The formal legal steps leading to the acquisition of United States naval vessels are confusing to many people but are very important to an understanding of the United States Navy's submarine programs. Generally speaking, the Navy cannot acquire a ship until Congress has both authorized the size of the fleet and appropriated funds for the procurement of new vessels. This requires two separate acts of Congress, as a result of which ships have frequently been authorized several years before funds were actually appropriated for their construction, and some authorized ships have never been built at all. Authorization and procurement procedures are usually quite formal in peacetime but more expedient methods are usually followed during wars or national emergencies. In the past, Congress was often very specific in defining the characteristics of particular ships, their cost, and sometimes even their names and where they were to be built.

USS Sea Cat (SS-399), the name being a shortened form of sea catfish, a marine fish of little food value found off the southeastern coast of the United States, was authorized to be built by the United States Congressional Act of 9 July 1942 ... which stated in part:

"...The authorized composition of the United States Navy in under-age vessels, as established by the Act of March 27, 1934...as amended by the Acts of May 17, 1938...June 14, 1940...July 19, 1940...December 23, 1941...and May 13, 1942 ... is hereby further increased by one million nine hundred thousand tons of combatant ships,"...Provided, that the foregoing increases in tonnages for each of the three classes of aircraft carriers, cruisers, and destroyers and destroyer escort vessels may be varied downward in the amount of

30 per centum of the total increased tonnage authorized herein, and if so varied downward, the tonnage so decreased may be used to increase the tonnage of any other class of vessel authorized above, or to increase the tonnage of submarines heretofore authorized, so long as the sum of the total increases in tonnages of these classes, including submarines as authorized herein, is not exceeded:...."

USS Sea Cat (SS-399) was built under the 1943-1944 Construction Program.

USS Sea Cat (SS-399) was laid down on the 1A Shipbuilding Way at the Portsmouth Navy Yard in Kittery, Maine, on 30 October 1943. The submarine was christened by Mrs. Edward L. Cochrane and launched on 21 February 1944.

Commissioning took place on 16 May 1944 with Commander Robert R. McGregor in command.

USS Sea Cat (SS-399) was a unit of the Balao Class. The design development of this class was accomplished by the Portsmouth Navy Yard...and she was built by the Portsmouth Navy Yard. Thus, USS Sea Cat is a "Portsmouth Boat."

One of the best-kept secrets of World War II was the increase in the operating depth of our submarines, from 300 feet in the Gato Class to 400 feet in the Balao Class. This was accomplished by shifting from mild steel to high-tensile steel and increasing the thickness of the pressure-hull plating, using the weight saved in previous classes by meticulous attention to design details in every area. Naturally, the Balao Class boats became known as the "thick skins"...while the Gato Class and earlier classes were dubbed "thin skins." In outward appearance and internal layout, the heavy-hull boats were practically identical to the earlier type, and many people--including the Japanese--were unaware that there had been any change. Most of the other new features in the Balao design had already been incorporated in the later Gato Class boats as alterations or contract changes, so the Bureau of Ships skipped the usual step of preparing a preliminary design and simply issued a so-called Circular of Requirements setting forth the changes and new test specifications.

Orders were placed for 256 units of this class, but only 119 were completed to the original design, the rest being either cancelled or reordered later in the war. World War II losses totaled nine, the low toll being due to the completion of many units too late in the war to encounter much opposition from the battered Japanese antisubmarine forces. Most of the Balao Class underwent conversion to new configurations after World War II, and made up the bulk of the Navy's active submarine force until nuclear-powered attack boats replaced most of them during the 1960s.

When commissioned, USS Sea Cat was 311 feet 6 inches in length overall and had a maximum beam of 27 feet 3 inches. Her standard displacement on the surface was 1,526 tons, her normal displacement on the surface was between 2,010 and 2,075 tons, and her submerged displacement was 2,391 tons. USS Sea Cat was designed to safely submerge to 400 feet...her operating depth. She has eight watertight compartments plus a conning tower. The pressure hull plating was 35 to 35.7 pound high tensile steel (approximately 7/8ths of an inch thick).

The designed compliment was for six officers and sixty enlisted men.

Armament consisted of 6 bow and 4 stern 21-inch torpedo tubes. The maximum torpedo load was twenty-four Mark 14 Mod. 3A torpedoes. In place of torpedoes, a maximum of 40 mines could be carried. One 5-inch/25-caliber dual-purpose deck gun was fitted. Antiaircraft guns consisted of one 40-mm, one 20-mm, and two .50-caliber machine guns.

Fuel capacity was 116,000 gallons (rated) of diesel oil, which fueled 4 main Fairbanks-Morse opposed piston 1,600 horsepower diesel engines, and one auxiliary Fairbanks-Morse opposed piston diesel engine... which turned generators...which made electricity...which turned four Elliot main propulsion motors of 2,740 shaft horsepower...which could drive the boat at 20.25 knots on the surface...and gave her a cruising range on the surface of 11,000 miles at ten knots (rated). The generators were also utilized to charge 2 Gould 126-cell main storage batteries...which could power the Elliot main propulsion motors...which could drive the boat at 8.75 knots when submerged. Her submerged endurance, at 2 knots, was two days. Her patrol endurance was rated at 75 days. USS Sea Cat had a mean draft of 15 feet 3 inches when on the surface in diving trim.

After shakedown and trials off the New England coast, the new submarine departed the United States Naval Submarine Base New London, Groton, Connecticut, on 28 August 1944, and proceeded, via the Panama Canal, to the Territory of Hawaii. Following training in Hawaiian waters, USS Sea Cat departed Pearl Harbor, on 28 October 1944, and headed, via Midway and Saipan, for the South China Sea, where the submarine operated in a wolf pack...which also included USS Pampanito (SS-383), USS Pipefish (SS-388), and USS Sea Raven (SS-196). During that war patrol, USS Sea Cat fired torpedoes at two Japanese merchantmen, which, together, displaced about 15,000 tons. Her commanding officer thought that they had both been sunk, but a postwar study of Japanese records did not confirm either sinking. After 61 days at sea, including 37 days in her patrol area, USS Sea Cat arrived at Guam for refit.

USS Sea Cat got underway, again, on 1 February 1945, for her second war patrol...which she conducted in the East China Sea in a wolf pack which included USS Segundo (SS-398) and USS Razorback (SS-394). During operations off the coast of Kyushu, she damaged a 300-ton cargo ship by gunfire and attacked a 2,000-ton ship with torpedoes. Although she reported sinking the latter, Japanese records failed to support that claim. USS Sea Cat completed her second war patrol upon arriving at Midway on 24 March 1945.

On 27 April 1945, USS Sea Cat transited to the Yellow Sea...where she and six other submarines preyed upon Japanese shipping. USS Sea Cat, herself, accounted for some 400 tons of enemy vessels by gunfire, and she picked up two survivors of the sunken enemy ships for questioning...before returning to Pearl Harbor on 25 June 1945.

During the refit period following the completion of her third war patrol, in July of 1945, USS Sea Cat was fitted with a second 5-inch/25-caliber deck gun and a rudimentary fire control system consisting of a Mark 6 computer, a Mark 6 stable element, and a Mark 2 Modification 1 gun order corrector; thus permitting central direction of gunfire. In addition to USS Sea Cat, USS Flying Fish (SS-229), USS Entemedor (SS-340), USS Sea Dog (SS-401), USS Sea Poacher (SS-406), USS Sea Robin (SS-407), and USS Sennet (SS-408) received this additional "gunboat" equipment...but the equipment was essentially a makeshift and was removed during the postwar period.

On the west coast of the United States, scientists from the University of California based at San Diego tackled the problem of submarines detecting and avoiding submerged minefields. During 1944, they tested several experimental "breadboard" sonar models capable of doing just that on USS S-34 (SS-139) and USS Redfin (SS-272). The most successful sonar set tested was a frequency modulated (FM) sonar that produced a characteristic ringing echo from mines and similar objects, and, accordingly, that sound was described as being "Hell's Bells."

The prototype of this equipment, the QLA, was sent on patrol with USS Spadefish (SS-411) and showed so much promise that additional sets were ordered on a rush basis from the laboratory and the Western Electric Company. They were installed on the boats of the so-called Hellcat wolf pack that penetrated Tsushima Strait in June of 1945 and rampaged through the Sea of Japan. Despite the success of this exploit, submariners were understandably unenthusiastic about picking their way through minefields. The QLA was good only at short ranges...about a quarter of a mile...and suffered from the usual limitations of sonars under less-than-perfect water conditions--and there was always the possibility of sideswiping one mine while maneuvering to avoid others. Because USS Sea Cat was a potential candidate for patrols in the Sea of Japan, Frequency Modulated QLA sonar equipment was installed in her prior to her fourth war patrol.

USS Sea Cat headed toward the Kurils on 6 August 1945 for her fourth and last Second World War patrol; but, upon arrival in her patrol area, learned that hostilities with Japan had ended. The submarine was ordered to proceed to the Japanese home islands and was in Tokyo Bay, Japan, during the formal surrender ceremony on 2 September 1945 when Japanese signed the instruments of surrender on board battleship USS Missouri (BB-63).

USS Sea Cat then transited to the Marianas and reached Guam on 7 September. Following a brief stay at Apra Harbor, Guam, the submarine crossed the Pacific Ocean to the west coast of the United States.

Following operations in the San Diego, California, area into the Spring of 1946, USS Sea Cat proceeded to San Francisco Bay and arrived at the Mare Island Naval Shipyard at Vallejo, California, on 15 April 1946, for overhaul.

Three months later, with all shipyard work completed, USS Sea Cat transited back to San Diego.

On 12 August 1946, USS Sea Cat deployed to the Western Pacific (WestPac) Ocean areas. During that cruise, the submarine visited the Hawaiian Islands; Canton Island; Swains, Samoa, and Atafu Islands; and Tsingtao and Shanghai, China.

Then, transferred to the United States Atlantic Fleet, USS Sea Cat transited to the Panama Canal Zone...and arrived at Balboa on 12 January 1947. The submarine conducted operations out of that homeport for two and one-half years. Then, her homeport was changed to Key West, Florida. The submarine then moved to the southernmost city in the continental United States...arriving there during June of 1949.

During the autumn of 1949, it was decided to have a number of experimental changes made to the submarine during her forthcoming overhaul; so, her designation was changed from "SS" (Submarine) to "AGSS" (Auxiliary Submarine) on 30 September 1949.

The classification of "AGSS" was established for those submarines destined to be converted to special noncombatant assignments, most of which were concerned with sonar research and testing.

On 7 November 1949, USS Sea Cat (AGSS-399) arrived at the Philadelphia Naval Shipyard at Philadelphia, Pennsylvania, and commenced overhaul.

During that overhaul, the submarine was fitted with the experimental XDG sonar ranging equipment being developed by the Naval Research Laboratory. The project scientist for that gear was Chester Buchanan who later achieved prominence as the developer of the underwater search equipment that located the wreckage of USS Thresher and other sunken objects. The forward torpedo-loading hatch was removed and the entire compartment filled with electronic equipment, leaving the torpedo tubes in place but incapable of being loaded except through the outer doors. Two large hydrophones were installed topside located as far apart as possible in order to provide the maximum base line for triangulation of the range to distant targets.

The repairs, modifications, and overhaul were completed on 11 March 1950, and USS Sea Cat returned, via the United States Naval Submarine Base New London, Groton, Connecticut, to the United States Naval Station at Key West, Florida.

USS Sea Cat operated from Key West until 9 January 1952. During that period, the submarine ran and completed a series of tests, during which it was found that the XDG sonar ranging equipment was less accurate than other forms of passive ranging which were then under development.

By 11 December 1951, the XDG sonar ranging equipment had been removed from USS Sea Cat, and, accordingly, her designation was changed back to "SS" from "AGSS."

During the period 9 January to 15 January 1952, USS Sea Cat (SS-399) transited from Key West to the Philadelphia Naval Shipyard.

Upon arrival, the submarine commenced overhaul and conversion from a fleet-type submarine to a fleet-snorkel submarine.

When even the less extensive of the GUPPY (Greater Underwater Propulsion Power. The "Y" has no significance.) modifications proved too expensive for the Navy to update as many submarines as it needed, the fleet-snorkel program was instituted. It was an austere modernization program intended to take advantage of the capabilities of the snorkel as perfected on USS Irex (SS-482). The formal program consisted of eighteen boats, which received snorkels and streamlined sails, and many other submarines ultimately were given similar installations. This was not properly a conversion program, because the alterations were carried out in the course of regular shipyard overhauls without the appropriation of funds under the shipbuilding and conversion budget. Internally, the fleet snorkels were only slightly changed from the original Balao or Tench designs. Additional sonar equipment was installed either in the forward torpedo room or in space formerly occupied by the magazines when the deck guns and associated installations were removed. Some of these boats received plastic sails like the Guppies, but all were phased out of regular service by 1970.

Overhaul and conversion completed, USS Sea Cat (SS-399) departed the City of Brotherly Love on 26 June 1952 and returned to Key West.

The submarine operated from Key West for the remainder of her active career, spending much of her time in the Caribbean, the Gulf of Mexico, and in waters off the southern coast of the United States.

During July of 1966, USS Sea Cat interrupted her customary routines by crossing the Atlantic Ocean for a four-month deployment with the United States Sixth Fleet in the Mediterranean Sea.

Upon returning to Key West on 30 October 1966, USS Sea Cat resumed her former routines and operated in Florida waters and in the Caribbean.

On 29 June 1968, USS Sea Cat (SS-399) was reclassified, for the second time, from "SS" to "AGSS."

On 2 December 1968, USS Sea Cat (AGSS-399) was decommissioned and struck from the Navy List.

From 1968 to 1972 the submarine was used as a test hulk and was subjected to a series of hull experiments.

On 18 May 1973, the submarine was sold for scrapping to the Southern Scrap Material Company of New Orleans, Louisiana, for $98,889.

USS Sea Cat (SS-399) earned three battle stars for her services during the Second World War.

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