A launchable rigid jacket of an offshore platform has a structure including an exterior framing and a plurality of cross-sectional frame sections. The exterior framing has four outside legs, which are spaced apart to define four corners of a trapezoidal cross section. The jacket also includes two launch runners mounted on adjacent parallel outside legs. The cross-sectional frame sections are horizontally positioned at periodic intervals along the height of the jacket and each has a plurality of members, which interconnect the four outside legs and are part of the exterior framing. The exterior framing in total defines an integral launch box for the jacket. A plurality of perpendicularly oriented conductors pass through each cross-sectional frame from the base to the top of the jacket and conductor guides connected to the respective frame sections slidably engage the conductors to laterally support them.