Key facts
- Three of the UK's four nuclear-armed submarines are currently at sea.
- The Vanguard-class submarines carry Britain's nuclear deterrent, Trident missiles.
- Crews often spend five months or more on patrol.
Three of the UK's four nuclear-armed submarines are currently at sea, according to the Royal Navy. These Vanguard-class submarines are responsible for carrying Britain's nuclear deterrent, the Trident missile system. Crews on these submarines often spend five months or more on patrol, a significant increase compared to their predecessors. Former Royal Navy submariner Commander (Ret'd) Roger Ireland noted that patrols for the Resolution-class boats, which carried the Polaris missile system, were typically eight weeks long. He described the longer patrols of today's submarines as 'horrendous' due to the lack of contact with families.