Yugoslav torpedo boat T6

T6 was a sea-going torpedo boat that was operated by the Royal Yugoslav Navy between 1921 and 1941, after spending World War I in Austro-Hungarian Navy service. Originally 93 F, she was a 250t-class torpedo boat built in 1915–1916. She saw active service during World War I, performing convoy, escort, patrol and minesweeping tasks, and anti-submarine operations. Following Austria-Hungary's defeat in 1918, "93 F" was allocated to the Navy of the Kingdom of Serbs, Croats and Slovenes, which later became the Royal Yugoslav Navy, and was renamed "T6". At the time, she and the seven other 250t-class boats were the only modern sea-going vessels of the fledgling maritime force. 
During the interwar period, "T6" and the rest of the navy were involved in training exercises and cruises to friendly ports, but activity was limited by reduced naval budgets. The ship was captured by the Italians during the German-led Axis invasion of Yugoslavia in April 1941. After her main armament was modernised, she served with the Royal Italian Navy under her Yugoslav designation, conducting coastal and second-line escort duties in the Adriatic. Following the Italian capitulation in September 1943, she was scuttled by her crew as she had insufficient fuel on board to reach an Allied port.
Background.
In 1910, the Austria-Hungary Naval Technical Committee initiated the design and development of a coastal torpedo boat, specifying that it should be capable of sustaining for 10 hours. This specification was based an expectation that the Strait of Otranto, where the Adriatic Sea meets the Ionian Sea, would be blockaded by hostile forces during a future conflict. In such circumstances, there would be a need for a torpedo boat that could still sail from the Austro-Hungarian Navy (, ) base at the Bocche di Cattaro (Bay of Kotor) to the Strait during the night, locate and attack blockading ships and return to port before morning. Steam turbine power was selected for propulsion, as diesels with the necessary power were not available, and the Austro-Hungarian Navy did not have the practical experience to run turbo-electric boats. Stabilimento Tecnico Triestino (STT) of Trieste was selected for the contract to build the first eight vessels, designated as the T-group. Another tender was requested for four more boats, but when Ganz & Danubius reduced their price by ten per cent, a total of sixteen boats were ordered from them, designated the F-group. The F-group designation signified the location of Ganz & Danubius' main shipyard at Fiume. "93 F" was the seventh boat of the F-group to be fully completed.
Description and construction.
The 250t-class F-group boats had a waterline length of , a beam of , and a normal draught of . While their designed displacement was , they displaced about fully loaded. The crew consisted of 38–41 officers and enlisted men. The boats were powered by two AEG-Curtiss steam turbines driving two propellers, using steam generated by two Yarrow water-tube boilers, one of which burned fuel oil and the other coal. The turbines were rated at with a maximum output of and designed to propel the boats to a top speed of . They carried of coal and of fuel oil, which gave them a range of at . The F-group had two funnels rather than the single funnel of the preceding T-group. Due to inadequate funding for a more robust design, "96 F" and the rest of the 250t class were essentially coastal vessels, despite the original intention that they would be used for "high seas" operations. The 250t-class were the first small Austro-Hungarian Navy boats to use turbines, and this contributed to ongoing problems with them.
The boats were armed with two Škoda L/30 guns, and four torpedo tubes. They could also carry 10–12 naval mines. Laid down on 9 January 1915, "93 F" was launched on 25 November 1915 and completed on 16 April 1916.
Career.
World War I and interwar period.
During World War I, "93 F" was used for convoy, patrol, escort and minesweeping tasks, and anti-submarine operations. On 3 May 1916, "93 F" and five other 250-class torpedo boats were accompanying four destroyers when they were involved in a surface action off Porto Corsini against an Italian force led by the flotilla leaders "Cesare Rossarol" and "Guglielmo Pepe". On this occasion the Austro-Hungarian force retreated behind a minefield with no damage to the torpedo boats, and only splinter damage to one of the destroyers. In 1917, one of her 66 mm guns was placed on an anti-aircraft mount. On the night of 11/12 May 1917, the , along with "93 F" and two other 250t-class boats, were pursued in the northern Adriatic by an Italian force of five destroyers, but were able to retire to safety behind a minefield. On 3 June, the destroyers and "Csikós", along with "93 F" and another 250t-class boat, had a brief encounter with three Italian MAS boats off the mouth of the Tagliamento River in the far north of the Adriatic. The boat survived the war intact.
In 1920, under the terms of the previous year's Treaty of Saint-Germain-en-Laye by which rump Austria officially ended World War I, "93 F" was allocated to the Kingdom of Serbs, Croats and Slovenes (KSCS, later Yugoslavia). Along with three other 250t-class F-group boats, "87 F", "96 F" and "97 F", and four 250t-class T-group boats, she served with the Royal Yugoslav Navy (, KJRM; ). Taken over in March 1921, in KJRM service, "93 F" was renamed "T6". When the navy was formed, she and the other seven 250t-class boats were the only modern sea-going vessels in the KJRM. In 1925, exercises were conducted off the Dalmatian coast, involving the majority of the navy. In May–June 1929, six of the eight 250t-class torpedo boats accompanied the light cruiser "Dalmacija", the submarine tender "Hvar" and the submarines and , on a cruise to Malta, the Greek island of Corfu in the Ionian Sea, and Bizerte in the French protectorate of Tunisia. It is not clear if "T6" was one of the torpedo boats involved. The ships and crews made a very good impression on the British while visiting Malta. In 1932, the British naval attaché reported that Yugoslav ships engaged in few exercises, manoeuvres or gunnery training due to reduced budgets.
World War II.
In April 1941, Yugoslavia entered World War II when it was invaded by the German-led Axis powers. At the time of the invasion, "T6" was assigned to the 3rd Torpedo Division located at Šibenik, which included her three former F-group sisters. On 8 April, the four boats of the 3rd Torpedo Division, along with other vessels, were tasked to support an attack on the Italian enclave of Zara on the Dalmatian coast. They were subjected to three Italian air attacks and, after the last one, sailed from the area of Zaton into Lake Prokljan, where they remained until 11 April. On 12 April, the 3rd Torpedo Division arrived at Milna on the island of Brač, and refused to follow orders to sail to the Bay of Kotor. All four F-group boats were then captured by the Italians.
"T6" was then operated by the Italians under her Yugoslav designation, conducting coastal and second-line escort duties in the Adriatic. Her guns were replaced by two L/40 anti-aircraft guns, but no other significant alterations were made to her. After the Italians capitulated in September 1943, in order to avoid her falling into German hands "T6" was scuttled by her crew north of Rimini on 11 September as she had insufficient fuel on board to reach an Allied port.