HMS Thetis (N25)

HMS Thunderbolt returning from patrol during WWII
History
United Kingdom
Name	HMS Thetis
Builder	Cammell Laird & Co Limited, Birkenhead
Laid down	21 December 1936
Launched	29 June 1938
Fate	Sank during trial dive 1 June 1939 Salvaged and repaired
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Renamed	HMS Thunderbolt
Commissioned	26 October 1940
Fate	Sunk 14 March 1943 in the Mediterranean Sea
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General characteristics
Class and type	T-class submarine
Displacement	1,090 long tons (1,107 t) (surfaced) 1,560 long tons (1,585 t) (submerged)
Length	275 ft (84 m)
Beam	26 ft 6 in (8.08 m)
Draught	12 ft 9 in (3.89 m) forward 14 ft 7 in (4.45 m) (aft)
Installed power	5,000 hp (3,700 kW) (diesel engines) 2,900 hp (2,200 kW) (electric motors)
Propulsion	2 × diesel engines 2 × electric motors 2 × shafts
Speed	15.25 knots (28.24 km/h; 17.55 mph) (surfaced) 9 knots (17 km/h; 10 mph) (submerged)
Range	4,500 nmi (8,300 km; 5,200 mi) at 11 kn (20 km/h; 13 mph)
Test depth	300 ft (91 m)
Complement	59
Armament	6 × internal, forward-facing 21-inch (533 mm) torpedo tubes 4 × external, forward-facing torpedo tubes (6 reload torpedoes) 1 × 4-inch (102 mm) deck gun

HMS Thetis (N25) was a Group 1 T-class submarine of the Royal Navy which sank during sea trials in Liverpool Bay, England on 1 June 1939. After being salvaged and repaired, the boat was recommissioned as HMS Thunderbolt in 1940. It served during the Second World War until being lost with all hands in the Mediterranean on 14 March 1943.^[1]

The Thetis accident happened after the inner hatch on a torpedo tube was opened while the outer hatch to the sea was also open. Four men successfully used the aft escape chamber to reach the surface and be rescued. A total of 99 men died as a result. The sinking led to the redesign of all torpedo tubes on British and Australian submarines. A latch, known as the "Thetis clip", was added to the inner torpedo tube door so it could be fractionally opened to check the tube was not open to the sea before being fully opened.^[2]