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Grampus-class submarine
HMS Porpoise-1-.jpg
Class overview
Name: Grampus-class submarine
Preceded by: River class
Succeeded by: T class
Completed: Six
General characteristics
Type: Submarine
Displacement: 1,768 tons (Porpoise), 1,810 tons (others) surfaced
2,035 tons (Porpoise), 2,157 tons (others) submerged
Length: 289 ft (88 m) (Porpoise), 293 ft (89 m) (others)
Beam: 29 ft 10 in (9.09 m) (Porpoise), 25 ft 6 in (7.77 m) (others)
Draught: 15 ft 10 in (4.83 m) (Porpoise), 16 ft 10 in (5.13 m) (others)
Propulsion: 2 shaft, Diesel (3300 hp) plus electric (1630 hp)
Speed: 15.5 knots surfaced
8.75 knots submerged
Complement: 59

6 x 21 in torpedo tubes (bow)
12 torpedoes
1 x QF 4-inch (101.6 mm) Mk XII deck gun

50 mines

The Grampus-class submarines were a group of minelaying submarines built for the Royal Navy in the late 1930s. These boats are sometimes referred to as the Porpoise class from the single prototype, HMS Porpoise built in 1932. Five boats to a modified design were built between 1936 and 1938. The ships were all named after marine mammals.


The mines were stored in a special "gallery" with a conveyor belt built into the outer casing as pioneered by the converted M-class submarine HMS M3. These boats were of a saddle tank type.


They were used extensively in the Mediterranean, particularly to supply the besieged island of Malta in a service nicknamed the "magic carpet".

Only one, HMS Rorqual, survived the war.

Boats in class

Ship Builder Launched Fate
HMS Porpoise (N14) Vickers, Barrow 30 August 1932 Sunk by Japanese aircraft in the Malacca straits, 16 January 1945.
HMS Grampus (N56) Chatham Dockyard 25 February 1936 Sunk by Italian torpedo boats Circe and Clio off Sicily 16 June 1940.
HMS Narwhal (N45) Vickers, Barrow 29 August 1935 Sunk 30 July 1940 by German aircraft near Norway.
HMS Rorqual (N74) Vickers, Barrow 21 July 1936 Arrived Newport to be broken up 17 March 1946.
HMS Cachalot (N83) Scotts 2 December 1937 Sunk by Italian torpedo boat Papa off Cyrenaica 30 July 1941.
HMS Seal (N37) Chatham Dockyard 27 September 1938 Captured by the Germans in the Kattegat 4 May 1940 after sustaining mine damage, commissioned as the UB, scuttled 3 May 1945, but later raised and scrapped.

See also


Coordinates: 37°05′N 17°30′E / 37.083°N 17.5°E / 37.083; 17.5

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