Stiesdal Offshore Technologies designed the TetraSpar floating wind turbine foundation concept used for the TetraSpar Demonstrator full-scale project. The design was a modular, industrial-fabrication tetrahedral spar configuration assembled from tubular steel components with a suspended keel, intended to enable welding-free, rapid assembly and deployment from an ordinary shallow-water port before tow-out to the METCentre test site offshore Norway.