Type 4 Ka-Tsu
A Ka-Tsu on display
Type	Amphibiousarmored personnel carrier
Place of origin	Empire of Japan
Production history
Designed	1942–1943
No. built	49[1]
Specifications
Mass	16 tons[1]
Length	11 m
Width	4 m
Height	2.25 m
Crew	5
Armor	10 mm[1]
Main armament	2x torpedoes[2]
Secondary armament	2x 13 mm machine guns[1]
Engine	gasoline (petrol) in a water-tight pressure box 62 HP
Power/weight	3 HP/1 ton
Suspension	-
Operational range	-
Maximum speed	(sea) 5 knots

Thespecial Type 4 LaunchKa-Tsu (特四式内火艇 カツ,toku-yon-shiki uchibitei Ka-Tsu) was a Japaneseamphibiouslanding craft ofWorld War II. The first prototype was completed in late 1943 and trials were conducted offKure in March 1944.

Japan's combat experience in theSolomon Islands in 1942, which revealed the difficulty of resupplying Japanese forces in such situations, prompted the IJN to commence an amphibious tractor program in 1943, as the Ka-Tsu.^[3]

The Ka-Tsu's primary purpose was to transport cargo and/or troops ashore.^[2] It had light armored shielding with a maximum of 10 mm.^[1] Its engine compartment and electric final drives were hermetically sealed, as it was intended to be launched from a submarine.^[3] The twin drive propeller shafts were designed to retract "into their ducts" once the vehicle reached the beach.^[2]

The first prototype was completed in late 1943 and trials were conducted offKure in March 1944.^[3] By the time development had been completed, it was proposed that the Ka-Tsu be used to attack US battleships anchored in atolls (such asUlithi), which could not readily be attacked using conventional means. It was proposed that a Ka-Tsu armed with a pair of navalType 93 torpedoes^[4] be dropped off by submarine away from theatoll, propel itself to the outer reef using its tracks, and then enter the lagoon on the inside of the reef.^[3] Tests were successfully carried out with a modified Ka-Tsu carrying two torpedoes on the submarine deck.^[3] A total of 49 units were produced.^[1]

In May 1944, the submarinesI-36,I-38,I-41,I-44 andI-53 and the auxiliary submarine tenderTsukushi Maru began training in the Seto Inland Sea offNasakejima for OperationTatsumaki ("Tornado"), which called for the submarines to transport modified Ka-Tsu's, each armed with two torpedoes, from Kure to Majuro.^[5][6] After the submarines launched the Ka-Tsu's, the operation called for the tracked vehicles to proceed to shore, moving overland across the atoll's, then enter the water of thelagoon and attack Allied ships with the torpedoes.^[5][6] The war ended before any such mission could be mounted and the Ka-Tsu deployed in combat.^[3]

• 
  Type 4 Ka-Tsu with machine guns mounted
• 
  Rear-side angle view of Type 4 Ka-Tsu
• 
  Two Type 4 Ka-Tsu with torpedoes on the deck of a IJN submarine

• Blockade Runner
• Type 3 submergence transport vehicle
• Ha-101 class submarine

• Tomczyk, Andrzej (2003).Japanese Armor Vol. 3. AJ Press.ISBN 978-8372371287.
• Zaloga, Steven J. (2007).Japanese Tanks 1939–45. Osprey Publishing.ISBN 978-1-8460-3091-8.

• Taki's Imperial Japanese Army Page - Akira Takizawa

• World War II armoured fighting vehicles of Japan
• Imperial Japanese Navy
• Landing craft
• Tractors
• Amphibious vehicles of World War II
• Tracked amphibious vehicles
• Amphibious military vehicles
• Military vehicles of Japan
• Blockades of World War II
• Mitsubishi
• Military vehicles introduced from 1940 to 1944
• Armoured personnel carriers of WWII
• Tracked armoured personnel carriers

• Articles with short description
• Short description is different from Wikidata
• Articles containing Japanese-language text