| Lead Boat: SS-78, U.S.S. R-1 |
| Length: 186' |
| Beam: 18' |
| Draft: 15' 6" (Surface trim) |
| Displacement: 574 tons (surfaced); 685 tons (submerged) |
| Speed: 12.5 knots (surfaced); 9.3 knots (submerged) |
| Diving Depth: 200' (test depth) |
| Range: 4,700 miles @ 6.2 knots |
| Endurance: |
| Crew: 4 officers; 3 CPO; 26 enlisted |
| Deck Gun: 1-3"/50-calibre |
| Anti-Aircraft Weapons: Machine guns |
| Light Weaponry: |
| Torpedoes: 4-21" torpedo tubes (bow), 8 torpedoes |
| Engines: 2 diesel, direct drive |
| Motors: 2 DC motor/generators |
| Radar: |
| Sonar: Hydrophones only |
| Wartime Modifications: |
