The Type A1 design was developed from the Type J3 design, with the hangar opening forward of the conning tower. This was to access the forward-mounted catapult, which was so positioned to take advantage of the forward motion of the ship when launching the aircraft. These three boats were equipped with communications gear to operate as command ships for groups of submarines.
I-9 was lost to destroyer USS Frazier in the Aleutians on 11 June 1943. I-10 was lost to destroyer USS David W. Taylor and destroyer escort USS Riddle east of Saipan on 4 July 1944. I-11 was an operational loss off Ellice Island on 11 January 1944. Two additional units were canceled in 1942.
| Units | 3 (none survived) |
|---|---|
| Ships | I-9, I-10, I-11 |
| Year(s) Completed | 1941-1942 |
| Displacement | 2,919 tons / 4,149 tons |
| Dimensions | 372.8 ft x 31.3 ft x 17.5 ft | Machinery | 2 diesels: 12,400 hp
electric motors: 2,400 hp |
| Speed | 23.5 knots / 8 knots |
| Range | 16,000 nm @ 16 knots |
| Armament | 6x533mm TT fwd + 1x14cm/50 cal. (18 Torpedoes) + one seaplane. |
| Max. Depth | 100 m (330 feet) |
| Crew | 114 officers and men |
