Japan 1926-46: I-56, 57, 59, 60, 61 large oceanic submarines. The Kaidai IIIb type (海大IIIb型, Navy large type IIIb) or I-56/156-class followed the design of the KD3a with strengthened hulls. They were a further development of the Kaidai type strongly influenced by German U-Kreuzer designs, especially U-139. I56 at berth, colorized by Irookoto JR Development … Read more
Japan 1926-46: I-53, 54, 55, 58, large oceanic submarines. The Kaidai IIIa type (海大IIIa型, Navy large type IIIa) or I-153-class followed the design of the KD1 and KD2 but with strengthened hulls. Four were built: I-53/I-153 (survived the war, sank in 1946 Operation Bottom) I-54/I-154 (scuttled by gunfire Operation Bottom), I-55/I-155 (scuttled by gunfire, Operation … Read more
Japan 1925-42: I-152. large oceanic submarines. The Type KD-2 (伊号第五十二潜水艦, I-go dai-go-jyuni sensuikan) or Kaidai-II (“navy large type”) was the second largest Japanese submarine design, part of a lineage going to the KD-VII or I-76 class, from 1921 to 1943. Albeit two were planned initially, the second, N°64, was re-planned as a KD-IIIa, leaving the … Read more
Japan 1921-40: I-51, large oceanic submarine. The Type KD1 (海大型潜水艦, Kaidai-gata sensuikan) or Kaidai-I (“navy large type”, or I-51 class) was the largest Japanese submarine design, the first of a lineage that went until the KD-VII or I-76 class. This serie ran from 1921 to 1943. The very first boat of the first class was … Read more
Japan 1922-24: RO-60 to RO-68 Here is the next big lineage for 2026-27: IJN submarines. First entry: The L class. The last were still active in WW2: The Type L4 (L4型（呂六十型）, Ro-roku-jū-gata, Ro-60-class) were a license production model of the British L class, submarine Group 3. The IJN was quite satisfied with them and stopped … Read more
