Sea-Based X-Band Radar is a floating, self-propelled, mobile radar station designed to operate in high winds and heavy seas. It is part of the U.S. Defense Department Ballistic Missile Defense System.
Under Construction, Offshore
The Sea-Based X-Band Radar is mounted on a fifth generation Norwegian-designed, Russian-built CS-50 semi-submersible twin-hulled oil-drilling platform. The hull was originally built at Vyborg Shipyard, hull number 101. Conversion of the platform was carried out at the AmFELS yard in Brownsville, Texas; the radar mount was built and mounted on the platform at the Kiewit yard in Ingleside, Texas, near Corpus Christi.
The CS-50 semi-submersible platform on which the radar is mounted was built as the "Moss Sirius" at the Vyborg shipyard in Russia for Moss Maritime (now part of the Saipem offshore company, which is a subsidiary of Italian energy corporation Eni S.p.A.). It was purchased for the Sea-based X-band Radar project by the Boeing company, outfitted with propulsion, power and living quarters at the AmFELS shipyard in Brownsville, Texas, and integrated with the radar at the Kiewit yard in Ingleside, Texas.
Three further platforms of the CS-50/Moss Sirius design were under construction or contract at the Severodvinsk shipyard in Russia as of early 2007, but as of that time it was unknown whether they would be purchased by the US for more SBX radars or sold to other buyers.
Links: en.wikipedia.org, cryptome.org