for Submariners

by Hamilton 1:1 Communications, LLC

Greater Underwater Propulsion Power Program
Guppy IIA

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The GUPPY IA program was succeeded by the nearly identical GUPPY IIA program (SCB 47C), implemented from 1952 to 1954. The GUPPY IIA, however, further alleviated the cramped internal conditions of earlier conversions by removing one forward engine and replacing it with pumps and air conditioning machinery. Some boats had the high-pressure air compressors relocated to the lower level of the forward engine room. The freezer and refrigerator units were moved to the space under the galley, and the sonar room was relocated to the forward end of the pump room. Sargo II batteries were installed in the existing battery wells. The USS Sea Fox (SS-402) when converted to GII status she was given the Southern Sail. A few years later she was fitted with the Northern Sail.


Externally, the GUPPY IIA differed from the GUPPY II and IA by having only three diesel exhaust outlets, whereas the earlier conversions had four.




307' 7" length
27' 4” Beam
17' Draft
2,040 tons Surfaced Displacement
2,400 tons Submerged Displacement
4,610 SHP Diesels, 2 Shafts
4,610 SHP Electric Motors, 2 Shafts
18 kt surfaced speed
17.5 kt submerged speed
15,000 nm at 11 kts surfaced endurance
192 nm at 4 kt submerged endurance
400 ft Test Depth
84 to 85 crew


6 x 21” TT Bow
4 x 21” TT Stern
24 x 21” Torpedoes