Royal Navy - Type 23 frigates secure the aircraft carriers

TAPS - these are the Royal Navy's Towed Array Patrol Ships, which usually traverse the waters of the North Atlantic for two months at a time. Their task: to protect the strategic submarines of the Vanguard class from potential underwater threats - recognised with the help of their highly sensitive towed array sonars.

The six remaining submarine frigates "Somerset", "Richmond", "Portland", "St Albans", "Sutherland" and "Kent" of the Duke class (Type 23, 133 metres, 4,300 tonnes) will be deployed. They take it in turns to depart from their home port of Devonport/Plymouth and take over the permanent watch for the SSBNs. These patrols form the basis of the British deterrent policy - CASD (Continuous At Sea Deterrent) - but usually remain invisible in the public eye.

Yet these missions are anything but comfortable: "Awfully slow warfare" is what some crew members call the monotonous journey in bad weather between Greenland, the North Cape and the Faroe Islands. Interesting foreign harbours? Not a chance. The ships move slowly, usually in the immediate vicinity of potential enemies, with 1,500 metres of sonar cable in tow.

Despite its age, the Towed Array Sonar Type 2087 with its active and passive capabilities is still one of the best underwater detection systems in the world. Combined with the data from the diving sonar of the ASW Merlin helicopter or an additional MPA (Maritime Patrol Aircraft), a situation picture of impressive range is created.

Although the Type 23 frigate dates back to the 1970s, it has been modernised over the decades and is still suitable for this cold war mission. Its special CODLAG propulsion system (diesel-electric plus gas turbine) ensures a particularly quiet journey. The sound-decoupled diesel generators on the upper deck also contribute to this.

But the tasks are growing: the British carrier group also requires extensive underwater protection - also from Type 23 frigates. At the same time, the Royal Navy is suffering from a shortage of sonar specialists and increasing maintenance costs, as the units are now around 30 years old.

A timely replacement with the new Type 26 U fighter frigates was missed. The last of the urgently needed eight newbuildings is not expected to be delivered before 2035. Until then, the old workhorses will have no breathing space.