Oste-class fleet service ship

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

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. The three new ships will cost €3.3 billion (2023).

List of ships
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. Later she was seen in Greenwich, UK in February 2017

Replacement
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.

The new building increased in price from 2.1 billion euros to 3.3 billion euros (2023).