Permit-class (SSN-594)
Summary
| Origin country | 🇺🇸 United States |
| Category | Submarine |
| Subtype | Nuclear attack submarine |
| Manufacturer | Portsmouth Naval Shipyard, Mare Island Naval Shipyard, Ingalls Shipbuilding, New York Shipbuilding, General Dynamics Electric Boat |
| Year commissioned | 1961 |
| Units | SSN-594 PERMIT, SSN-595 PLUNGER, SSN-596 BARB, SSN-603 POLLACK, SSN-604 HADDO, SSN-605 JACK, SSN-606 TINOSA, SSN-607 DACE, SSN-612 GUARDFISH, SSN-613 FLASHER, SSN-614 GREENLING, SSN-615 GATO, SSN-621 HADDOCK |
Description
The Permit-class, initially known as the Thresher-class until the lead boat USS Thresher was lost, served as nuclear-powered fast attack submarines in the United States Navy. These submarines were in service from the early 1960s until 1996 and marked an advancement over the Skipjack class they succeeded, boasting improved sonar, diving depth, and acoustic silencing capabilities. This class laid the groundwork for all following American SSN designs.
Commissioned following Project Nobska in 1956, the design process included insights from submarine and anti-submarine warfare experiences, managed under the project SCB 188. Physically, the Permit-class maintained the S5W reactor plant from the Skipjacks but heavily altered other aspects of the design. A notable change was an advanced bow-mounted sonar sphere coupled with angled amidship torpedo tubes. These submarines incorporated HY-80 steel, akin to their predecessors, but featured an improved pressure hull design that extended test depth to 1,300 feet. Additionally, the engineering spaces were acoustically optimized with suspended turbines, while the exterior design minimized drag. Although the initial propulsion configuration aimed to maximize speed, subsequent modifications to the screw design slightly reduced velocity but improved stealth.
As for armament, the Permit-class was equipped with cutting-edge fire control systems and weapons, including Mark 37 torpedoes, SUBROC missiles, Harpoon anti-ship missiles, and could be armed with various combinations of mines, torpedoes, and missiles in its armory. The class underwent mid-life upgrades, receiving enhancements like the AN/BQQ-5 sonar suite and newer torpedo fire control systems.
In the wake of USS Thresher's tragic loss in 1963, the class was renamed to the USS Permit. This event led to the initiation of the SUBSAFE program, aiming to improve submarine safety through rigorous design, construction, quality control, and crew training standards.
Construction variations within the class accounted for larger sails to accommodate more masts, additional SUBSAFE features, and improved living conditions. An innovative direct-drive propulsion system was also tested on the USS Jack, albeit with underwhelming results due to technical challenges.
Technical specifications
| Permit | |
|---|---|
| Displacement | 3759 tons |
| Displacement submerged | 4369 tons |
| Range | Unlimited, except by food supplies |
| Crew | 112 members |
| Width | 9.63 m (31.6 ft) |
| Length | 84.86 m (278.4 ft) |
| Max. depth | 400 m (1312.3 ft) |
| Propulsion | 1 S 5W PWR nuclear reactor with a power of 25,000 hp - 1 propeller |
| Armament | 4 533mm TLTs for Mk-37 torpedoes + SUBROC |
| Maximum speed | 15 knots |
| Max. speed submerged | 30 knots |
Photo of Permit class
