R/O class 
USA: 27 (Electric Boat Co. design)
| SS 78 R1 | Fore River S.B. Co. | - | - | - | - |
| SS 79 R2 | Fore River S.B. Co. | - | - | - | - |
| SS 80 R3 | Fore River S.B. Co. | ||||
| SS 81 R4 | Fore River S.B. Co. | ||||
| SS 82 R5 | Fore River S.B. Co. | ||||
| SS 83 R5 | Fore River S.B. Co. | ||||
| SS 84 R7 | Fore River S.B. Co. | ||||
| SS 85 R8 | Fore River S.B. Co. | ||||
| SS 86 R9 | Fore River S.B. Co. | ||||
| SS 87 R10 | Fore River S.B. Co. | ||||
| SS 88 R11 | Fore River S.B. Co. | ||||
| SS 89 R12 | Fore River S.B. Co. | ||||
| SS 90 R13 | Fore River S.B. Co. | ||||
| SS 91 R14 | Fore River S.B. Co. | ||||
| SS 92 R15 | Union I.W. San Fransc. | ||||
| SS 93 R16 | |||||
| SS 94 R17 | |||||
| SS 95 R18 | |||||
| SS 96 R19 | |||||
| SS 97 R20 | |||||
| SS 98 R21 | |||||
| SS 99 R22 | |||||
| SS 100 R23 | |||||
| SS 101 R24 | |||||
| SS 102 R25 | |||||
| SS 103 R26 | |||||
| SS 104 R27 |
Peru: 4
| R-1 Islay | Electric Boat Co. | - | - | -26 | stricken 1960 |
| R-2 Casma | Electric Boat Co. | - | - | -26 | - |
| R-3 Pacocha | Electric Boat Co. | - | - | -28 | |
| R-4 Arica | Electric Boat Co. | - | - | -28 |