Permit-class submarine: Difference between revisions

The '''''Permit''-class submarine''' (known as the '''''Thresher'' class''' until the lead boat {{USS|Thresher|SSN-593|6}} was lost) was a class of [[Nuclear marine propulsion|nuclear-powered]] fast attack [[submarine]]s ([[Hull classification symbol#Submarine type|hull classification symbol]] SSN) in service with the [[United States Navy]] from the early 1960s until 1996. They were a significant improvement on the {{sclass-|Skipjack|submarine|4}}, with greatly improved [[sonar]], diving depth, and silencing.<ref name="FriedmanSubs1"/> They were the forerunners of all subsequent US Navy SSN designs. They served from the 1960s through to the early 1990s, where they were decommissioned due to age.<ref>Friedman, pp. 235-236</ref> They were followed by the {{sclass-|Sturgeon|submarine|5}} and {{sclass-|Los Angeles|submarine|5}} classes.

 

 

==Design==

The first submarine commissioned in the class was the ill-fated {{USS|Thresher|SSN-593|2}}, and so the class was known by her name. When ''Thresher'' was lost on 10 April 1963, the class took the name of the second ship in the class, {{USS|Permit|SSN-594|2}}. ''Thresher'' had numerous advanced design features and embodied the future of US Navy submarine design, and her loss was a serious blow. As a result, the [[SUBSAFE]] program was instituted to correct design flaws and introduce strict manufacturing and construction [[quality control]] in critical systems. The seawater and main ballast systems of future classes (''Sturgeon''-class SSNs and {{sclass-|Benjamin Franklin|submarine|0}} [[SSBN]]s) were redesigned, and some ''Thresher''s and other submarines were rebuilt to SUBSAFE standards. SUBSAFE includes specific training of SUBSAFE [[quality assurance]] inspectors in the engineering crew, and tracks extremely detailed information about every component of a submarine that is subject to sea pressure. Joints in any equipment carrying seawater must be [[Welding|welded]] (not [[Brazing|brazed]]), and every hull penetration larger than a specified size can be quickly shut by a remote hydraulic mechanism.<ref name="Friedman, pp. 143-146"/> The program has been very successful, as no SUBSAFE submarines have been lost as of 2019 ({{USS|Scorpion|SSN-589|2}} was not SUBSAFE).{{citation_needed|date=August 2019}}

 

 

The engine room of {{USS|Jack|SSN-605|2}} was lengthened by {{convert|10|ft|m}} to accommodate an experimental [[direct drive|direct-drive]] propulsion system using concentric counter-rotating propellers. Although counter-rotating propellers produced impressive gains in speed on the experimental {{USS|Albacore|AGSS-569|2}}, in ''Jack'' the results were disappointing because of the difficulty in sealing the shaft. ''Jack'' was also used to test polymer ejection that could reduce flow noises that degraded sonar performance.{{citation_needed|date=August 2019}}

* [[List of submarines of the United States Navy]]

* [[List of submarine classes of the United States Navy]]

 

==References==