The need to reduce energy consumption and emissions to bring global warming to a halt is unprecedented. Although there are energy saving strategies, most innovations cannot simply be merged in conventional ship design. As the solution for making ships carbon neutral will likely come from the use of several energy sources, a clever energy management becomes a key element in a unified ship system. Derating of engines combined with sailing at slower speed seems to be a relatively easy way to reduce fuel consumption and GHG emissions and will most likely be used in the industry. However, this does come with reduced transport work per ship and reduced earnings. In our view, most other savings methods can deliver savings up to about 15%, not the substantial savings that are required. OPTIWISE aims at two solutions that when combined go well beyond 30% when the innovations are delivered as proposed in this project: Wind propulsion with a rigorous, holistic optimised ship design, control and operation, including a change in conventional propeller propulsion. Wind propulsion is showing its potential in research and market introductions. The holistic ship design and operation pair well with that. For common ships there is much to be gained, especially with the increased freedom in the aft ship geometry with a shift to electric propulsion. Making best use of wind propulsion also requires a rethink of designs, control and operations. To meet the objectives of this call, generic tool and methodology development are planned for optimization, performance and energy management. New developments will be applied to 3 Demo cases, consisting of a Bulk Carrier, a Tanker and a Passenger Vessel. Verification of the results will be done by testing a rotor sail rig, model tests on two ships and Bridge simulations with crew training. By the end of this project it will be clear how much energy can be save with the latest sail propulsion systems for the three types of vessels investigated