| Displacement | 665t surface, 1000t submerged |
|---|---|
| Length | 74.2m oa |
| Width | 6.1m |
| Draught | 3.7m |
| Machinery | 2-shaft diesel/electric motor, 1200bhp surface, 1200shp submerged |
| Speed | 13kt surface, 8kt submerged |
| Armament | 4-53cm TT, 1-12cm/45cal gun, 1-7.7mm MG |
| Complement | 43 |
| Name | Plan | Builder | Laid down | Launch | Complete | ||
|---|---|---|---|---|---|---|---|
| Ro-29 (SS-68) | FY1918 | Kawasaki, Kobe | 1921. 6. 2 | 1922.12. 5 | 1923. 9.15 | SS2 (SS-68) | 1924.11. 1 renamed(Ro-29) 1936. 4. 1 disc |
| Ro-30 (SS-69) | FY1918 | Kawasaki, Kobe | 1921. 6.27 | 1923. 1.18 | 1924. 4.29 | SS2 (SS-69) | 1924.11. 1 renamed(Ro-30) 1942. 4. 1 disc 1945 BU |
| Ro-31 (SS-70) | FY1918 | Kawasaki, Kobe | ? 1924.12.20 (laid down) | (1923. 2) 1926. 9.25 | (1923. 8.21 lost incomplete by accident) 1927. 5.10 | SS2 | 1945. 5.25 disc 1946. 4. 5 scuttled |
| Ro-32 (SS-71) | FY1918 | Kawasaki, Kobe | 1921.10.24 | 1923. 3.19 | 1924. 5.31 | SS2 (SS-71) | 1924.11. 1 renamed(Ro-32) 1942. 4. 1 disc 1945 BU |