The maritime shipping sector is responsible for nearly 3% of the global GHG emissions [1] and have set ambitious goals to reduce the emissions to net zero emissions around 2050 [2]. This can only be achieved by a combination of clean fuels and energy reduction. Energy density characteristics of clean fuels cause the need for more energy storage space on board or take up more weight. OPTIWISE set out to accelerate the market implementation of Wind assisted ship propulsion (WASP) to achieve fuel reduction, by: 1. improving ship design methods for ships with WASP; 2. demonstrating three applications of three WASP solutions (rotor sails, Oceanwings, and solid sails); 3. promoting the energy saving potential of WASP. Maritime research institutes MARIN and RISE employ state-of-the-art numerical models to address the complex interactions involved in wind-assisted propulsion systems. Numerical simulations play a pivotal role in optimizing the design and performance of these innovative technologies, offering a detailed understanding of their aerodynamic, hydrodynamic, and structural dynamics. MARIN’s holistic optimization tool CREATOR encompasses global design aspects of WASP vessel, including hull design, cargo carrying capacity, powering in calm water, manoeuvring, seakeeping, and aerodynamic performance. The basis of the global ship design lies in a parametric ship model, supported by surrogate models generated through machine learning. These models leverage high-fidelity tools such as RANS, potential flow, lifting line and model testing. From the performance prediction, the required power profile is derived and used for the engine room optimisation integrated into the overall design process. An optimisation loop is performed around CREATOR to find the optimum in terms of for example transport efficiency, while satisfying various constraints such as limiting ship motions or minimum cargo capacity. RISE employs the in-house developed software SEAMAN Wind investment decision support as base for the design process. The ship performance and the voyage & routing modules of SEAMAN Winds allows predicting in an effective way the KPIs of a WASP vessel. The ship performance uses hydrodynamic manoeuvring derivatives determined using RANS simulations coupled with efficient aerodynamic models. The ‘polars’, output from the ship performance module, are applied in the voyage module to the intended trading route and weather statistics.