USS Razorback (SS-394)- Details of the GUPPY Program
By 1946 the Soviet Union was already seen as the future adversary of the United States. It was estimated that the Soviet Union had 229 submarines, of which only 13 were obsolete types. It was also estimated that over the next 20 years the Soviet Navy would be able to build over 1200 new submarines. Clearly, the United States could not build enough new submarines to keep up, so existing submarines would have to be modernized.
At the end of World War II, cutting edge German submarine technology, including complete submarines, examples of snorkel technology, highly advanced torpedoes, and even sound absorbing tiles for submarine hulls had been evenly distributed between the three major allied powers (the United States, Great Britain and the Soviet Union). In this distribution, the United States and the Soviet Union both received 10 German submarines. In addition, American and British Naval leaders believed that advancing Soviet armies, while occupying much of Germany, had captured additional items including blueprints, prototypes and possibly even as many as 40 nearly complete submarines.
It was clear to American Naval leaders that the US submarine fleet would need to be rapidly modernized in order to keep pace with the expected advances in Russian submarine technology. The surface Navy also needed to learn how to detect, defend against, and if necessary, attack the fast, modern submarines the Soviets were building, so they needed similarly fast, modern submarines to train against.
The primary elements of the GUPPY Program were:
- Increased battery capacity
- Streamlined outer hull
- Addition of a snorkel
- Improved sensors
Increased Battery Capacity
The underwater endurance of a diesel-electric submarine is defined by the capacity of it's batteries. The GUPPY program increased the number of battery cells in each submarine with some later boats receiving improved batteries that provided even more power per cell.
Streamlined Outer Hull
WWII submarines like Razorback were basically surface ships that could submerge, but were very slow under water (8.5 knots vs 18 knots surfaced). A submarine's underwater speed is limited by the amount of drag created by it's fairwater, periscopes, guns, and other deck machinery. All of these items created a great deal of drag. Reducing this drag meant that the submarine could go faster while using the same amount of power. Streamlining also had the advantage of reducing an opponent's sonar effectiveness by 10% or more. Significant changes included:
- Removal of deck guns
- Removal of 20mm and 40mm anti-aircraft guns
- Rebuilding of the bridge/periscope shears structure as a streamlined "sail"
- Capstans made retractable
- Deck cleats made retractable
- Deck safety rail stanchions made flush with the deck
- All deck safety rails made removable
- Replacement of the pointed bow and towing fairlead with a rounded bow (known as the "Guppy Bow")
Addition of a Snorkel
The snorkel, often credited to the German Navy, was actually a Dutch invention. The Dutch Navy began experimenting with snorkels as early as 1938. When the Netherlands fell to German invasion in 1940, the invention fell in to German hands, and was being installed on German U-Boats by 1943.
The snorkel allows a submarine to run its diesel engines while submerged (down to about periscope depth), greatly increasing its underwater endurance while also greatly reducing its vulnerability to detection by radar. (A snorkelling boat was actually more vulnerable to detection by sonar, but this was considered an advantage for US submarines, since existing sonars and torpedoes, designed to detect and attack surface ships, could still be used to detect and attack a snorkelling submarine. Also, the Soviet Navy operated from a very limited number of bases, allowing US submarines to "lurk" off these bases waiting for their noisy targets to approach.)
The GUPPY program added a wide variety of sensors, including better sonars, better electronic warfare systems, and even new fire control systems in the later boats.
The GUPPY program eventually led to seven different variants:
- GUPPY I
- GUPPY II
- GUPPY IA
- Fleet Snorkel
- GUPPY IIA
- GUPPY IB
- GUPPY III
The apparent out of order sequence is correct. Furthermore, some boats that went through an early part of the program were upgraded a second time in a later phase. For example, both GUPPY I boats (USS Odax (SS 484) and USS Pomodon (SS 486)) went through the GUPPY II program while all nine GUPPY III boats had themselves previously been through the GUPPY II program. A total of 50 submarines went through some phase of the GUPPY program.
While many of the museum submarines in the United States went through some form of the GUPPY program, Razorback is the only Balao class GUPPY IIA boat on display anywhere in the world. Furthermore, she is one of only two GUPPY submarines to have had her hull reinforced so she could act as a live target for torpedo tests, a role Razorback would fulfill regularly during her career. (The other submarine was USS Thornback (SS 418), a Tench class submarine that also served in the Turkish Navy. She is now a museum submarine in Istanbul.)