Grampus Class Submarines

Beneath the casing ran two rails which stretched the entire length of the casing, except in Porpoise. The mines were stowed on the rails until the time of laying the minefield. The casing had large stern doors which were opened when laying the mines and the mines were strewn through these stern doors.

Original intentions were to build more of this class but with the introduction of a special mine which could be accommodated and laid through the torpedo tubes these never materialised.

Though the new type of mine was developed with the intention of patrol submarines being able to lay minefields this was never the case during WWII and all mine laying was carried out by this class during the duration of WWII.

6 Built

Submarine	Builder	Built
Cachalot	Scotts, Greenock.	1937
Grampus Seal	H.M. Dockyard, Chatham.	1936 - 1938
Narwhal Porpoise Rorqual	Vickers, Barrow-in-Furness.	1935 - 1937

The following were cancelled: P.411, P.412 and P.413 all unnamed.

Technical Information

Displacement (tons):	1,520 sf 2,117 sm Porpoise 1,500 sf 2,053 sm
Length (ft):	293 oa Porpoise 288 oa
Breadth (ft)	25.5 oa Porpoise 29.75 oa
Draught/Height (ft):	15.75 Porpoise 13.75
Machinery:	2 Admiralty x 1,650 bhp diesel engines. 2 Admiralty x 1,630 bhp electric motors. Twin screws.
Speed (kts):	16 kts sf 8.75 kts sm
Oil Supply (tons):	150 tons
Armament:	6 x 21 inch bow tubes. 12 reloads. 1 x 4 inch gun. 2 x Machine guns. 50 mines.
Range:	7,400 nm at 10 kts sf.
Complement:	55 Officers and Ratings.
sm = submerged, sf = surfaced, oa = overall, hp = horsepower, na = not available.

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'Minelayer'

H.M. Submarine Cachalot (Minelayer)

Type:	Grampus (Minelayer) Class
Pennant No.:	84.M N.84
Laid Down:	12th May 1936.	Scotts, Greenock.
Commissioned:	15th August 1938.	Not known at present.
Commander:	1940	Cdr. J.D. Luce.
Complement:	59	Officers and Ratings.
Service Career:	1938-1939. 1939. 1939 1940-1941	Home Fleet (Working Up). Mediterranean. West Indies. Served in Home Waters.
	July/August 1940 - Patrols and minelaying off Biscay ports. 20th August 1940 - Sank the U51 in the Bay of Biscay by tropedo. October 1940 - Minelaying of Norway. 1941 - Served in the Mediterranean at Alexandria. During her war service she laid a total of 300 mines.
Fate:	Rammed by an Italian torpedo boat off Cyrenaica on 4th August 1941.

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'Minelayer'

H.M. Submarine Grampus (Minelayer)

Type:	Grampus (Minelayer) Class
Pennant No.:	56.M N.56
Laid Down:	20th August 1934.	H.M. Dockyard, Chatham.
Commissioned:	10th March 1937.	Not known at present.
Commander:	1940.	Lt. Cdr. C. A. Rowe.
Complement:	59	Officers and Ratings.
Service Career:	1937-1939. 1940 - 1st Flotilla.	China Station. HMS Medway, Alexandria. (At Malta in June 1940).
	Laid a minefield of the Port of Augusta 13th June 1940. During her war service she laid a total of 50 mines.
Fate:	Depth charged by Italian torpedo boat Circe and Clio off Syracuse 24th June 1940 after completing a mine lay off Augusta.

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'Minelayer'

H.M. Submarine Narwhal (Minelayer)

Type:	Grampus (Minelayer) Class
Pennant No.:	45.M N.45
Laid Down:	29th May 1934.	Vickers-Armstrong, Barrow-in-Furness.
Commissioned:	28th February 1936.	Not known at present.
Commander:	1940	Lt. Cdr. R. J. Burch.
Complement:	55	Officers and Ratings.
Service Career:	1940 - 2nd Flotilla.	H.M.S. Forth, Rosyth.
	Laid a minefield of 50 mines North of Laeso Island in the Kattegat, April 1940. It is assumed that the following were sunk by this minefield: 4 trawlers totalling 1,200 tons, Deutschland 432 tons, M.1701 250 tons, M.1702 218 tons, she also sank the Buenos Aires on the 1st May 1940, 6,097 tons. Laid another minefield near the island of Laeso towards the end of April 1940, size not known.
Fate:	Lost cause unknown, off the Norwegian coast on or about 1st August 1940.

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'Minelayer'

H.M. Submarine Rorqual (Minelayer)

Type:	Grampus (Minelayer) Class
Pennant No.:	74.M N.74
Laid Down:	1st May 1935.	Vickers-Armstrong, Barrow-in-Furness.
Commissioned:	10th February 1937.	Not known at present.
Commander:	1940. 1941.	Lt. Cdr. R. H. Dewhurst. Cdr. R. H. Dewhurst.
Complement:	59	Officers and Ratings.
Service Career:	1940 - 1st Flotilla. 1941 - 10th Flotilla.	H.M.S. Medway, Alexandria. (At Malta June 1940) Malta.
	This boat was the most successful of the class, laying a total of 2,284 mines. Participated in the 'Magic Carpet' runs. Sank the Italian submarine Pier Capponi south of Stromboli on 31st March 1941.
Fate:	Sold and scrapped 1946.

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'Minelayer'

H.M. Submarine Seal (Minelayer)

Aerial picture of Seal (possibly from aircraft which forced her to surrender).
This picture and the one below courtesy of Stephen Johnson.

Seal in captivity showing the results of bombing.
Richard Caville covers the capture of seal in more detail.

H.M. Submarine Seal - Crew

Type:	Grampus (Minelayer) Class
Pennant No.:	37.M N.37
Laid Down:	9th December 1936.	H.M. Dockyard, Chatham.
Commissioned:	24th May 1939.	Lt. Cdr. R. P. Lonsdale.
Commander:	1940.	Lt. Cdr. R. P. Lonsdale.
Complement:	59	Officers and Ratings.
Service Career:	1939 - 4th Flotilla. 1940 - 2nd Flotilla.	China Station. (Due to hostilities she returned home before reaching the China Station). H.M.S. Forth, Rosyth.
	Seal was intercepted by enemy aircraft and attacked before being able to lay her mines in the designated area. On reaching the designated minelay area she found anti-submarine trawlers at the position, having been alerted by the aircraft sighting. It was decided to lay the mines in the alternative area. The Germans had gathered more anti-submarine trawlers in Seals area which restricted her movements. Whilst trying to evade the enemy Seal suffered an explosion in her stern. It is believed that she had wandered into an unchartered minefield and hit a mine with her stern. Seals stern sank and buried itself in the mud, it was decided not to attempt to free her until darkness by which time she had been dived for some eighteen hours. All attempts to surface Seal failed until as a last attempt all the crew were ordered to move forward, fortunately this worked and Seal surfaced some twentythree hours after diving. It was intended to make for neutral Sweden, but Seal found her bow pointing towards Denmark and had no means of steering as the rudder had been damaged in the explosion. It was decided that this operation would have to be done with the submarine going astern. Shortly after this decision one of her engines broke down which disabled Seal completely as she was unable to steer with one propellor and no rudder and was only able to move in a circle. Whilst all this was going on Seal was sighted by a German seaplane which attacked her with gunfire and eventually with bombs as did a second seaplane which joined the attack. Seal attempted to defend herself with her Lewis guns but to no avail. She was continuously hit by cannon-shell which punctured one of the port ballast tanks making her take on a heavy list to port, her remaining engine at this time decided it had enough and also stopped. Now finding herself totally helpless steps were taken to make sure that nothing of a confidential nature would fall into enemy hands. Seal was fitted with two depth charges in her bilges which were set to explode at 50 feet if the boat was flooded. Lonsdales concern was that if the boat sank before the crew were rescued the boat would explode killing them in the water, on the other hand if the boat was taken in tow he was convinced that she would sink before being docked or beached. He decided that he could not risk the lives of his crew and decided to surrender. Seal was taken in tow to Frederikshavn where she was repaired sufficiently enough to make the trip to Germany. She reached Germany by 11th May and was commissioned in the German Navy in 1941. At his court martial after the war Lt. Cdr. Lonsdale was honourably acquitted. Accounted for the following vessels which were sunk by mines. Vogesen 4,240 tons , Aimy 200 tons, Skandia 1,248 tons all on the 4th May 1940.
Fate:	Mined in the Kattegat 4th May 1940, surrendered and later put into service by the German Navy as UB, scuttled at Kiel in May 1945, salved and scrapped.

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