Editing USS Threadfin (section)

== Post-war activities ==

From 27 July to 12 August, the submarine refitted at Guam in preparation for her fourth war patrol, but that patrol never occurred. While she conducted post-refit training, the Japanese capitulation ended hostilities. On 18 August, she got underway from Guam to return to the [[United States]]. She transited the [[Panama Canal]] on 16 September and reported for duty with the [[United States Atlantic Fleet|Atlantic Fleet]].  Six days later, she tied up at the naval base at [[Staten Island, New York]].

The balance of ''Threadfin''’s 28-year career proved to be routine in nature. Initially, she operated out of [[New London, Connecticut]], serving as a training platform for the officers and men learning the ropes at the Submarine School.  That duty apparently lasted until December 1952, at which time the submarine was decommissioned to enter the [[Portsmouth Naval Shipyard]] for an extended conversion overhaul.

Over the next eight months, ''Threadfin'' received extensive modifications in an effort to make her more effective in underwater operations—more truly a submarine than simply a submersible. When she emerged from the shipyard the following summer, her hull had been streamlined and her sail modified. In addition, she lost one of her four diesel engines to make room for auxiliary equipment displaced by an expanded sonar facility. Finally, her underwater performance was boosted by the installation of two "greater capacity" [[battery (electricity)|batteries]]—they actually produced the same power as the old style batteries but in a smaller, lighter physical plant—and a [[Submarine snorkel|snorkel]] for extended submerged cruising.

At the completion of her [[Greater Underwater Propulsion Power Program]] (GUPPY) conversion, ''Threadfin'' was recommissioned at Portsmouth on 7 August 1953. In October, she conducted her post-conversion shakedown cruise and, early the following month, reported for duty as a unit of Submarine Squadron 4 at [[Key West, Florida]].

Over the remaining 19 years of her career, ''Threadfin'' operated off the East Coast. She participated in several exercises each year and frequently conducted summer training cruises for [[United States Naval Academy]] and N[[ROTC]] midshipmen. Though based in Key West, she made visits to ports on the [[Gulf of Mexico]] such as [[New Orleans, Louisiana]], and often ventured north to [[New London, Connecticut]]. In October 1962, she participated in [[President of the United States]] [[John F. Kennedy]]'s quarantine of [[Cuba]] during the [[Cuban Missile Crisis]]. The following summer, the submarine made what, on the basis of sparse records, appears to be her only post-war overseas deployment with the [[U.S. 6th Fleet|Sixth Fleet]] in the [[Mediterranean Sea]].  Actually, Threadfin made two 6th Fleet deployments of about 4 months each in 1970 and 1972.  At the end of the 1972 deployment she was loaned to Turkey and did not return to the USA.  The turnover occurred in Izmir.