operations.

A NEW FLEET OF HUNTER-KILLER SUBMARINES: THE ASTUTE CLASS

Each of the new submarines will cost around £1bn to make.
They have space for 38 weapons to stowed - including Spearfish heavy torpedoes and Tomahawk cruise missiles.
Each will measure 97m (318 ft) in length and weigh 7,400 tonnes.
Almost 40,000 acoustic tiles are placed on the Astute class submarines to mask their noise as they move through water, and make the ships virtually undetectable by enemies.
The Astute Class is being built by BAE Systems and were ordered 15 years ago.
Similarly to the Vanguard class, the ships have space for each member of the crew to have their own bunk.
The ships are fitted with a dry-deck so special forces can deploy while they are submerged.
They can circumnavigate the world without ever surfacing.
Each will have a sonar system so powerful it can detect ships leaving harbour in New York City from a listening point below the waters of the English Channel, 3,000 nautical miles away.

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