To marine biologists, the guppy (scientific name Poecilia reticulata), AKA the rainbow fish or the millionfish, is one of the world’s most popular tropical fish and one of the most widely distributed freshwater aquarium fish species.

It should come as no surprise then that, given the U.S. Navy’s long-standing historical tradition of naming its submarines after aquatic creatures (a tradition that Admiral Hyman G. Rickover unfortunately ixnayed after the commissioning of the first nuclear-powered submarine, the USS Nautilus, in 1954), that the Navy would name at least one of its undersea boats for these little fish. Actually, in this lucky fish’s case, an entire class of subs bears its namesake. Say hello to the Navy’s GUPPY submarine program of the early Cold War.

(NOTE: There’s also a “mechanical flying fish,” i.e., an airplane, bearing the name “Super Guppy,” but that’s a whole separate discussion topic in and of itself.)

Guppy-class Submarines: Early History and Specifications

Okay, if you want to be technically nitpicky, the GUPPY-class boats weren’t merely named for the fish, but in this case the ichthyological moniker also has a double meaning as an official acronym (what do you expect from a government that loves its metaphorical alphabet soup, eh?): Greater Underwater Propulsion Power Program (the “Y” was added to complete the catchiness of the acronym).

The GUPPY boats were World War II veteran diesel submarines that were selected for four specific upgrades:

-Increased battery capacity

-Streamlined submarine structures

-Addition of snorkels

-Improved fire control systems

The program was approved in 1946 by then-Chief of Naval Operations Admiral Chester W. Nimitz. It commenced with the testing and reverse engineering of two Nazi German Kriegsmarine Type XXI U-boats, which had been surrendered to the Americans as a war reparation. Eventually, a total of six program variants came into being: GUPPY I; GUPPY II; GUPPY IA, Fleet Snorkel; GUPPY IIA; GUPPYIB; and GUPPY III.

The first two warships of the GUPPY I class were the Tench-class boats USS Odax (SS-484) and USS Pomodon (SS-486). Commissioned on July 11, 1945, and September 11, 1945, respectively, these two subs received the following upgrades in 1947:

-Streamlining of the bridge and shears structures

-Streamlining of the periscope and radar mast supports

The traditional deck gun was removed (along with one of the periscopes, which was replaced by an SV radar aerial atop the sail) to reduce hydrodynamic drag. The original V-shaped bow was morphed into a more rounded “Guppy” bow that improved the boats’ underwater performance.

Internally, the ships were given the following improvements:

-Expanded battery wells

-High-speed motors

-Splash-proof switchboard cabinets

-Lighting and electrical loads were converted from 120 volt 60 hertz alternating current to 120 volt 400 hertz AC

-New and improved air conditioning system (this must’ve been especially appreciated by crews assigned to the tropical climes of the Pacific Ocean)

Interestingly enough, these two Tench boats were not retrofitted with snorkels during this first stage of the program, though subsequent classes in the program would be. A total of twenty-four submarines (including Odax and Pomodon) received upgrades via GUPPY II.

Subsequent to these upgrades, the Tench warships bore the following specifications and vital stats:

Displacement: 2,440 tons fully laden and submerged

Hull length: 307 ft (93.6 m)

Beam Width: 27 ft 4 in (7.4 m)

Draught: 17 ft (5.2 m)

Propulsion: Batteries with capacity expanded to 504 cells (1 × 184 cell, 1 × 68 cell, and 2 × 126 cell batteries)

Max Speed: 18.2 knots (33.7 km/h; 20.9 mph); this was more than double the mere 8.75-knot speed of the pre-modified Tenches

Range: 15,000 nm (28,000 km) surfaced at 11 knots (20 km/h)

Crew Complement: nine to ten commissioned officers, five petty officers, and seventy junior enlisted seamen plus trainees

Armament: ten x 533 mm 21-in forward tubes (six fore, four aft)

Operational History

Since the Cold War thankfully never became a full-scale “hot war,” i.e., World War III, the GUPPYs ended up never firing any shots in anger. Moreover, once the aforementioned nuclear-powered Nautilus went operational, the writing on the wall appeared on the scene for the GUPPYs and diesel-electric boats in the U.S. Navy in general (though certainly plenty of other nations use diesel submarines to this day, thanks especially to air-independent propulsion technology).

As my colleague Harrison Kass notes:

“The GUPPY program continued through the 1950s, with GUPPY IA, Fleet Snorkel, GUPPY IIA, and GUPPY IB. By 1961, GUPPY III – the program’s last iteration – began and ran until 1963, when the program concluded. The GUPPY III, while the program’s swan song, did entail extensive modifications. For example, the Tiru, which was the GUPPY III prototype, was cut in half and lengthened with a 12.5-foot section forward of the control room, added to make space for a new sonar room, berthing, electronics, and storerooms…Of course, modern nuclear-powered submarines are more advanced than the GUPPY subs. However, the GUPPY program was an important stepping stone towards developing the submarine technology that is used today.”

Where Are They Now?

Several of the GUPPY II boats found a second lease on life with foreign navies, such as the USS Trumpetfish (SS-425; Brazil), the USS Grenadier (SS-525; Venezuela), and the USS Tusk (SS-426; China).

Fast-forward to the present day and GlobalSecurity reports that a total of three of the GUPPY submarines survive: the Tench-class GUPPY II USS Torsk (SS-423), now docked at Pier 3 of Baltimore’s Inner Harbor as part of the Historic Ships in Baltimore exhibition; the Gato-class GUPPY II USS Becuna (SS/AGS-319), now at the Independence Seaport Museum in Philadelphia, Pennsylvania (though I haven’t actually done her onboard tour, I saw her from a distance whilst touring the famous Spanish-American War vessel USS Olympia in 2023); and the Balao-class USS Clamagore (SS-343) which was housed at Patriots Point Naval & Maritime Museum on South Carolina’s Charleston Harbor until 2022, when the unfortunate decision was made to scrap her due to untenable preservation costs.

About the Author: Christian D. Orr

Christian D. Orr is a Senior Defense Editor for the National Security Journal (NSJ). He is a former Air Force Security Forces officer, Federal law enforcement officer, and private military contractor (with assignments worked in Iraq, the United Arab Emirates, Kosovo, Japan, Germany, and the Pentagon). Chris holds a B.A. in International Relations from the University of Southern California (USC) and an M.A. in Intelligence Studies (concentration in Terrorism Studies) from American Military University (AMU). He has also been published in The Daily Torch, The Journal of Intelligence and Cyber Security, and Simple Flying. Last but not least, he is a Companion of the Order of the Naval Order of the United States (NOUS).