:: J CLASS (1915-1917) ::

J class attack submarine (1915-1917) High resolution picture

The J class was a small series of attack submarines built for the Royal Navy between 1915 and 1917, as a response to the mistaken claims about the German development of submarines which should be fast enough to operate alongside a surface fleet. The British Admiralty stated that the submarines of the new class should reach a speed of 20 knots while in surface. Other requirements were an increased operational range and a more powerful radio-transmitter, for the devices installed in the D and E classes had a range of only 50 miles. The projectists faced a problem when designing the propulsion plant: the Diesel engines available then would be not powerful enough to satisfy the requirements, if using a conventional layout with two engines and two propellers. There was not better solution than to install three 12-cylinder engines and three propellers. This provided a speed in surface of about 19 knots, rendering these submarines as the fastest of their time. Besides, the hull was notably narrow and relatively devoid of external elements.

Albeit larger and more powerful than previous classes of British submarines, the J class could not keep up with the expectatives of operating in conjunction with surface warships. This was not only because the actual speed did not reach the original requirements, but also because this kind of role was not really appropriate for the submarine weapon, which had been created primarily for surprise attacks. Therefore these submarines operated during war time in their habitual role. However the power of their electric motors, which were confined into the reduced space of the two outer shafts, was somewhat subpar if compared with that of the E class, the widest family of British submarines on the World War I era.

The wartime record of the J class comprised two battleships damaged and one submarine sunken. The submarine J6 was sunk during the war by friendly fire from a "mystery ship" (a heavily armed merchant ship intended to lure enemy submarines to the surface). The other six units survived the war and were sold to the Royal Australian Navy. They were decommissioned in 1922 and sunk or scuttled in subsequent years.

J class: 7 units (J1 to J7)

Type: Attack submarine

Length: 84 meters

Beam: 7 meters

Draught: 4.3 meters

Displacement (surfaced): 1210 tonnes

Displacement (submerged): 1760 tonnes

Propulsion: 3 x shaft, 3 x Diesel engine Vickers 1200 horsepower, 2 x electric motor 675 horsepower

Speed (surfaced): 19 knots (35 kilometers/hour)

Speed (submerged): 9.5 knots (17.5 kilometers/hour)

Range (surfaced): 5000 nautical miles (9260 kilometers) at 12.5 knots

Range (submerged): N/A

Test depth: 91 meters

Complement: 45

Armament: 6 x 457-millimeter torpedo tube (4 at prow, 2 in transverse), 12 x torpedo, 1 x 102-millimeter deck cannon, 1 x 76-millimeter deck cannon

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