The Semi-Submersible SBX-1

  • Client:
    The Boeing Company
  • Completion Date:
    January 2012
  • Project Type:
    Vessel Design & Modification, Special Purpose Vessels
  • Service Categories:
    Naval Architecture
    Marine Engineering
    Owner Services & Onsite Support
  • Vessel Overview:
    Self-propelled semi-submersible platform outfitted with US Missile Defense Agency X-band radar systems
  • Challenge:
    Develop unique missile defense vessel from concept through delivery.


SBX-1 is part of the US Missile Defense Agency’s Ground-Based Midcourse Defense system. It combines a large X-Band radar—housed in a distinctive air-inflated radome—and a semi-submersible platform. Outfitted with a full suite of dynamic positioning thrusters and marine systems for world-wide operation, SBX-1 stands more than 280 feet (85.3 meters) tall and displaces more than 50,000 tons.

Glosten provided a wide range of marine technical services to Boeing through the design, acquisition, repositioning, construction modifications, sea trials, and dry transport of this unique vessel. The advancement from a bare platform to an active naval asset required full integration of a core team including the American Bureau of Shipping, Boeing, Raytheon, US Missile Defense Agency, vessel crew, and Keppel Amfels and Kiewit shipyards. The combined requirements for radar function, agency classification, and vessel performance required a complex hybridization of semi-submersible and radar ship engineering.



Glosten worked as the project engineering integrator and designer for all marine aspects of this $900 million project. Our work included platform modification architecture, engineering, construction, outfitting power and accommodations modules, propulsion and control systems, and complex payload support modules and systems.

Glosten developed full global models for structural and hydrodynamic analysis. The models were used to determine the operability of the vessel and payload, as well as to complete an eigenvalue analysis to ensure the payload would not be affected by any of the natural frequencies of the vessel. Glosten engineers worked in Seattle, Washington DC, Brownsville, Ingleside, Adak, and Honolulu supporting Boeing through construction and delivery.

Our team successfully integrated a complex set of owner’s requirements into a verifiable design that met demanding performance, schedule, and cost objectives, working closely with multiple shipyards to ensure construction budget and schedule adherence. The initial SBX concepts were developed in 2001, and SBX-1 began operations in 2006. Glosten continues to provide sustaining engineering support.

  • SBX_at-sea