Abstract: A tie line in the form of a mooring line comprising a tube of elastomeric material reinforced with coaxial layers of helically wound relatively inelastic filaments. Adjacent pairs of layers are spaced apart by the elastomeric material and their filaments are wound in oppositely handed helices. The tube contains a pressurized fluid which supplements the elastic properties of the tube in resisting an axial load on the tube. The mooring line may be used to moor a buoyant wave energy device, and may be combined with a turbine to form an electric power system.