The Truss Spar is a new floating platform concept that is rapidly becoming one of the preferred systems for developing deepwater Gulf of Mexico fields. The Truss Spar provides a stable, cost-effective platform for dry-tree completions over a wide range of water depths. The Truss Spar is an extension of technology developed on previous "Classic" Spar projects, but has several specific advantages. These advantages were exploited to provide a fit-for-purpose platform solution for the Nansen/Boomvang Field Development. This paper describes the design of the Truss Spars for the Nansen/Boomvang Field Development. The paper reviews the Truss Spar concept, past development work, and comparison with the Classic Spar concept. The paper describes the specific Nansen/Boomvang project requirements and design criteria and how they influenced the platform configuration. The paper includes summaries of analysis results for global motions, mooring design, and hull structural design. The paper also includes a description of unique design features, including heave plates, SCR pulltubes, hard tank-to-truss connections, and toptensioned riser guides. These novel features, and other technology proven on the Nansen/Boomvang project, are readily transferable to other Truss Spars now under design.

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