| Displacement | 689t surface, 1047t submerged |
|---|---|
| Length | 60.5m pp, 65.6m oa |
| Width | 6.1m |
| Draught | 4.2m |
| Machinery | 2-shaft diesel/electric motor, 2800bhp surface, 1200shp submerged |
| Fuel | oil 58.4t |
| Speed | 13kt surface, 8kt submerged |
| Range | 3500nm by 10kt surface, 75nm by 4kt submerged |
| Armament | 5-45cm TT, 1-7.7mm MG |
| Complement | 43 |
| Name | Plan | Builder | Laid down | Launch | Complete | ||
|---|---|---|---|---|---|---|---|
| Ro-1 (SS-18) | FY1915 | Kawasaki, Kobe | 1917. 1. 5 | 1919. 7.28 | 1920. 3.31 | SS2 (SS-18) | 1924.11. 1 renamed(Ro-1) 1932. 4. 1 disc |
| Ro-2 (SS-21) | FY1915 | Kawasaki, Kobe | 1918. 7. 1 | 1919.11.22 | 1920. 4.20 | SS2 (SS-21) | 1924.11. 1 renamed(Ro-2) 1932. 4. 1 disc |