The objective of the ENDOW project was to evaluate, enhance and interface wake and boundary-layer models for utilisation offshore. The project resulted in a significant advance in the state of the art in both wake and marine boundary layer models leadingto improved prediction of wind speed and turbulence profiles within large offshore wind farms. Use of new databases from existing offshore wind farms and detailed wake profiles collected using a sodar provided a unique opportunity to undertake the firstcomprehensive evaluation of offshore wake model performances. The wake models evaluated vary in complexity from empirical solutions to the most advanced models based on solutions of the Navier-Stokes equations using eddy viscosity combined with ak-epsilon turbulence closure. Results of wake model performance in different wind speed, stability and roughness conditions provided criteria for their improvement. Mesoscale model simulations were used to evaluate the impact of thermal flows, roughnessand orography on offshore wind speeds. The model hierarchy developed under ENDOW forms the basis of design tools for use by wind energy developers and turbine manufacturers to optimise power output from offshore wind farms through minimised wake effectsand optimal grid connections. The design tools are being built onto existing regional scale models and wind farm design software which was developed with EU funding and is in use currently by wind energy developers. This maximises the expected impact ofthis project through efficient use of existing resources and ease of upgrade for end-users.