A structural flotation device formed of two elongated shear panels embodied as substantially planar sheets of high-density polyethylene (HDPE) that are spaced apart by two or more substantially parallel and spaced apart heavy-gauge HDPE buoyancy tubes. The buoyancy tubes are transversely oriented relative to the elongated shear panels. All of the buoyancy tubes are of a substantially identical length that is foreshortened relative to the elongated shear panels. The openings in both ends of each buoyancy tube are joined to a substantially planar and unbroken surface of each of the elongated shear panels with substantially water-tight structural seams along its entire circumference.