Permit and Sturgeon classes used the same basic hull! Some valve penetration differences, different sails (god, those 594s sucked to work on!!!!!), of course different sonar suites, etc. But, in the end the 292' hulls were the same (material, diameter, length, curves, etc.). Technically speaking, the 594s were obsolete before they hit the water, the class being finished out as the 637s that replaced them even beat a few into commission. 637s drove a whole lot better!
An old 637 driver,
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"If you ignore the problem long enough, it will go away. Even flooding stops eventually!"