F-29 Class Minelayer:
Following the requirements of the Rearmament Bills passed by Morimoto's Governments, a new class of large multipurpose Minelayers (that could also act as netlayers and escorts in some extent) emerged in the late 30's as a modified and improved design of the older F-13 and F-16 classes. Known as the fusetsukan-29 class, from the pennant number of the lead unit. The class was ordered at first as a group of three. Stretched to a length of 110,1m the were 11,8m abeam and drafted 4m, displacing 2.531T at full load. Pushed by oil-firing boilers driving two screws they could made 20knots and had a range of 6.000 nautical miles at 16knots. Capacity-wise, they could carry 360 mines or 260 mines and 24 510m anti-submarine nets. Fitted with an hydrophone, they also carried twenty depth charges for escort roles. This last planned secondary task led them to be equipped with two single 76mm guns, leaving them woefully underarmed for their size, especially when compared to the half-siblings of the preceding F-13 and F-16 classes which sported 120 and 140mm barrels. For anti-air defence they also carried two twin 25mm machine guns. The three ships, F-29, F-30 and F-35, were laid down between 1938 and 1940 and commissioned between 1939 and 1941.
For the entire duration of the war, the ships were stationed in the Aleutians, laying mines or escorting convoys in and out of the archipelago. In 1944 all were refitted with radars, new hydrophones and extra machine guns (eight triple and six single 25mm, for a total of 30), had lower deck portholes sealed and an arctic dazzle camouflage painted. None recieved the improved Kokoan or Thiarian radars and all three were soon out of the war: F-29 was torpedoed and sunk by an American submarine, F-30 sunk in an air Raid and F-35 damaged beyond repair after being torpedoed as well. Never repaired F-35 was left in Attu to act as a floating AA platform and was ultimately decommissioned and scrapped just after the end of the war.
Just after the start of the Pacific War, a second batch of three units was ordered, named F-49, F-54 and F-60. The first was laid down in 1943 and commissioned by late 1944. Compared to the earlier batch, the new ships had a straigther stem to ease construction, improved sonar and hydrophones, a longer forecastle, no portholes on the lower hull and radars fitted since completion. More strikingly, they replaced the whimpy 76mm guns with three 127mm ones, one shielded mount on the forecastle and a twin unshielded mount aft. Anti-air armament was made up by six triple and four single 25mm machine guns for a total of 22 barrels. No anti-submarine nets were embarked but depth charge complement was increased to 48 warheads by also slightly reducing the number of mines carried.
F-54 was commissioned in early October 1945, sporting a further improved radar suite and the new twin 40mm/Type5 machine guns (reverse-engineering of captured Bofors). The ship carried 10 twin and two single mounts for 22 barrels, plus five more single of the older 25mm types. With the mines carried further reduced F-54 could easily carry as high as 80 depth charges. She had her hull painted blue and the superstructure filled with green patches for camouflage.
F-49 was bombed and sunk during one of the american air raids on Shirominato during Koko uprisings, while F-60 -whih had been laid down in early 1945- was never completed and scrapped on the ways after the war.
F-54, the only survivor of the class, was renamed Mirai in 1947 after Koko no Kaigun was reorganized into Koko Kaijou. During the years, she recieved somemodifications, with the addition of US-built electronics. The aft 127mm mount was also removed and the aft deckhouses covered with a landing platform for helicopters. All wartime light anti-aircraft was removed and replaced by four twin 40mm bofors and three twin 20mm oerlikons. The rest of the portholes on the hull were sealed.
Mirai was finally decommissioned in late 1953, after the end of the Korean War. She remained in the mothball fleet until 1970, when she was finally scrapped.
Ships in class: (laid down-launched-commissioned - fate)
F-29 1938-1939-1939 - Sunk 1945
F-30 1939-1940-1940 - Sunk 1945
F-35 1940-1941-1941 - Decommissioned 1946
F-49 1943-1944-1944 - Sunk 1946
F-54 1944-1945-1945 - Renamed Mirai 1947, Decommissioned 1953
F-60 1945-/-/ - not completed