This project aims at designing mooring system for floating wave energy converters (WECs) using a design approach based on numerical uncertainty quantification to estimate loads to a given tolerance level. This approach is to be compared to traditional deterministic approach with safety factors in terms of cost of the designed system. This is to be achieved by: (i) using an uncertainty quantification (UQ) toolbox based on general polynomial chaos (gPC) into a state-of-the-art mooring dynamics solver; (ii) to perform detailed numerical investigation on the influence on snap-loads on the mooring design. All parts aim at providing a base for lowering the economic cost of the mooring system.