A floating offshore platform is disclosed with one or more extension plates fixedly coupled to one or more pontoons on the offshore platform and extending from the pontoons. As the floating platform moves, the pontoon-coupled extension plates separate the water and cause drag on the platform. The water moving with the extension plates also increases the dynamic mass. The added drag and dynamic mass increases the natural period of the motion away from the wave excitation period to minimize the wave driven motion compared to a platform without the extension plates. The extension plates can be coupled to the pontoons during fabrication at the yard directly or through frame members. The extension plates generally are generally located inclusively between the top and bottom elevations of the pontoons, and therefore do not significantly reduce the clearance between the seabed and the hull at the quayside.