The Seawolf-class attack submarine began design work in 1983, when the U.S. Navy wanted a successor to the Los Angeles class that could hunt quiet Soviet submarines, the Typhoon ballistic missile boats and the Akula attack boats, in the deep ocean. The plan called for 29 boats over 10 years. Then the Cold War ended. By 1995 the projected cost of just 12 boats was $33.6 billion, almost $3 billion each, and only three were completed: USS Seawolf, USS Connecticut and USS Jimmy Carter. The design used HY-100 steel for a 1,600-foot test depth and a single S6W reactor sending 45,000 horsepower to a pump jet, for a top speed of 35 knots and a silent speed of 20 knots in a 353-foot hull displacing 8,600 tons surfaced.

The third boat took a different path. USS Jimmy Carter (SSN-23) cost $3.5 billion in total, roughly $887 million of it for General Dynamics Electric Boat modifications that stretched it to 452.8 feet and over 12,000 tons submerged. The added Multi-Mission Platform can launch and recover Navy SEALs and remotely operated vehicles and serves as an underwater splicing chamber for tapping undersea fiber optic cables, a role previously handled by the decommissioned USS Parche. The Seawolf class remains the second most expensive submarine class ever built, behind France’s Triomphant class, and its technology carried into the cheaper Virginia class.

• Diving below a thermocline lets the boat hide under a temperature layer that bends or bounces enemy sonar.
• The pump jet places the rotor inside a shroud to prevent cavitation, the noisy collapse of vapor bubbles behind open propeller blades.
• Eight 26.5-inch torpedo tubes, twice the Los Angeles class, serve up to 50 Tomahawk, Harpoon and Mark 48 weapons.
• The ARCI-modified AN/BSY-2 combat system links a spherical bow array, a wide aperture flank array and a towed array.
• Roughly 99 percent of international data travels on seafloor cables, which is why the intercept mission goes to the ocean floor.