T7
a black and white photograph of a small ship underway
T7's sister ship, T3. The only significant external difference was that T7 had two funnels.
History
Austria-Hungary
Name96 F
BuilderGanz & Danubius
Laid down24 February 1915
Launched7 July 1916
Commissioned23 November 1916
Out of service1918
FateAssigned to the Kingdom of Serbs, Croats and Slovenes
Kingdom of Yugoslavia
NameT7
AcquiredMarch 1921
Out of serviceApril 1941
FateCaptured by Italian Royal Navy
Italy
NameT7
AcquiredApril 1941
Out of serviceSeptember 1943
Independent State of Croatia
NameT7
AcquiredSeptember 1943
FateRun aground by British MTBs on 24 June 1944 and then destroyed
General characteristics
Class and type250t-class, F-group sea-going torpedo boat
Displacement
  • 243.9 t (240 long tons)
  • 267 t (263 long tons) (full load)
Length58.76 m (192 ft 9 in)
Beam5.84 m (19 ft 2 in)
Draught1.5 m (4 ft 11 in)
Installed power
Propulsion
Speed28–29 kn (52–54 km/h; 32–33 mph)
Range1,200 nmi (2,200 km; 1,400 mi) at 16 kn (30 km/h; 18 mph)
Complement41
Armament

T7 was a sea-going torpedo boat operated by the Royal Yugoslav Navy between 1921 and 1941, after spending World War I in Austro-Hungarian Navy service. Originally 96 F, she was a 250t-class torpedo boat, and saw active service during World War I, performing convoy, patrol, escort and minesweeping tasks, and anti-submarine operations. Following Austria-Hungary's defeat in 1918, 96 F was allocated to the Navy of the Kingdom of Serbs, Croats and Slovenes, which later became the Royal Yugoslav Navy, and was renamed T7. 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, T7 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 handed over by the Germans to the Navy of the Independent State of Croatia. She was driven aground by British motor torpedo boats in June 1944 and destroyed by the British Army to prevent her salvage.

Background

In 1910, the Austria-Hungary Naval Technical Committee initiated the design and development of a 275-tonne (271-long-ton) coastal torpedo boat, specifying that it should be capable of sustaining 30 knots (56 km/h; 35 mph) for 10 hours.[1][2] At the same time, the committee issued design parameters for a high seas or fleet torpedo boat of 500–550 t (490–540 long tons), top speed of 30 kn and endurance of 480 nautical miles (890 km; 550 mi). This design would have been a larger and better-armed vessel than the existing Austro-Hungarian 400-tonne (390-long-ton) Huszár-class destroyers.[3] 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 Navy (German: kaiserliche und königliche Kriegsmarine, Hungarian: Császári és Királyi Haditengerészet) 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.[2] Despite having developed these ideas, the Austro-Hungarian Navy then asked shipyards to submit proposals for a 250 t (250-long-ton) boat with a maximum speed of 28 kn (52 km/h; 32 mph).[1] 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.[2] The F-group designation signified the location of Ganz & Danubius' main shipyard at Fiume.[4]

Description and construction

The 250t-class F-group boats had short raised forecastles and an open bridge, and were fast and agile, well designed for service in the Adriatic.[5] They had a waterline length of 58.76 metres (192 ft 9 in), a beam of 5.84 m (19 ft 2 in), and a normal draught of 1.5 m (4 ft 11 in). While their designed displacement was 243.9 t (240 long tons), they displaced 267 tonnes (263 long tons) fully loaded.[6] The boats were powered by two AEG-Curtis steam turbines driving two propellers, using steam generated by two Yarrow water-tube boilers,[2] one of which burned fuel oil and the other coal.[4] There were two boiler rooms, one behind the other.[7] The turbines were rated at 5,000 shaft horsepower (3,700 kW) with a maximum output of 6,000 shp (4,500 kW) and were designed to propel the boats to a top speed of 28–29 kn (52–54 km/h; 32–33 mph).[6] They carried 20.2 tonnes (19.9 long tons) of coal and 31 tonnes (30.5 long tons) of fuel oil, which gave them a range of 1,200 nautical miles (2,200 km; 1,400 mi) at 16 kn (30 km/h; 18 mph).[7] The F-group had two funnels rather than the single funnel of the T-group.[2] 79 T 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.[1][8] The naval historian Zvonimir Freivogel states that this type of situation was common due to the parsimony of the Austro-Hungarian Navy.[1] They were the first small Austro-Hungarian Navy boats to use turbines, and this contributed to ongoing problems with them,[2] which had to be progressively solved once they were in service.[5] The crew consisted of three officers and thirty-eight enlisted men.[9] The vessel carried one 4 m (13 ft) yawl as a ship's boat.[10]

The boats were armed with two Škoda 66 mm (2.6 in) L/30[lower-alpha 1] guns, with the forward gun mounted on the forecastle, and the aft gun on the quarterdeck.[7] A 40 cm (16 in) searchlight was mounted above the bridge.[12] They were also armed with four 450 mm (17.7 in) torpedo tubes mounted in pairs, with one pair mounted between the forecastle and bridge, and the other aft of the mainmast.[7] They could also carry 10–12 naval mines.[4]

96 F was the second-to-last of its group to be completed, and was laid down on 24 February 1915, launched on 7 July 1916 and completed on 23 November of that year.[13] Prior to her commissioning, one 8 mm (0.31 in) Schwarzlose M.7/12 machine gun was included in the armament of all boats of the class 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.[14]

Career

World War I and the interwar period

During World War I, 96 F was used for convoy, patrol, escort and minesweeping tasks, and anti-submarine operations.[2] In 1917, one of the 66 mm (2.6 in) guns on each boat of the class was placed on an anti-aircraft mount.[4] On the night of 11 May 1917, the Huszár-class destroyer Csikós, accompanied by 96 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 Wildfang and Csikós, along with 96 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.[15]

96 F survived the war intact.[2] 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, she was allocated to the Kingdom of Serbs, Croats and Slovenes (KSCS, later Yugoslavia). Along with three other 250t-class F-group boats, 87 F, 93 F and 97 F, and four 250t-class T-group boats, she was transferred in March 1921 to the Navy of the KSCS, which later became the Royal Yugoslav Navy (Serbo-Croatian Latin: Kraljevska Jugoslovenska Ratna Mornarica, KJRM).[16] Renamed T7 in KJRM service,[4] she and the other seven 250t-class boats were, at the outset, the only modern sea-going vessels in the KJRM.[17] In 1925, exercises were conducted off the Dalmatian coast, involving the majority of the navy.[18] In May and June 1929, six of the eight 250t-class torpedo boats – including T7 – accompanied the light cruiser Dalmacija, the submarine tender Hvar and the submarines Hrabri and Nebojša, on a cruise to Malta, the Greek island of Corfu in the Ionian Sea, and Bizerte in the French protectorate of Tunisia.[19] The ships and crews made a very good impression while visiting Malta.[20] In 1932, the British naval attaché reported that Yugoslav ships engaged in few exercises, manoeuvres or gunnery training due to reduced budgets.[21]

World War II

Map of the Independent State of Croatia showing the location of Murter Island

In April 1941, Yugoslavia entered World War II when it was invaded by the German-led Axis powers. At the time of the invasion, T7 was assigned as the flagship of the 3rd Torpedo Division located at Šibenik, which included her three F-group sisters.[22] 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 (Zadar) on the Dalmatia 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.[23] 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.[24] All four F-group boats, including T7, were captured by the Italians.[25]

T7 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 76 mm (3 in) L/40 anti-aircraft guns,[26] but no other significant alterations were made to her.[27] The Italians capitulated in September 1943, and once under German control, T7 was handed over to the Navy of the Independent State of Croatia, serving under her Yugoslav designation. Her crew came under the influence of the Yugoslav Partisans, and were preparing to mutiny when the Germans intervened.[2][28] On 24 June 1944, she and the German S-boats S 154 and S 157 of the 7th S-Boat Flotilla were sailing between Šibenik and Rijeka, protecting German sea supply routes along the Adriatic, when they were attacked by the Royal Navy Fairmile D motor torpedo boats MTB 659, MTB 662 and MTB 670 near the island of Kukuljari, south of Murter Island.[29] Considering T7 one of the few significant threats to British vessels in the region, the British commander ordered MTB 670 to launch a torpedo attack. The two torpedoes missed, so the MTBs pursued and approached the ship from abaft the beam. T7 opened fire at 150 yards (140 m). The MTBs returned fire with their forward and port guns, and within 30 seconds they had disabled T7's weapons and set her ablaze. At a speed of about 12 knots (22 km/h; 14 mph), T7 suddenly veered starboard, narrowly avoiding a collision with MTB 662 (it is not known whether her steering was damaged or if her crew was attempting to perform a ram) before running aground on Murter Island.[30] The MTBs rescued 21 crew.[29] The British crews later examined the wreck, capturing five more sailors and leaving her flooded and burning. A British Army demolition team destroyed the hulk to ensure it could not be salvaged.[30]

Notes

  1. ↑ L/30 denotes the length of the gun's barrel. In this case, the L/30 gun is 30 calibre, meaning that the barrel was 30 times as long as the diameter of its bore.[11]

Footnotes

  1. 1 2 3 4 Freivogel 2022, p. 60.
  2. 1 2 3 4 5 6 7 8 9 Gardiner 1985, p. 339.
  3. ↑ Freivogel 2022, p. 59.
  4. 1 2 3 4 5 Greger 1976, p. 58.
  5. 1 2 Freivogel 2020, p. 102.
  6. 1 2 Freivogel 2022, p. 70.
  7. 1 2 3 4 Freivogel 2020, p. 115.
  8. ↑ O'Hara, Worth & Dickson 2013, pp. 26–27.
  9. ↑ Freivogel 2020, p. 103.
  10. ↑ Freivogel 2022, p. 65.
  11. ↑ Friedman 2011, p. 294.
  12. ↑ Freivogel 2022, pp. 64–65.
  13. ↑ Greger 1976, p. 60.
  14. ↑ Freivogel 2022, p. 67.
  15. ↑ Cernuschi & O'Hara 2016, p. 67.
  16. ↑ Vego 1982, p. 345.
  17. ↑ Chesneau 1980, p. 355.
  18. ↑ Jarman 1997a, p. 733.
  19. ↑ Adriatic Guard 1930.
  20. ↑ Jarman 1997b, p. 183.
  21. ↑ Jarman 1997b, p. 451.
  22. ↑ Niehorster 2016.
  23. ↑ Terzić 1982, p. 333.
  24. ↑ Terzić 1982, p. 404.
  25. ↑ Greger 1976, pp. 58 & 60.
  26. ↑ Brescia 2012, p. 151.
  27. ↑ Chesneau 1980, p. 304.
  28. ↑ Chesneau 1980, p. 357.
  29. 1 2 Paterson 2015, p. 223.
  30. 1 2 Reynolds 2009, Chapter 7.

References

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  • Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. London: Conway Maritime Press. ISBN 978-0-85177-146-5.
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