A cladding section for mounting upon an elongate member and suppressing vortex induced vibration of it, the cladding section being formed of plastics sheet shaped to define two or more parallel, part tubular portions having respective vortex induced vibration suppression features, material joining neighboring part tubular sections being sufficiently pliant to allow the cladding section to be re-configured from a quasi-flat state to a state in which it forms a tube for receiving the elongate member. Also disclosed is a method of manufacturing a cladding section for mounting upon an elongate underwater member and suppressing vortex induced vibration of it, the method including thermoforming the cladding section in one piece.