ORP Sep was launched on 17.X.1938, in Rotterdamsche Droogdok Maatschappij N.V. in Rotterdam, under command of cmdr. Wladyslaw Salmon. In the beginning of 1939 the pace of works with Sep was slowed probably because of activity of German spies.
So on 16.IV.1939 boat was "kidnapped" by Poles and under escort of destroyer Burza she safely sailed into Gdynia port.
|Sep when building in R.D.M.|
After break out of the war Sep sailed into operational area. On 2.IX.1939 she spotted German destroyer Friedrich Ihn and fired one torpedo, which failed to hit the target. After unsuccessful attack Sep was bombed by German destroyer and slightly damaged. Next day on 3.IX.1939 Sep was attacked by German U-boot U 14 (cmdr. Horst Wellner). One torpedo fired by Germans exploded to soon and didn't damaged Polish ship. On 8.IX.1939 ship was moved further to the North, near the coasts of Gotland. Because of bad mental state of crew and damages, on 17.IX.1939 she was interned in Stavnas (Sweden). During the war Sep was kept in Mariefred until the end of war.
After the war Sep was returned to People's Polish Navy on 5.IX.1945. Until the December of 1946 ship was staying in dock in repairs. The 105 mm gun was replaced by Russian 100 mm gun (which was later in 1958 removed). In the beginning of 1949 ship received new tactical number "B-11" which was in 1955 changed to "P-11". In 1964 Sep took part in drills in Atlantic Ocean with submarine Orzel II. Ship was decommissioned on 15.IX.1969 and two years later scrapped.