Editing Gato-class submarine (section)

===Hunter-killer===
[[Image:USS Bluegill (SSK-242) underway during the 1950s (NH 78979).jpg|thumb|right|{{USS|Bluegill|SSK-242}}]]
The threat of the [[Soviet Navy]] building hundreds of [[Type XXI submarine|Type XXI]]-derived submarines (eventually the 215-strong {{sclass2|Whiskey|submarine|4}} and dozens of others) in the Atlantic led the U.S. Navy to adapt submarines to specifically hunt other submarines, a radically new role for the 1950s. Concluding that this role did not require a fast or deep-diving submarine (this line of thought would quickly change with the advent of nuclear power), seven ''Gato''s were converted to [[Hull classification symbol#Submarine type|SSK]]s ([[hunter-killer submarine]]s) between 1951 and 1953, joining three purpose-built [[United States Barracuda-class submarine (1951)|''K-1''-class SSKs]] entering service at that time. The ''Gato'' class was chosen because large numbers were available in the [[United States Navy reserve fleets|reserve fleet]] should rapid mobilization become necessary, and the deeper-diving classes were more suitable for GUPPY rather than SSK conversions. A streamlined GUPPY-style sail was installed, a large sonar array was wrapped around the bow (losing two [[torpedo tube]]s in the process), the ships were extensively silenced including the removal of the two forward diesel engines, and they received a [[Submarine snorkel|snorkel]]. {{USS|Grouper|SS-214|2}} was converted under project SCB 58 as the test ship for the concept, having her sonar array at the forward end of the sail instead of the better position at the bow. The other ships in the program included {{USS|Angler|SS-240|2}}, {{USS|Bashaw|SS-241|2}}, {{USS|Bluegill|SS-242|2}}, {{USS|Bream|SS-243|2}}, {{USS|Cavalla|SS-244|2}}, and {{USS|Croaker|SS-246|2}}.<ref name="Alden, Part IV"/>

Eventually more advanced sonars were installed on the new nuclear subs: {{USS|Tullibee|SSN-597|2}}, commissioned in 1960, introduced the bow-mounted sonar sphere. ''Tullibee'' was an attempt to develop a slow but ultra-quiet nuclear-powered SSK equivalent; no others were built due to her unexpectedly high cost relative to the more capable {{USS|Thresher|SSN-593|2}}, and the SSK mission was folded into the regular attack submarine role.<ref>{{harvnb|Friedman|1995|pp=80–85}}</ref> The slow and less capable diesel SSKs were decommissioned or reassigned to other roles in 1959, and all except ''Croaker'' and ''Cavalla'' (eventually preserved as memorials) were scrapped in 1968 and 1969.<ref name="Alden, Part IV"/>