HMS R4

R-class submarine
History
Name:	HMS R4
Builder:	Chatham Dockyard, Kent
Laid down:	4 March 1917
Launched:	8 June 1918
Commissioned:	23 August 1919
Nickname(s):	"The Slug"
Fate:	Sold, 26 May 1934
General characteristics
Class and type:	R-class submarine
Displacement:	410 long tons (417 t) surfaced 503 long tons (511 t) submerged
Length:	163 ft 9 in (49.91 m)
Beam:	15 ft 3 in (4.65 m)
Draught:	11 ft 6 in (3.51 m)
Installed power:	240 bhp (180 kW) (diesel) 1,200 hp (890 kW) (electric)
Propulsion:	1 × diesel engine 1 × electric motor
Speed:	9.5 knots (17.6 km/h; 10.9 mph) surfaced 15 knots (28 km/h; 17 mph) submerged
Range:	2,400 nmi (4,400 km; 2,800 mi) at 9 knots (17 km/h; 10 mph) surfaced; 60 nmi (110 km; 69 mi) at 5 knots (9.3 km/h; 5.8 mph) submerged
Test depth:	150 feet (45.7 m)
Complement:	2 officers and 20 ratings
Sensors and processing systems:	Bow hydrophone array
Armament:	6 × bow 18-inch (45 cm) torpedo tubes

HMS R4 was one of 10 R-class submarine built for the Royal Navy during the First World War. The boat was not completed before the end of the war and was sold for scrap in 1934.

Design and description

The R-class submarine was designed to meet an Admiralty requirement for a specialised hunter-killer submarine with an emphasis on submerged performance. The boats had a length of 163 feet 9 inches (49.9 m) overall, a beam of 15 feet 3 inches (4.6 m) and a mean draft of 11 feet 6 inches (3.5 m). They displaced 410 long tons (420 t) on the surface and 503 long tons (511 t) submerged. The R-class submarines had a crew of 2 officers and 20 ratings.^[1] They had a diving depth of 150 feet (45.7 m).^[2]

For surface running, the boats were powered by a single eight-cylinder ^[3] 240-brake-horsepower (179 kW) diesel engine that drove the single propeller shaft. When submerged it was driven by a 1,200-horsepower (895 kW) electric motor. They could reach 9.5 knots (17.6 km/h; 10.9 mph) on the surface and 15 knots (28 km/h; 17 mph) underwater. On the surface, the R class had a range of 2,400 nautical miles (4,400 km; 2,800 mi) at 9 knots (17 km/h; 10 mph) and 60 nmi (110 km; 69 mi) at 5 knots (9.3 km/h; 5.8 mph) submerged.^[4]

The boats were armed with six 18-inch (45 cm) torpedo tubes in the bow. They carried six reload torpedoes for a grand total of a dozen torpedoes. They were equipped with an array of five hydrophones in the bow to allow them to locate and engage targets while submerged.^[4]

Construction and career

HMS R4 was laid down on 4 March 1917 at Chatham Dockyard, launched on 8 June 1918 and commissioned on 23 August 1919. She came too late to see any combat in World War I, like most of the other R-class submarines. Her shape resulted in her being nicknamed "The Slug".^[5]

On 1 November 1926, R4 ran aground at Exmouth, Devon, England. She was refloated 10½ hours later.^[6]

R4 was the only boat to survive through to the 1930s. Additions to her casing produced slightly better sea keeping at the cost of a reduced speed from 15 knots submerged to 13 knots. She was used as a fast underwater target at the Portland anti-submarine school until 1934, then sold on 26 May 1934 to Young, Sunderland.

Notes

1. Gardiner & Gray, p. 93
2. Harrison, Chapter 19
3. Harrison, Chapter 25
4. Harrison, Chapter 10
5. Tall, J.J; Paul Kemp (1996). HM Submarines in Camera An Illustrated History of British Submarines. Sutton Publishing. p. 71. ISBN 0-7509-0875-0.
6. "Submarine aground". The Times (44421). London. 5 November 1926. col A, p. 16.

References

• Akermann, Paul (2002). Encyclopaedia of British Submarines 1901–1955 (reprint of the 1989 ed.). Penzance, Cornwall: Periscope Publishing. ISBN 1-904381-05-7.
• Colledge, J. J.; Warlow, Ben (2006) [1969]. Ships of the Royal Navy: The Complete Record of all Fighting Ships of the Royal Navy (Rev. ed.). London: Chatham Publishing. ISBN 978-1-86176-281-8. OCLC 67375475.
• Gardiner, Robert & Gray, Randal, eds. (1984). Conway's All the World's Fighting Ships: 1906–1921. Annapolis, Maryland: Naval Institute Press. ISBN 0-85177-245-5.
• Harrison, A. N. (January 1979). "The Development of HM Submarines From Holland No. 1 (1901) to Porpoise (1930) (BR3043)". Submariners Association: Barrow in Furness Branch. Retrieved 19 August 2015.