Sea Shadow (IX-529) was an experimental stealth ship built by Lockheed for the United States Navy to determine how a low radar profile might be achieved and to test high stability hull configurations that have been used in oceanographic ships.
Sea Shadow was built in 1984 to examine the application of stealth technology on naval vessels, and was used in secret until a public debut in 1993. In addition, the ship was designed to test the use of automation to reduce crew size. Watch the video from Found And Explained for more info:
Sea Shadow had a SWATH small-waterplane-area twin hull design. Below the water were submerged twin hulls, each with a propeller, aft stabilizer, and inboard hydrofoil. The portion of the ship above water was connected to the hulls via the two angled struts. The SWATH design helped the ship remain stable in rough water up to sea state 6 wave height of 18 feet (5.5 m) or “very rough” sea.
The shape of the superstructure was sometimes compared to the casemate of the ironclad ram CSS Virginia of the American Civil War.Sea Shadow had 12 bunks, one small microwave oven, a refrigerator and table. It was not intended to be mission-capable and was never commissioned, although it is listed in the Naval Vessel Register.