HMS Thetis

1939

Liverpool Bay, the tail above the surface Location: Liverpool Bay, Irish Sea · Coordinates: 53.57°N 4.25°W · Casualties: 99 · Survivors: 4 · Depth: 49 m (raised) · Cause: flooded · valve error — On her first dive trials on 1 June 1939. A torpedo tube left flooded during maintenance let the sea into the fore-ends when the inner door was opened. The boat settled stern-up at 49 metres with her tail visible above the surface for nearly twenty-four hours. · Fate: raised · recommissioned as HMS Thunderbolt · Type: submarine · T class · Tonnage: 1,090 tons · Crew: 103 · Flag: United Kingdom · Launched: 1938 British T-class submarine, her first dive trials in Liverpool Bay on 1 June 1939. A torpedo tube left flooded during maintenance let the sea into the fore-ends when opened; she settled stern-up at 49 metres with her tail visible above the surface. 99 of 103 aboard died while rescue ships watched the tail above the waterline; the hull-cutting torches took too long. Raised four months later, recommissioned as HMS Thunderbolt, and lost in the Mediterranean in 1943. The Vessel HMS Thetis was a British T-class submarine of the Royal Navy, built at the Cammell Laird yard at Birkenhead between 1936 and 1939 and launched on 29 June 1938. She was 84 metres long, 1,090 tons surfaced displacement (1,575 tons submerged), and armed with ten 21-inch torpedo tubes (six bow tubes, four external tubes) plus one 4-inch deck gun. Her propulsion was diesel-electric: two 2,500-horsepower diesel engines for surface operation and two 1,450-horsepower electric motors for submerged operation. The T-class was the Royal Navy's standard long-range patrol submarine of the late 1930s and through the Second World War, a class of 53 boats eventually built. Thetis was the third boat of the class to be commissioned; her subsequent operational history was expected to be a standard submarine deployment pattern of the late-1930s Royal Navy: commissioning trials, fleet exercises, and operational patrols in the Atlantic and Mediterranean. Her master on her final voyage was Lieutenant-Commander Guy Bolus, 37, an experienced career submariner. Her complement on the final voyage was 53 Royal Navy crew, 6 Cammell Laird shipyard personnel (present for trial-voyage technical observations), 2 Vickers-Armstrong armament specialists (present for torpedo-tube observations), 2 Admiralty civilian observers, 1 Admiralty's caterer, 1 Liverpool pilot, plus 38 additional observers from the shipyard and Admiralty - a total of 103 aboard, substantially beyond her design complement of 53. The presence The Disaster At approximately 13:45 on 1 June 1939, the No. 5 torpedo tube's inner door was opened by the embarked Vickers-Armstrong armament specialist. The specialist's operational expectation was that the tube was dry; his observation of the blocked drain hole had confirmed this expectation. When the inner door was opened, however, the tube was fully flooded with seawater, and the sudden inrush of seawater under submerged pressure was uncontrollable. The seawater entered Thetis's forward torpedo compartment at a rate of approximately 30 tonnes per minute. The specific consequence was the rapid flooding of the forward end of the submarine; her bow trimmed down; her stern rose; and within approximately three minutes, the submarine's forward third was substantially submerged below the trim angle at which her ballast-tank operations could maintain trim. Lieutenant-Commander Bolus's immediate response was to blow ballast tanks and attempt emergency surfacing. The flooding forward, however, was substantially beyond the ballast tank's compensating capacity. HMS Thetis settled to the Liverpool Bay seabed at approximately 13:52 on 1 June 1939 in approximately 45 metres of water, her bow buried in mud and her stern approximately 10 metres above the seabed angle. Initial rescue operations were initiated within hours: Royal Navy surface ships were sent to the location, salvage vessels were mobilised, and the submarine's position was marked by the emergency surface buoy that Bolus had released. By