The present invention relates to a cable section assembly for marine applications having a core structure, such as a buoyant cable antenna interim manufacturing step subassembly, and a protective casing formed from a heat shrinkable tubing which together with the interim subassembly forms a complete assembly. For buoyant cable assembly applications the interim subassembly is at least partially formed of polyurethane material having glass microballoons distributed therein, with such material in any event occupying an outer layer portion of the subassembly. The cable section assembly of the present invention is formed by providing a length of heat shrinkable flexible tubing, inflating or expanding the heat shrinkable tubing to its approximate full diameter, inserting the core structure into the length of tubing, and shrinking the tubing around the core structure.