The B class was an enlarged and improved version of the preceding A class. The submarines had a length of 142 feet 3 inches (43.4 m) overall, a beam of 12 feet 7 inches (3.8 m) and a mean draft of 11 feet 2 inches (3.4 m). They displaced 287 long tons (292 t) on the surface and 316 long tons (321 t) submerged. The B-class submarines had a crew of two officers and thirteen ratings.[1]
For surface running, the boats were powered by a single 16-cylinder 600-brake-horsepower (447 kW) Vickerspetrol engine that drove one propeller shaft. When submerged the propeller was driven by a 180-horsepower (134 kW) electric motor. They could reach 12 knots (22 km/h; 14 mph) on the surface and 6.5 knots (12.0 km/h; 7.5 mph) underwater.[1] On the surface, the B class had a range of 1,000 nautical miles (1,900 km; 1,200 mi) at 8.7 knots (16.1 km/h; 10.0 mph).[2]
The boats were armed with two 18-inch (450 mm)torpedo tubes in the bow. They could carry a pair of reload torpedoes, but generally did not as they would have to remove an equal weight of fuel in compensation.[3]
B4 collided with a dredger when entering Portsmouth harbour on 21 July 1906 and was badly damaged as a result, having to be beached before being taken into dry dock for repair.[5] When the war began in 1914, the boat was assigned to defend the Straits of Dover. B4 was sold for breaking up on 1 April 1919 to the Ardrossan Dry Dock Co.
^Harrison, A. N. (2018) [1979, London: Ministry of Defence]. "Appendix I: List of RN Submarines in the 1901 to 1936 Programmes"(PDF). BR3043: The Development of British Submarines: From Holland No. 1 (1901) to HMS Porpoise (1930). RN Subs: Website of the Barrow Submariners Association. Retrieved 25 March 2018.
^"Naval Matters—Past and Prospective: Portsmouth Dockyard". The Marine Engineer and Naval Architect. Vol. 29. 1 September 1906. p. 41.
References
Akermann, Paul (2002). Encyclopaedia of British Submarines 1901–1955 (reprint of the 1989 ed.). Penzance, Cornwall: Periscope Publishing. ISBN1-904381-05-7.
Gardiner, Robert & Gray, Randal, eds. (1985). Conway's All the World's Fighting Ships 1906–1921. Annapolis, Maryland: Naval Institute Press. ISBN0-85177-245-5.
Kemp, Paul & Jung, Peter (1989). "Five Broken Down B Boats: British Submarine Operations in the Northern Adriatic 1915–1917". Warship International. XXVI (1): 10–29. ISSN0043-0374.
Wilson, Michael (1981). "The British 'B' Class Submarine". In Roberts, John (ed.). Warship Volume V. London: Conway Maritime Press. pp. 38–44, 74–79. ISBN0-85177-244-7.