A group of A-class submarines
History
United Kingdom
Name	A11
Builder	Vickers, Sons & Maxim Ltd. Barrow-in-Furness
Laid down	1903
Launched	8 March 1905
Commissioned	11 July 1905
Fate	Scrapped, May 1920
General characteristics
Class and type	A-class submarine
Displacement	190 long tons (193 t) surfaced 206 long tons (209 t) submerged
Length	105 ft (32.0 m)
Beam	12 ft 9 in (3.9 m)
Draught	10 ft 8 in (3.3 m)
Installed power	600 bhp (450 kW) (petrol engine) 150 hp (110 kW) (electric motor)
Propulsion	1 × 16-cylinder Wolseley petrol engine 1 × electric motor
Speed	11 knots (20 km/h; 13 mph) surfaced 6 knots (11 km/h; 6.9 mph) submerged
Range	500 nautical miles (930 km; 580 mi) at 10 kn (19 km/h; 12 mph) surfaced
Complement	2 officers and 9 ratings
Armament	2 × 18-inch (45 cm) torpedo tubes

HMS A11 was an A-class submarine built for the Royal Navy in the first decade of the 20th century. After surviving World War I, she was sold for scrap in 1920.

Design and description

A11 was a member of the first British class of submarines, although slightly larger, faster and more heavily armed than the lead ship, HMS A1. The submarine had a length of 105 feet 1 inch (32.0 m) overall, a beam of 12 feet 9 inches (3.9 m) and a mean draft of 10 feet 8 inches (3.3 m). They displaced 190 long tons (190 t) on the surface and 206 long tons (209 t) submerged. The A-class submarines had a crew of 2 officers and 9 ratings.^[1]

For surface running, the boats were powered by a single 16-cylinder 600-brake-horsepower (447 kW) Wolseley petrol engine that drove one propeller shaft. When submerged the propeller was driven by a 150-horsepower (112 kW) electric motor. They could reach 11 knots (20 km/h; 13 mph) on the surface and 6 knots (11 km/h; 6.9 mph) underwater.^[1] On the surface, A11 had a range of 500 nautical miles (930 km; 580 mi) at 10 knots (19 km/h; 12 mph); submerged the boat had a range of 30 nautical miles (56 km; 35 mi) at 5 knots (9.3 km/h; 5.8 mph).^[2]

The boats were armed with two 18-inch (45 cm) torpedo tubes in the bow. They could carry a pair of reload torpedoes, but generally did not as doing so that they had to compensate for their weight by removing an equal weight of fuel.^[3]

Construction and career

A11 was ordered as part of the 1903–04 Naval Programme from Vickers.^[4] She was laid down at their shipyard in Barrow-in-Furness in 1903, launched on 8 March 1905 and completed on 11 July 1905.^[2]

On 7 September 1910 A11 collided with a barge when leaving Portsmouth Harbour. The barge was sunk, although her two crew were rescued, and A11's bow was slightly damaged.^[5] In February 1913, A11 was one of three submarines based at Lamlash on the Isle of Arran off the west coast of Scotland.^[6]