Ha-201-class submarine

At the end of 1944, the Imperial Japanese Navy decided it needed large numbers of high-speed coastal submarines to defend the Japanese Home Islands[2] against an anticipated Allied invasion (named Operation Downfall by the Allies). To meet this requirement, the Ha-201-class submarines were designed as small, fast submarines[2] incorporating many of the same advanced ideas implemented in the German Type XXI and Type XXIII submarines. They were capable of submerged speeds of almost 14 knots (26 km/h; 16 mph).[2]

The Ha-201 class displaced 325 metric tons (320 long tons) surfaced and 447 metric tons (440 long tons) submerged.[2] The submarines were 53 meters (173 ft 11 in) long, had a beam of 4.00 meters (13 ft 1 in) and a draft of 3.44 meters (11 ft 3 in).[2] For surface running, the submarines were powered by a single 400-brake-horsepower (298 kW) diesel engine that drove one propeller shaft.[2] When submerged the propeller was driven by a 1,250-shaft-horsepower (932 kW) electric motor.[2] They could reach 11.8 knots (21.9 km/h; 13.6 mph) on the surface and 13.9 knots (25.7 km/h; 16.0 mph) submerged.[2] On the surface, the Ha-201-class submarines had a range of 3,000 nautical miles (5,600 km; 3,500 mi) at 10 knots (19 km/h; 12 mph); submerged, they had a range of 105 nmi (194 km; 121 mi) at 2 knots (3.7 km/h; 2.3 mph).[2] Their armament consisted of two 533-millimeter (21 in) torpedo tubes with four torpedoes and a single mount for a 7.7-millimeter machine gun.[2]

The Japanese planned to build 79 Ha-201-class submarines (Submarines No. 4911 through 4989) under the Maru Sen Programme, prefabricating large sections of the boats, then completing them on the slipway. This was an ambitious goal considering the U.S. bombing campaign, which disrupted Japanese production, and by the time hostilities ceased on 15 August 1945 the Japanese had laid down only 22 submarines[2] and completed only ten.[2]

None of the submarines made operational patrols.[2] Except for one submarine that was wrecked, the Allies after the war scuttled all the submarines that had been completed as well as all the incomplete ones that had been launched. Those which remained on the building ways at the end of the war were scrapped incomplete.

Comparable submarines

• German Type XXIII submarine
• I-201 class submarine
• Vessel Number 71
• Kairyū-class submarine

• "Rekishi Gunzō"., History of Pacific War Vol.17 I-Gō Submarines, Gakken (Japan), January 1998, ISBN 4-05-601767-0
• Rekishi Gunzō, History of Pacific War Extra, "Perfect guide, The submarines of the Imperial Japanese Forces", Gakken (Japan), March 2005, ISBN 4-05-603890-2
• The Maru Special, Japanese Naval Vessels No.43 Japanese Submarines III, Ushio Shobō (Japan), September 1980, Book code 68343-43
• The Maru Special, Japanese Naval Vessels No.132 Japanese Submarines I "Revised edition", Ushio Shobō (Japan), February 1988, Book code 68344-36
• Ships of the World special issue Vol.37, History of Japanese Submarines, "Kaijinsha"., (Japan), August 1993