The escort vessels (in German called "Flottenbegleiter") F1 - F10 could be described with a single word: Failure.
In the early 1930s the group of ten escort vessels was build. Since those ships should not only have used as fast escort ships but also as fast mine-sweepers, submarine hunter and test beds for the new high-pressure destroyer engines, too much was out into this small design.
The result was a very bad designed ship with a totally unreliable engine system that spend long times in shipyards for repair. As a result, the Flottenbegleiter were almost never seen in operational action and were transferred for several different secondary tasks. Some were used as fleet tenders, some for training Uboat crews.
As the number of engine breakdowns increased to not tolerable level in the later years of the war, the ships were taken out of action. Only one of them, the F9
, was lost through enemy actions, when it was hit by an torpedo of the British submarine Ursula in December 1939 and sunk within 3 minutes.
A successor class of "Schnelle Flottenbegleiter" - fast escort vessels - was planned but never realized. To close the gap of desperately needed escorts, several captured ships (French and Dutch) in combination with destroyers, torpedo boats and mine hunters were used for this task, especially in the British Channel and French waters.