The class was redesigned to SUBSAFE requirements concurrently with the construction of the first units, with seawater, main ballast, and other systems modified for improved safety.

[1] The biggest difference was the much larger sail, which permitted a second periscope and additional intelligence-gathering masts, and which reduced the risk of the submarine broaching the surface in heavy seas.

Several Sturgeon boats and related submarines were modifications of the original designs to test ways to reduce noise.

Beginning with Archerfish, units of this class had a 10-foot (3.0 m) longer hull, giving them more living and working space than previous submarines.

Parche received an additional 100-foot (30 m) hull extension containing cable tapping equipment that brought her total length to 401 feet (122 m).