Rapid developments in the field of synthetic fibres have lead to serious alternatives for the traditional catenary mooring systems in several applications. The use of synthetic fibres in mooring systems has received increasing attention, especially for deeper water. However, a design based on these fibres requires modification in the analysis methods.Here the feasibility of mooring systems using a synthetic rope (with Dyneema) compared to a wire rope is analyzed, for a water depth of 800 m. Differences between the systems are elucidated by showing results of a time domain analysis on a turret moored tanker. Different optimization criteria are considered.Generally speaking optimum mooring systems based on synthetic rope are stiffer and impose lower vertical turret loads than a wire rope mooring at increasing water depth. In return for the smaller tanker excursions, the vertical forces at the seabed are considerable for a synthetic mooring.