T4 was a seagoing torpedo boat operated by the Royal Yugoslav Navy between 1921 and 1932. Originally 79 T, a 250t-class torpedo boat of the Austro-Hungarian Navy built in 1914, she was armed with two guns, four torpedo tubes, and could carry 10–12 naval mines. She saw active service during World War I, performing convoy, patrol, escort and minesweeping tasks, anti-submarine operations and shore bombardment missions. In 1917 the suffixes of all Austro-Hungarian torpedo boats were removed, and thereafter she was referred to as 79. Present in the Bocche de Cattaro during the short-lived mutiny by Austro-Hungarian sailors in early February 1918, her crew remained loyal. She was part of the escort force for the Austro-Hungarian dreadnought during the action that resulted in the sinking of that ship by Italian torpedo boats in June 1918.
Following Austria-Hungary's defeat in 1918, 79 was allocated to the Navy of the Kingdom of Serbs, Croats and Slovenes, which later became the Royal Yugoslav Navy, and was renamed T4. 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, T4 and the rest of the navy were involved in training exercises and cruises to friendly ports, but activity was limited by reduced naval budgets. In 1932, she ran aground on the Dalmatian coast and became a total loss.
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 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 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 Triest was selected for the contract to build eight vessels, the T group, ahead of one other tenderer. The T-group designation signified that they were built at Triest.
Description and construction
The , T-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 about fully loaded. The crew consisted of three officers and thirty-eight enlisted men. The boats were powered by two Parsons 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 and designed to propel the boats to a top speed of , although a maximum speed of could be achieved. They carried of coal and of fuel oil, which gave them a range of at . The T group had one funnel rather than the two funnels of the later groups of the class, and had a large ventilation cowl under the bridge and another smaller one aft of the funnel. Due to an inadequate budget, 79 T and the rest of the 250t class were essentially large coastal vessels, despite the original intention that they would be used for "high seas" operations. They 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 originally to be armed with three Škoda L/30 guns, and three torpedo tubes, but this was changed to two guns and four torpedo tubes before the first boat was completed, to standardise the armament with the F group to follow. The torpedo tubes were mounted in pairs, with one pair mounted between the forecastle and bridge, and the other on a section of raised superstructure above the aft machinery room. They could also carry 10–12 naval mines. The sixth of its class to be completed, 79 T was laid down on 1 December 1913, launched on 30 April 1914 and completed on 30 September 1914, two months after World War I began. Later that year, one machine gun was added for anti-aircraft work.