The Type 423 Oste class are purpose built signals intelligence (SIGINT/ELINT) and reconnaissance ships of the German Navy.^[1] Officially designated as "fleet service ships", they replaced the Type 422 class.

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Quick Facts Class overview, General characteristics ...

A52 Oste in 2006
Class overview
Builders	Flensburger Schiffbau-Gesellschaft, Flensburg
Operators	German Navy
Preceded by	Type 422 class
Succeeded by	Type 424 class
In commission	1988–present
Completed	3
Active	3
General characteristics
Displacement	3,200 tonnes
Length	83.5 m (273 ft 11 in)
Beam	14.6 m (47 ft 11 in)
Draught	4.2 m (13 ft 9 in)
Propulsion	2 diesel engines, 3,300 kW (4,400 hp) each
Speed	21 knots (39 km/h)
Range	More than 5,000 nautical miles (9,300 km)
Complement	36 + up to 40 mission specialists
Sensors and processing systems	ELINT/COMINT sensors
Electronic warfare & decoys	Electronic countermeasures[specify]
Armament	None

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The Oste-class ships were designed as reconnaissance units during the Cold War. From the 1990s, the tasks were expanded to early warning and telecommunications reconnaissance in cooperation with other units of German and international armed forces. Civil officers of BND are working on the ships on a regular basis.

Accommodation for the crew was designed to meet civil standards, and the Oste class offers much more comfort for the crew than other ships in the German Navy.

The ships are set to be replaced from 2027-2029 when the new Type 424 is planned to come into service.^[2] The three new ships will cost €3.3 billion (2023).

The ships were built at Flensburger Schiffbau-Gesellschaft in Flensburg.

All ships are currently based in Eckernförde and belong to the 1st Ubootgeschwader (1st Submarine Squadron) stationed in Eckernförde. The vessels received the same name and pennant numbers as the three Type 422 class vessels they replaced. To avoid the confusion, the ship names are sometimes suffixed with II.

Oker (A53) was reportedly spotted near the Syrian coast in August 2012.^[3] Later she was seen in Greenwich, UK in February 2017^[4]

In June 2021, the Bundestag approved the development and procurement of three fleet service boats as well as a training and reference reconnaissance facility (ARAA) for sea-based signal detection reconnaissance (ssA). As the main contractor, Lürssen was commissioned to develop the systems by February 2023. All services should be completed by 2029. The first of the three boats is scheduled to be put into service in 2027 and will mark the replacement of the fleet service boats Oker, Alster and Oste, which have been in use for over 30 years.^[5]

The new building increased in price from 2.1 billion euros to 3.3 billion euros (2023).^[5][6]