T6 was a sea-going torpedo boat that was operated by the Royal Yugoslav Navy between 1921 and 1941. Originally 93 F, a 250t-class torpedo boat of the Austro-Hungarian Navy built in 1915–1916, she was armed with two Škoda guns and four torpedo tubes and could carry 10–12 naval mines. She saw active service during World War I, performing convoy, escort, patrol and minesweeping tasks, as well as anti-submarine operations. In 1917 the suffixes of all Austro-Hungarian torpedo boats were removed, and thereafter she was referred to as 93.
Following Austria-Hungary's defeat in 1918, 93 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 boat 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 Sea. Immediately 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. At the same time, the committee issued design parameters for a high seas or fleet torpedo boat of , top speed of 30 kn and endurance of . This design would have been a larger and better-armed vessel than the existing Austro-Hungarian s. The specification for the high seas torpedo boat was based on 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 sail from the Austro-Hungarian naval base at the Bocche di Cattaro (the Bocche or 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.
Despite having developed these ideas, the Austro-Hungarian Navy then asked shipyards to submit proposals for a boat with a maximum speed of . Stabilimento Tecnico Triestino (STT) of Triest 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.
Description and construction
The F-group boats had short raised forecastles and an open bridge and were fast and agile, well designed for service in the Adriatic. They had a waterline length of , a beam of , and a normal draught of . While their designed displacement was , they displaced fully loaded. The boats were powered by two AEG-Curtis steam turbines driving two propellers, using steam generated by two Yarrow water-tube boilers, one of which burned fuel oil and the other coal. There were two boiler rooms, one behind the other. The turbines were rated at with a maximum output of and were 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 T-group. The crew consisted of three officers and thirty-eight enlisted men. The vessel carried one yawl as a ship's boat.
93 F and the rest of the 250t class were classified as high seas torpedo boats by the Austro-Hungarian Navy, despite being smaller than the original concept for a coastal torpedo boat. The naval historian Zvonimir Freivogel states that this type of situation was common due to the parsimony of the Austro-Hungarian Navy. The 250t class were the first small Austro-Hungarian Navy boats to use turbines, and this contributed to ongoing problems with them, which had to be progressively solved once they were in service.
The boats were armed with two Škoda L/30 guns, with the forward gun mounted on the forecastle and the aft gun on the quarterdeck. A searchlight was mounted above the bridge. They were also armed with four torpedo tubes mounted in pairs, with one pair mounted between the forecastle and bridge and the other aft of the mainmast. One Schwarzlose M.7/12 machine gun was carried for anti-aircraft work. Four mounting points were installed so that the machine gun could be mounted in the most effective position depending on the expected direction of attack. The boat could also carry 10–12 naval mines.
The fifth of the F-group to be completed at Ganz-Danubius' main shipyard at Fiume, 93 F was laid down on 9 January 1915, launched on 25 November and commissioned on 4 April 1916.
Career
World War I The original concept of operation for the 250t-class boats was that they would sail in a flotilla at the rear of a cruising battle formation and were to intervene in fighting only if the battleships around which the formation was established were disabled, or to attack damaged enemy battleships. When a torpedo attack was ordered, it was to be led by a scout cruiser, supported by two destroyers to repel any enemy torpedo boats. A group of four to six torpedo boats would deliver the attack under the direction of the flotilla commander. 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 without damage. On 12 June, 93 F and her M-group sisters 98 M and 99 M were tasked to search for the and two small torpedo boats after they had attacked the town of Parenzo on the west Istrian coast, but the Italian ships escaped unharmed, apart from Zeffiro which was damaged in an attack by seaplanes. On 12 and 13 July, 93 F conducted trials with new smoke generators. On 29 October, she underwent repairs at the main Austro-Hungarian naval base at Pola in the northern Adriatic.
In 1917, one of 93 Fs 66 mm guns may have been placed on an anti-aircraft mount. According to Freivogel, sources vary on whether these mounts were added to all boats of the class, and on whether these mounts were added to the forward or aft gun. In March, the noted inventor Dagobert Müller von Thomamühl was in command of the boat with the rank of . At this time, 93 F was allocated to the 7th Torpedo Boat Group of the 5th Torpedo Division. On 11 May 1917, the British submarine stalked 78 T off Pola, missing her with two torpedoes. In response, 93 F, 96 F and 78 T, accompanied by the Huszár-class destroyer , unsuccessfully pursued H1. On 21 May, the suffix of all Austro-Hungarian torpedo boats was removed, and thereafter they were referred to only by the numeral. Also in May, 93 conducted several minesweeping missions. On 3–4 June, 93, along with 96 as well as Csikós and her sister ships and , were returning from a seaplane support mission when Wildfang struck a mine and sank, with 93 assisting with the rescue of her surviving crew. On 11 July, 93 was transferred south from Pola to the Bocche. On 23 September, she was patrolling near the mouth of the Bojana River that marks the border between Montenegro and Albania, when an unidentified Allied submarine fired a torpedo at her, but it passed under her hull without exploding. During 1917, 93 conducted further minesweeping missions and escorted 36 convoys.
On 1 February 1918, a mutiny broke out among the sailors of some vessels of the Austro-Hungarian Navy at the Đenovići anchorage within the Bocche, largely over poor food, lack of replacement uniforms and supplies, and insufficient leave, although the poor state of the Austro-Hungarian economy and its impact on their families was also a factor. In response, the three pre-dreadnought battleships of the 3rd Division were despatched from Pola to the Bocche the following day to put down the rebellion, and 93 was part of their escort. In the event, the mutiny had been suppressed before they arrived, and 93 returned to Pola with the battleships soon after. On 22 April, 93 was part of an escort for the dreadnoughts and when they sailed to the Fasana Channelbetween the Brijuni Islands and the Istrian Peninsulafor gunnery practice. 93 escorted the minelayer while she laid a minefield on 22 July. On 11 August, 93, along with her sisters 78 and 80, the destroyer and the submarine chasers and , were despatched to chase the Italian submarine which had sunk the steamship Euterpe off the island of Pag but had to terminate the pursuit due to poor weather. Two days later she joined the vessels of the anti-submarine flotilla in a hunt, but despite claims of success, no enemy submarine was sunk. On 20 August, 93 was transferred to the Bocche and was part of the 1st Torpedo Flotilla. On 29 September, 93 along with 82, 87 and 96 plus the s , and , laid mines in the Bay of Drim off northern Albania. During 1918, 93 also performed 55 more convoy escorts. As the end of the war approached in November the Austro-Hungarian Empire broke apart. On 1 November 1918, 93 was ceded to the State of Slovenes, Croats and Serbs. This was a short-lived fragment of the empire which united with the Kingdom of Serbia and Kingdom of Montenegro on 1 December, becoming the Kingdom of Serbs, Croats and Slovenes (from 1929, the Kingdom of Yugoslavia).
Interwar period The Austro-Hungarian Empire sued for peace in November 1918, and 93 survived the war intact. Immediately after the Austro-Hungarian capitulation, French troops occupied the Bocche, which was treated by the Allies as Austro-Hungarian territory. During the French occupation, the captured Austro-Hungarian Navy ships moored at the Bocche were neglected, and 93s original torpedo tubes were destroyed or damaged by French troops. 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 was allocated to the Kingdom of Serbs, Croats and Slovenes. Along with 87, 96 and 97, and four 250t-class T-group boats, she served with the Royal Yugoslav Navy (, KM; Краљевска Морнарица). Transferred in March 1921, in KM service, 93 was renamed T6. When the navy was formed, she and the other seven 250t-class boats were its only modern sea-going vessels. New torpedo tubes of the same size as originally fitted were ordered from the Strojne Tovarne factory in Ljubljana. In KM service T6 was rearmed with a single Bofors L/60 gun, and was also fitted with two Zbrojovka machine guns. Her crew was increased to 52, and she was commissioned in 1923.