| Displacement | 689t surface, 1047t submerged |
|---|---|
| Length | 60.5m pp, 65.6m oa |
| Width | 6.1m |
| Draught | 4.1m |
| Machinery | 2-shaft diesel/electric motor, 2600bhp surface, 1200shp submerged |
| Fuel | oil 58.4t |
| Speed | 14kt 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-3 (SS-31) | FY1917 | Kawasaki, Kobe | 1919.10.28 | 1921. 3.10 | 1922. 7.17 | SS2 (SS-31) | 1924.11. 1 renamed(Ro-3) 1932. 4. 1 disc |
| Ro-4 (SS-32) | FY1917 | Kawasaki, Kobe | 1919.12.22 | 1921. 6.22 | 1922. 5. 5 | SS2 (SS-32) | 1924.11. 1 renamed(Ro-4) 1932. 4. 1 disc |
| Ro-5 (SS-33) | FY1917 | Kawasaki, Kobe | 1920. 3. 1 | 1921. 9.17 | 1922. 3. 9 | SS2 (SS-33) | 1924.11. 1 renamed(Ro-5) 1932. 4. 1 disc |