NAVYPEDIA

Ships

Name	No	Yard No	Builder	Laid down	Launched	Comp	Fate
Grampus	M56 - N56		Chatham DYd	8.1934	25.2.1936	3/1937	sunk 16.6.1940
Narwhal	M45 - N45		Vickers-Armstrong, Barrow	5.1934	29.8.1935	2/1936	sunk 30.7.1940
Rorqual	M74 - N74		Vickers-Armstrong, Barrow	5/1935	21.7.1936	2/1937	BU 3.1946
Cachalot	M83 - N83		Scotts, Greenock	5.1936	2.12.1937	8/1938	sunk 30.7.1941
Seal	M37		Chatham DYd	12.1936	27.9.1938	5/1939	captured by Germany 30.5.1940 (UB)
P411			Scotts, Greenock	1941	---	---	cancelled 9.1941
P412			Scotts, Greenock	1941	---	---	cancelled 9.1941
P413			Scotts, Greenock	1941	---	---	cancelled 9.1941

Technical data

Max speed, kts, kn	15.75 / 8.75
Displacement standard, t	1520
Displacement normal, t	1810 / 2157
Length, m	89.3
Breadth, m	7.77
Draught, m	5.13
No of shafts	2
Machinery	2 Admiralty diesels / 2 electric motors
Power, h. p.	3300 / 1630
Fuel, t	diesel oil 119 - 147
Endurance, nm(kts)	5880(9.3) / 64(4)
Armament	1 x 1 - 102/40 QF Mk XII, 6 - 533 TT (bow; 12), 50 M3 mines
Electronic equipment	type 129 sonar
Complement	59
Diving depth operational, m	60

Standard scale images

Project history

Unique British purpose-built minelaying submarines. Porpoise was built under the 1930 Programme. Design was created on basis of "Р" class. Saddle-tank submarine had an operational diving depth 60m, maximal depth 95m. Fuel tanks were arranged out of a pressure hull and were welded. Two horizontal mine tubes placed in a superstructure and extended from an aft end in a bow on about 70m.

After a lead boat 5 more were followed (1932-1935 Programmes), built on modified design. They had double-hulled construction similar accepted on Thames class fleet submarines. Hull lines were streamlined to raise speed a little at same engine power. Fuel tanks have placed in a pressure hull, the truth, for it was necessary to pay by reduction of fuel stowage.

Already after a beginning of war, under the "War emergency" Programme it was decided to built 3 more submarines of this class and in January, 1941 even the order has been given out. Soon, however, they were cancelled, as necessity in specialised minelayer has disappeared after appearance of the special mines laid from TTs.

Modernizations

1940s, Rorqual: can carry 12 M2 mines in TT instead of torpedoes

1942 - 1943, Rorqual: + 1 x 1 - 20/70 Oerlikon Mk II/IV, type 286W or type 291W radar

1/1946, Rorqual: 1 x 1 - 102/40 S Mk I, 1 x 1 - 20/70 Mk IIA S/M, 6 - 533 TT, 50 mines, type 286W or type 291W radar, type 129 sonar

Naval service

One submarine, Seal, became the unique British ship which has surrendered to the enemy (4.5.1940 was mined in Skagerrak, badly damaged and surrendered to German patrol ships; subsequently she served in German Navy as UB; she was scuttled 3.5.1945). Grampus was sunk by DCs of Italian torpedo boats Circe and Clio off coast of Sicily 16.6.1940. Narwhal was sunk by German aircraft off coast of Norway 30.7.1940. Cachalot was sunk by ramming of Italian torpedo boat Generale Achille Papa at Bengasi 30.7.1941.