A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to 6 or 8, with little or no on-board living accommodation. Midget submarines normally work with mother ships, from which they are launched and recovered, and which provide living accommodation for the crew and other support staff.

Both military and civilian midget submarines have been built. Military types work with surface ships and other submarines as mother ships. Civilian and non-combatant military types are generally called submersibles, and normally work with surface ships.

Most early submarines, such as the United States Navy's USS Holland and the British Royal Navy's Holland 1, would now be considered midget submarines.

Military submarines

Uses

The best known role for midget submarines is probably harbour penetration, although only two World War Two boats, the British X-craft and the unsuccessful Welman submarine were specifically designed with this in mind. Japan's Ko-hyoteki class submarines were originally designed to take part in decisive fleet actions. However, as circumstances changed, they ended up tasked with harbour penetration. Germany’s various World War II designs were mostly designed to attack Allied shipping off landing beaches and harbours, although the Seehund had a great enough range to attack shipping off the Thames estuary.

Midget submarines have also seen some use in support roles. X-craft were used for reconnaissance, and the Seehund was used to carry supplies. A number of modern midget submarines have also been built for submarine rescue.

Armament

Midget submarines are commonly armed with torpedoes and mines. Alternatively, they may carry timed explosive charges.

Types by nation

Belgium

• FNRS-2 pioneering research submersible

Colombia

• Narco submarine for smuggling

Finland

• MIR for research and submarine rescue

France

• FNRS-4 second generation research submersible
• Nautile research submersible to depth of 6 kilometers

France also acquired a number of German midget submarines at the end of WW2.

Germany

Most German midget submarines were developed late in World War II in a attempt to stop the Allied invasion of Europe and used later to disrupt its supply lines. As a result, the submarines mostly engaged in open water attacks rather than harbour penetration.

• Biber (324 built by AG Weser of Bremen)
• Delphin (2 built) 2-man 5-ton torpedo with top speed of and submerged radius of at .
• Hai prototype of improved Marder.
• Hecht type XXVIIA 2-man 12 ton submarine with 1 mine or 1 torpedo carried outboard to a range of 38 miles at 4 knots.
• Marder (~300 built) similar to Neger with breathing apparatus to allow submerged operation.
• Molch
• Neger (~200 built) 1-man 5-ton torpedo with underslung G7E torpedo. Top speed 20 knots and range of 30 miles at 3 knots.
• Seehund type XXVIIB
• V.80 4-man 76-ton prototype completed in 1940 to test Walther geared turbine propulsion system. Range was at .

Iran

• Ghadir
• Nahang

Italy

• Siluro a Lenta Corsa (SLC) low speed torpedo chariot
• Bathyscaphe Trieste was first to explore the Challenger Deep of the Mariana Trench
• CA type First series was a 2 man midget submarine the second series carried a crew of three.
• CB type 45 ton 4 man design first introduced in 1941
• CE2F/X100 post-war torpedo chariot
• SX404 a 70 ton submarine design. 4 were sold to Columbia and 4 to Taiwan in the 1970s.

Japan

• Type A Ko-hyoteki-class midget submarines were used in the 1942 Attack on Sydney Harbour and the 1941 attack on Pearl Harbor, in which the type 97 torpedo was used operationally. One of these five midget submarines was shot and sunk by the USS Ward as it was spotted trying to enter Pearl Harbor. The wreckage of the submarine was located by NOAA's Hawaii Undersea Research Laboratory (HURL) in August 2002. Photographic analysis conducted by the United States Naval Institute in 1999 indicates one of the five Ko-hyoteki-class submarines managed to enter Pearl Harbor, and successfully fired a torpedo into the USS West Virginia. The submarine's final resting place is unknown.
  
• Type B Midget Ha 45 prototype built 1942 to test Type A improvements.
• Type C Midget Ha 62-76 similar to Type A with crew of 3 and radius increased to at surfaced or at submerged.
• Type D Koryu (115 completed) improved Type C with crew of 5 and radius increased to 1000 miles at 8 knots surfaced and 320 miles at 16 knots submerged.
• Kairyu class submarine
• Kaiten Submarine suicide torpedo.
• DSV Shinkai research submersible to a depth of 6.5 kilometers.

North Korea

• Yugo class submarine

Poland

• Błotniak

Russia

• In the late 19th century Russia built a class of treadle powered submarines 4.5 meters in length designed by Stefan Drzewiecki they were withdrawn from service in 1886.

Spain

• SA-40 of the Foca class
• SA-50 of the Tiburón class

United Kingdom

The Royal Navy has used a number of midget submarines. Most were developed during WW2. The decommissioning of the Stickleback class marked the end of Midget submarines designed for combat in the Royal Navy.

• Stickleback class A post world war 2 development of the XE class.
• X class were used to attack German warships in the North of Norway. One notable target of a successful attack was the battleship Tirpitz. The submarines had a crew of three (plus a diver) and carried two large mine containing Amatol – one on each side. Their strategy was to lay mines on the sea bottom beneath the target, set a time fuse, and exit.
• XE class were used in the Far East, where they carried out a number of attacks and special missions.
• Welman submarine was a single person submersible widely considered a failure.

United States

• Aluminaut
• DSV Alvin (DSV-2)
• DSRV-2 Avalon
• DSRV-1 Mystic
• Nemo (DSV-5)
• DSV Sea Cliff (DSV-4) of the Alvin class
• Bathyscaphe Trieste II (DSV-1)
• DSV Turtle (DSV-3) of the Alvin class
• X-1 Submarine

Yugoslavia

• Una class. After the Yugoslav Wars, both Croatia and Serbia held examples.

See also

• Submersible
• Human torpedo
• Royal Navy Submarine Museum
• Wet sub

Notes

1. Lenton, H.T. GERMAN WARSHIPS of the Second World War Arco Publishing (1976) pp.285-286
2. Taylor, J.C. German Warships of World War II Doubleday & Company (1967) p.109
3. Taylor, J.C. German Warships of World War II Doubleday & Company (1967) p.110
4. Lenton, H.T. GERMAN WARSHIPS of the Second World War Arco Publishing (1976) p.212
5. Watts, Anthony J. Japanese Warships of World War II Doubleday & Company (1967) p.213
6. Watts, Anthony J. Japanese Warships of World War II Doubleday & Company (1967) p.216