The Sea Shadow is a US Navy experiment in low-observable (stealth) technology. Constructed in the mid-1980s in a program headed by the Navy and including ARPA and Lockheed Martin Corporation, the Sea Shadow is based on a catamaran hull and looks -- you guessed it -- like a floating, mutant F-117. In addition to its stealth characteristics, the Sea Shadow has been used in testing automation and advanced information technologies as part of ongoing Navy efforts to reduce crew sizes throughout the fleet.
The Sea Shadow sports a diesel
electric powerplant and runs at an (official) top speed of 10 knots. Displacement
is roughly 560 tons fully loaded, with a length and beam of roughly 164 by 68 feet. The vessel draws 14.5 feet of water and is crewed by a standard complement of 10, though being a testbed it does not undergo extended cruises.
Like many of the projects to come out of Lockheed Martin's Skunk Works the Sea Shadow was classified, and until made public in 1993 was operated only under cover of darkness. Following declassification the Sea Shadow was used in daytime tests of its stealth systems, and in 1994 entered the semi-retirement of lay-up status at Naval Station San Diego. The vessel was reactivated in early 1999 to evaluate systems for the (now canceled) DD-21 Zumwalt-class Land Attack Destroyer.
Though the Navy can never expect to make a ship the size of a destroyer or aircraft carrier "disappear" in the manner of the B-2 Stealth Bomber or the F-117, the ability to avoid detection long enough to fire missiles or to launch and recover aircraft could prove invaluable in the conflicts of the future.
Sources: FAS and the US Navy