USS Seawolf (SSN-575) was the third ship of the United States Navy to be named for the seawolf, the second nuclear submarine, and the only US submarine built with a liquid metal cooled (sodium), beryllium-moderated nuclear reactor, the S2G. Her overall design (known as SCB 64A) was a variant of , but with numerous detail changes, such as a conning tower, stepped sail, and the BQR-4 passive sonar mounted in the top portion of the bow instead of further below. This sonar arrangement resulted in an unusual bow shape above the water for a U.S. submarine. Originally laid down in 1953, her distinctive reactor was later replaced with a standard pressurized water reactor, the replacement process lasting from 12 December 1958 to 30 September 1960.
Comparison to Nautilus
Seawolf was the same basic "double hull" twin-screw submarine design as her predecessor , but her propulsion system was more technologically advanced. The Submarine Intermediate Reactor (SIR) nuclear plant was designed by General Electric's Knolls Atomic Power Laboratory and prototyped in West Milton, New York. The prototype plant was eventually designated S1G and Seawolfs plant as S2G.
The Atomic Energy Commission historians' account of the sodium-cooled reactor experience was: The S2G reactor was replaced with a pressurized water reactor similar to Nautilus and designated S2Wa, the replacement process lasting from 12 December 1958 to 30 September 1960.
Although fully armed, Seawolf, like the first nuclear submarine, Nautilus, was primarily an experimental vessel. Seawolf was originally thought of publicly as a hunter-killer submarine, but in fact was intended to be a one-off test platform for the SIR (aka S2G) LMFR reactor and future sonar platforms. Its future uses, after the reactor plant was replaced with a light water system, included covert operations in foreign waters, for which it was converted January 1971 – June 1973.
Initial construction
Seawolf'''s keel was laid down 7 September 1953, by the Electric Boat division of General Dynamics Corporation in Groton, Connecticut. It was launched on 21 July 1955 sponsored by Mary Elizabeth (Thomas) Cole, wife of New York Congressman W. Sterling Cole, and commissioned on 30 March 1957.
Like all of the original nuclear subs, the project manager at Electric Boat was the general manager of the company, Bill Jones. During the parallel construction of the first nuclear submarines, the Navy, the Atomic Energy Commission, its independent labs, and the shipyard all worked together to learn together.
For the yard, the Power Plant Project manager was a separate function on these original nuclear subs. Dennis B. Boykin III would lead EB's power plant installation, and return to the project two years later for the reactor conversion. His counterpart at the Office of Naval Reactors, Gardner Brown, did the same.
Lieutenant James Earl "Jimmy" Carter, the only US President to qualify in submarines, was to be her Engineering Officer, but had resigned his commission upon the death of his father in 1953.
1957–1959 Seawolf departed New London, Connecticut, on 2 April for her shakedown cruise off Bermuda and returned on 8 May. Between 16 May and 5 August, she made two voyages to Key West and participated in intensive training exercises. On 3 September, she steamed across the North Atlantic to participate in NATO exercises. The submarine surfaced off Newport, Rhode Island, on 25 September after cruising 6,331 nonstop miles. The next day, President of the United States Dwight D. Eisenhower embarked and was taken for a short cruise onboard her.Seawolf cruised to the Caribbean Sea for an exercise in November. In December, she began an availability period that lasted until 6 February 1958. She then participated in exercises along the east coast until early August.Seawolf submerged on 7 August and did not surface again until 6 October. During this period, she logged over 13,700 nautical miles (25,400 km). She received the Navy Unit Commendation for demonstrating the ability of the nuclear-powered submarine to remain independent of the atmosphere for the period of a normal war patrol.Seawolf returned to Electric Boat Company in Groton, Connecticut, on 12 December 1958, for conversion of her power plant from a S2G sodium-cooled LMFR to a S2Wa PWR. She was out of commission until 30 September 1960. The Office of Naval Reactors had determined that the unique superheated steam powerplant was too difficult to maintain, since the superheaters were rarely operational. Constructed of rolled steel (vs forged steel), the superheaters were usually unable to allow the plant to operate at full capacity.
