SM UB-8 - Bulgarian Career

Bulgarian Career

Upon acceptance of UB-8 by the Bulgarian Navy, she was renamed Podvodnik No. 18 (in Cyrillic: Пoдвoдник №18). Although the commissioning ceremony for Podvodnik No. 18 was kept out of newspapers, it was attended by Crown Prince Boris and his brother Prince Kiril, who both boarded the submarine for a ceremonial first voyage to Euxinograd, the Bulgarian summer palace located just north of Varna. In Bulgarian service, the submarine was armed with a 47-millimeter (1.9 in) deck gun that supplemented its machine gun.

Podvodnik No. 18's first patrol under the Bulgarian flag took place on 4 and 5 July 1916 when she sailed to Cape Shabla and Mangalia. The submarine was used for reconnaissance and coastal defense, and patrolled a regular route. This route was a loop that began in Varna and went northward to Kaliakra, Mangalia, and Constanţa; then southward to Burgas, and Sozopol; then ended at Varna. On 6 September, she had an encounter with the Russian destroyers Bystry and Gromki, drove off Russian submarines on other occasions, and on 16 December helped turn back a Russian sortie against Balchik. After the Russian withdrawal from World War I in 1917, Podvodnik No. 18's activities were greatly reduced.

After the end of the war, Podvodnik No. 18 was surrendered to the French on 23 February 1919. Towed to Bizerta, she was scrapped after August 1921.